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October 24-27, 2022 | Winter Storm Northern Plains and Severe Threat Southern Plains


StLweatherjunkie

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  • Meteorologist

5% tornado issued for Monday and Tuesday. Sounds like it's primarily a squall line event, no warm sector storms suggested.

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Day 1 says primary severe threat is going to be after dark. Not surprising in this case.

   
..SOUTHERN PLAINS  
  
A SQUALL LINE SHOULD DEVELOP ALONG/AHEAD OF THE SURFACE COLD FRONT  
AT THE START OF THE PERIOD (12Z), FROM CENTRAL OK TO WEST-CENTRAL  
TX. 00Z OBSERVED SOUNDINGS ACROSS SOUTHERN TX DEPICT UPPER 60S TO  
LOW 70S F DEWPOINTS IN PLACE, AND THIS MOISTURE IS EXPECTED TO  
ADVECT NORTHWARD TOWARD THE RED RIVER THROUGH THE DAY AS THE SQUALL  
LINE AND COLD FRONT ADVANCE EASTWARD. 5-6 C/KM TROPOSPHERIC LAPSE  
RATES WILL OVERSPREAD THE RICH LOW-LEVEL MOISTURE, CONTRIBUTING TO  
TALL, THIN MLCAPE ROUGHLY IN THE 750-1000 J/KG RANGE. THOUGH  
BUOYANCY IS MEAGER, RAPID STRENGTHENING OF THE WINDS WITH HEIGHT  
WILL CONTRIBUTE TO ELONGATED HODOGRAPHS AND 40-50 KTS OF EFFECTIVE  
BULK SHEAR. AS SUCH, SOME STRENGTHENING OF THE SQUALL LINE APPEARS  
LIKELY BY EARLY AFTERNOON, ESPECIALLY ACROSS TX, WITH DAMAGING GUSTS  
THE MAIN THREAT.  
  
BY LATE AFTERNOON, SURFACE LOW DEVELOPMENT IS LIKELY ACROSS WESTERN  
TX, AND THIS LOW SHOULD EJECT INTO THE LOWER MS VALLEY BY LATE  
EVENING AS A STRONG EMBEDDED MID-LEVEL IMPULSE OVERSPREADS TX.  
RE-INVIGORATION OF THE SQUALL LINE IS EXPECTED, ALONG WITH SOME  
BACKING OF THE SURFACE WINDS NOTED ACROSS CENTRAL AND EASTERN TX.  
SIZEABLE CURVED HODOGRAPHS AMID MODEST BUOYANCY MAY SUPPORT A FEW  
TRANSIENT SUPERCELLS IMMEDIATELY AHEAD OR EMBEDDED WITHIN THE SQUALL  
LINE AND A COUPLE OF TORNADOES ARE POSSIBLE, ESPECIALLY ACROSS  
EAST-CENTRAL INTO SOUTHEAST TX AFTER 00Z.  

 

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Day 2

DAY 2 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1248 AM CDT MON OCT 24 2022  
  
VALID 251200Z - 261200Z  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER MS  
VALLEY/MID-SOUTH INTO THE SOUTHEAST STATES...  
   
..SUMMARY  
  
STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED FROM THE LOWER  
MISSISSIPPI VALLEY/MID-SOUTH ACROSS THE SOUTHEAST STATES ON TUESDAY.  
   
..SYNOPSIS  
  
A COMPACT BUT INTENSE SHORTWAVE TROUGH IS FORECAST TO MOVE QUICKLY  
NORTHEASTWARD FROM THE SOUTHERN PLAINS THROUGH THE MID-SOUTH AND  
INTO THE LOWER OH VALLEY ON TUESDAY. STRONG MID-LEVEL FLOW WILL  
ACCOMPANY THIS SHORTWAVE, WITH 80+ KT OF 500-MB FLOW EXPECTED TO  
SPREAD ACROSS THE MID-SOUTH/LOWER MS VALLEY TUESDAY MORNING AND INTO  
THE TN VALLEY BY TUESDAY AFTERNOON.  
  
