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Archive for March 2012

29
Mar

Monday/Tuesday Strong Storm. Very Warm Weekend From TN/ARK…West

The weekend looks pretty nice for all outdoor activities but a weak front and upper system will traverse the mid South Friday into Saturday, with a few showers or storms. Otherwise, skies will be partly cloudy (much cooler in VA–still above normal) and by early next week there will be a major warm up, even HOT, for western Tennessee, the Delta and throughout Texas to Ok, Ark. areas.  Temps aloft will soar, and southerly winds will kick in ahead of a developing cutoff system, so before the rains and storms arrive, it will get warm, even some 90 degree readings possible.  We continue the pretty incredible warm spell throughout the South.

The big question now for the next system is regarding the track and type of system that evolves next Monday through Wednesday.  The GFS  and GGEM are in basic agreement keeping a southerly tracking cutoff separated from the northern stream. Unlike the ECMWF.  The jury is still out on this but it wouldn’t surprise me to see the GFS closer to accurate. If so, a severe outbreak could occur in Tx/Ok later Monday and then spread across the mid South on Tuesday, reaching the southern Appalachians by Tuesday evening. Plenty of scattered storms in the soupy, warm airmass would be mixed around the edges of any severe as well, so that would bring very welcome rains to northern Florida , Ga and the Carolinas where the drought is growing rapidly.

However, if the GFS isn’t right and the ECMWF version verifies, then there will be just a quick glancing blow for the Tenn. Valley and the Southeast, with some quick hitting severe or storms, then quickly drying out in northwest flow.  The GFS also brings in cold air following the system by Thursday, with temperatures falling sharply, but it may be overdone like most cold outbreaks this season.

Regarding rain totals, ECMWF wouldn’t be much, especially for the drought stricken central Ga, northern FL and central SC region.  GFS would be a very decent event however.  We’ll fine tune this soon.

Long range:  ECMWF wants to quickly bring in a heat wave for the southern Plains to Southeast with very high heights and southerly flow.  It’s showing upper 80s to around 90 being common by days 9 and 10, but again that model has major issues at beyond 120 hours lately.

25
Mar

Central Canada to Southern Greenland Ridging to Change the Flow

Looks like the GFS idea of a supressed flow has legs. Most models agree that strong ridging will work into Southern Greenland by later next week, setting up a Northeast US vortex (50/50 low) , separated by more strong riding in the Hudson Bay area. The strong ridge near Hudson Bay , combined with the 50/50 low, will help “split” energy eventually, so this means an active supressed type of flow. Where was this during Winter?

The ECMWF has been back and forth with just how far south the storms will travel, even one run cutoff a deep system which would be good news for rain in parched Georgia and most of the Carolinas.  Further west in the Southeast, it would still be mostly drier thanks to be under the longwave ridge.  The jury is still out on details, but I think GFS is too far offshore with its latest runs of the surface system around days 8 through 10. Usually blocking brings systems closer to the coast, but since this would be vastly different than the entire Fall and Winter flow, its hard to say yet.  Any slight adjustment to the 50/50 low or blocking in Canada could indeed mean everything is located more north or east, which would be just cooler with little rainfall.  For now, its’ something to watch.   Regardless what ends up happening later on, atleast there are two fronts slated to hit the Tenn. Valley and Southeast by mid to late week, but since they’re coming from the Ohio Valley, they shouldn’t be major rain makers.  The second event, probably next weekend, will spread convective rains from Texas , eastward across the Southeast, and then the major low pressure system could be to develop shortly thereafter, but right now that looks geared to hit eastern Tennessee and NC/VA and the Apps, but keep an eye on this system.  If the block is stronger than forecast (which would also be a first this season–but used to happen often), then snow in the mountains would be possible at some point in early April from NC, Va to Pennsylvania, with a strong east coast storm and hard freeze following.  All speculation at this point.

 

GFS when the splitting of the flow begins (hour 120–Valid Fri 12z)

 

GFS hour 180 Surface (low could be too far east) but a general track through lower Ohio Valley/Apps to Carolinas would fit climo blocking:

24
Mar

Little Cooler Next Week, Esp. NC/ VA. Stormy Late Next Week. Block in Canada?

After the current upper low moves offshore, the weather will improve and dry out for the Southeast. For Virginia and NC, a backdoor front will bring in much cooler weather Tuesday and Wednesday, fueled by a northeast vortex that looks to lock in place.  The ECMWF has this feature (with a CAD high) Tuesday and Wednesday east of the Apps, but the main effect will be cooler morning lows.  West of the Apps, it will still be above normal, but not quite as warm as much of March was.

