2009

Mesoscale Discussion #0089


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 8...9...CONTINUES.

   

THREAT FOR MAINLY DAMAGING WIND APPEARS TO BE INCREASING WITH EVOLVING SQUALL LINE ACROSS CNTRL OK. HOWEVER...ISOLATED TORNADOES AND LARGE HAIL REMAIN POSSIBLE WITH EMBEDDED SUPERCELL STRUCTURES. MORE DISCRETE STORMS FROM NW TX INTO ERN OK HAVE BEEN SLOW TO INCREASE...BUT THREAT FOR A FEW TORNADOES WILL REMAIN POSSIBLE WITH THIS ACTIVITY NEXT SEVERAL HOURS.

   

TREND HAS BEEN FOR STORMS THAT INITIATED ALONG THE DRYLINE OVER CNTRL OK TO GROW UPSCALE INTO A QUASI-LINEAR MCS. ORGANIZED STORM STRUCTURES ARE EVIDENT WITHIN THE LINE INCLUDING SUPERCELLS ON THE NRN END AND A BOW ECHO MOVING RAPIDLY NE THROUGH CNTRL OK NEAR NORMAN. A COLD FRONT CURRENTLY FROM WRN OK SSWWD THROUGH WRN TX WILL SURGE RAPIDLY EWD OVERNIGHT AND OVERTAKE DRYLINE AS SHORTWAVE TROUGH EJECTS THROUGH OK AND TX. DEEP LAYER LIFT ASSOCIATED WITH EJECTING UPPER JET AND INCREASING LINEAR FORCING SHOULD HELP SUSTAIN THE QLCS. THROUGH THE PRIMARY THREAT MAY TRANSITION TO DAMAGING WIND AND HAIL ALONG THE LINE...ISOLATED TORNADOES WILL REMAIN POSSIBLE WITH ANY EMBEDDED SUPERCELLS.

   

FARTHER EAST IN WARM SECTOR...STORMS HAVE BEEN SLOWER TO INCREASE MOST LIKELY DUE TO WEAKER MID LEVEL LAPSE RATES ASSOCIATED WITH A THERMAL RIDGE DOWNSTREAM FROM UPPER TROUGH. HOWEVER...LEADING EDGE OF MID LEVEL COOLING SHOULD BEGIN TO OVERTAKE THIS REGION LATER THIS EVENING. THIS ALONG WITH STRENGTHENING LOW LEVEL JET WITHIN APPROACHING UPPER JET EXIT REGION SUGGEST THE MORE DISCRETE WARM SECTOR STORMS SHOULD INTENSIFY THIS EVENING WITH A THREAT OF SUPERCELLS CAPABLE OF PRODUCING TORNADOES AND LARGE HAIL.


**This MCD preceded the Lone Grove, Oklahoma EF4

Mesoscale Discussion #0127


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 24 CONTINUES.

   

THROUGH 23Z...EXPECT THE GREATEST THREAT FOR SUPERCELLS CAPABLE OF LARGE HAIL...DAMAGING WINDS AND TORNADOES TO EXIST OVER NERN PORTION OF WW AREA...NAMELY FROM JUST NE OF BHM TO NEAR OR E OF RMG.

   

AS OF 21Z...REGIONAL RADAR IMAGERY INDICATED SEVERE STORMS /INCLUDING SUPERCELLS/ OVER CHATTOOGA AND FLOYD COUNTIES IN FAR NWRN GA AND ST. CLAIR COUNTY AL MOVING GENERALLY EWD AT 45-50 KT.  AIR MASS IN WAKE OF WARM FRONTAL PASSAGE OVER NERN GA IS RAPIDLY DESTABILIZING AND MODIFICATION OF 18Z ATL/BHM SOUNDINGS FOR CURRENT SURFACE CONDITIONS YIELDS MLCAPE APPROACHING 1000 J/KG.  IN ADDITION TO SMALLER T/TD SPREADS AND RESULTANT LOWER LCL HEIGHTS OVER NERN AL INTO NWRN GA...LOCAL VWPS AND RUC OBJECTIVE FIELDS INDICATE NOTABLY STRONGER LOW-LEVEL SHEAR WITH 0-1 KM SHEAR OF 30-35 KT AND EFFECTIVE SRH VALUES OF 300-400 M2/S2.  AS SUCH...ONGOING SUPERCELLS WILL REMAIN CAPABLE OF TORNADOES IN ADDITION TO LARGE HAIL AND DAMAGING WIND GUSTS.

