February 28th-March 1st 2017 Severe Thread

[monsoonman1]

Since the threat will cover multiple sub-forums, and with potential for a robust event, figured we might as well start the thread here. For Tuesday, while NAM/SREF are stingy on daytime development, the global models all develop activity in the warm sector to some degree. The extent of the warm sector is quite impressive; anywhere from NE TX to IL/IN could see a tornado threat if storms do develop. Wednesday looks more like an extensive line of storms with wind/some tornado risk. 

[monsoonman1]

I should also mention that there is now a 5% tornado risk for NE TX today.

[janetjanet998]

AY 2 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1155 AM CST MON FEB 27 2017  
  
VALID 281200Z - 011200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EXTENDING FROM  
CENTRAL ILLINOIS AND ADJACENT WEST-CENTRAL AND SOUTHWEST INDIANA  
THROUGH THE SOUTHEAST HALF OF MISSOURI...EXTREME WESTERN KENTUCKY  
INTO NORTHERN AND CENTRAL ARKANSAS...AND A SMALL PART OF EASTERN  
OKLAHOMA...  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE  
ENHANCED RISK FROM EASTERN OKLAHOMA AND NORTHEAST TEXAS INTO  
NORTHERN MISSOURI...AND THE LOWER OHIO VALLEY AND SOUTHERN GREAT  
LAKES REGION...  
  
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE  
SLIGHT RISK FROM EASTERN PORTIONS OF THE SOUTHERN PLAINS TO THE  
UPPER OHIO VALLEY AND SOUTHWEST GREAT LAKES...  
   
..SUMMARY  
  
SEVERE THUNDERSTORMS WILL BE POSSIBLE ON TUESDAY AND TUESDAY NIGHT  
FROM EASTERN PORTIONS OF OKLAHOMA AND TEXAS NORTHEASTWARD INTO PARTS  
OF THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND OHIO VALLEY.  
   
..SYNOPSIS  
  
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT IN SHOWING A LARGER-SCALE  
POSITIVELY TILTED MID-LEVEL TROUGH MOVING FROM THE GREAT  
BASIN/SOUTHERN CA REGION EASTWARD TO THE GREAT PLAINS BY LATE  
TUESDAY NIGHT.  AS THIS TROUGH MOVE INTO THE PLAINS STATES, IT IS  
EXPECTED TO TAKE ON A MORE NEUTRAL ORIENTATION, RESULTING IN  
STRENGTHENING DEEP-LAYER WIND FIELDS.  A VERY STRONG 500-MB SPEED  
MAX OVER NORTHWEST MEXICO WILL MOVE DOWNSTREAM AND STRENGTHEN FROM  
THE SOUTHERN PLAINS TO THE MID-MS AND LOWER OH VALLEYS, LIKELY  
EXCEEDING 100+ KT BY TUESDAY EVENING.  SUBSEQUENT STRENGTHENING OF A  
BROAD SOUTHWESTERLY LOW-LEVEL JET WILL ALLOW MOISTURE TO SPREAD  
POLEWARD ACROSS THE WARM SECTOR, WITH A LARGE AREA OF PRECIPITABLE  
WATER VALUES EXCEEDING 1-1.25 INCHES SPREADING ACROSS MUCH OF THE  
EASTERN HALF OF THE UNITED STATES THIS FORECAST PERIOD.  
  
AT THE SURFACE, AN AREA OF LOW PRESSURE SHOULD TRACK FROM THE  
VICINITY OF THE NE/IA BORDER TO THE IL/WI BORDER BY 01/00Z, AND THEN  
ACROSS LOWER MI TO SOUTHWEST ONTARIO.  A TRAILING COLD FRONT WILL  
ADVANCE EAST FROM THE CENTRAL PLAINS INTO THE MIDDLE MS AND LOWER OH  
VALLEYS, WHILE A SECOND DEEPENING AREA OF LOW PRESSURE TRACKS ALONG  
THIS BOUNDARY FROM OK TUESDAY AFTERNOON TO CENTRAL IL AND LOWER MI  
TUESDAY NIGHT.  CONCURRENTLY, A WARM FRONT WILL ADVANCE NORTHWARD  
THROUGH THE OH AND UPPER TN VALLEYS.  
   
