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March 1-3, 2023 | Severe Weather Outbreak


ElectricStorm

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SPC put up a MD for it

MD 222 graphic

Quote
Mesoscale Discussion 0222
   NWS Storm Prediction Center Norman OK
   1021 PM CST Wed Mar 01 2023

   Areas affected...South Texas

   Concerning...Severe potential...Watch unlikely 

   Valid 020421Z - 020615Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated severe storms -- capable of producing very large
   hail -- will be possible over the next few hours across parts of
   South Texas.  The very isolated nature of the expected convection
   may preclude the need for WW issuance.

   DISCUSSION...Latest radar loop shows that a large/lone supercell has
   developed over Zavala County in South Texas, and is moving into
   southwestern Frio County at this time.  The storm is occurring
   within a moderately unstable environment, where weak low-level flow
   but strong southwesterlies aloft are providing sufficient shear for
   this storm to acquire updraft rotation.  Latest MRMS MESH continues
   to show very large hail with this storm, as it moves eastward. 
   Though any more than very isolated/additional development appears
   unlikely, any storm across this area will be capable of producing
   very large/destructive hail, and possibly locally damaging wind
   gusts.

   ..Goss/Guyer.. 03/02/2023

 

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New day one is out, pretty strong wording

Quote
Given the high magnitudes of shear, at least a
   few sustained, strong tornadoes are likely and an intense (EF3+)
   tornado or two cannot be ruled out. One caveat which precludes the
   issuance of higher tornado-driven probabilities this outlook is the
   advection of warm 700 mb temperatures into the low-level jet axis
   during the evening, which may temper low-level updraft stretching
   and in turn, dampen tornado potential with a subset of storms that
   do occur. 

 

Edited by ElectricStorm
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  • Meteorologist

Surprised to see a mention of tornado-driven high risk... unless they're talking about the potential for extending the moderate risk further east.

As is usually the case... warm sector storms have the higher-end tornado potential but are very hard to predict. Gotta have confidence in that in order to get a high risk in this case imo. 

oLgnvcY.png

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1200 AM CST THU MAR 02 2023  
  
VALID 021200Z - 031200Z  
  
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF  
THE ARKLATEX...  
   
..SUMMARY  
  
A REGIONAL SEVERE-THUNDERSTORM OUTBREAK APPEARS LIKELY ACROSS PARTS  
OF THE SOUTHERN PLAINS INTO THE ARKLATEX AND ARKLAMISS REGIONS TODAY  
INTO TONIGHT. WIDESPREAD DAMAGING WINDS, LARGE HAIL, AND TORNADOES  
ARE ALL EXPECTED. A FEW LONG-LIVED, INTENSE TORNADOES ARE POSSIBLE.  
   
..SYNOPSIS  
  
A POTENT MID-LEVEL SHORTWAVE TROUGH WILL TRAVERSE THE SOUTHERN  
PLAINS TODAY AND APPROACH THE LOWER MS VALLEY TONIGHT WHILE A  
SURFACE LOW RAPIDLY INTENSIFIES OVER THE ARKLATEX. MULTIPLE ROUNDS  
OF SEVERE THUNDERSTORMS ARE EXPECTED THROUGH THE PERIOD, WITH AN  
INITIAL ROUND OF STORMS MOVING ACROSS THE ARKLATEX DURING THE LATE  
AFTERNOON AND A SECOND ROUND MOVING ACROSS THE ARKLATEX INTO THE  
LOWER MS VALLEY DURING THE NIGHT. AHEAD OF THE SURFACE LOW, AN  
INTENSIFYING LOW-LEVEL JET BENEATH UNSEASONABLY STRONG MID-LEVEL  
FLOW WILL PROMOTE VERY STRONG DEEP-LAYER ASCENT/SHEAR ATOP RICH  
LOW-LEVEL MOISTURE, ENCOURAGING SIGNIFICANT SEVERE WEATHER IN  
ASSOCIATION WITH BOTH ROUNDS OF STORMS. A REGIONAL SEVERE  
THUNDERSTORM OUTBREAK IS EXPECTED, INCLUDING THE POTENTIAL FOR  
DAMAGING TORNADOES.  
   
