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Archive for November 2012

29
Nov

Drought Update..And What Could December Hold?

Overall, for most of the Southeast it has been a cool Fall, following a HOT year overall, so nothing will change the fact this will probably be one of the warmest years on record nationwide (although Southeast has seemed to mostly lean toward “less warm” relative to the rest of the country, especially Summer and Fall when you average out the numbers.  Here’s a look at October rankings, and I think November will come in either at or slightly below normal for many in the Southeast as well. There have been quite a few cold fronts as the trough has been in the East a while now, especially following Sandy.

Next up, the precip.   All the northwest flow and lack of Gulf taps has made for a dry Georgia and Carolinas especially, but Sandy brought substantial to heavy rains to eastern NC and much of VA.  But mostly, what’s been going on , has been going on all year long, that is wetter on the West side of the Apps than east. This last front was just another example of the moisture completely drying up in eastern GA to most of the Carolinas, but did have enough lift and dynamics west of the Apps in Tennessee Valley.  Less than 8″ fell in most of Carolinas, southern VA, Georgia for the 3 month period.

(insert 1)

Here’s a look at 90 day departures. As you can see, most have been below normal, except parts of TN Valley (Ky, Tn, Al)

The yearly departures all paint a dry picture for most of the South and East.   Here’s a breakdown of various cities: (strong departures in BOLD. Notice Tropical systems helped some areas)

Georgia

Atlanta       -14.41″
Athens        -10.83″
Columbus    -12.17″
Macon       -13.82″
Savannah    -6.54″
Augusta        -2.43″
Valdosta    -7.20″

South Carolina

Columbia    -1.93″
Florence    -2.20″
Charleston    -7.34″
Greeville-Spa   -9.74″

North Carolina

Fayettevile    -4.95″
Greensboro    -4.95″
Raleigh        -2.21″
Elizabeth City      .08″
New Bern    -1.44″
Wilmington    -7.89″
Asheville    -1.42″
Charlotte    -8.30″

Virginia

Norfolk          .82″
Richmond    -6.42″
Wallops Isl.     7.97″
Blacksburg    -3.62″
Roanoke        -7.75″
Charlottesville -5.56″

West Virginia

Bluefield     3.85″
Elkins        -0.29″
Charleston    -3.89″
Parkersburg    -1.31″

Tennessee

Memphis        -5.31″
Jackson       -9.91″
Nashville    -1.56″
Chattanooga    -1.98″
Knoxville     4.42″
Tri-Cities     4.75″

Mississippi

Tupelo        -5.65″
Greenwood    -8.85″
Jackson         12.20″
Meridian     2.96″

Alabama

Mobile         4.15″
Huntsville    -2.72″
Birmingham    -6.03″
Montgomery    -11.43″

Kentucky

Lexington    -4.91″
Frankfort    -6.75″
Louisville    -2.74″
Jackson         1.59″
Paducah       -18.02″

Louisiana

New Orleans     6.25″
Baton Rouge     0.96″
Lake Charles   14.67″
Alexandria    -1.29″
Shreveport    -0.30″
Monroe         3.49″

Arkansas

Little Rock    -7.74″
Pine Bluff    -4.85″

Texas

Dallas-Ft Worth    -4.13″
Waco        -0.23″
Victoria   -12.05″
Laredo        -9.92″
Corpus Christi    -11.05″
Houston        -6.26″

Florida

Miami         26.49″
Naples        -14.16″
Melbourne    -11.69″
Orlando        -8.17″
Jacksonville     1.67″
Tallahassee     0.98″
Key West     8.88″

What’s up next, with Winter Approaching?

A warm start will begin Meteorological Winter, with a western trough and ridging beginning in the East. Temps could reach 70s in Texas to central Ga to eastern NC by Sunday and Monday, and maybe Tuesday if high clouds aren’t too thick.  So some 10 to 15 degree above average air is coming, but no rain. Already the next front looks to do exactly like the last few, which is drop some rain in the Tenn. Valley but probably not much east of the Apps, atleast for NC, SC, GA and FL regions…dynamics peter out.  Meanwhile out west, they will be slammed on the northern and central coast of California and points north, with high mountain snow of FEET, with flooding at the PAC NW coast.