SURFACE LOW ATTENDANT TO THIS SHORTWAVE IS EXPECTED TO BEGIN THE  
PERIOD OVER AR BEFORE MOVING NORTHEASTWARD THROUGHOUT THE DAY. THIS  
LOW WILL LIKELY REACH THE MIDDLE OH VALLEY BY EARLY WEDNESDAY  
MORNING. AN ASSOCIATED COLD FRONT WILL MOVE EASTWARD ACROSS THE  
LOWER MS VALLEY/MID-SOUTH, TN VALLEY, AND MUCH OF SOUTHEAST DURING  
THE PERIOD. A LINE OF STRONG TO SEVERE THUNDERSTORMS IS ANTICIPATED  
ALONG THIS FRONT AS IT PROGRESSES EASTWARD.  
   
..LOWER MS VALLEY/MID-SOUTH INTO THE AL AND MS  
  
RECENT GUIDANCE HAS TRENDED TOWARDS SLIGHTLY HIGHER DEWPOINTS WITHIN  
THE AIR MASS IMMEDIATELY AHEAD OF THE FRONT, WITH MOSTLY UPPER 60S  
NOW FORECAST ACROSS SOUTHERN MS AND SOUTHWEST AL AND MID-60S ACROSS  
THE REMAINDER OF MS AND AL. TWO SCENARIOS APPEAR POSSIBLE FOR  
CONVECTIVE LINE THAT IS EXPECTED TO BE ONGOING ALONG THE FRONT EARLY  
TUESDAY. ONE SCENARIO IS FOR THE LINE TO BE NEAR MAX STRENGTH EARLY  
TUESDAY MORNING AS IT MOVES ACROSS THE LOWER MS VALLEY/MID-SOUTH,  
GRADUALLY WEAKENING THROUGHOUT THE DAY. THE OTHER SCENARIO, WHICH IS  
SUGGESTED BY MOST OF THE RECENT CONVECTION-ALLOWING GUIDANCE,  
FORECASTS THAT THE LINE WILL BE RATHER WEAK EARLY TUESDAY BEFORE  
THEN REINVIGORATING AS IT MOVES EASTWARD THROUGHOUT THE DAY. GIVEN  
THE TREND FOR MORE LOW-LEVEL MOISTURE AND BUOYANCY AHEAD OF THE  
FRONT ACROSS MS AND AL, THE SECOND SCENARIO IS FAVORED, MERITING THE  
EXPANSION OF SLIGHT-RISK-EQUIVALENT PROBABILITIES INTO MORE OF AL.   
  
DAMAGING GUSTS WILL BE THE PRIMARY THREAT ALONG THE LINE, BUT STRONG  
VEERING LOW-LEVEL PROFILES COULD RESULT IN LINE-EMBEDDED/QLCS  
TORNADOES AS WELL. THE HIGHEST TORNADO POTENTIAL CURRENTLY APPEARS  
TO EXIST FROM SOUTH-CENTRAL MS NORTHEASTWARD INTO WEST-CENTRAL AL  
WHERE THE BEST OVERLAP BETWEEN THE ENHANCED LOW/MID-LEVEL FLOW AND  
UPPER 60S DEWPOINTS OCCURS.  

 

Edited by ClicheVortex2014
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  • Meteorologist

Here we go

image.png.002fa33d37fb90f0b3108be317741b57.png

 Mesoscale Discussion 1893
   NWS Storm Prediction Center Norman OK
   0648 PM CDT Mon Oct 24 2022

   Areas affected...portions of central Texas

   Concerning...Severe potential...Watch likely 

   Valid 242348Z - 250145Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The severe threat is expected to increase across portions
   of central Texas over the next few hours. Damaging gusts are the
   main threat, but a couple of tornadoes are also possible, especially
   along an outflow boundary. A WW issuance may be needed soon.