..OHIO AND TENNESSEE VALLEYS TUESDAY MORNING AND AFTERNOON  
  
DESPITE THE LACK OF HEIGHT FALLS DURING THE FIRST HALF OF THE  
FORECAST PERIOD, FORCING FOR ASCENT ATTENDANT TO A WEAK TRANSIENT  
MIDLEVEL IMPULSE TRACKING ACROSS THIS REGION AND LOW-LEVEL WARM AIR  
ADVECTION SUGGESTS AN ONGOING CLUSTER AND/OR NEW THUNDERSTORM  
DEVELOPMENT WILL SPREAD FROM WEST TO EAST.  THE EASTERN EXTENT OF A  
PLUME OF STEEP MIDLEVEL LAPSE RATES SPREADING EAST ATOP LOW-LEVEL  
MOISTENING SHOULD PROVE FAVORABLE FOR MAINLY ELEVATED STORMS WITH  
HAIL BEING THE PRIMARY THREAT.  HOWEVER, FORECAST SOUNDINGS SUGGEST  
SOME POTENTIAL FOR A FEW SURFACE-BASED STORMS, ESPECIALLY BY TUESDAY  
AFTERNOON ACROSS PARTS OF NORTHERN AL THROUGH MIDDLE TN AND EASTERN  
KY.  VERTICALLY VEERING WINDS SUGGEST A TORNADO AND LOCALLY STRONG  
WIND GUSTS CANNOT BE RULED OUT WITH THESE AFTERNOON STORMS.  
  
..ARKLATEX/EASTERN OK NORTHEASTWARD INTO THE MID MS AND OH VALLEYS  
TUESDAY AFTERNOON THROUGH TUESDAY NIGHT...  
  
CONSENSUS OF DETERMINISTIC AND CONVECTIVE ALLOWING MODELS SUGGEST  
THERE WILL BE THE POTENTIAL FOR SEVERAL ZONES OF STORM DEVELOPMENT  
LATE TUESDAY AFTERNOON THROUGH TUESDAY EVENING ACROSS THE FULL  
EXTENT OF THE SEVERE RISK AREAS FROM ALONG THE COLD FRONT WITH  
NORTHWARD EXTENT TO ALONG LOW-LEVEL CONFLUENCE ZONES FARTHER SOUTH.   
GIVEN THE 12Z ESRL HRRR AND 12Z NAM 4KM SUGGESTING A BROKEN BAND OF  
DISCRETE STORMS DEVELOPING FROM EAST-CENTRAL MO INTO CENTRAL AND  
NORTHEAST IL, THE ENHANCED SEVERE RISK AREA HAS BEEN EXPANDED NORTH  
ACROSS TO NOW INCLUDE MORE OF EASTERN MO AND INTO CENTRAL IL, WITH A  
NORTHWARD EXPANSION OF THE SLIGHT AND MARGINAL RISKS AS WELL.   
MODERATE INSTABILITY AND STRENGTHENING DEEP-LAYER AND LOW-LEVEL  
SHEAR WILL FAVOR ALL SEVERE HAZARDS, WITH SOME INDICATION FOR A  
STRONG TORNADO THREAT FROM PARTS OF AR TO SOUTHERN IL ALONG A  
STRENGTHENING LOW-LEVEL JET ENHANCING HODOGRAPH CURVATURE.  THE  
POTENTIAL EXISTS FOR STORMS TO EVOLVE INTO A QLCS TUESDAY EVENING  
FROM MISSOURI INTO THE LOWER OH VALLEY, WITH DAMAGING WINDS AND  
MESO-VORTICITY TORNADOES BEING THE PRIMARY THREATS.  
  