I noted that the models were probably too fast in cooling the East with severe cold, and as you know they’ve all backed down from the super strong NAO pattern. This is a result of a warring regime of -PDO and -NAO fighting each other. This also helps keep the Southeast from being “too warm” for too long. Those indices produce enough troughing out west, yet also allow no ridging in the Southeast, so this isn’t a case of what happened last year. Have you noticed so far the warm ups in November never really amounted to much in the Southeast?  Thats because troughs had a tendency to dig more along the Northeast coast, which brought northwest flow, so that helped squelch any warm ups.
Now we are truly about to get into a hard core western trough, so that will allow the next mid week front to bring up warmer air, much more than seen recently, hence the warmup the next few days.
But I also noted on my website that we are approaching a stepping down or retrograding pattern, and I still see that.  The GFS has over the last week been showing this in general, with this next front, then another, then another front. Each one dropping a little more south than the preceeding one.  And at this point, the cold air will be tremendous in Canada and Alaska, so as the main trough (Gulf of Alaska low) retrogrades over the next   7 to 10 days, this will bring shortwaves into the Rockies, then the Plains.  And within 7 to 10 days now, there will be some serious Arctic Air coming into the northern Rockies and northern Plains and all over western and central Canada.
Look how snowpacked Canada is to become (GFS) as there will be system after system laying down snowpack.  With the shortening days, cold air is going to lock in, and there’s not exactly zonal flow in Canada, thanks to some weak -NAO, so the cold is going to build. (snow cover day 1, day 10, day 15)





The CPC has recently released a Winter Outlook that highlights Tenn. Valley with above normal precip, and I’m not surprised. That area has been a max zone (until recently) and I think it returns this Winter.  This also lines up with what I have been thinking for most of last Summer and this Fall for an area for above normal snowfall and probably below normal temps…roughly the Tenn. Valley to Apps to MidAtlantic region.

The first real round of True Arctic air is probably less than 10 days away for the northern tier of states, with both the ECMWF ensembles and operational showing a weak PNA+ pattern and downstream trough digging into the Rockies.  Slight neg NAO as well, so this will combat Southeast ridging (unlike what we saw last year–when there was no -NAO)

The next question is “how do you know the trough doesn’t unload totally out West”?  Already GFS and ECMWF tried to do just that 2 weeks ago, and it never happened. But it is about to happen, esp. Northwest.   This goes back to the warring factions of -NAO and -PDO, but now we’re seeing the westerlies drop more southward, as they should since we’re entering that time frame. It could  mostly out west and some runs have done just that, but they seem to always correct themselves the next run.  Same thing for the runs that show extreme Eastern Trough and western Ridge….they correct themselves soon.

This probably argues for generally speaking, a supressed flow, instead of one regime dominating the other.  Very cold Canada, stepping down to moderately cold northern tier and bouts of below and above normal in the Southeast next 2 weeks.  But there is one strong possibility that could occur, that I’m a little nervous of, and that’s a strong Arctic Outbreak in the Plains.

Tropical Storm/Typhoon Bopha in the Pacific may add energy to the retrograding Gulf of Alaska low, which ***could** help pump up more ridging than shown by models around day 10 out west. If that happens, which is a totally risky *IF*, that would dislodge a giant chunk of Arctic air (abetted by 1050mb HIGH) and bring it down into the US.  I don’t know if that will happen around day 10 or beyond but it’s a possibility.

Regardless, I do see a general pick up in storminess (which is normal for December) across the nation and colder and colder for the northern half, and there’s the chance that with these dueling indices, the Arctic Front lays down in the South somewhere by mid month of so. And if that happens, we’ll atleast get rains. North of the front will deal with Wintry precip patterns.  I also think the NAO and AO goes toward more negative as time goes along in December, so with some lag time effects, those effects will be felt in the TN Valley (and Southeast) with cold air and increasing moisture.  Some of the models like CFSv2 and Beijing Model like the idea of high latitude blocking ruling this Winter (CFS is back and forth)…so this could just be a volatile Winter with no ruling pattern.  I’ve noticed 9 or so major blocking regimes in Canada and Greenland since late last Spring and into the current timeframe, whereas NONE or nearly none last Winter.  So obviously if that continues to repeat, I’m absolutely positive Wintry Precip is coming to parts of the Southeast, but just because some Decembers were good in the past doesn’t mean bank on this one. Overall, with neutral conditions most likely, and a tendency for Greenland blocking to repeat, I think odds are good that a Winter storm or 3 is likely this Winter, unlike last Winter where there was practically no blocking.



