Skip to content

Archive for October 2012

29
Oct

Update On Sandy

Sandy will come ashore southern NJ as a strong CAT 1 Hybrid Hurricane and the pressure at latest NHC Advisory was an astonishing 940 mb….which is equal to a CAT 3 pressure.
Aside from the historic flooding and overwash and 40 foot waves that is crashing inland, this is going to go down as perhaps the biggest overall storm to attack the East Coast on record. Millions are going to lose power (700,000 currently) and billions will be the damage.

The latest models have it cruising inland and tracking west and looping southwest toward northwest Maryland, possibly even rotating as far south as the northwest part of DC.  The 850 low is amazing from  a Meteorological standpoint, and has isobars so tightly wrapped it’s hardly viewable.  This means that its going to turn cold core rapidly thanks to the northern jet that helped the big phase.

On to exact weather.  Blizzard warnings are expanding in West Virginia and now include western, nw Virginia. And Winter Weather Advisories expanded in eastern TN some.

It now looks like more rain and moisture will spiral south into NC than I thought, with periods of light rain east of the mountains through Tuesday with winds up to 40 mph. The mountains could have 60 mph or more.

The lower elevations in NE TN are vulnerable to switching back and forth from rain to snow, depending on the rates.  Tri Cities is very close to getting a sizeable amount of snow , if the rates could really deliver, but its a close call.  The mountains along NC/TN border show up to 18″ or more (probably 2 feet in the highest slopes) but the biggest snow will still be in central and southern West Virginia closer to the coldest air and most moisture with extreme lifting developing tonight and Tuesday as Sandy’s remains swirl to just the right spot to smack the central Apps.  The RAP model and GFS has -3 or -4 occuring at 850 right over the Southern Apps to central West VA and thats where the bulk of the snow falls. With winds over 50 mph, this will be a blizzard and will result in devastation above 2000 feet.

The NAM looks reasonable (except its snow in central to east VA where its going to be too warm). A foot in the panhandle of VA and increasing rapidly north to 3 to 4 feet in the high mountains of West Va, and between 1500 feet to 3000 feet atleast 1 to 2 feet of snow will fall.  A few inches is very possible in the lower elevations of eastern KY and TN and lower parts of VA southwest areas outside the mountains, depending on rates, but it would like go back to rain at times as well at those lower elevations.  For eastern KY and parts of ne TN and sw VA its touch and go and extremely close to being a major snowfall, but if the rates are too weak, then it will be a mix of rain and snow and go back and forth, unless youre in higher elevations.  Tough call, but GFS gives more snow than NAM.

The High Smokies and Blue Ridge will get atleast 18″ on the top and probably places like Leconte and Roan and Mitchell surpass 2 feet as well.  Most moisture will dry up east of the mountains on Tuesday for most areas east of the mountains, but light rain is possible.
The storm only slowly lifts north through Wednesday, and gradually warms so snow levels will lift, but snow will continue off and on for NC/TN mtns and West VA mtns through Wednesday before tapering.  A truly amazing snowstorm on the backside, with rain even reaching as far west as Chicago.

This is a record breaking storm that will likely stand most of our lifetimes in terms of early season snowfall.  On the East Coast with the CAT 1 Sandy (CAT 3 pressure) slamming due west through the MidAtlantic causing millions in terms of powerful and billions in terms of damage, also historic and we’ll likely not see another setup like this one.

29
Oct

Sandy Turning West/Northwest This Morning

Lots to cover. As expected Sandy began turning northwest and now is turning more and more west and will make landfall in central to southern New Jersey, this is slightly south of NYC where some models and forecasts had it. Here’s a look at her now.

The RAP model which goes only out to 18 hours (and is great for short term trends) has it making landfall in central NJ coast with a pressure of 952 mb.  This landfall will occur around 6 to 8 PM Monday night.

 

The winds on north side will pile up water in Long Island sound and northeast NJ coast, meaning flooding and overwash there to the tune of nearly unheard of storms.  This is why evacuations were needed several days ago when all models agreed on the track close to the NJ coastline, so hopefully folks have prepared as there’s not much time. Winds at landfall will have hurricane gusts and remember the tropical force winds extend out to 400 miles from center or more, so the impact will be felt from NC to New England and as she works west inland, winds will spread west to the Apps and Ohio Valley.  A big, far reaching storm.

By Tuesday the center of the storm will slow down in southern Penn or northern and western Maryland, which will then spin or pinwheel moisture bands all around it. One place that won’t get much moisture from this will be the lee of the Appalachians from northeast Ga, western SC the foothills of NC and southern Va because of how the flow is northwesterly. This is downsloping. However some showers won’t be ruled out if some heavy bands can make it across the mountains, right now that looks unlikely for places like Spartanburg Charlotte and Winston.  However it will be windy with winds actually increasing as the storm moves inland. However today the storm will create showers for most of southern VA and northern NC as it spreads west and theres no downsloping.  The rain goes up quickly in intensity for eastern and central and northern VA and points north.