Day 3:

 

By 7 days (April 1), Still in place:

 

Even by day 10, this model develops a healthy Hudson Bay closed high, whereas GFS has more ridging in southern Greenland. Either way, some high latitude blocking could lead to an active storm track from west to east across the Midwest to MidSouth, starting later next week and beyond. If the GFS is right, the last few runs have developed such a big Greenland ridge, coupled with ridging in eastern Pacific to drive much cooler, drier air into the country for days 10 and beyond, but we will have to wait and see how that develops. That would be a pattern that hasn’t set up in over a year, so I will be skeptical of if for now.

 

21
Mar

Closed Low To Bring Showers/T-storms/Hail West to East this Weekend..Then Cooler!

I’m pretty excited about finally heading into a much cooler pattern for the Southeast, but it will take some time. First, the strong cutoff will continue swirling in Oklahoma the next couple of days before slowly weakening and pulling northeast, then getting shoved southeast. The track looks like it will take the center from OKC to STL to CVG to GSO by Sunday, with a possible surface system developing along the coast of northeast NC or Eastern VA by late Sunday or Monday.  The band of rain and storms will begin moving into Ga and the western Carolinas late Friday night and spread east Saturday, but the cold core will wobble through central Kentucky and northern middle Tennessee at that time, possibly accompanied by strong hailers.

The moisture will rotate around the ever-increasingly large circulation, so skies may clear Sunday in Ga and the Carolinas, but fill back in with the approach of the upper cold core, again, watch for HAIL when this happens.  The rain is badly needed in Georgia to the Carolinas, with all the record heat and pretty dry conditions widespread. Meanwhile way too much rain still occurs for Mississippi, Arkansas and parts of Texas.

This system will pull off the East coast, and drag down colder air, and even quite chilly air (below normal) for Virginia to start the new week. At this point, all models bring another strong Midwest system down to the Tennessee Valley later next week, with substantial cold air with it as well, and that system may close off “somewhere” in the Southeast, so pay attention to trends of the models.

The GFS develops neg NAO for a while between days 7 through 16, slight ridging north of Greenland and slight troughing in the Southeast, so we may be headed for *GASP* cooler than normal??  We’ll have to see how this unfolds, hopefully we’re due some cooler temps and more rainfall.

19
Mar

Severe Threat Tx/Ok Turns into Heavy Rain with Cut-Off…Very Warm Southeast

As I mentioned a few days ago, the SPC would likely upgrade it’s outlook for Texas and Oklahoma, and it now they’ve upgraded to moderate.  Strong Gulf inflow and a dryline will intersect along the front, so severe is likely on both sides of the Red River today and into Tuesday. This will spread slowly toward the east toward Arkansas, western Louisiana and southern Missouri, then die out before hitting western Tennessee, Mississippi. There could be a redeveloping round of severe at some point Tuesday, then the Upper Low will fully cutoff, and set up “training” of the rainfall.  This could turn into “too much of a good thing” for Texas, Oklahoma and western Arkansas, with flooding being the result.  Each run of the models stalled the system slightly further west, and it appears it will be the weekend before the eastern seaboard gets anything from it.

 

East of the system, another very warm week is in store with temperatures in the upper 70′s to mid 80′s especially areas east of the Mississippi River.  Parts of NC and VA will experience onshore flow, and be on the front side of the upper ridge over the Appalachians, so showers and thunderstorms will be possible much of the week, but won’t be widespread.

18
Mar

Sunday Update On Next Storm…Model Disagreement

Just a quick update on the storm/cutoff next week. Big disagreements now on ECMWF and GFS handling.  The latest GFS trends are to stall it in Oklahoma, then eventually lift it northward to the Lakes or Ohio Valley, bypassing much of the Southeast from Alabama to Carolinas.  It’s too early to know if this trend is legit. But it is more west and slow, similar to UKMET and GGEM, but ECMWF is more progressive, taking it slowly east bound from southern Missouri across the Carolinas this weekend.  I’ll wait to choose which I believe.

Either way, bigtime rains in central and eastern Texas, Ok, western half of Ark, and north Louisiana from this system. Its nearly 4 contours closed, and has an excellent tap to the Gulf at this time from early to mid week.  The GFS has 5″ of rain very widespread. There’s a 10″ max near Texarkana, which may be overdone since the 6z looks too slow.  The rains east of the mountains are mostly from early on, as this system is slated on GFS to bypass Ga and the Carolinas especially. Unfortunately that’s been the trend much of the Fall and Winter. If there’s no substantial rain soon from southern /central Ga to central and eastern Carolinas, then the drought will start growing rapidly now that evapo-transpiration rates are skyrocketing.