   

FARTHER W...AN ISOLATED STORM CONTINUES TO ORGANIZE OVER LAUDERDALE COUNTY MS AS OF 21Z.  GIVEN THE RATHER STRONGLY SHEARED ENVIRONMENT AND SIMILAR THERMODYNAMIC CONDITIONS IN PLACE THROUGH CNTRL AL...THIS STORM MAY BE ABLE TO PERSIST FOR THE NEXT FEW HOURS WITH THE THREAT FOR DAMAGING WINDS...HAIL AND PERHAPS A TORNADO.

Mesoscale Discussion #0129


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 25 CONTINUES.

   

TORNADO WATCH 25 CONTINUES UNTIL 04Z...WITH A RISK OF TORNADOES AS WELL AS LARGE HAIL/DAMAGING WINDS. ALTHOUGH QUESTIONS EXIST REGARDING DOWNSTREAM INSTABILITY ACROSS SOUTHEAST/COASTAL GA AND CENTRAL/COASTAL SC...WILL CLOSELY MONITOR FOR THE POSSIBILITY OF AN ADDITIONAL WATCH GIVEN THE FAST MOVING NATURE OF THE UPSTREAM TSTMS ACROSS GA.

   

POTENTIALLY TORNADIC SUPERCELLS WILL CONTINUE TO QUICKLY SPREAD EASTWARD ESPECIALLY ACROSS NORTH CENTRAL/CENTRAL GA OVER THE NEXT FEW HOURS...AND PERHAPS INTO EASTERN GA AND UPSTATE SC. AS OF 2330Z...THE MOST PROLIFIC SUPERCELLS/POSSIBLE TORNADOES WITHIN TORNADO WATCH 25 ARE OCCURRING NEAR THE ATLANTA METRO ALONG/SOUTH OF I-20. LATEST SURFACE ANALYSIS REFLECTS A SOUTHWESTERLY MOIST LOW LEVEL INFLUX ACROSS AL/GA...WITH SPATIALLY MAXIMIZED PRESSURE FALLS AND LOCALLY BACKED SURFACE FLOW ACROSS NORTH CENTRAL/NORTHEAST GA ALONG/SOUTH OF A WEDGE-WARM FRONT. AS SUCH...OVERALL KINEMATIC SCENARIO WILL REMAIN FAVORABLE FOR QUASI-DISCRETE SUPERCELLS CAPABLE OF TORNADOES OVER THE NEXT SEVERAL HOURS. ASIDE FROM THE TORNADO RISK...AMPLE SHEAR FOR UPDRAFT ROTATION AND STRONG EARLY SEASON LAPSE RATES WILL SUPPORT A RISK OF LARGE HAIL WITH THE STRONGEST/MOST SUSTAINED STORMS.

Mesoscale Discussion #0211


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 49...50...CONTINUES.

   

TORNADIC POTENTIAL APPEARS TO BE INCREASING ACROSS PARTS OF NERN IL INTO N-CNTRL IN 1915-2100Z AS SEMI-DISCRETE SUPERCELLS INTERACT WITH NWD RETREATING WARM FRONT.

   

RECENT SATELLITE IMAGERY SHOWS SCTD TO BROKEN CLOUD COVER ALONG BEHIND NWD RETREATING WARM FRONT.  THIS IS ACTING TO RAPIDLY DESTABILIZE AIRMASS AHEAD OF NEWD MOVING STORMS OVER IND/IL BORDER WITH SBCAPE INCREASING TO AROUND 500 J/KG.  WITH LOCALIZED BACKED WINDS /PRESSURE FALLS 2MB PER HR/ ALONG RETREATING WARM FRONT...ENHANCED LOW LEVEL SHEAR MAY AUGMENT UPDRAFTS--SUPPORTING A LOCALIZED GREATER THREAT FOR ISOLD TORNADOES BEFORE STORMS CROSS THE BOUNDARY AND MOVE INTO MORE STABLE AIR.  TRENDS WILL NEED TO BE MONITORED ACROSS NRN IN...AS A LOCAL WW EXTENSION-IN-AREA MAY BE NEEDED.

Mesoscale Discussion #0302


CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   

VALID 272253Z - 280030Z

   

THE SEVERE THREAT WILL INCREASE ACROSS SRN AR...NRN LA AND WRN MS OVER THE NEXT FEW HOURS. THUNDERSTORMS SHOULD INCREASE SIGNIFICANTLY IN COVERAGE WEST OF THE MCD AREA AND BEGIN TO AFFECT NRN LA AND SRN AR EARLY THIS EVENING. TORNADOES...LARGE HAIL AND WIND DAMAGE WILL BE POSSIBLE WITH THE STRONGER STORMS. A TORNADO WATCH WILL LIKELY BE NEEDED ACROSS THE MCD AREA EARLY THIS EVENING.