 

Simulated radar on Tuesday clearly shows this phenomenon.

As I suspected for more counties in Oh, Ky, Tn, Va and WVa, there are now more warnings and advisories. The Blizzard warning in the Spine of the Apps for West VA up to northwest Maryland and now Winter Weather Advisories for more of Eastern Kentucky and Northeast Tennessee, with Winter Storm Warnings in most Mountain Counties of NC.

Lets look at the snow part of the storm.  The RAP shows it beginning tonight for the southern areas of the advisories, and has already begun in West VA mountains.

There is a difference on NAM and GFS snow charts for TN and eastern KY however. I think NAM is not producing quite enough there, but overall both models ar about the same as they’ve been for days, with major snow for the blizzard counties and another maximum area in the TN,NC border counties.

I think NAM maybe overdone on overall totals in West VA and not have enough in southwest Va, southeast Ky, northeast TN, but my snow map forecast still holds.

Heres a look at both GFS and NAM mid runs overnight, showing the varying amounts. Higher up will see the most of course, with some mountains seeing nearly 3 feet of actual snow totals (but remember the melting underneath) so an hour by hour tally will be different than what actually lies on the ground.  The winds will make it hard to measure the snow on Tuesday when the winds really pick up.

GFS Latest Snow totals Through 84 hours

As you can see GFS puts down more snow in places like Tri Cities and maybe even some for Knoxville, but not much there, as well as more in eastern Kentucky. It will depend on the orientation of the flow on Tuesday and how far west Sandy’s center can rotate before stopping and lifting north.  Nothing changes my thinking for central and southern West Virginia or the panhandle of southwest VA where Im’ expecting extreme amounts of snow and wind, and all time October records and top 10 snow amounts from any snowstorm. Ever. In West Virginia especially.

With so much snow and wind coming, I’m certain for those folks power outages and tree damage will be inescapable from this storm.

Here’s a look at GFS temperatures tonight around midnight, a model whose surface temperatures I trust a great deal most of the time.  The upper 30′s line goes from central and western Va down to around Atlanta. Notice the sub 30 temps in the mountains of TN, NC and northward, which is plenty cold enough for snow to stick.

 

28
Oct

Update On The Phasing Of Sandy and Eastern US Trough…”Frankenstorm”

The storm is well underway as you can see on this map. Almost every conceivable type of NWS warning is displayed with red flag warnings in Florida due to subsidence and strong winds, to Frost and Freeze Advisories, High Wind Watches which cover a large chunk of real estate and Coastal Flood Watches, Tropical Storm Watches in the Northeast and Hurricane Watches, as well as Winter Storm Watches in the Appalachians.

The storm is now within the RAP models 18 hour window and it has a 960 mb Sandy (which is soon to become extratropical and more cold core on Monday) heading more and more northwest then most likely due west on Monday, slamming into New Jersey south of New York City.

The rains in eastern and northeast NC will intensify and especially in most of Virginia and very heavy rains will swell westward ahead of the circulation as opposed to the north side of  the circulation.  This is a very interesting aspect of this unique storm.  Imagine wringing out a towel that is drenched.  Sandy will be pushing northwest and then west, and with the convergence so strong on it’s west side and with baroclinic cold energy feeding into from the west, there will be a large area of strong lift between the circulation center and the frontal trough over the Appalachians that has stalled. So in between is where we are going to see the most intense rates of rain and the most duration, meaning the highest storm totals of rain over the next several days.  As the storm moves west through New Jersey, it will pinwheel southwest some toward western Maryland Panhandle and then slowly fill and lift due north.  The process may take longer than models are showing and already they are seeing and forecasting this type of track.  There is an enormous 582 dm block in eastern Canada that is the final piece of this puzzle and assures a west landfall and impact on the Coast of NJ around NYC to Cape May.

GFS totals through Friday:

Already there has been pier damage and high tide flooding in the sounds of NC and southern NJ and this will get worse for the VA coast and points north pretty rapidly as Sandy deepens and heads northwest.  This will place NYC and Long Island on the north side of circulation so northeast winds will flood Long Island Sound. Just south NYC along northeast NJ could also take a direct hit with extreme sound flooding, as the center passes just south with hurricane force winds piling water up quickly. Even though the rain itself won’t be as heavy as it will be further south in southern NJ, DE, Md, VA, the winds will be dangerous and tidal flooding combined with Full Moon and very deep storm and angle of trajectory all conspire to make this a very unique, once in a lifetime attack on the East Coast.