..CENTRAL TEXAS INTO THE MID-SOUTH - DAYTIME  
  
SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING AT THE START OF THE  
PERIOD ACROSS EASTERN TX INTO SOUTHERN AR, TOWARD NORTHERN AL ALONG  
A DIFFUSE EFFECTIVE WARM FRONT, DELINEATING THE NORTHWARD EXTENT OF  
THE WARM SECTOR. AS THE MID-LEVEL TROUGH TRAVERSES THE SOUTHERN  
ROCKIES, RAPID SURFACE CYCLOGENESIS SHOULD ENSUE ACROSS TX,  
SUPPORTING THE VIGOROUS NORTHWARD ADVECTION OF RICH LOW-LEVEL  
MOISTURE INTO EASTERN OK/AR. 7-8 C/KM MID-LEVEL LAPSE RATES WILL  
OVERSPREAD UPPER 60S F SURFACE DEWPOINTS, CONTRIBUTING TO 1500-2000  
J/KG MLCAPE ACROSS THE WARM SECTOR. DURING THE DAY, A 30+ KT  
LOW-LEVEL JET WILL BE SITUATED ACROSS THE SOUTHERN PLAINS,  
OVERSPREAD BY 50+ KT SOUTHWESTERLY MID-LEVEL FLOW, RESULTING IN  
WIDESPREAD 50-75 KT EFFECTIVE BULK SHEAR ACROSS THE WARM SECTOR.  
APPRECIABLE LOW-LEVEL SHEAR WILL ALSO BE PRESENT, WITH HODOGRAPHS  
GRADUALLY ELONGATING/CURVING THROUGHOUT THE DAY. WITH THE MID-LEVEL  
TROUGH/300 MB JET STREAK STILL LAGGING TO THE WEST, SOME QUESTIONS  
REMAIN IN TERMS OF HOW WIDESPREAD DIURNAL WARM-SECTOR COVERAGE WILL  
BE. NONETHELESS, THE EASTWARD ADVANCE OF A MERGING DRYLINE/PACIFIC  
FRONT WILL ENCOURAGE AT LEAST ISOLATED SUPERCELL STORMS DURING THE  
AFTERNOON INTO EARLY EVENING, WITH SUPERCELLS INITIATING ACROSS  
CENTRAL TX INTO SOUTHEAST OK, PROGRESSING EASTWARD INTO THE  
ARKLATEX. SEVERE GUSTS, LARGE HAIL (INCLUDING 2+ INCH STONES) AND  
TORNADOES ARE ALL POSSIBLE. ANY SUPERCELL THAT CAN BECOME SUSTAINED  
WITHIN THE WARM SECTOR MAY PRODUCE STRONG TORNADOES.  
   