 

 

29
Nov

Stormy West….Warmup Sunday Through Wednesday…Then Colder

The big news coming up will be the warmer air for the entire Southeast and most of the Eastern Seaboard, starting Sunday.  Southwest flow on the backside of the current high will bring in warmer air and atleast partly sunny skies for a few days, which will warm most of  the Southeast into the 60′s.  The 70 degree line on Monday will stretch from coastal NC southwest through central and southern SC through southern half of Georgia to eastern Texas, so it will be a mild start to December.  The next front, which had offered a good chance of rain next week looks like it will instead be more like the fronts this Fall, with most of the rain on the western sides of the Apps and not much for Georgia or Carolinas east of the mountains.  We’ll continue to watch this and see if more moisture can organize than shown, but already all models agree on the lift and moisture mostly begin west of the Apps, which fits the pattern nearly all year long.

Right after this front, another bout of cold (near or slightly below normal) will drop into the East, but that high slides out after a couple of days.

By this point, all models have some typhoon energy in the Pacific helping to dislodge the Gulf of Alaska trough and pump up a little bit of ridging.  This will help to shove some very cold Arctic air southward through the Rockies and begin to really invade the northern and northwest half of the country, and it appears ridging is going to develop in eastern Canada and southern Greenland by about days 9 and 10.  If the models are right, and so far they have been basically sticking to this series of events and timeline, then the coldest air of the Winter will drop down into this Rockies trough.  It looks like this front could be a potential “Blue Norther” type, but it’s a little too far out to say if it’s that severe, since it’s beyond 10 days.   But as you can see on the day 10 images below, we haven’t seen a deep trough like this in a very long time in the Rockies or Plains (usually they’re right along the East Coast)…so this could be something to watch for finally delivering some decent rains, followed by an Arctic Blast.

ECMWF Ensemble:

 

28
Nov

Warm Up Coming, But Step Down Process Too. Canada Gets SnowPacked

Already the big warm up shown on some models is looking weaker and shorter. Yes there will be a period of above normal air, but not too long and as I previously mentioned the models would miss an amplification during next week. And here it is. Now both ECMWF and GFS have a decent amplifying trough that quickly puts the brakes on any sustained warm up.  Seems to me the models have been warm biased for a couple of months especially from TN-NC and northward, but overall the entire Southeast has been coolest relative to averages this Fall.

The GFS brings a decent trough through the mid South and crosses the East around Tuesday into Wednesday and this will *probably* have a better Gulf tap than previous fronts, but still it won’t be that much rain.  I’ll fine tune this as time goes along, but I think most folks have a shot at a line of showers crossing west to east.  Then turning sharply colder, but the coldest air really is probably going to be from TN and VA northward, so no really true Arctic air, just a normal early December front.

 

By Day 10, both the GFS and ECMWF have begun the process of retrograding the flow, which allows more troughing to move west in the Aleutians, building more ridging in the eastern Pacific , which causes more downstream troughing from the Rockies, eastward and this is about like I have been speaking of for nearly a week now.

Day 10:

Day 11:

Day 12:

As you can see, a PNA pattern is trying to form, along with more neg NAO, which acts in tandem to bring a large trough in the nations midsection.  This is about normal for early December, but what’s not normal is just how cold it has been (and will continue to be) across Canada.  VERY cold air just sitting up there and going nowhere, other than occasionally dropping in behind the Eastern fronts every few days.

One thing worth mentioning now is the Snowpack that’s coming to Canada during the next 2 weeks.  This is about as highest as I can recall in early December.  Here’s a look at day 1, day 5, day 10, and day 15 on the GFS projected snowdepth.

As you can see, the 2 foot snow line begins in northern to central Canada as of now, and steadily works southward to include the northern tier of US states…as there is going to be a slew of systems that track just south of Canada and drop a lot of snow.  By day 15, the GFS paints a nearly obsene amount of snowcover over vast chunks of Canada, so it resembles  a Tundra if this is right over the next 2 weeks.  Very impressive. With the still-shortening days, airmasses certainly wont’ modify at all crossing Canada and most of the Country will become snow packed, even some areas nearly 3 feet of snowcover.