 

As the storm rolls inland it will begin to feel the effects of the strong cutoff low in the Southern Appalachians (another unique piece of a puzzle) and will get fully absorbed.  The cold air west of the mountain chain will get pulled into the south side of the storm and snow will begin to develop early Monday from West Virginia down to the mountains of NC and TN.  The models all show enough moisture wrapping so far south and west this will create the biggest snow storm on record in October for the panhandle of Virginia (southwest Va) and much of central and southern West Virginia. There is a big unknown as to exactly how far south the shield of moisture and uplope will get to, but most models push the storm so far west as to push the precip shield down into the Smokies and Blue Ridge, and right now that looks like a safe bet.  This will be a very heavy , wet type of snow, no powder type snows, since the cold air isn’t terribly cold and certainly not arctic. Unfortunately, those areas would be better off with Arctic Air since the powder snow wouldn’t stick to trees.

This will ultimately prove disastrous in the Southern and especially Central Appalachians from central West Virginia and points southbound toward Pike County KY and northeast TN, northwest NC mountains.  The snow will accrete to all surfaces except maybe the roads at first since it’s only October and grounds are warm. However, trees will be like magnets for the white stuff.  If the models are right on the amount of moisture and lift that will rotate so far south and west, then this could be one of the biggest snowstorms on record in West Virginia, and will certainly be the biggest October snowstorm in all the areas affected.  To top it off, the winds will easily topple trees as winds could gust to 70 mph in some mountain passes Monday and Tuesday, with sustained high winds as well.

If you have loved ones or family in the path of the storm, either the rain or snow side, please tell them to take this one seriously.  I’m certain power outages are coming for hundreds of thousands of people , if not millions, thanks to the size and power of this storm.  The effects could linger for days.

You’ll find My Callmap For Snow below.  About this map, with the variable topography of the Apps, it’s difficult to draw, but this is a general idea.  For lower elevations in northeast TN, and southwest VA outside the mountains and in eastern Kentucky possibly, this event looks remarkable and very unusual. The models have surface temps cold enough thanks to so much lift and the snow falling so rapidly it will be hard for surface temps to climb much past the mid 30′s on Tuesday for places like Tri Cities and Johnson City and Bristol, Va.  Even colder in the mountains with elevation.  So this could be a case where the snow rates trump temperatures somewhat, but snow will first stick to trees and grass, not roads. But eventually overnight, it appears it will. And further east in northern NC and central Va its possible once the storm stalls to the north that enough moisture and cold wraps around it to create cold rain or possibly snow or mix in those areas, but it shouldn’t accumulate.  Strong west winds at the surface usually equal downsloping east of the Appalachians. But it’s not out of the question since this is a strange setup.

 

 

 

 

28
Oct

About The Big Snow Potential…

The GFS might not be strong enough as the storm is dropping pressures rapidly and already is about as strong as the 6z run had it for later today and at landfall.

Here’s a loop of the GFS. As Sandy turns extratropical, it will feed on baroclinic energy and go cold core, wrapping cold air into it. Again, the southern and southwest sides of the storm is where the cold enough air will be , so snow should start to fly pretty quickly on Monday morning for the high mountains of Va, West Va and extreme ne TN and nw NC before growing in coverage and intensity by Monday night.

(trouble adding animated loops– I’ll fix it soon)

Here is a still at 48 hours (Monday night Midnight)

One thing that will make this a special unique setup is how the storm is pushing west across southern Pennsylvania and arriving in northwest Maryland, it lands exactly in the right spot to really drill the Apps of West VA and points south with sustained heavy wet snow.  This is barely cold enough to snow, as temperatures aloft are not that cold, but cold enough to do the job of snow production.  As the circulation (and this is a monster ) moves west, it will squeeze the atmosphere and really cause a lot of upward motion, so the snow should fall at the hardest rates you’ll ever see in the mountains of West Virginia especially. I’m not that certain how far south the moisture gets yet, so the northern Mountains of NC are still somewhat a question mark, but it will most certainly snow a good bit, and it could snow well over a foot. Same for Northeast TN.  But just immediately north of that area, the panhandle of Virginia stands to have a tremendous snowstorm by any month of the year much less October.  Many types of records will fall with this setup.

Here’s a county by county breakdown.

For the biggest snow worries in northeast Tennessee, the higher

elevations of Johnson, Sullivan, Hawkin, and especially most of

Johnson.  Then Carter and Unicoi and down to the Smokies of Cocke

and Sevier on the northwest slopes.

For Virginia, Grayson, Carroll, and Floyd are the eastern extent,

then increasing rapidly west into the Panhandle of Wythe, Tazwell,

Smyth, especially the higher spots of Russell Tazwell and Buchanan.