..ARKLATEX INTO THE MID-SOUTH - NIGHTIME  
  
BY EVENING, THE MID-LEVEL TROUGH WILL BECOME NEGATIVELY TILTED AND  
WILL ACCELERATE TOWARD THE LOWER MS VALLEY, WITH THE SURFACE LOW  
ALSO EXPECTED TO UNDERGO RAPID INTENSIFICATION. IMPRESSIVE VERTICAL  
WIND PROFILES WILL DEVELOP AS A RESULT OF THE DEEP-LAYER MASS  
RESPONSE TO THE APPROACHING TROUGH, WITH A REGIONAL BUT VOLATILE  
SEVERE WEATHER SETUP TAKING PLACE. AS THE PACIFIC FRONT RAPIDLY  
ADVANCES EASTWARD INTO A BUOYANT AIRMASS (500-1500 J/KG MLCAPE,  
DRIVEN PRIMARILY BY UPPER 60S F SURFACE DEWPOINTS), SEVERAL STRONG  
TO SEVERE STORMS SHOULD INITIATE ALONG THE FRONT. AN INTENSE QLCS  
MAY DEVELOP, COMPRISED OF A MIX OF EMBEDDED SUPERCELLS AND  
POTENTIALLY LONG-LIVED MESO-GAMMA SCALE VORTICES. A 50-60 KT  
LOW-LEVEL JET OVERSPREAD BY 100+ KTS OF 500 MB FLOW WILL SUPPORT  
VERY LARGE/CURVED HODOGRAPHS AMID RESIDUAL SURFACE-BASED  
INSTABILITY. IN ADDITION TO WIDESPREAD SEVERE GUSTS, SEVERAL  
QLCS/POSSIBLE EMBEDDED SUPERCELL TORNADOES APPEAR LIKELY WITH THIS  
MAIN ROUND OF STORMS. GIVEN THE HIGH MAGNITUDES OF SHEAR, AT LEAST A  
FEW SUSTAINED, STRONG TORNADOES ARE LIKELY AND AN INTENSE (EF3+)  
TORNADO OR TWO CANNOT BE RULED OUT. ONE CAVEAT WHICH PRECLUDES THE  
ISSUANCE OF HIGHER TORNADO-DRIVEN PROBABILITIES THIS OUTLOOK IS THE  
ADVECTION OF WARM 700 MB TEMPERATURES INTO THE LOW-LEVEL JET AXIS  
DURING THE EVENING, WHICH MAY TEMPER LOW-LEVEL UPDRAFT STRETCHING  
AND IN TURN, DAMPEN TORNADO POTENTIAL WITH A SUBSET OF STORMS THAT  
DO OCCUR.   
  
THE QLCS MAY UNDERGO GRADUAL WEAKENING AFTER CROSSING THE MS RIVER  
AROUND 09Z. NONETHELESS, IMPRESSIVE LOW-LEVEL SHEAR PROFILES AND AT  
LEAST SOME SURFACE-BASED BUOYANCY (ALBEIT SCANT) SHOULD PRECEDE THE  
LINE, WITH AT LEAST SOME RISK OF DAMAGING GUSTS/LINE-EMBEDDED  
TORNADOES CONTINUING TOWARD THE END OF THE PERIOD.  

 

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Kinda interesting from ILN.

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.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Multiple impacts are expected from a very strong storm system
Friday/Friday night. Threats for heavy rain/flooding, strong
synoptic winds and severe weather all exist.

Looking at the details...a negatively tilted mid level shortwave
to eject from the Lower MS Valley thru the Ohio Valley Friday
and into the Great Lakes Friday night as 100-110 KT jet rotates
around the base of this trof. Very deep surface low to track
thru northwest Ohio late Friday afternoon and Friday evening.

In response to a 60-65KT low level jet ahead of this system --
widespread rain showers to overspread the area late tonight
into Friday morning. This widespread warm advection
precipitation shifts north thru the FA Friday.

Some of the hi resolution model solutions are showing a thin
ribbon of surface based instability advecting into northern
KY/Southern Ohio, Friday afternoon ahead of cold front. Given
the intense wind fields, if even marginal instability develops,
damaging winds will be possible -- with also the potential for
a few tornadoes. Some of the CAM solutions show favorable
updraft helicity with supercell storms Friday afternoon.

The pressure gradient tightens with strong winds outside of
storms and the potential for wind gusts of 50 to 55 mph Friday
afternoon into Friday evening.

A signal for heavy rain also exists with PW values of 1.2 to
1.4 inches which is 250-300 percent of normal. HREF mean QPF
showing values of 2 to 3 inches -- with the highest totals over
the west and southwest. Have issued a Flood watch from late
tonight through late Friday night for all but the far southeast.

Will continue to highlight the severe and wind potential in the
HWO product.

 

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