 

 

 

17
Mar

Strong to Severe Outbreak in Ok, Tx, Ark…then Cutoff-Low Next Week

After quiet weather recently other than the extreme heat for March and some scattered convection, the next big thing will be the incoming deep trough. The models show a deep trough coming into the Southern Plains Monday and begins to cut it off by midweek. This will offer up several rounds of severe weather in the eastern half of Texas, northward to eastern Oklahoma and northwest Arkansas.

So far the SPC isn’t that impressed with the severe chances for the Day 3 outlooks, but most likely things will get an upgrade soon since all models are on the same page and this looks (to me atleast) very likely to have Tornadoes and other Severe parameters between Monday and Tuesday.

 

As the system cuts off, it will turn slightly negative tilt which will be located in just the right spot to pull in a narrow but extremely heavy, intense line of rain for the Mississippi Valley, and that line will probably sweep east across the Tennessee Valley before losing dynamics in Georgia and the Carolinas by mid to late week.  We will have to wait and see how the evolution of the cutoff occurs, but there’s good model agreement on this, and the GFS usually handles cutoffs at this time frame fairly well.  The further south and slower it is, the more rains for the western Tn. Valley and especially for La, western MS, much of Ark, and eastern Tx/Ok.  The GFS has over 5″ of rains most of it falling in only a few rounds of extremely heavy rains. Unfortunately, areas east of the Appalachians could miss out on the abundant rainfall, but over the next few days there will be the hope for some scattered convection almost daily, and there could be enough Bermuda High influence early in the week to produce and onshore flow, so showers could pop at any time in Ga to the Carolinas and southern VA, but won’t be widespread or heavy enough to really help the drought.

 

The ECMWF has a major east coast to New England snowstorm, with such strong dynamics and a deep coastal to classify as a blizzard, but its the famous 10 day prog, and likely to change. Several times this season that model has had a few fluke runs showing a major east coast storm, which never materializes. It also has a pretty sharp cold intrusion for the mid-South and MidAtlantic, with a 1040mb High pressing down. We’ll see how this evolves.

15
Mar

Record Heat for March…Watching A Potential Cutoff Next Week

Record heat dominated the nation midweek, surpassing the March 2000 heatwave. As I predicted last week when the GFS showed enormous riding in the Lakes and eastern States, temperatures soared at the surface and aloft, combined with abundant sunshine this led to a pattern more like May than March. Meanwhile the west coast is under a deep trough.

 

It looks like more of the same, with scattered convection in the Southeast over the next few days, before a slight cooldown occurs. More importantly is what the models are showing for the middle of next week. Another major cutoff. It’s too early yet to go with it, but it fits climo time of year, and the pattern we seem to find showing up over and over the last 6 months or so. Right now it appears the deep western trough will arrive in the lower Plains by Monday or Tuesday and then begin to cutoff in eastern Texas to the Lower Mississippi Valley. I’ll fine tune this with maps and graphics with rain amounts once we know the speed and location and intensity of the system. It could end up being a major rain maker, especially in eastern part of the Lonestar state to western Tennessee. Hopefully the Carolinas can get some beneficial rain from the system. February was extremely dry and the drought is spreading in Georgia to the Carolinas rapidly and now that Spring and heat is here, with high vegetation growth, you need plentiful rains at regular intervals to combat the seemingly perpetual drought.

 

 

 

13
Mar

Unusually Warm, Muggy, Scattered Showers/Storms

It seems we bypassed Spring and went straight to early Summer, with muggy dewpoints and daily highs in the low 80′s.  Showers and storms will be possible almost every day in this soupy airmass, as the upper levels will be cool, so instability and strong lifted indices will offer up a chance of convection with several weak disturbances coming out of the west through the week and into the weekend.  The other thing to watch for the East Coast will be the possibility of a back door cold front around Sunday.  This could bring cooler air east of the Appalachians Sunday/Monday, but it’s uncertain.  The deep trough is still slated for the West this weekend, but the only affect that has on the Southeast would be to pump up the subtropical ridge. Temperatures will continue to be well above normal.  Keep an eye on the skies this week for any storms that suddenly pop up, as they could contain hail and high winds, but pretty localized and unorganized.

11
Mar

Lower Miss. Valley Storms Today, Then a “May-like” Week Ahead

SPC has put out an alert for slight risk today in eastern Texas to western Mississippi in advance of the opening Upper Low. This system will pull north to the Lakes, largely bypassing much of the Southeast, especially from the Apps eastward.  Those suffering with allergies could use an all day rain, especially where the Winter rains were only hit and miss in much of Georgia to the Carolinas.  Unfortunately, rain will become sparse, and far apart, with mid level instability most of the week offering up afternoon shower/T’storm chances, typical of May or June.  Temps will be 10 to 15 degrees above normal almost everywhere.