It will be interesting to see how longwave troughs align later in December…usually snowcover breeds cold air and Arctic Highs , so if there is a deep trough, strong + PNA pattern or strong -NAO coming (which is likely) then a Cross-Polar Flow could really open the gates to an Arctic Outbreak. I’m NOT calling for that right now, but instead mentioning things well ahead of time as to what’s possible.  For now, I think we’ll see several fronts cross ever more south over the next 2 weeks into the Country and snow pack really builds in the northern tier and Especially in Canada.  Also, as I mentioned yesterday the models are really going gung-ho for California Mountain snow. Over 2 feet will easily fall in the Nevadas, and probably the higher mountains much more, with flooding possible north of San Francisco.  So enjoy the warm up and relatively nice weather in The Southeast while we can in early December…things will be changing later on.

 

27
Nov

Warmer Air Coming Back Next Week…But What About After That?

Most folks are interested in snow, and I see where you’re coming from, but right now the Southeast needs rain, and lots of it. Unfortunately we still look dry for a while.  The next week and beyond looks like increasing westerly flow, with little rain chances. There is the chance of a dip occurring in the jet by about a week, just in time to tap the Gulf and deliver the first widespread rains, but it’s too early to bank on. More often than not, the dynamics and lift continue to favor the western side of the Appalachian Chain, so the Gulf States to Tennessee Valley have been seeing more rain than areas east like eastern GA to the Carolinas.

The big news next week will be the above normal temperatures as we get into early December.  There will be good return flow around a High offshore, and the 850 temps climb above normal, so southerly flow will bring in more humidity and higher temperatures, but probably nothing “too warm”, although I wouldn’t rule out a couple records for somewhere in the Southeast. The Carolinas and Virginia will initially be prone to weak damming with a couple of highs to the north funnelling in northeast winds before finally switching to the Southeast.

Now, for what many folks are interested in: Where’s Winter?  Be patient, as we’re only about to enter the first of December and technically it doesn’t start until December 21 or so.   I still think the pattern will shake out to one that will be a Wild Winter, with some major Cold waves and atleast 2 or 3 significant Winter Storms based on reasoning I laid out much earlier.  But that doesn’t neccessarily mean I mean for it to occur in December.  Although there have been quite a few “good” Wintry Decembers since 2002, that is still quite uncommon in most of the Southeast to expect any type of Wintry storm system.

The models a couple of weeks ago were too quick in leading to an Eastern Invasion of Cold air, as I thought they would be. Almost always, they drop too much cold following a neg. NAO pattern and the atmosphere is still adjusting from the previous heat release of superstorm Sandy and the Nor’easter. Now the -PDO pattern is dominating and soon we’ll see warring factions between it, and negative PNA and -AO patterns, but eventually this will become a solidly Winter Pattern in the East, and probably Southeast at some point in late December, maybe mid December.

I’ve been playing close attention to the runs of GFS lately and watching it inch the pattern change closer and closer. As usual, anything out at day 15 is troublesome and full of error potential, but if a model shows major change daily and keeps rhythm and synchronicity, and maintains timing without delay, then real change is likely. And so far, believe it or not, GFS does show the change, at first it showed day 15, then worked steadily into the day 11.  I still wouldn’t be too comfortable with its outlooks until within day 10 or so, but this time ECMWF now pretty much agrees on the Aleutian low working West, retrograding.

This is probably just the impetus needed to change the Pacific, so a ridge will form just offshore Western North America and allow broad troughing from the Rockies to the Plains and East….being squelched somewhat beneath a building negative NAO and negative AO pattern.  This is also a recipe for volatility, so I won’t comment too much beyond that right now since it would be dangerous, but overall, STORMINESS is coming to a good chunk of the US.

First, the west coast will be battered.  Several feet of snow is coming to the Olympics and Sierra Nevada mountains. From northern California, northward there will be an onslaught of Pacific moisture.  Flooding could occur at some point in the next 10 days there.