   

LATEST SFC ANALYSIS SHOWS A SFC LOW NEAR THE RED RIVER IN FAR NE TX/FAR SE OK WITH A DIFFUSE QUASI-STATIONARY FRONTAL BOUNDARY EXTENDING EWD ACROSS SRN AR. SOUTH OF THE BOUNDARY...DEWPOINTS ARE IN THE MID 60S F WITH AN AXIS OF MODERATE INSTABILITY EXTENDING SWD ACROSS MUCH OF LA. THIS ENVIRONMENT ALONG WITH STRONG VERTICAL SHEAR PROFILES EVIDENT ON REGIONAL WSR-88 VWPS WILL BE FAVORABLE FOR STRONG UPDRAFTS WITH LARGE HAIL POTENTIAL. STORMS SHOULD INITIATE AND INCREASE IN COVERAGE AS A VORTICITY MAX ANALYZED BY THE RUC IN NE TX MOVES INTO SRN AR. IN ADDITION...LOW-LEVEL SHEAR WILL INCREASE AS A LOW-LEVEL JET STRENGTHENS AND DRIFTS EWD INTO THE MCD AREA EARLY THIS EVENING MAKING CONDITIONS FAVORABLE FOR SUPERCELLS AND TORNADOES. THERE IS A POTENTIAL FOR A STRONG TORNADO WITH ANY SUPERCELL THAN TRACKS EWD ALONG THE FRONTAL BOUNDARY AND IS NEAR THE DEEPENING SFC LOW. THE WIND DAMAGE SHOULD ALSO ACCOMPANY THE STRONGER CELLS ESPECIALLY WITH ORGANIZED FAST-MOVING LINE SEGMENTS.

Mesoscale Discussion #0430


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 132 CONTINUES.

   

THREAT FOR STRONG/DAMAGING TORNADOES WILL LIKELY PERSIST NEXT FEW HOURS WITH STORMS MOVING THROUGH MIDDLE TN INTO NRN AL. LARGE HAIL AND DAMAGING WIND MAY ALSO ACCOMPANY SOME OF THE STRONGER STORMS.

   

COUPLE OF LINES OF MOSTLY DISCRETE SUPERCELLS CONTINUE FROM MIDDLE TN SWWD THROUGH EXTREME NERN MS INTO NW AL. THE ATMOSPHERE REMAINS MODERATELY UNSTABLE WITH MINIMAL CONVECTIVE INHIBITION ALLOWING STORMS TO CONTINUE DEVELOPING ALONG CLOUD STREETS IN WARM SECTOR AHEAD OF THE EWD ADVANCING COLD FRONT. BULK SHEAR OF 50+ KT AND LARGE HODOGRAPHS WITH 0-1 KM STORM RELATIVE HELICITY FROM 200-300 M2/S2 ASSOCIATED WITH THE EWD ADVANCING SHORTWAVE TROUGH WILL CONTINUE TO PROMOTE SUPERCELLS WITH LOW LEVEL MESOCYCLONES. GIVEN THE PROPENSITY TO MAINTAIN DISCRETE STORMS WITHIN THE FAVORABLY SHEARED AND MODERATELY UNSTABLE ENVIRONMENT...SOME SUPERCELLS WILL REMAIN CAPABLE OF PRODUCING STRONG TORNADOES NEXT FEW HOURS.

Mesoscale Discussion #0433


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 133 CONTINUES.

   

TORNADIC POTENTIAL APPEARS GREATEST OVER ERN KY FOR THE NEXT HR OR TWO.

   

RECENT SINGLE SITE RADAR IMAGERY SHOWS SUPERCELLS AHEAD OF SQUALL LINE NEAR/S OF THE I-64 CORRIDOR.  THESE STORMS HAVE DEVELOPED IN AN INCREASINGLY FAVORABLE THERMODYNAMIC ENVIRONMENT /LOWER LFC/S AND MODERATE POTENTIAL INSTABILITY 1000-1500 J/KG SBCAPE/ AS AIRMASS HAS RECOVERED THIS AFTN.  RECENT SURFACE ANALYSIS SHOWS 1-2 MB /HR PRESSURE FALLS CENTERED OVER SERN KY INTO NERN TN.  AS STORMS MOVE EWD...LOW LEVEL FLOW IS ANTICIPATED TO REMAIN RELATIVELY BACKED...ENHANCING LOW LEVEL SHEAR.  AS A RESULT...THE STRONGLY VEERING LOW LEVEL PROFILES ARE CONTRIBUTING TO SUBSTANTIAL 0-1 KM SHEAR /25 KTS PER JKL VWP/--FAVORING NEAR-TERM TORNADO POTENTIAL WITH EMBEDDED AS WELL AS DISCRETE SUPERCELLS.