All of the Panhandle should see accumulating snow even far

southwest Lee County since models show surface temps near freezing

for many hours during the heavy snow Monday night and Tuesday

morning, then gradually lifting in elevation during the day Tuesday

and possibly snow returning Tuesday night and Wednesday, depending

on how far southwest the circulation gets too.
All of the Alleghany Mountain Counties near the West Virginia

border should see snow especially the higher elevations of Bath and

Highland where over a foot could fall, but actually the colder air

resides more south and west in the panhandle.
In West Virginia the highest elevations in the central and southern

part of the state will score the coupe.  This could be one of the

biggest, if not THE biggest snow on record to ever fall there. In a

few mountain counties I think it will be.
Randolph, Webster, Tucker, Pocahontas and Greenbrier should be hit

hard especially above 1500 feet, and the higher up and the further

south is where it will be maximized. Again the coldest air is

actually in the southern half of the state with this unique setup.

So I think Greenbrier, eastern Fayette and most of Raleigh County

to Mercer county will end up with feet of snow.

Even in the not so high elevations just west of where the mountains

really grow from Charleston West Va down to Pikeville Kentucky and

most of extreme eastern Kentucky could do surprisingly well on snow

totals because this will turn into an upslope nature snowfall, and

extra orographic lift on the west sides of mountain chains usually

enhance lift and produce its own dynamic cooling effects. So if

surface temperatures will get low enough, the snow will accumulate.

I think in extreme eastern Kentucky Pike, Letcher, Harlan and Bell

but the most in Pike County where higher elevations and the coldest

air at surface and aloft, combined with the most wrap around

moisture could give over a foot of wet snow.

 

27
Oct

Been Thinking About…The Great Appalachian Snowstorm of October 2012

Been Thinking about…

It’s hard to envision before Halloween, all the tricks and treats of Winter. Who would have ever thought, that the perfect storm scenario such that is before us on the East Coast, could ever really come into being? There could be so much to this storm that meteorology students will study one day and say “Wow, I wish we could see that again”.  I’ve often done the same thing when thinking about big weather events, like March 1993, or January 1987,or 1988. Or the cold wave of December 1989.

While it’s true that big weather monsters like this create way too much heartache and misery and even loss of life, there is enough intensity and curiosity for at seeing the most that mother nature can throw out at us. Hard core weather weenies salivate at the notion of such a storm. But nobody wants to really and truly see the painful side of her though, the part where trees come down and land on a house.  The part where power goes out and stays out for days, making the simplest tasks impossible in modern life. Or to see all you’ve worked for your whole life get swept out into the ocean, or into a raging river. Or to go outside after the storm and discover your beloved pet and companion is gone and never will return.  All those and more, will accompany this storm.

Yet the hard core weather lover longs to see the good and fascinating side of storms like this, while trying just not to think of all the bad things.

About two weeks ago WxSouth noted a few times on Facebook and on the website that signs were being manifest in global models that a major blocking episode was possible. As time went on, I got more and more interested and sent out a few hints and tidbits to my followers and subscribers about how I feel on blocking, especially double blocking. I’ve studied 500mb maps long enough to know what they are capable of and I mentioned that big blocks in certain spots often lead to big events.  It turns out, we’re knocking at that door now.  This very second, a 576 dm block is building in eastern Canada and southern Greenland. I have to admit though, even though I also mentioned two weeks ago to watch the Caribbean on tropical development, I’d never thought a hurricane would phase with a deep eastern trough to combine into the Perfect Storm. And that’s exactly what’s about to happen.

I’ll leave all the details of meteorology and technical jargon out of this, but in essence, it all boils down to a few simple facts.  We have perfect timing and perfect placement of the perfect features needed to create the perfect storm.  A simple, but energetic upper impulse is diving into the Tennessee Valley and upper South on Sunday.  Hurricane Sandy is churning due north or slightly northeast off the Georgia coastline, and a powerful block is developing in the southern part of Greenland and far eastern Canada.  All these, each of which would be pretty unique in it’s own right, have landed on the weathermap at precisely the right time and precisely the right place.  A catastrophic storm will be the result.  It could be New Jersey’s Katrina. Or New York City’s Katrina.  There’s a narrow zone from Washington DC to Long Island that lies in the crosshairs, and it will be impossible to pin down from this distance exactly which region gets it the most.

But in the end, this storm is coming inland and will rotate around southwest to affect a huge population with a variety of very wild weather.

I’ve been thinking of how heavy snow is so beautiful and why so many people in the South (really nationwide?) love it so much. But this could be too much of a good thing. The leaves are still on a few trees in Wild, Wonderful West Virginia and especially on the trees in northeast Tennessee, eastern Kentucky and the panhandle of Virginia.  This will spell disaster in the end.  So much heavy snow will begin to materialize on Monday in the higher elevations first, then the lower elevations down to 2000 feet, perhaps 1500 feet in the foothills, that snow will begin to bring down trees. The weight of heavy, wet snows on top of trees and powerlines and manmade structures could be enough to create a spellbinding nightmare, the effects could last for many days.  The last time an early snowstorm of this magnitude occurred was the Great Appalachian 1950 snowstorm, but that was accompanied by Arctic Air. We’re lucky on this one. Just barely cold enough aloft to snow.