Then as the heights build a little, and troughing develops in the Rockies, systems will deepen en route to the East, so colder air will be pulled south. And there is PLENTY of cold air in the Canadian and Alaskan areas.

I really don’t want to go too far into December, other than to say the storminess and action is really going to pick up. For the Southeast, I think we’ll finally begin to see some rain potential and north of this region, snow and ice will become quickly a factor.  Looking at the Beijing Model latest release for Days 11 through 40, it’s certainly being adamament that a Colder (relative to normal) Southeast will be the rule for most of December into early January. Here is a look at its 40 day outook, which goes just into early January.  You can clearly see the Aleutian Low worked enough west to build western Ridging and in tandem it shows Greenland Ridging, so that would equate to below normal heights in the South and East. I am totally new to that model and don’t know if it will be right, other than to say it has done “pretty good ” with the big heat wave and early June cool wave of  this year.  I really have no idea of its Winter forecasts (I think it missed last Winter though).  I will be scrutinizing it carefully through December to see how accurate it was and for which regions.

 

 

The GFS also show the Pacific changing, one that will bring more frequent storminess as we approach the second week of December.

Below are GFS 288 and day 10 European:

 

Now, what could go wrong, or what could delay the pattern change?  The Pacific could remain strong in negative PDO and -PNA mode which would overwhelm the tendency for the -AO pattern. This would mean near normal temps.  And the duo could battle back and forth at times, allowing one to dominate the other, meaning we’d have Arctic air masses in, then out, quickly and bounce back and forth, with no sustaining pattern.  I don’t see anything solidly sustaining right now, and not warm or cold air any time soon.  I will say the “warm ups” shown for the Carolinas and points north have seemed to always be not nearly as warm as models show this Fall. We’ll see how the next one shakes out. Beyond that, overall I like stormy and turning colder as being the prevailing theme.  If you’re looking for snow, well, this is December and in the Southeast, that’s unusual.  But the AO is forecast to go strongly negative, and if other factors cooperate, usually that does mean snow follows in the not to distant future, depending on where you are.  I’m sure at some point this Winter, the -AO and -NAO pattern will produce quite  a Winter Pattern, but I won’t say right now “when” that occurs. I’ll certainly let my readers know the first moment I become confident in calling it.

 

27
Nov

Full Update This Afternoon

I have to take care of my dad’s appointments this afternoon and will take a look at 12Z Euro and do a full update this afternoon when I return.  Already the 12z GFS looks like it’s bringing the changes in December.  If you have been following it, it began to show changes around days 14, then 13 then 12 now it’s worked to day 11, so it’s remaining consistent on the pattern in the Pacific changing which will eventually lead to deep troughs in the Southeast.  Therefore if this change occurs, some rain will finally arrive.  Also, following the deep troughs, more cold air will be pulled down and some degree of high blocking will occur.  A quick warm up occurs next week just before this process gets started.

26
Nov

Very Little Rain…Dry Pattern Continues

I still don’t see the likelies in POPS that I see with some forecasts in Ga/Carolinas. Usually when GFS shows a hole of precip in Ga, SC and lower NC, it’s right.  We’ll see.  Sprinkles or very light showers are possible but generally I think GFS will look more realistic when this front passes.  Areas from KY to southern PA will be one max of precip, mostly light snow. The other will be west of the Apps in northwest GA, Al, and TN, and Gulf Coast before it begins to dry up crossing the southern Apps.

After this front, the flow turns very zonal.   Weak warm advection shows up as the week goes along, so temps will be inching up. But on Friday and Saturday a weak damming event could show up for NC and points north. Again, very little rain chances unfortunately.

Looking out in time, I think I see signs of real change, but it’s so far out I’m not sure yet. And I wouldn’t take any model too seriously yet until we see major changes within 10 days on both GFS and ECMWF.  But the operational ECMWF does begin to retrograde the Bering Sea Omega Block between days 7 and 10.  GFS also shows warm advection in the Southeast (where we’ve had more west or northwest flow, not southerly flow) around that time as well.  So this may be the start of a change, one that might allow big scale Arctic air to start coming into the Heartland where it’s been above normal.  This would also finally allow central troughs to tap the Gulf, and bring a real, widespread rain event finally.  Don’t get too excited yet though, but it may head in that direction. Until then, a yawner overall, but nice weather for outside activities.