FARTHER NORTH, A MARGINAL RISK FOR SEVERE STORMS MAY DEVELOP AND  
AFFECT PARTS OF EAST-CENTRAL IA AND SOUTHEAST WI TUESDAY AFTERNOON  
AND EVENING, WITH THE MARGINAL RISK EXPANDED NORTH TO NOW INCLUDE  
THESE AREAS.  
  

[Derecho!]

Hope this thread gets going and people move.

God how I hate the regional sub-forums, terrible for widespread severe wx and tropical (only really makes sense for snow events).  I don't live near the event but am following with interest.  

[nrgjeff]

Event covers at least 3 sub-forums, so good idea to put it on the Main Board. 12Z Monday Euro and NAM Para have a little more backed 925 mb winds Tue night early Wed. Mid-South may face an overnight tornado threat from Arkansas through southeast Missouri all the way to southern maybe central Illinois. Then on Wednesday upper winds continue to strengthen all levels, but more veered off low-levels. Could be QLCS time for the Tennessee Valley or parts of the interior Deep South. Wind fields are impressive with the system. Main cyclone ejects to the Great Lakes, but that Southern jet energy supports Dixie Alley severe.

[Hoosier]

12 minutes ago, Derecho! said:

Hope this thread gets going and people move.

God how I hate the regional sub-forums, terrible for widespread severe wx and tropical (only really makes sense for snow events).  I don't live near the event but am following with interest.  

I disagree a bit.  Severe does seem to have more of a niche following but I'm not sure how this event is that much different than a moderate sized snowstorm from the Carolinas to New England.  There are similar issues with subforums in that case for those who want to see what's going on in other areas.

We have had some severe threads in the main forum before, but usually it's been reserved for the big boy events.  One way to solve this issue about where to post for widespread events would be to have a separate severe forum (like the tropical forum) but it hasn't been discussed lately.  

[janetjanet998]

22 minutes ago, Hoosier said:

I disagree a bit.  Severe does seem to have more of a niche following but I'm not sure how this event is that much different than a moderate sized snowstorm from the Carolinas to New England.  There are similar issues with subforums in that case for those who want to see what's going on in other areas.

We have had some severe threads in the main forum before, but usually it's been reserved for the big boy events.  One way to solve this issue about where to post for widespread events would be to have a separate severe forum (like the tropical forum) but it hasn't been discussed lately.  

Last Sunday was a nightmare...although the storms were in a rather small area it covered 3-4 subforums within a 50 mile radius or whatever

Of course you had some people in the active Mid Atlantic forum complaining about someone posting a tornado on the ground in PA just north of them... the correct forum was rather dead(update NY/PA)  but be careful once that cell crosses over a magic line you better be posting in the  Philly forum.....

so in this case you have a potential widespread event over 4 subforums central/western. OHIO valley, TN Valley and SE...perhaps all at or close to the same time....

There are several of us that follow severe weather no matter where it is and its silly to jump around and follow/post multiple subforums at once 

not sure what the answer is..perhaps the severe subforum idea..or a "NOWCAST" thread in the main forum once an event in underway?

 

 

 

[Quincy]

Greatest multi-model confidence zeroes in on the Arkansas vicinity, particularly with moderate instability and a juiced airmass with dew-points progged into the 60s.

The NCAR ensembles have two clusters, the first of which focuses on the Arkansas area. The second and somewhat less consistent is over Illinois. Although CAM solutions vary on initiation, there's a signal in virtually all the models for a convergence zone from central AR into southeastern MO, where at least a couple of cells should be able to mature.

There are many details to pin down, but I think it's safe to say that some significant severe supercells/clusters are probable, somewhere from AR/Ozarks into the middle Mississippi Valley. Can't discount the threat for significant wind with line(s) and/or QLCS segments into the night ahead of the cold front.  

A broad area is under the threat, but we may still only have a few isolated significant storms. Although large scale forcing appears modest immediately following peak heating, this is a case where that's not necessarily a negative, especially with respect to a more discrete storm mode.

[Thundersnow12]

Another thread that shouldn't of been started...

perfectly fine and covered in the sub forums. 

[Quincy]

5 minutes ago, Thundersnow12 said:

Another thread that shouldn't of been started...

perfectly fine and covered in the sub forums. 