Mesoscale Discussion #0435


CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   

VALID 102042Z - 102145Z

   

SEVERE THREAT WILL LIKELY CONTINUE E OF WW 133 INTO PARTS OF SRN WV WRN VA AND NWRN NC.  A WW MAY BE REQUIRED IN THE NEXT HR OR TWO.

   

RADAR MOSAIC SHOWS EXPANSIVE MCS OVER PARTS OF ERN TN/KY.  DISCRETE SUPERCELLS HAVE DEVELOPED AHEAD OF LINE IN ERN KY AND POSE A HEIGHTENED RISK FOR TORNADO/S BEFORE AND DURING MERGER INTERACTION WITH MCS.  FURTHER S OVER THE CUMBERLAND GAP...STORMS ARE DEVELOPING IN A SEEMINGLY FAVORABLE THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY MODERATE INSTABILITY /1000 J/KG SBCAPE/ DESPITE MARGINAL LOW LEVEL MOISTURE /DEWPOINTS IN THE LOWER 50S F/.  RECENTLY DEVELOPED CONVECTION INCLUDING A SUPERCELL OVER MITCHELL COUNTY NC WILL LIKELY POSE AN ISOLD LARGE HAIL/DMGG WIND THREAT...AS KINEMATIC FIELDS ARE MORE THAN ADEQUATE FOR UPDRAFT ROTATION.  CONVECTIVE TRENDS WILL BE MONITORED OVER THE NEXT HOUR OR TWO WITH A WW POSSIBLY BEING NEEDED DOWNSTREAM OF WW 133 PRIOR TO 22Z.

Mesoscale Discussion #0438


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 134...135...CONTINUES.

   

SEVERAL DISCRETE SUPERCELLS ALONG WITH SHORT-LINE SEGMENTS SHOULD PROGRESS E/SEWD ACROSS SERN PORTION OF WW 134 INTO WW 135. LOCAL AREAL EXTENSION MAY BE NEEDED ALONG THE SRN PERIPHERY OF WW 134 IN AL. THREATS OF LARGE HAIL AND TORNADOES /A FEW OF WHICH COULD BE SIGNIFICANT/...AND DAMAGING WINDS WILL CONTINUE.

   

AS OF 2330Z...NUMEROUS DISCRETE SUPERCELLS HAVE EVOLVED INTO CNTRL/E-CNTRL AL AND NWRN GA...WITH A SHORT LINE SEGMENT CONSISTING OF EMBEDDED SUPERCELLS ACROSS N-CNTRL GA. DESPITE THE ONSET OF STABILIZATION WITH LOSS OF DAYTIME HEATING...A SWLY INFLUX OF UPPER 50S TO LOWER 60S SURFACE DEW POINTS SHOULD HELP OFFSET THIS TENDENCY TO SOME EXTENT. MEANWHILE...AREA VWPS INDICATE A GRADUAL STRENGTHENING TREND IN LOWER-LEVEL FLOW WHICH IS ENLARGING ALREADY VERY FAVORABLE HODOGRAPHS FOR UPDRAFT ROTATION. AS SUCH...SIGNIFICANT SEVERE POTENTIAL IS EXPECTED TO CONTINUE THROUGH ABOUT 02-03Z.

Mesoscale Discussion #0579


CONCERNING...OUTLOOK UPGRADE 

   

VALID 261554Z - 261700Z

   

SEE GRAPHIC FOR MDT-HIGH RISK LINES EXPECTED FOR 1630Z SWODY1 UPDATE.

   

HIGH RISK UPGRADE WILL INCLUDE SCNTRL KS AND NWRN/NCNTRL-WCNTRL OK WITH A MDT RISK SPANNING FROM NWRN TX/ERN TX PNHDL ENEWD INTO CNTRL OK AND CNTRL/ERN KS.