25
Nov

Still Dry Southeast, Especially GA/NC/SC…Some Light Snow Ky/Tn/Va/Md/De

The flat wave still looks unimpressive for most of us in the Southeast on Tuesday.  The NAM looks way overdone on precip, especially east of the mountains. GFS looks more reasonable and reflects more of what’s been happening the last couple of months.

GFS shows there will be two main bands with this front:  One furthern north where the colder air is , so overrunning will occur from northern and eastern KY and stretch eastward quickly across West Va and into western VA and northern VA, which could produce a few hours of light snow fall.  Even DC region should experience some early morning Tuesday snowfall, before temperatures warm a little and what moisture is left could turn to rain, but this doesn’t look like a big deal for the East Coast.  The timing is bad for DC to New Jersey, and looks like a total miss for NYC.  However, since it’s a night event further west, northern and eastern KY could get an inch, maybe 2, also West VA.   On the backside of this weak system, a weak upslope snow (flurries) could occur in northeast TN, nw NC on Tuesday and into early Wednesday as cold air wraps back in, but again this won’t be much either.  Most of the Carolinas and Georgia will miss the brunt of the rain, as there is little dynamics to keep the Gulf tap going, but areas west of the Chain will see more rain, again, we’ve seen this play out time and time again.  Bottom line, sprinkles mostly in Ga/SC/NC.

After this, the flow goes zonal and the big Gulf of Alaska low is staying put a while.   One thing worth mentioning is both GFS and ECMWF bring a wave west to east about Friday or Saturday.  I mentioned a couple of days ago that the models would miss this weak development, and sure enough, they both now have something showing up in the Plains, but this too looks weak (oddly enough it may give a better chance of rain than the Tuesday system though).

The West Coast will get pelted, especially the Pac NW over the next week to 10 days as the Gulf of Alaska trough sends pieces of storms into the West Coast, but these all minor out mostly as they move inland.  We will have to wait until the Pacific gets shuffled to see a really good chance of rain, and so far , that is well out in time.  The northwest cool flow, and weak westerly flows aren’t doing it for most of us. But over the last few days, GFS has been honing in on just this, first starting at around day 15, then 14 and now its inching closer to day 10.  I won’t get too excited though any longer term precip chances until we get both models clearly showing a true change within 10 days, but I do think will eventually get there.  Right now the Atmosphere is still readjusting after releasing all that energy from Sandy and the following Nor’easter, and it’s also hard to ignore the forecast from NAO and AO heading downward around the second week of December.  So, over the next few days we’ll know if the GFS is showing a phantom on its days 11 throgh 15 panels, where it builds  a strong neg. NAO block and allows Arctic Air to drop strongly southward and turn the nation cold and stormy.  Last year, interestingly, if you recall, we never even saw much of that at all in “fantasy” land on the GFS…a testament to just how truly warm the pattern was last Winter.  So we’ll soon know if the GFS is up to it’s old tricks of yesteryear, by have false alarms well out in time.  I will say over the last couple of years, when it showed  a big system in that time frame (either outbreak severe, heat wave, etc) then it was usually onto something.   But since it so happens it’s been 2 years since we’ve really experienced Winter like conditions, I’ll reserve judgment on this.  But closely watching things……

 

24
Nov

Cold Southeast, Some Rain Coming Next Week…Snow North?

The Cold Saturday WxSouth promised a few days ago is here. I see all NWS offices and TV markets from Atlanta to Richmond have ratcheted down the highs. Atlanta to Athens may have a little downslope component enough to touch 50, but generally most between central/northern Alabama to eastern VA are going to be cold and in the 40′s.

The models have been shifting with the next wave on Tues/Wed and how much Gulf tap it can generate, now it’s “back on”.  This should be a relatively weak wave and one that still probably won’t be able to give much of GA and the Carolinas much rain, with the maximum moisture being in TENN Valley, like has been the case most of the year.  This could also drop some snow in the northeast part of Kentucky, across West Virginia and into northern Virginia from about Charlottesville north, if the timing occurs early enough on Saturday.  If this system goes just slightly south then the rain /snow line would shift a little south toward central VA (and ECMWF hinted at that, so does GFS) but usually these types of events are slightly further north than progged, so I’d hedge close to a compromise right now.  This system will be gaining ever-increasing neg. tilt as it moves up the Northeast Coast, therefore deepening and snow increasing for the Northeast, with a switchover to snow at the coast once the system passes (NYC, coastal New England).  Here’s a look at rain totals and snow totals per GFS:

As you can see this could be a big snowmaker once it gets into New England, with plenty of cold air and moisture to work with and stronger dynamics, similar to Miller B type snowstorms.