I don't see the harm in it. Keep localized discussions in the sub-forums, but this is a fairly broad threat and I was finding trouble deciding where to post. (without sounding too repetitive or skimming over non-local details) This is an ENH risk that covers at least three subforums and seven states, with 13 states under a SLGT risk.

[Jim Martin]

North of Paducah, Kentucky tomorrow night off the 18z NAM.

[MattPetrulli]

Parameters are there. Question is, do storms fire? NAM doesn't fire anything but global models do. 

[janetjanet998]

18z NAM still being stubborn with convection over AR Tuesday afternoon/evening

[janetjanet998]

18z GFS still has storms developing over AR around 23z and moves them NE overnight and also has less of a threat in northern/central IL then the NAM

hoe can two models be so different 24-30 hour out....00z may clear it up some

[Derecho!]

3 hours ago, janetjanet998 said:

Last Sunday was a nightmare...although the storms were in a rather small area it covered 3-4 subforums within a 50 mile radius or whatever

Of course you had some people in the active Mid Atlantic forum complaining about someone posting a tornado on the ground in PA just north of them... the correct forum was rather dead(update NY/PA)  but be careful once that cell crosses over a magic line you better be posting in the  Philly forum.....

so in this case you have a potential widespread event over 4 subforums central/western. OHIO valley, TN Valley and SE...perhaps all at or close to the same time....

There are several of us that follow severe weather no matter where it is and its silly to jump around and follow/post multiple subforums at once 

not sure what the answer is..perhaps the severe subforum idea..or a "NOWCAST" thread in the main forum once an event in underway?

 

 

 

I blame the whole subforum business and the some of the subforum-nazi-police business on the snow weenies - they get enraged at having to have their eyes contaminated by discussion of any Wx or future Wx that isn't literally their backyard. 

One of the reasons I rarely post or read here anymore is the subforums. I personally don't really care about my day to day weather, whether the local NWS office busted 3 degrees low on the temp forecast yesterday, and I only care about snow if it is a significant (8+ inch) event.  I am interested in wherever in the country or world the weather is most interesting. 

I much more enjoyed the very active single main forums of EasternWx or even Wright-Weather. 

This event neatly splits 4 subforums and you completely lose the synergy of the redtaggers in each commenting on the same event to each other. 

To make this work I'd support the mods shutting down the regional threads on this, actually. 

[janetjanet998]

00z NAM caving a little and develops some convection over northern AR around 00z

also 00z NAM and 00z RAP mix out western and Northern MO and drop dews into the upper 30's and 40's ......dry line forming?

[janetjanet998]

4km NAM has two segments  of storms 

the lead one moving over SE MO..SIL and into IND will be likely tornado supercells...moving very fast

[janetjanet998]

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1139 PM CST MON FEB 27 2017  
  
VALID 281200Z - 011200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM AR TO  
IL/IN...  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN OK TO  
OH...  
  
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST  
TX TO WESTERN PA...  
   
..SUMMARY  
  
SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP FROM PORTIONS OF THE  
LOWER MISSISSIPPI VALLEY TO THE OHIO VALLEY TUESDAY.  LARGE HAIL,  
DAMAGING WINDS, AND A FEW STRONG TORNADOES ARE POSSIBLE.  
   
..DISCUSSION  
  
RIDGING APPEARS TO BE RESPONSIBLE FOR DELAYING MEANINGFUL CONVECTION  
ACROSS THE MS VALLEY LATE THIS EVENING.  HOWEVER, LLJ IS BEGINNING  
TO INCREASE ACROSS MO/IL AND ISOLATED THUNDERSTORMS ARE EVOLVING  
WITHIN A CORRIDOR FROM THE BOOTHEEL OF MO INTO CENTRAL IL.  THIS  
ACTIVITY SHOULD GRADUALLY EXPAND IN AREAL COVERAGE AS WARM ADVECTION  
LIFTS NORTH TOWARD THE GREAT LAKES REGION.  GIVEN THESE TRENDS,  
THERE IS INCREASING CONFIDENCE THAT MUCH OF THE SOUTHERN  
PLAINS/LOWER MS VALLEY WILL REMAIN CONVECTION-FREE INTO THE  
AFTERNOON HOURS.  AS A RESULT, SIGNIFICANT BOUNDARY-LAYER RECOVERY  
IS EXPECTED INTO THE OH VALLEY PRIOR TO FRONTAL PASSAGE.  
  