   

IMPRESSIVE INGREDIENTS COMING TOGETHER LATER THIS AFTN FOR A HIGH POTENTIAL FOR WAVES OF LONG-LIVED SUPERCELLS WITH STRONG TORNADOES...DESTRUCTIVE HAIL AND DAMAGING WIND GUSTS. 

   

BRIEF THOUGHTS /DETAILS FORTHCOMING IN SWODY1 UPDATE/...

   

MORNING ACTIVITY DEVELOPING OUT OF ACCAS FIELD WILL TRANSLATE NWD INTO CNTRL/ERN KS AND NWRN OK THROUGH EARLY AFTN.  PORTIONS OF THIS ACTIVITY COULD BECOME SFC-BASED AS POCKETS OF HEATING LOCALLY ERODE CINH.  ANOTHER WAVE OF STORMS IS LIKELY TO FORM UPSTREAM ALONG THE DRYLINE/FRONT IN ERN TX PNHDL/NWRN TX LATER THIS AFTN AND EVE...TRANSLATING ENE ACROSS THE MDT/HIGH RISK AREAS.

   

PLENTIFUL BOUNDARY LAYER MOISTURE ALREADY IN PLACE BELOW VERY STEEP LAPSE RATES WILL CONTRIBUTE TO VERY UNSTABLE CONDITIONS...MLCAPES 3000-4000 J/KG.  BULK SHEAR OF 45-50 KTS ORIENTED NORMAL TO THE INITIATING BOUNDARIES AND PERSISTENT RICH MOISTURE INFLUX WILL FAVOR LONG-LIVED DISCRETE SUPERCELLS.  LOW-LEVEL FLOW WILL REMAIN BACKED IN A CORRIDOR FROM NWRN TX INTO SCNTRL KS...IMMEDIATELY DOWNSTREAM FROM AN INTENSIFYING SFC LOW OVER OK PNHDL/SWRN KS...BOOSTING SRH AND RESULTING IN POTENTIAL FOR STRONG TORNADOES.

Mesoscale Discussion #0584


CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

   

 VALID 261941Z - 262215Z

   

THIS DISCUSSION CONCERNS SVR TSTM WATCH 189 AND TORNADO WATCHES 190; 191.

   

19Z SFC ANALY SHOWS 2-3 MB PRESSURE FALLS CENTERED OVER ERN KS. MESOLOW CONTINUES TO MIGRATE SLOWLY NEWD ALONG THE NEB-KS BORDER NW OF KMHK.  WRMFNT HAS DEVELOPED N OF I-80 WITH A BROAD WARM SECTOR CHARACTERIZED BY CAPES RANGING FROM 1000 IN SRN IA TO 2000 J/KG IN ERN KS.  HBR PROFILER...RESIDING IN INFLOW REGION OF THE SFC LOW...EXHIBITS OVER 225 M2/S2 OF 0-1KM SRH AND 50+ KTS OF BULK SHEAR.  WITH MINIMAL CINH NOTED ACROSS THE REGION...TSTMS WILL CONTINUE TO DEVELOP AND SLOWLY TRANSLATE ENE ACROSS THE DISCUSSION AREA THRU LATE AFTN.

   

CONVECTIVE MODE WILL CONTINUE TO BE MESSY WITH NUMEROUS STORMS BEING GENERATED WITH VARIOUS COMPLEX MERGERS. OBVIOUSLY... MAGNITUDE OF SHEAR AND INSTABILITY WILL REMAIN CONDUCIVE FOR HIGH PCPN SUPERCELLS CAPABLE OF STRONG TORNADOES...LARGE HAIL AND DESTRUCTIVE WIND GUSTS. THIS WILL ESPECIALLY BE TRUE ACROSS ERN KS SWD WHERE BEST JUXTAPOSITION OF RICH MOISTURE INFLUX AND SHEAR WILL EXIST. HOWEVER...FARTHER N...INSTABILITY GRADIENT WILL DEVELOP NWD WITH TIME AND TORNADOES...DMGG WINDS AND HAIL RISKS WILL SPREAD ACROSS CNTRL/NRN IA THROUGH EARLY EVENING.  

   

FINALLY...THERE WILL BE A LARGE HAIL THREAT ACROSS ERN NEB AND NWRN IA AS LEFT-SPLITS OF SUPERCELLS DEVIATE AND MOVE ATOP THE COLDER BOUNDARY LAYER.

Mesoscale Discussion #0763


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 267 CONTINUES.