Canadian Model also has been showing a possible weak snow event in and around Apps and the East Coast from eastern KY to northern VA to Md and points north:

 

 

Following in it’s wake, another cold shot for the East.  I definitely see a pattern here and the models were right a week ago showing the lower heights Vortex over the Northeast, and I mentioned that this region would be one to watch for several snow events possibly.

Out in time, as usual, the models are not in agreement as the Pacific fights against the NAO type of evironment. This is a continual source of headaches for the forecaster in a broad scale. Hopefully things get much simpler and an easier pattern soon, but in general my ideas from yesterday still hold.  With cold troughing in the MidAtlantic and Northeast, with a Pacific trough, and calm weather in the middle. But that “in the middle” zone is what has my attention as that is too zonal for too long, and I suspect we’ll see something weak show up around the Plains, especially Southern Plains or Miss. Valley before too long.  GFS hinted at this yesterday and ECMWF hints at this today, but don’t make much of a deal with it.  I have a sneaky suspicion that the next wave that shows up late next week across the South (not shown much) could be a little like what developed a week ago in the Southeast, with some significant rains and damming again.

 

 

23
Nov

Eastern Storm Still Possible, Then Greenland Block Maybe….Watch the Southern Stream

Models are in a very chaotic mode right now, and thats to be expected with the changes going on. All models have been hinting at strong northern Latitude blocking to develop soon, but don’t know exactly where to do it.  And where it happens is absolutely key for what happens at the Southern US latitudes.  Already I see signs of more active southern stream showing up later next week, even though models don’t explicitly show much yet.  More on that later on.

First, the models all backed off last night on the upcoming weak mid nation trough that slides through the East later Tuesday into Wednesday.  This was the wave that could develop quickly just off the East Coast on Wednesday and Thursday before entering Eastern Canada as a powerful storm.  But that’s still sketchy.  The latest GFS and GGEM make a much bigger deal of it than ECMWF and those models offer a chance at part of the Northeast (and Apps) to switch over to snow before ending.  But there is so much energy that’s not consolidated and moving so fast, the models could easily miss this.  The latest ECMWF has a few showers developing Monday Night and Tuesday in the lower Miss. Valley but it falls apart to almost nothing for  the vast majority of the Southeast.  But GFS has much more development and Gulf Tap (after losing it night).  So still we don’t have good model agreement on this, and I’d be a little nervous to go against the ECMWF lately, also the Southeast has been exceedingly dry mostly for a couple of months now, so it’s hard to bet against this in such a dry pattern and with a weak wave shown.  But still, this front’s not certain yet, and there could be more than shown on ECMWF.

And what happens with this offshore system means a lot upstream in the flow for the lower Plains and the Southeast eventually by late next week, or weekend.

The GFS develops a strong Negative NAO and strong Greenland Block.  This combined with an active Pacific could open the door to a weak s/w cutting through the southern Plains/Texas late next week, with some weak Gulf return.  Meanwhile GFS shows strong confluence in the Lakes and Northeast, where Arctic Air and High Pressure is pouring in around the Northeast Vortex and under the Block in Greenland.  This could be something to watch for a Winter Weather Event on the far northeast edges of the precip shield, but I’m not calling for that yet.  I think it’s worth a mention as a possibility but not a likelihood at 7 plus days out.  If the 5H ends up looking like GFS (which is a risky gamble since models are flipping a lot lately), then that could be a cold rain event with damming in the Southeast.