LATE EVENING MODEL GUIDANCE CONTINUES TO SUGGEST A CORRIDOR OF  
STRONG SOUTHWESTERLY FLOW ALOFT WILL EXTEND FROM THE SOUTHERN  
ROCKIES, INTO THE GREAT LAKES WITH 500MB FLOW EXPECTED TO INCREASE  
IN EXCESS OF 80KT BY EARLY AFTERNOON ACROSS WESTERN PORTIONS OF THE  
SEVERE RISK AREA.  LARGE-SCALE HEIGHT FALLS WILL OVERSPREAD THE  
MISSISSIPPI VALLEY AND SEVERAL CONVECTIVE SCENARIOS MAY ULTIMATELY  
EVOLVE WITHIN A BROAD MOISTENING WARM SECTOR.  
  
1.  WARM-ADVECTION CORRIDOR (NORTHERN IL):  
  
STRENGTHENING LLJ OVER IL WILL AID NORTHWARD ADVANCE OF HIGHER  
QUALITY AIR MASS AS SURFACE DEW POINTS RISE THROUGH THE 40S INTO THE  
50S AS FAR NORTH AS NORTHERN IL BY LATE MORNING.  WARM ADVECTION IS  
EXPECTED TO INDUCE SCATTERED STRONG/SEVERE THUNDERSTORMS EARLY IN  
THE PERIOD AS WARM FRONT LIFTS NORTHWARD IN ADVANCE OF THE PRIMARY  
SURFACE WAVE.  CONVECTION MAY BE AIDED BY A WEAK MID-LEVEL  
DISTURBANCE EMBEDDED WITHIN THE STRONGER SOUTHWESTERLY FLOW.   
INITIAL ACTIVITY WILL BE ELEVATED IN NATURE AND HAIL IS THE PRIMARY  
RISK WITH THESE STORMS.  
  
2.  WARM SECTOR (AR/MO/IL):  
  
28/00Z SOUNDING FROM OUN EXHIBITED A STEEP-LAPSE-RATE ENVIRONMENT  
WITH SUBSTANTIAL LOW-LEVEL MOISTURE.  STRONG CAPPING AND  
NEUTRAL-WEAK SUBSIDENCE WILL ALLOW THIS AIR MASS TO ADVECT NORTHEAST  
SUCH THAT SURFACE DEW POINTS SHOULD RISE INTO THE LOWER 60S ACROSS  
MUCH OF THE WARM SECTOR SOUTH OF I-70.  BREAKS IN CLOUD COVER DURING  
THE DAY SHOULD ALLOW SURFACE PARCELS TO APPROACH THEIR CONVECTIVE  
TEMPERATURES FROM EASTERN OK INTO SOUTHWESTERN MO BY MID-LATE  
AFTERNOON.  LATEST THINKING IS ISOLATED SUPERCELLS MAY EVOLVE WELL  
AHEAD OF THE COLD FRONT ALONG NOSE OF A SECONDARY BRANCH OF LLJ THAT  
WILL STRENGTHENING ACROSS AR DURING THE DAY.  IT'S NOT CLEAR HOW  
MUCH STORM COVERAGE WILL BE NOTED ACROSS THIS REGION BUT  
ENVIRONMENTAL SHEAR AND INCREASING INSTABILITY/BUOYANCY FAVOR ROBUST  
SUPERCELLS.  FORECAST SOUNDINGS SUGGEST VERY LARGE HAIL COULD  
ACCOMPANY THIS ACTIVITY AND A FEW STRONG TORNADOES ARE POSSIBLE,  
ESPECIALLY IF DISCRETE STRUCTURES EVOLVE AS IT APPEARS THEY MAY.  
  
