Jim Martin Posted December 16, 2016 Share Posted December 16, 2016 Once again, I am somewhat surprised no one has brought this up. It is looking like there will be a severe weather risk Saturday and Saturday Night across portions of the Southeast... Link to comment Share on other sites More sharing options...
downeastnc Posted December 16, 2016 Share Posted December 16, 2016 The LA/AR/MS/AL posters tend to post in the Central US or Tenn Valley forums, typically the SE forum is more GA/FL/SC/NC/VA/TN and some west Alabama folks..... Link to comment Share on other sites More sharing options...
Jim Martin Posted December 16, 2016 Author Share Posted December 16, 2016 Ah. Thank you. Link to comment Share on other sites More sharing options...
cbmclean Posted December 16, 2016 Share Posted December 16, 2016 9 hours ago, downeastnc said: The LA/AR/MS/AL posters tend to post in the Central US or Tenn Valley forums, typically the SE forum is more GA/FL/SC/NC/VA/TN and some west Alabama folks..... It even seems like most VA posts make it to the Middle-Atlantic Forum, and I don't see much from TN or FL. I do see some GA. Link to comment Share on other sites More sharing options...
andyhb Posted December 17, 2016 Share Posted December 17, 2016 There's not enough activity in the Tennessee Valley sub-forum to support individual threads. Growing a bit more interested in this thing with the high res guidance coming in. The NCAR ensemble has an appreciable amount of members with a window for discrete supercell development near the Mississippi River early this evening (possibly close to the Memphis area), which also well in tandem with the highest parameter overlap on the 03z SPC SREF. The vort max coming out of the SW looks impressive on WV and I wonder if the model guidance may be shearing it out a bit too quickly, which would portend slightly greater height falls and wind fields over the warm sector, perhaps coinciding with a meso low developing within the surface trough extending from the primary Great Lakes low. Certainly plenty of deep layer shear available and moisture looks to be a non-issue, going to depend if it all stays frontal and also if there are pockets of more southerly flow leading to stronger directional shear. Could be a sneaky event though. Link to comment Share on other sites More sharing options...
janetjanet998 Posted December 17, 2016 Share Posted December 17, 2016 ..THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT FOR THE MID SOUTH AND ARKLAMISS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM KY SOUTHWESTWARD TO EXTREME EAST TX... ..SUMMARY SEVERE STORMS ARE POSSIBLE LATE THIS AFTERNOON INTO TONIGHT ACROSS THE MID SOUTH AND ARKLAMISS. DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT, BUT A COUPLE OF TORNADOES AND ISOLATED LARGE HAIL WILL ALSO BE POSSIBLE THIS EVENING. ..MID SOUTH/ARKLAMISS THIS EVENING INTO TONIGHT A POSITIVE-TILT SHORTWAVE TROUGH OVER AZ THIS MORNING WILL TRANSLATE EASTWARD TO THE SOUTHERN HIGH PLAINS BY THIS AFTERNOON, AND THEN EAST-NORTHEASTWARD TO THE OH VALLEY OVERNIGHT. MEANWHILE, AN ASSOCIATED SURFACE COLD FRONT WILL PROGRESS SOUTHEASTWARD ACROSS THE SOUTHERN PLAINS/LOWER MS VALLEY/OH VALLEY BY LATE TONIGHT. A MARITIME TROPICAL AIR MASS, AS EVIDENCED BY THE LOWER 70S BOUNDARY LAYER DEWPOINTS ACROSS THE UPPER TX COAST, WILL CONTINUE TO SPREAD NORTHEASTWARD IN ADVANCE OF THE COLD FRONT. AT LEAST WEAK SURFACE-BASED BUOYANCY SHOULD DEVELOP AS FAR NORTHEAST AS PARTS OF WEST AND MIDDLE TN WITH THE NORTHEAST EXTENT OF THE MID 60S DEWPOINTS. THE BOUNDARY LAYER WILL BE CAPPED MUCH OF THE DAY BY THE RELATIVELY WARM BASE OF A STEEP LAPSE RATE LAYER NOTED IN 12Z SOUNDINGS AT CRP, FWD, SHV AND LZK. POCKETS OF SURFACE HEATING WILL BOOST MLCAPE VALUES TO 1000 J/KG OR A LITTLE GREATER ACROSS THE ARKLAMISS BY MID-LATE AFTERNOON. AS CONVECTIVE INHIBITION ERODES SLOWLY, SCATTERED THUNDERSTORM DEVELOPMENT IS EXPECTED BY 22-00Z ALONG AND IMMEDIATELY AHEAD OF THE COLD FRONT ACROSS THE MID SOUTH AND ARKLAMISS. THERE WILL BE SOME POTENTIAL FOR SEMI-DISCRETE STORMS FOR THE FIRST FEW HOURS, WITH STRONG LOW-LEVEL SHEAR (0-1 KM SRH OF 300 M2/S2 OR GREATER) AND EFFECTIVE BULK SHEAR NEAR 60 KT FAVORING SUPERCELL STRUCTURES AND SOME RISK FOR TORNADOES AND LARGE HAIL. OTHERWISE, A TRANSITION TO LINEAR CONVECTION IS EXPECTED EARLY TONIGHT GIVEN PRONOUNCED LINEAR FORCING FOR ASCENT ALONG THE COLD FRONT, AND DEEP-LAYER SHEAR VECTORS ALIGNED PARALLEL TO THE BOUNDARY. THUS, THE PRIMARY SEVERE STORM RISK WILL BE DAMAGING WINDS EARLY TONIGHT, AND THE OVERALL SEVERE RISK WILL SLOWLY DIMINISH LATE TONIGHT AS WARM SECTOR BUOYANCY WEAKENS AND THE FRONT TENDS TO UNDERCUT CONVECTION. Link to comment Share on other sites More sharing options...