GFS (Saturday 180 hours):

One important thing to note is the models may be losing that warm look in the Plains and central US they were showing recently (for next week).  I was skeptical because it seems like each time a warmer pattern is shown in the East especially, it fails to materialize, other than a one day warm pre-frontal advection.  This map looks more like supression , but still not arctic cold since the vortex never allows one huge dump of cold air to drop into the central states yet, despite neg. NAO.  Remember blocking can take up to 2 weeks to allow cold results in the Southeast to show up.  Still I’d keep my eyes on next weekend time frame for any energy that cuts through Texas and encounters a High Pressure with damming in the East, from northern GA to Virginia especially.  Hopefully some rain can fall though.

The latest ECMWF looks substantially different than GFS just 7 days from now. It doesn’t make the strong block or confluence zone, and has nothing in Texas.  What blocking it does create is much further east than GFS and almost everything is shifted further east and it has much more ridging/warmer look for the Southeast and most of MidAtlantic, with no southern stream hints at all.

This is hard to say which will be right, but since both have changed a lot, I won’t really decide just yet on those time frames beyond 5 days. I think GFS is too wet for the early week system in the Southeast and most of the East, but ECMWF is probably too dry.  It also had a good precip event shown a couple times.  But ECMWF looks too far east with its strong vortex later next week and looks too warm in the Southeast by late week.  One thing it has been showing a few runs now is that Europe is going to turn very cold and stormy.  It shows  a big snowstorm and deep trough in France, the southern UK and maybe northern Italy, with a very deep snowstorm and major event there.

I think the strong -PDO look in the Pacific is waging war on the tendency for Greenland blocking and that’s why we see such flips in modeling beyond 5 days.  Until we get settled into a regime or until it’s really crystal clear, it’s going to be hard to guess at weather beyond 5 days in the Southeast,(and entire East)  but eventually that will change.

I’ll also say with pretty high certainty that in general, I think the Pacific pattern shuffles soon and will begin to send systems inland and eventually the nation will get into a stormy and colder pattern, but the timing is uncertain.

 

 

 

 

22
Nov

Cold/Windy Saturday…Vortex In Northeast Means Stormy There For a While

Here’s a look at Saturday afternoon highs and Sunday morning lows. As you can see, this will be the coldest air this season atleast outside the mountains.  Sections along I-20 will likely have the first frost/freeze on Sunday morning from Ms, Al, Ga, SC.

 

Winds and Wind Chills also noticeable Saturday.  A relative min of wind is shown in the Sav. River Valley of Ga/SC thanks to the winds muted by the high Apps just northwest.

A quick moderation is in store, but not necessarily a big warm up.  Another system will cruise through the MidSouth by later Tuesday and into Wednesday, picking up moisture and laying down the first decent rain totals in long time. Not every body will get the needed rains and I’m afraid central GA to eastern SC may not get that much, being more removed from dynamics.  The GFS and ECMWF are a little different on how this evolves and ECMWF is slower, and has more overrunning type of event in Ky/Va region, where it’s actually cold enough to snow, or switch quickly to snow.

The 12z run of ECMWF actually has the airmass and moisture combining so that snow is *possible* around Wednesday into Thursday as a system takes shape just offshore, but since this is 6 to 7 days out, I wouldn’t bank on that but watch for the trends.  It takes the storm just offshore NJ and then curves it back into Canada, helping to carve out a deep Northeast trough.

This trough is so strong that it remains nearly stationary for several days and has several s/w that could spiral around it, each may generate a snowstorm in the far northern New England and Eastern Canada.

The Ensembles show this setup, as well as operational.

So I wouldn’t be suprised to hear about several rounds of snow in the Northeast over the next 6 to 14 days with that vortex in place. Meanwhile the rest of the country is under more zonal flow and the further west and southwest you go, the warmer relative to normals.  There will be a deep Eastern Pacific trough that will counteract the developing neg. NAO pattern, so until that Pacific changes up (strong -PDO now) then I think we’re seeing a trend here for troughing in the East Coast region, followed by normal temps.

As time goes along, I think the Neg. NAO will work more west and north, and eventually the entire pattern changes below the blocking up north, so that at some point in December, the throws of the Arctic plunge straight down into the heart of the Country and Eastern Half.  But this process will take time. Remember the atmosphere is now readusting after the big burst of energy release known as Sandy and the Nore’asters.  The rubber band has snapped and tension will build again, but this initial batch of pent up energy will be offset because of the Pacific.  That won’t be the case most likely later on December.

 

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