The next big thing will a deep western trough, and corresponding huge ridge.  The ECMWF develops a major eastern ridge by days 7 to 10, with temperatures soaring well above normal, even more so than they will be this week. We’re definitely living in very warm times, having been above normal many months now…most of 2011 and now the first part of 2012.

 

 

 DAY 1 CONVECTIVE OUTLOOK
   NWS STORM PREDICTION CENTER NORMAN OK
   0748 AM CDT SUN MAR 11 2012

   VALID 111300Z - 121200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN AND SE TX NNE INTO THE
   OZARKS AND LWR MS VLY...

   ...SYNOPSIS...
   TX PANHANDLE UPR LOW SHOULD ACCELERATE NEWD THIS PERIOD AS CYCLONIC
   NRN STREAM JET PERSISTS FROM THE NE PACIFIC ACROSS WA/ORE AND THE
   NRN RCKYS INTO SK/MB.  THE TX LOW SHOULD REACH CNTRL KS THIS EVE AND
   NW IA EARLY MON...AS ASSOCIATED VORT LOBE NOW OVER W TX ASSUMES A
   NEGATIVE TILT AND PIVOTS NE INTO WRN MO/NW AR THIS EVE...AND INTO
   ERN IA/NRN IL BY 12Z MON.

   AT LWR LVLS...A BROAD ZONE OF LOW LVL S TO SWLY FLOW WILL PERSIST
   OVER THE PLNS AND MS VLY.  WHILE FRONTAL FEATURES WILL REMAIN WEAK
   OR NON-EXISTENT...A CONFLUENCE ZONE SEPARATING MODIFIED GULF AIR
   FROM AIR ORIGINATING OVER NRN MEXICO AND SW TX WILL BECOME
   ESTABLISHED FROM SABINE RVR VLY NNE INTO THE WRN OZARKS TODAY.  THIS
   FEATURE LIKELY WILL SERVE AS THE MAIN FOCUS OF STRONG TO POTENTIALLY
   SVR TSTMS THIS PERIOD.

   ...SE TX/LA NEWD INTO OZARKS TODAY/TNGT...
   SHOWERS AND TSTMS SHOULD SLOWLY INCREASE IN COVERAGE AND STRENGTH
   THROUGH THE REMAINDER OF THIS MORNING FROM E CNTRL TX AND THE MIDDLE
   TX GULF CSTL PLN NEWD INTO THE ARKLATEX AS UPR DIVERGENCE/ASCENT
   INCREASE AHEAD OF SRN PART OF AFOREMENTIONED VORT LOBE.  OTHER
   STORMS...LIKELY MORE ELEVATED...SHOULD SIMULTANEOUSLY INCREASE FROM
   N TX AND ERN OK INTO SE KS...NW AR...AND SW MO.

   CLOUDS/PRECIPITATION AND MODEST MID LVL LAPSE RATES WILL LIMIT
   DIURNAL DESTABILIZATION ACROSS SLGT RISK AREA TODAY.
   NEVERTHELESS...COMBINATION OF INCREASING LOW LVL MOISTURE AND
   FORCING FOR ASCENT SHOULD SUPPORT DEVELOPMENT OF SFC OR NEAR
   SFC-BASED STORMS ALONG SSW-NNE CONFLUENCE ZONE FROM SE TX INTO THE
   ARKLATEX LATER THIS MORNING.  COUPLED WITH STRONG WIND FIELD AND
   HODOGRAPHS THAT WILL EXHIBIT SUBSTANTIAL LOW TO MID LEVEL VEERING
   /I.E...40-50 KT SSWLY 850 MB FLOW BENEATH 50-60 KT SW WINDS AT 500
   MB/...EXPECT SCTD SUSTAINED STORMS/SUPERCELLS CAPABLE OF BOTH
   TORNADOES AND DMGG WIND.

   WIND PROFILES AND THERMODYNAMIC ENVIRONMENT SUGGEST THAT THE STORMS
   MAY ORGANIZE INTO ONE OR TWO BROKEN BANDS ORIENTED ROUGHLY PARALLEL
   TO THE CONFLUENCE AXIS.  THESE BANDS SHOULD MOVE/DEVELOP NNE INTO
   CNTRL AR AND NW LA BY EVE.  WHILE THE GREATEST SVR RISK SHOULD EXIST
   BETWEEN MID AFTN AND EARLY TNGT FROM E TX INTO PARTS OF AR AND
   LA...A LIMITED SVR RISK MAY CONTINUE THROUGH EARLY MON NEWD INTO
   PARTS OF MO...SRN IL...WRN KY...AND WRN TN AS LOW LVL SPEED MAX
   STRENGTHENS AND MOVES NEWD WITH STRONGEST FORCING FOR ASCENT.

   ..CORFIDI/SMITH.. 03/11/2012

Day 10 ECWMF

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