janetjanet998 Posted December 17, 2016 Share Posted December 17, 2016 12z update .SUMMARY SEVERE STORMS ARE POSSIBLE LATE THIS AFTERNOON INTO TONIGHT ACROSS THE MID SOUTH AND ARKLAMISS. DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT, BUT A COUPLE OF TORNADOES AND ISOLATED LARGE HAIL WILL ALSO BE POSSIBLE THIS EVENING. ..MID SOUTH AND LOWER MISSISSIPPI VALLEY A PROGRESSIVE SHORTWAVE TROUGH IS NOTED IN WATER VAPOR IMAGERY MOVING ACROSS NM INTO THE SOUTHERN PLAINS. THIS FEATURE WILL STRENGTHEN SOUTHERLY LOW-LEVEL WINDS OVER THE GULF COAST REGION AND TN/OH VALLEYS TODAY, LEADING TO RAPID WARM/MOIST ADVECTION. SURFACE MOISTURE IS STREAMING INTO THE REGION, WITH DEWPOINTS NOW IN THE MID 50S TO MID 60S THROUGHOUT THE SLIGHT RISK AREA. PRESENT INDICATIONS ARE THAT SCATTERED THUNDERSTORMS WILL FORM ALONG/AHEAD OF AN APPROACHING COLD FRONT BY LATE AFTERNOON - MAINLY FROM WESTERN KY INTO EASTERN AR, THEN SPREADING INTO WEST TN AND NORTHERN MS. VISIBLE SATELLITE IMAGERY SUGGESTS A FEW BREAKS IN THE CLOUDS IN THIS REGION, WHICH MAY HELP TO WEAKEN THE CAP AND LEAD TO A FEW DISCRETE CELLS FOR A FEW HOURS BEFORE CONGEALING INTO A MORE ORGANIZED SQUALL LINE AFTER DARK. FORECAST SOUNDINGS IN THIS REGION SUGGEST THE POTENTIAL FOR SUPERCELLS CAPABLE OF DAMAGING WINDS, HAIL, AND ISOLATED TORNADOES. EVEN AFTER DARK, THE INTENSE LOW-LEVEL SHEAR MAY BE SUFFICIENT FOR AN OCCASIONAL QLCS TORNADO SPIN-UP, BUT DAMAGING WINDS SHOULD BECOME THE DOMINANT THREAT. THE SLIGHT RISK AREA HAS BEEN EXTENDED NORTHWARD INTO SOUTHERN KY FOR THIS UPDATE TO REFLECT 12Z MODEL SOLUTIONS SHOWING MORE PERSISTENT AND ROBUST CONVECTION ON THE NORTHERN END OF THE SQUALL LINE. UNCERTAINTY EXISTS HOW FAR SOUTHEAST THE THREAT WILL PERSIST OVERNIGHT INTO AL, BUT WILL NOT MAKE ANY CHANGES TO THIS AREA AT THIS TIME. ..HART/LEITMAN.. 12/17/2016 Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 17, 2016 Share Posted December 17, 2016 TODAY 12/17Scattered severe thunderstorms in west and central KY, west and north-central TN, north and west-central MS, east and south AR, north LA, extreme east TX. TORCON - 5 MS and TN areas; 4 AR area; 3 rest of area through midnight. Severe thunderstorms spread overnight into east TN, northwest GA, north and west-central AL, central and southwest MS, central and southwest LA. TORCON - 2 to 3 -Dr. Greg Forbes Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 17, 2016 Share Posted December 17, 2016 Do think today may over preform if the convention remains discrete. Like what Andy said, could be a sneaky event from what high res guidance such as HRRR and RAP are showing. Link to comment Share on other sites More sharing options...
andyhb Posted December 17, 2016 Share Posted December 17, 2016 MCD with 95% watch issuance probability out. http://www.spc.noaa.gov/products/md/md1890.html I'm a bit spooked by the degree of low level shear being indicated across western into middle Tennessee and N MS later on. Short range RAP is indicating 0-1 km SRH rising to over 400 m2/s2 with 500-1000 J/kg MLCAPE in place, which would certainly be sufficient for significant tornadoes should we have any supercells in progress by then. Link to comment Share on other sites More sharing options...
MattPetrulli Posted December 17, 2016 Share Posted December 17, 2016 Looks like bulls eye for tornadic activity should be in areas N and E of Memphis. Conditions most favorable in that area. Especially up near the KY line by Dyersburg ish Link to comment Share on other sites More sharing options...
andyhb Posted December 17, 2016 Share Posted December 17, 2016 Watch with some fairly substantial probabilities out (70/40). http://www.spc.noaa.gov/products/watch/ww0517.html Link to comment Share on other sites More sharing options...
janetjanet998 Posted December 17, 2016 Share Posted December 17, 2016 where is everyone? ULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE MEMPHIS TN 420 PM CST SAT DEC 17 2016 THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A * TORNADO WARNING FOR... NORTHERN HARDEMAN COUNTY IN WESTERN TENNESSEE... * UNTIL 445 PM CST * AT 420 PM CST, A CONFIRMED TORNADO WAS LOCATED NEAR CLOVERPORT, OR NEAR BOLIVAR, MOVING NORTHEAST AT 35 MPH. HAZARD...DAMAGING TORNADO. SOURCE...WEATHER SPOTTERS CONFIRMED TORNADO. Link to comment Share on other sites More sharing options...
andyhb Posted December 17, 2016 Share Posted December 17, 2016 Looks like this is going to bust most of the tornado watch at least -> dewpoints underperforming most guidance, lack of forcing for ascent ahead of the front, vort was slower than projected and WAA aloft are all combining to mitigate the threat. Link to comment Share on other sites More sharing options...
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