3.  COLD FRONT:  
  
LARGE-SCALE FORCING WILL CONTRIBUTE TO A CONVECTIVELY ACTIVE COLD  
FRONT BY EARLY EVENING AS THE WIND SHIFT SURGES INTO AN INCREASINGLY  
MOIST/UNSTABLE AIR MASS FROM EASTERN IA INTO NORTHERN MO.   
THUNDERSTORMS ARE EXPECTED TO MATURE INTO A STRONG SQUALL LINE THAT  
WILL SURGE EAST ACROSS THE MID MS VALLEY INTO THE OH VALLEY AS 500MB  
FLOW INCREASES TO NEAR 100KT BY 01/12Z.  DAMAGING WINDS SHOULD BE  
NOTED WITH THIS FRONTAL CONVECTION AND TORNADOES MAY ALSO BE  
EMBEDDED ALONG THE LINE.  EASTWARD MOMENTUM SHOULD EASILY ALLOW THIS  
ACTIVITY TO SPREAD ACROSS MUCH OF OH BY SUNRISE WEDNESDAY MORNING. 

[janetjanet998]

AY 2 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0100 AM CST TUE FEB 28 2017  
  
VALID 011200Z - 021200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF  
MISSISSIPPI AND ALABAMA NORTHEASTWARD INTO EASTERN KENTUCKY AND THE  
UPPER OHIO VALLEY...  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER  
MISSISSIPPI VALLEY NORTHEASTWARD INTO THE OHIO VALLEY AND WESTERN  
CAROLINAS AND NORTHWARD INTO THE MID-ATLANTIC STATES AND INTO NEW  
JERSEY AND PENNSYLVANIA...  
  
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE  
SLIGHT RISK...  
   
..SUMMARY  
  
STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE FROM THE LOWER  
MISSISSIPPI VALLEY NORTHEASTWARD ACROSS THE TENNESSEE VALLEY AND  
SOUTHERN APPALACHIANS, AND NORTHWARD INTO PARTS OF THE MID-ATLANTIC  
STATES AND INTO PORTIONS OF THE NORTHEAST.  DAMAGING WINDS ARE  
FORECAST TO BE THE PREDOMINANT SEVERE HAZARD.  
   
..SYNOPSIS  
  
A LARGE-SCALE MID-LEVEL TROUGH AXIS OVER THE CENTRAL STATES WILL  
MOVE EASTWARD INTO THE LOWER GREAT LAKES/MID-ATLANTIC STATES.  A  
100+ KT 500-MB SPEED MAX WILL TRANSLATE GENERALLY EASTWARD FROM THE  
OH VALLEY THROUGH NEW ENGLAND AND THE MID-ATLANTIC REGION DURING THE  
PERIOD.  IN THE LOW LEVELS, A SURFACE LOW IS FORECAST TO DEVELOP  
NORTHEASTWARD FROM NEAR DETROIT TO NORTHERN PARTS OF NEW ENGLAND  
WEDNESDAY NIGHT AS A WARM FRONT ADVANCES NORTHWARD ACROSS MUCH OF  
THE NORTHEASTERN U.S.  A COLD FRONT INITIALLY OVER THE OH VALLEY  
EXTENDING SOUTH-SOUTHWESTWARD INTO THE LOWER MS VALLEY WILL SWEEP  
EASTWARD ACROSS MUCH OF THE EASTERN U.S. BY EARLY THURSDAY MORNING.   
  