   DISCUSSION...Latest surface observations and regional radar loops
   depict a nearly stationary surface boundary remnant from earlier
   convection, which delineates a moderately unstable surface-based
   airmass to the south and a weakly buoyant, mainly elevated airmass
   farther north. This boundary is oriented west-to-east along a LZZ to
   OCH line, with near 80F surface temperatures and 68-70 F dewpoints
   located along the boundary. Though low- and mid-level lapse rates
   are only around 5.5-6.5 C/km, the rich low-level moisture is
   contributing up to 2000 J/kg MLCAPE. Southeasterly 10-20 kt flow
   along the boundary quickly veers to southwesterly with height. Both
   regional VADs and RAP forecast soundings depict large, curved
   low-level hodographs, and 23Z mesoanalysis shows up to 200 m2/s2
   effective SRH already developing in the warm sector. As the LLJ
   strengthens this evening, low-level shear should intensify further
   across central TX.

   Current thinking is that storms in the Menard and Mason County areas
   should intensify as they move deeper into the instability axis and
   low-level shear strengthens. The storms may start off as transient
   supercellular before strong frontogenetic forcing encourages more
   linear segments. Either way, damaging gusts are the main threat, but
   a couple of tornadoes are possible, both with any semi-discrete
   storms or QLCS segments. The greatest overall severe threat and the
   best chance for a tornado will be with any storms that can interact
   favorably with the boundary.

 

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  • Meteorologist
5 minutes ago, Iceresistance said:

Got reports of a Semi Overturned with cars in the ditch along I-35 near Jarrell, this is likely from a Tornado.

Could still be damaging winds, assuming they were all blown in the same direction. But yeah, it certainly could've been a tornado based on velocity and reflectivity signatures.

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  • Meteorologist

Plenty of low-level shear tomorrow for this squall. Also gotta watch closer to the Gulf coast for stronger instability and higher likelihood for (semi-?)discrete cells. Otherwise, there should be a sweet spot where low-level shear and cape are the most balanced and tornadoes are most likely. However, I think most of that squall could get a tornado warning.

Seems like SPC got it right... no surprise

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image.thumb.png.505c4f1b8ef17855f659596dbdec4c00.png

image.png.256c5720fdb38606f428a1cb851b7cdf.png

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  • Meteorologist

Fairly large slight risk for tornadoes for this time of year. I'm fully expecting to lose power tomorrow for several hours because it apparently doesn't take much.

image.thumb.png.99f1aa349a4467b6ffefb05633e1a0f5.png

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   WESTERN TENNESSEE INTO MISSISSIPPI AND CENTRAL ALABAMA...

   ...SUMMARY...
   Strong to severe thunderstorms are likely from the Lower Mississippi
   Valley into the Southeast States today. Damaging gusts and tornadoes
   will be possible.

   ...Synopsis...
   A negatively tilted mid-level shortwave trough will progress across
   the Lower Mississippi Valley as a 1002 mb surface low tracks from
   northern Arkansas to the Ohio Valley today. Adequate moisture and
   associated instability will advect ahead of the surface low across
   portions of the Southeast into the Tennessee Valley to support
   scattered to widespread strong thunderstorms. An organized severe
   threat may materialize across the Southeast where the stronger
   buoyancy and shear are expected to overlap.

   ...Portions of the Southeast into the TN Valley...
   Widespread clouds and precipitation are expected to precede the
   surface low and cold front at the start of the period. While the
   overall lack of insolation will hamper more robust buoyancy from
   materializing, mid to upper 60s F dewpoints should advect northward
   to the TN border through the afternoon, promoting 500-1000 J/kg of
   tall, thin MLCAPE (given 6 C/km mid-level lapse rates). Buoyancy
   should diminish with northward extent toward the OH Valley. A squall
   line should be ongoing at the start of the period across the
   Mid-South and is poised to move into a more unstable airmass across
   MS, AL and southwest TN by afternoon. In these areas, forecast
   soundings depict impressively sheared vertical profiles,
   characterized by long, largely curved hodographs with well over 50
   kts of effective bulk shear and 300-500 m2/s2 of effective SRH. As
   storms intensify within the squall line, QLCS mesovortices may
   develop, with tornadoes and severe gusts being the main concerns.
   Farther north into Middle TN and points northward, scant buoyancy
   should limit the severe threat to a sparse damaging gust and perhaps
   a brief tornado.

 

Edited by ClicheVortex2014
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