But the models insist on the circulation center drifting southwest into Maryland, so that will assure that West Virginia, especially the central and southern mountains of the state are hard hit, with possibly one of the biggest snowstorms of all time, much less Winter.  I think it’s possible we’ll be including the panhandle in southwest Virginia on this, and the same for extreme northeast Tennessee and the northern mountains of North Carolina (by October standards…not January)  , and if it rotates far enough west, then eastern Kentucky too.

It’s a fascinating system to watch unfold from a meteorological standpoint.  But from a human being and concerned brother, it’s also worrisome. I know folks are going to go through a period of suffering. And all I can do is warn them with the best of my knowledge of how weather works and why I think this is going to be an historic, once in a lifetime  type of storm that folks will tell their children about.

So be prepared and take this one seriously. No one wants to think that snow can kill. But 170 people died in West Virginia during the big 1950 storm. And his one could rival it in terms of snow production and winds. Trees will come down by the grovestands . Roofs will collapse in some mountain communities. And thousands could go without power for a long time. The rate of snowfall at times will like a driving blizzard, with nothing to see but a wall of white sheets as far as you can see across the fields and mountains.  I’ve lived through such a scenario. It’s beautiful and mesmerizing ….at first.

But later on as the hours pass and flashes of blue transformer lights flash in the distance, and as the crackle of trees snapping in the nearby woods keep you awake at night, maybe you’ll think it’s not the perfect storm after all.

27
Oct

East Coast Storm…A Record Breaker On Many Levels

Not much has changed with all the new model runs except that NAM and GFS both are in very good agreement and closely match old ECMWF runs which have been steadfast.  This storm will produce an array of extreme weather records. Let’s take a look.

By early Monday morning all models show Sandy beginning to feel the effects of the incoming trough that is starting to cut off in the Southern Apps region.  At this point, rain will be falling in the Apps and parts of KY, TN, VA, NC and up into Pennsylvania thanks to a lee trough and frontal zone that will attempt to merge with Sandy well offshore NC coast.  That line of rainfall will slowly begin to switch to snow from just north of Asheville to just south of Pittsburg, more on that in a minute. At this point the heavy rains and lashing winds will be on the northeast NC coast and stretching into Virginia, arcing northwest faster and faster as the day goes on and the storm begins to deepen. One very curious note on this hybrid Nor’easter/Hurricane storm..the models all show this as a “west flank” loaded rain maker, instead of the usual north and east sides.  This will place areas west and southwest of the center of circulation under the heaviest most intense rain bands. However the winds will be widespread and affect the northeast side of the circulation. By later Monday night the storm will be coming ashore central New Jersey, just south of New York City and begin to wobble west and southwest as it feels a Fuji-wara or Loop-de-Loop effect from the trough cutting off and it turns into a hybrid Nor’easter rather than pure Hurricane.  Here’s alook at NAM showing the overall trough capturing and then phasing with Sandy:

One key aspect that is rare on this 5H setup is just how large and strong the block is in Canada, growing to 576 dm, which is about as strong as they ever get in Winter.  All models force Sandy to cut northwest and then west thanks to the block, then all models rotate this combined storm through central NJ and into central and southern PA, and possibly into northern or western panhandle of Maryland, where the transformation is complete.  By Monday Night, the snow begins to fly in the Appalachians especially where the coldest air aloft and surface has sucked into the circulation in eastern Kentucky, central and southern West Virginia and the northern Mountains of TN and NC.  Further north, the deep low pressure will slowly fill through the week, but overall the storm will be slow to move and vorts will round the circulation, becoming a huge swirling vortex of cold and snow to the south and west sides, with showers gradually weakening overall on the east and north sides. But the rain totals look very high, up to 7″ of rain in eastern Virginia and Flooding 10″ or more in all of Delaware most of Maryland and New Jersey, especially Southern NJ.  The Winds will gradually die down around the vortex but as it comes ashore Monday night in coastal NJ and around Long Island there will be strong coastal and sound Flooding as northeast winds spiral in the western sides of Long Island and northeast NJ.  High winds are also shown in the Appalachians from eastern Ohio through West Virginia and into NC mountains, where record breaking snows look likely.  Not only October snow records will fall, but perhaps some all time snow records could fall in some parts of West Virginia, where up to 4 feet of total snow could fall. The snow and wind will cause massive power outages in parts of the Appalachians and even though surface temperatures aren’t terribly cold, this may fall into a practial Blizzard of nearly unprecendented proportions, rivalling the Great Appalachian November 1950 storm.

Certainly this is one of the most intense and varied East Coast Monsters in a very long time, and could end up being a costly storm in terms of devastation, property and unfortunately , lives lost.  Please take this storm seriously and prepare now.