...NORTHERN PARTS OF AL/MS NORTHEASTWARD INTO THE CENTRAL  
APPALACHIANS AND MID-ATLANTIC STATES...  
A SQUALL LINE WILL LIKELY BE ONGOING WEDNESDAY MORNING ACROSS THE OH  
VALLEY WITH SOME POSSIBLE BREAKS AND LOWER STORM COVERAGE FARTHER  
SOUTH INTO THE LOWER MS VALLEY.  A RISK FOR DAMAGING WINDS WILL  
ACCOMPANY THE CONVECTIVE LINE AS A PLUME OF LOW-LEVEL MOISTURE  
--FEATURING SURFACE DEWPOINTS RANGING FROM AROUND 60 DEGREES F AT  
THE OH RIVER TO THE MIDDLE 60S IN MS/AL-- CONTRIBUTES TO 500-1000  
J/KG MUCAPE AHEAD OF THE COLD FRONT. ALTHOUGH SOME SLIGHT TIMING  
DIFFERENCES STILL EXIST IN THE MODELS, FAVORING A TIMING SOLUTION  
SIMILAR TO THE ECMWF/CMC.    
  
A STRONG DEEP-LAYER WIND FIELD OF SOUTHWESTERLY FLOW FROM 50-60 KT  
AT 850 MB AND INCREASING WITH HEIGHT TO 70-100 KT IN THE MIDLEVELS,  
WILL AID IN THE POTENTIAL RISK FOR WIDESPREAD WIND DAMAGE ASSOCIATED  
WITH A SQUALL LINE AND OTHER LINEARLY ORGANIZED STORM CLUSTERS.   
SOME TORNADO RISK MAY DEVELOP AS WELL WITH MATURE LINEAR BANDS  
(SHORT-LIVED QLCS VARIETY) OR WHERE GREATER DESTABILIZATION OCCURS.   
UNCERTAINTY REMAINS REGARDING DESTABILIZATION TO THE EAST OF THE  
MOUNTAINS IN THE MID-ATLANTIC REGION.  WILL DEFER ADDING HIGHER  
SEVERE PROBABILITIES FOR THIS AREA FOR THE TIME BEING.    
  
THE ACTIVITY WILL PUSH EAST OF THE APPALACHIANS BY EARLY EVENING AND  
ENCOUNTER GRADUALLY DECREASING BUOYANCY IN PART DUE TO THE LOSS OF  
HEATING AND DEEPER INLAND MIXING FROM SOUTHERN GA NORTHEASTWARD  
ALONG THE CAROLINA COASTAL PLAIN.  AS A RESULT, THERE WILL LIKELY BE  
A CORRESPONDING DECREASE IN THE POTENTIAL FOR DAMAGING WINDS FARTHER  
SOUTH IN PARTS OF THE SOUTHEAST.  
   
..NORTHERN PA INTO NY AND SOUTHERN NEW ENGLAND  
  
STRONG LOW-LEVEL MOISTURE/WARM-AIR-ADVECTION INTO THIS AREA WILL  
LEAD TO WEAK DESTABILIZATION AHEAD OF THE COLD FRONT.  MODELS VARY  
ON THE DEGREE OF DESTABILIZATION LEADING TO UNCERTAINTY REGARDING  
COVERAGE OF STRONG/SEVERE STORMS.  VERY STRONG LOW- TO  
MID-TROPOSPHERIC FLOW COUPLED WITH SEVERAL HUNDRED SBCAPE MAY RESULT  
IN SOME OF THE STRONGER STORMS OR A CONVECTIVE LINE TO POTENTIALLY  
BE CAPABLE OF A RISK FOR PRIMARILY DAMAGING WINDS.  

[Jim Marusak]

looking d2 for a minute, have to admit in the northern part of the slight risk area in PA/NJ/LI/MD/DE, there are some decent similarities between Saturday's event that yielded a few twisters ahead of the main squall line and this one for Wednesday. The big questions though will be, will the first squall line developing tonight in the moderate and enhanced risk areas actually hold up overnight into central PA in the morning? if so will they lay any type of boundaries down that could be used as foci for rotating storms later on from the frontal squall line? and 3, given that it will be more a low-top/high dynamics environment, could all of this over-dynamicize the environment leading to pre-frontal band storms tearing themselves apart instead of holding together?

[Jim Martin]

Impressive amount of hail/wind/tornado reports from this particular severe weather episode.

[Hoosier]

To get several EF3+ tornadoes north of the Ohio River prior to March (granted it was the last day of Feb) is pretty impressive.