   

GREATEST THREAT FOR MORE WIDESPREAD DAMAGING WIND STILL APPEARS TO BE ALONG LEADING GUST FRONT FROM N CNTRL TN...WRN KY INTO SWRN IND AS WELL AS IN COMMA HEAD REGION OVER SRN IL. THREAT FOR ISOLATED TORNADOES APPEARS TO BE GREATEST ACROSS MIDDLE AND PARTS OF WRN TN BUT CONDITIONAL UPON ADDITIONAL STORM DEVELOPMENT. LARGE HAIL AND A MORE ISOLATED DAMAGING WIND THREAT EXISTS FARTHER WEST ACROSS NERN AR INTO WRN TN.

   

THIS AFTERNOON AN ORGANIZED MESOSCALE SYSTEM WITH A COMMA HEAD OVER SRN IL AND BOWING LINE FARTHER SE ACROSS WRN KY INTO NRN PORTIONS OF MIDDLE TN IS MOVING EAST AT AROUND 50 KT. THREAT FOR DAMAGING WIND WILL CONTINUE WITH THIS FEATURE NEXT FEW HOURS...ESPECIALLY WITH BOWING SEGMENT AS WELL AS WITHIN COMMA HEAD REGION. STORMS HAVE BECOME MORE DISCRETE IN NATURE ALONG SRN END OF THE LINE ACROSS MIDDLE TN...CONCURRENT WITH INCREASING 0-2 KM WINDS...PER 18Z BNA SOUNDING AND VWP DATA...ASSOCIATED WITH A NEWD DEVELOPING LOW LEVEL JET. THREAT FOR ISOLATED TORNADOES APPEARS GREATEST IN THIS REGION NEXT COUPLE HOURS. FARTHER WEST ALONG TRAILING E-W PORTION OF THE BOUNDARY ACROSS NERN AR...THE SWLY LOW LEVEL JET CONTINUES TO PROMOTE THUNDERSTORM DEVELOPMENT PRIMARILY JUST NORTH OF THE BOUNDARY. SWD DEVELOPMENT COULD BE LIMITED BY A CAP IN WARM SECTOR. HOWEVER...STORMS THAT ARE TRAINING EWD IN THIS REGION WITH HAVE THE POTENTIAL TO PRODUCE ISOLATED LARGE HAIL...VERY HEAVY RAIN AND POSSIBLE ISOLATED STRONG WIND GUSTS. THERE IS ALSO SOME CONCERN THAT STORMS DEVELOPING ALONG TRAILING OUTFLOW BOUNDARY COULD BECOME SURFACE BASED AND DEVELOP A LITTLE FARTHER SEWD...WHICH WOULD INCREASE THE THREAT OF DAMAGING WIND AND ISOLATED TORNADOES. THE 18Z RAOB FROM LIT INDICATES THE CAP HAS WEAKENED SOMEWHAT SINCE 12Z THIS MORNING.

Mesoscale Discussion #1180


THE SEVERE WEATHER THREAT FOR TORNADO WATCH 440 CONTINUES.

   

ISOLATED SEVERE/TORNADO THREAT CONTINUES ACROSS PARTS OF WW 440. WITH THIS WATCH SCHEDULED TO EXPIRE AT 18/02Z...NEW WW WILL LIKELY BE REQUIRED.

   

LATEST RADAR LOOP SHOWS ISOLATED SEVERE STORMS CONTINUING ACROSS NRN PORTIONS OF WW 440 -- I.E. ACROSS CENTRAL AND INTO E CENTRAL NEB ATTM.  THE CONVECTION IS ONGOING WITHIN A VERY UNSTABLE AIRMASS IN PLACE ACROSS THIS REGION...N OF A SURFACE WARM FRONT WITHIN ESELY LOW-LEVEL FLOW REGIME.  

   

LATEST FBY /FAIRBURY NEB/ PROFILER SHOWS FLOW VEERING/INCREASING WITH HEIGHT TO 50 KT WLYS AT MID LEVELS...YIELDING DEEP-LAYER SHEAR FAVORABLE FOR SUPERCELLS....AS WELL AS 20 KT 0-1 KM SHEAR -- SUPPORTIVE OF LOW-LEVEL ROTATION.  GIVEN THE KINEMATIC AND THERMODYNAMIC ENVIRONMENT...THREATS FOR VERY LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES WILL LIKELY CONTINUE FOR THE NEXT SEVERAL HOURS. THIS WILL LIKELY NECESSITATE REPLACEMENT OF WW 440.


**This MCD preceded the infamous Aurora, NE EF2