The NAM and GFS snow maps are astonishing. Even though snow will continuously melt from underneath, the hour by hour per inch snow tallies could be over 3 feet in some parts of West Virginia with perhaps some spots of the high elevations of TN and NC getting over a foot or more from this storm.  Generally above 2000 feet will be the best snow totals will be found be even on the foothills sides on both sides of the Apps could see significant snow at times especially at night or when heavy bands rotate through.

 

 

26
Oct

Possible Historic October Snowstorm In Appalachians

The ECMWF model total QPF through 168 hours is about unchanged from previous runs. On the eastern side of the circulation from eastern NC and jutting north, northwest through Virginia and up much of the East Coast shows Sandy’s onlslaught of heavy rains, with 9 to 12″ of total rains in northeast NC, se VA with 12″ + around Elizabeth City, Ne OBX islands. Eastern 2/3 of Virginia is atleast 5″ of rain and includes DC, Balt and southern Delaware.

Central and western PA, most of the eastern 3/4 of Ohio, and northern half of West Virginia has 4″ shown, and much of that would be snow in central West Va and probably half of that snow in eastern Ohio.  The southern portion of West Virginia and western VA and eastern KY has 3.5 ” to 4″ and the 1.75 to 2″ drops down to eastern TN and northwest NC, with Bristol TN and Boone NC at around 1.75″ mostly snow in Boone and much of it it snow in northeast TN.  In eastern Ky and southwest VA the amounts tick upward rapidly to around 2.5″ to 3″ , again mostly snow.

The liquid equivalent to snow ratios would be low since this is a hybrid storm, quickly turning cold core, but it would be plenty cold enough aloft for snow in central West VA and eastern Ohio and points south to eastern Kentucky, northeast TN and western NC, the only question during the week will be surface temperatures.

If the ECMWF model is right on timing and all the other important factors, like track, intensity, temperatures,  lobes or bands of precip rotating around the phased system, then snow would quickly begin Monday morning for the High Country in the Southern Apps and by afternoon in the West Virginia mountains, esp. southern and central West Virginia. As the day wears on, the colder air wraps in under the system, so it’s colder to the south and southwest than it will be north and northeast, so heavy snow would fall (probably extreme snowfall rates) in the Southern Appalachians by Monday Night, with periods of off and on snow through the week until Thursday. Occasionally the snow in central and northern West Virginia and western Maryland will switch back to rain, thanks to how the warm air occludes in this swirling vortex, and cold air wraps completely to it’s south and east toward eastern Virginia and NC coasts.  For a time snow could get down to Asheville, which is usually shadowed on northwest snowfall systems as well as a few flakes in northern Georgia.

This is a very unusual setup and since we’re literally in unchartered waters with this unique event, I would take any forecast with a grain of salt now.  A lot of factors have to come together perfectly and the models are only predicting what they can, with no regard for precedent.   Even though the ground will be warm and the snow will melt nearly as quickly as it falls, eventually it will accumulate. Several feet of snow is possible in some mountain locations, atleast in theory.  Usually Spring and Fall snowfalls have big totals with cutoff systems in the Apps…and the hour by hour snow tallies could be very high, even though actual snow on the ground won’t match those hourly tallies. If the model holds, it ups the chances of a very unusual, blockbuster early Season Snowstorm that could stand the test of time. We will see.

 

Snowfall Animation ECMWF in 6 Hour Increments Monday Through Thursday

25
Oct

Possible “SuperBomb” For East Coast

In the world of meteorology, this is like winning the PowerBall Lottery.  The weather models have pulled all 5 winning numbers now, and the powerball is bouncing down the tube.  They forecast every day of the year and we get our regular day to day weather, some good, some bad and some ho-hum average weather.

But this, this is a special once in-a-lifetime-event. That is, it could be a once-in-a-lifetime event. But we’ve heard that before regarding the “Superstorm of 93″ and the Blizzard of ’96, and again several more times in different parts of the country. Each storm has it’s own unique circumstances and may affect different geographic regions, but not many storms can drop pressure to 945 to 955 mb range and suddenly plow due west into the East Coast like this is could do.  And not many hurricanes have produced snow, and especially as much snow as this one could do.

Right now all the pieces of this complex puzzle are on the table and have been for days. Usually by now, some pieces would have been removed.  There is an enormous block developing as I write over southern Greenland to eastern Canada, which the models showed nicely for about 1 to 2 weeks now. So it’s very likely to verify, and what a healthy block it is, no matter the season.  Then there is “Sandy” a strong hurricane that all models show deepening again just north of the Bahamas. It will start to lash the Carolinas’ coast on Saturday and focus on the NC coast spreading into eastern Virginia by Sunday and early Monday.

Meanwhile, early Monday the final piece of the puzzle could come into play. An upper disturbance, pretty strong for October, and certainly very cold air for October, will come barrelling from the Plains states across the Tennessee Valley and collide with Sandy, who has nowhere to go.  Here is where it gets very iffy and uncertain.

The GFS has been saying for days this disturbance would push Sandy out to sea, and possibly recurve back inland around New England, it especially liked the idea of a Maine landfall. Now it’s slowly coming more west and more quickly and much further South.

The ECMWF model (Euro) has been staying with the idea that Sandy will actually get absorbed by this Tennessee Shortwave and thanks to our healthy Block to the north, be forced back inland, very rapidly.  This is extremely unusual, but it does fit the synoptic meteorology playbook…and as a synoptician, I love this idea and it looks legitimate.  The only real question is exactly when it cuts northwest and then due west (possibly even turning southwest?)  A system as large and as powerful as Sandy will be on Sunday and Monday will find a hard time turning on a dime. However , if it is only crawling north, then surely enough, it would feel the effects of the block and disturbance and have no other path to take other than to accelerate inland.  In fact, it could really be pulled like a gyro spinning, as some models hint at the fact the disturbance to it’s west gets so powerful that it cuts off aloft and usually with blocks in East Canada/Greenland, this is in fact what happens. So imagine Sandy, beginning to press on the gas pedal and slam right into the East Coast.

Still, where it happens exactly is yet to be determined.  It’s an extremely complex scenario, but it boils down to basic and simple pieces of a puzzle, literally. So we have to rely on the models to decide for now (which I never like relying on models)…yet hurricane track forecasting can be extremely “off” and usually is. This one though has excellent model agreement on a general north, then northeast, then northwest track. Hard to argue with that.

Once it’s inland, if this scenario plays out, after the big lashing on Carolinas Coastal plains and beaches, the Virginia coast will become directly on the western flank and with a west bound Sandy aiming right for eastern Virginia and eastern Maryland/DE, then the rains will pick up quickly. So will hurricane force winds. The pressure could be well down there thanks to all the perfect ingredients for strengthening, straight into the coastline.  Some models go down to the 940′s, but the likely number would be 950′s to 960s….still an extremely powerful Hurricane, living off the rich fuel of the Gulf Stream it has just crossed. By Monday night, snows would be flying fast and furiously as the western bands interact with unusually cold air in West Virginia, western Virginia, eastern Kentucky, northeast Tennessee and the northern mountains of NC.  The system will rapidly lose it’s tropical characteristics and morph into hybrid cold season vortex. To the north of the circulation, warm air promises rain in much of central and eastern PA, New Jersey and eastern Maryland.  Western Maryland and western foothills of VA will be a battle ground between low thicknesses, but maybe not low enough for snow, just depending on the cold air thickness and track of the center of circulation.   A Sandy that comes inland near southern NJ would place western MD and central and western VA in a much better spot for the snow. Regardless, we can fine tune the track later.  Wxsouth is just laying out possibilities.

Here’s a look at the GFS which is a little more north than ECMWF, with an 850 megalow pressure. The cold on the southwest side of the storm is impressive with -6 at 850…plenty cold enough for mountain snows.

Other possibilities are mass evacuations in the storms path of the East Coast where this system aims. Right now that could be anywhere from Long Island to New Jersey to the Chesapeake to eastern NC, but that’s still a couple days away and dependent on models holding on to this perfect phase idea. Winds, cold air and snow, hurricane force winds, floods, tidal flooding, record low pressures, record snow fall, record rainfall, lots of records could fall with this one.   But in weather there’s never any guarantees…all this could not happen, or happen in a very different location if that final powerball number misses by one digit.  It’s a waiting game and we’ll have to see how the odds shake out.

25
Oct

Sandy Near CAT 3…Will brush East Florida and Carolinas this Weekend

Sandy will cross Cuba today and by tomorrow be in the Bahamas. Most models have a turn to northwest or wobble, then it turns north and maybe northeast to just offshore the Outer Banks. GFS is the most offshore but the latest runs are closer to the coast and the 6z run allows it to curve northwest into Maine earlier than it had been showing. ECMWF model is very consistent with a 955 hurricane hitting eastern DE/Maryland/NJ coast Monday night then travelling west and quickly becoming a hybrid storm.

The ECMWF is one for the record books and maintains good consistency, but that is still no guarantee it will make landfall exactly where the runs have been showing…it could be a blend of it and GFS  , meaning further up the East Coast. It depends on a lot of complicated factors at play like the 576 dm ridge to its north stalling its northward motion and when the Eastern Trough captures the giant storm.  This storm is so large and will be so powerful that a regular eastern trough will have a tough time influencing it but in the end, it should.  Since the circulation of Sandy is so enormous, it could be sluggish to move in any direction, but once it begins to jog northwest later Sunday afternoon, it should be a monster with high winds, and very deep pressure, and on the west side, heavy snow develops in the mountains.

First the flooding would be a concern for eastern NC and eastern and northern Virginia, possibly stretching well inland through Virginia and all points north through Md, De, Pa and NJ, NYC.  The GFS shows a well developed inverted trough stretching completely from Sandy all the way over a thousand miles west through the Lakes….Thats a trough I’ve never seen..but it’s most likely a sign of strong mid level shear, so any coastal storm would likely retrograde. Future runs of GFS will probably come more west, but we’ll see.

Aside from East Coast heavy rains and hurricane force winds that will probably require evacuations in NJ, De, VA, MD, the western side of the storm will begin to pull in cold air on Monday. Shear axis will develop in the mountains of western Md and West VA and snow levels will drop rapidly to near 2000 feet Monday night, if the ECMWF is right with precip shield.

ECMWF has 1.75″ to 3″ liquid equivalent in the southern and Central Apps of West VA being the center. So up to 2 feet of snow would be possible in the higher mountains, esp. central and southern West Virginia, with snow in parts of eastern Ohio, eastern KY , northwest NC, ne TN, sw  and central to western Virginia where the cold has wrapped in, while its actually hard rain in central Penn and NY state, north where the warm air has circulated in from the Coast.  It’s still far enough out in time that the track could change and that would change the entire forecast, but ECMWF is being very consistent, so all folks along the eastern Seaboard have to keep very close watch on Sandy’s track and motion this weekend and be ready in case the worse case scenario some models are showing actually verify.

Beyond this, and this is low confidence, GFS and CMC have some energy rotating through the Tenn. Valley middle of next week, with still pretty cold 850 temps around, so snow showers would be possible and light rain showers, depending on time of day and elevation, but it looks weak.

I’ll have a full update with extensive graphics and discussion after the 12z models are out, with my own precip and forecast charts along with numerical models guidance.

 

24
Oct

Sandy Likely (But not yet Certain) To Curve Northwest near Outer Banks

All models are now pushing Sandy northwest after a brush with Outer Banks, and with Eastern Florida, possibly grazing Ga and SC coasts as well.  The ECMWF shows an historic storm down to 936 mb just offshore Norfolk on Monday morning, then takes the storm ashore in eastern Maryland or southern New Jersey, with heavy winds and strong sustained winds of hurricane force from eastern NC up the east coast to Near New York City.  On the west side, it drops snow as cold air wraps around the closing off/phasing storm.

This is still too early to bank on , but with each passing hour and run of the models, most are in very good agreement on the synoptic setup:

The drivers for this type of rare Hurricane motion will be the sudden building strong 570+ DM ridge in southern Greenland to Eastern Canada, and (if it were to go out to sea, the Ocean Low)..but right now that looks less likely, although GFS still goes with that somewhat, before bringing it back into Maine.  A critical shortwave will be diving into the eastern Trough about Sunday and Monday, and this could be stout enough to pull Sandy back to the coast, when combined with the big ridge lying to its north, so it makes sense that a recurve to the northwest will take place.

However, Where that takes place is a LOT of ground. It could occur as early as the NC coast, but more likely it will occur somewhere between northern VA coast/MD to around Long Island, however each run of the models could shift some and it could really be anywhere from NC northward to Maine…it depends on many factors.  If it turns out that GFS was more correct a couple days ago on the more eastern track of Sandy then it would be very hard for the storm to cut back northwest and phase, instead it would go extratropical and stall a few days, possibly getting absorbed much later around Eastern Maine or even eastern Canada, but the GFS is strongly trending toward a phase further south, even if not explicitly.

This could be a once in a lifetime type of event for part of the East Coast and Appalachians if the ECMWF model is right. There’s still time for adjustments and path, but for now if you have interests along that area, pay close attention to official forecasts and monitor this closely and begin to prepare and protect your property as quickly as possible.

It’s rare that a Hurricane merges with enough cold air to produce snow, especially as far south as West Virginia, Virginia and NC mountains and this is possible. The more complete the phase, the colder the air will be that gets absorbed and a lot of snow could fall in the mountains on it’s southwest side of circulation.  Also, there would be more cold advection following the storm.  All this though is based on a perfect storm scenario, which is roughly the most extreme case possible, which is what ECMWF is going with so far.

One other option, is with a Sandy going out to sea, there could still be enough of a cutoff trough to develop (thanks to large ridge) that could ignite a strong  coastal storm or possibly inland cutoff, that still packs a substantial weather wallop in the eastern Ohio Valley to Midatlantic or Northeast region.

In a nutshell, the effects could cover a lot of geographical zones with multiple types of weather:

*Sustained hurricane winds (CAT 1)

*Gusts to CAT 3

*Flooding rains along east Coast and possibly well inland to the Apps

*Tidal Flooding (Full moon)

*Blizzard Conditions Mountains

*Hard Advective Freeze through MidSouth and Southeast Region

s2Member®