2006

Mesoscale Discussion #0256


CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

   

VALID 121729Z - 121930Z

   

SUPERCELLS WILL LIKELY INITIATE THIS AFTERNOON ALONG A DRYLINE FROM ERN KS TO CNTRL OK. DAMAGING TORNADOES...VERY LARGE HAIL AND WIND DAMAGE WILL BE LIKELY AS STORMS INITIATE AND TRACK ENEWD ACROSS THE REGION THIS AFTERNOON. A TORNADO WATCH WILL BE ISSUED SHORTLY.

   

SFC ANALYSIS CURRENTLY SHOWS A DRYLINE ORIENTED FROM NORTH TO SOUTH FROM SCNTRL KS TO SOUTHWEST OK. SFC DEWPOINTS EAST OF THE DRYLINE ARE IN THE LOWER TO MID 60S F WHERE MODERATE INSTABILITY IS PRESENT. THE CAPPING INVERSION IS VERY WEAK AND STORMS SHOULD INITIATE AS LARGE-SCALE ASCENT INCREASES AS A 100 KT MID-LEVEL JET MAX NOSES INTO THE REGION THIS AFTERNOON. SUPERCELLS WILL BE LIKELY DUE TO THE MODERATE INSTABILITY AND STRONG VERTICAL SHEAR. IN ADDITION...STRONG LOW-LEVEL SHEAR EVIDENT ON REGIONAL PROFILERS WILL CREATE AN ENVIRONMENT FAVORABLE FOR TORNADOES. LONG TRACK STRONG TO VIOLENT TORNADOES WILL BE POSSIBLE WITH LONG-LIVED SUPERCELLS THAT DEVELOP AND TRACK ENEWD ACROSS ERN OK AND ERN KS LATE THIS AFTERNOON. STEEP MID-LEVEL LAPSE RATES WILL BE FAVORABLE FOR VERY LARGE HAIL WITH WIND DAMAGE ALSO LIKELY WITH THE STRONGER STORMS.

Mesoscale Discussion #0259


CONCERNING...TORNADO WATCH 73...

   

VALID 121929Z - 122100Z

   

PDS TORNADO WATCH 73 CONTINUES UNTIL 04Z...WITH SIGNIFICANT SEVERE THREAT OVER THE NEXT FEW HOURS ESPECIALLY ACROSS EASTERN KS/WESTERN MO...INCLUDING THE KC METRO AREA. 

   

SPECIFICALLY REGARDING THE WESTERN PORTION OF TORNADO WATCH 73 ACROSS EASTERN KS/WESTERN MO...SCATTERED SUPERCELLS /ALREADY POTENTIALLY TORNADIC/ CONTINUE TO DEVELOP ACROSS EASTERN KS AND MOVE ENE...ALONG A OTTAWA-CHANUTE-INDEPENDENCE CORRIDOR AS OF 1930Z. SURFACE MESOANALYSIS/VIS SATELLITE IMAGERY DEPICT WARM FRONT STEADILY LIFTING NORTHWARD ACROSS NORTHEAST KS/KC METRO AREA AND CENTRAL MO. 

   

ALONG/SOUTH OF THE WARM FRONT...AMBIENT WARM SECTOR IS CHARACTERIZED BY A RATHER FAVORABLE COMBINATION OF STRONG INSTABILITY/VERTICAL SHEAR FOR A SIGNIFICANT SEVERE THREAT... REFERENCE 18Z SPRINGFIELD MO OBSERVED RAOB. POTENTIAL FOR SUPERCELLS PRODUCING VERY LARGE HAIL/POSSIBLY SIGNIFICANT TORNADOES WILL CONTINUE TO INCREASE IN THE SHORT TERM FROM FAR EASTERN KS INTO WESTERN MO...INCLUDING THE GREATER KANSAS CITY METRO AREA SOUTHWARD TO THE JOPLIN VICINITY.

Mesoscale Discussion #0261


CONCERNING...TORNADO WATCH 73...

   

VALID 122102Z - 122230Z

   

PARTICULARLY DANGEROUS TORNADO WATCH #73 CONTINUES ACROSS EASTERN KS/MUCH OF MO INTO WESTERN/CENTRAL IL THROUGH 04Z...WITH PRIMARY THREAT FOR TORNADOES/VERY LARGE HAIL SPREADING INTO WEST CENTRAL MO AT MID AFTERNOON.

   

PRONOUNCED/DISTINCT SUPERCELLS ONGOING EAST/SOUTHEAST OF THE KC METRO AREA AT THIS TIME...FROM RAY COUNTY MO TO BATES/HENRY COUNTIES MO AT 21Z. MESOANALYSIS/SATELLITE TRENDS CONTINUE TO PORTRAY WARM FRONT STEADILY LIFTING NORTHWARD ACROSS NORTHEAST KS AND NORTH CENTRAL MO. AS IT DOES...NEAR STORM ENVIRONMENT ALONG/SOUTH OF THE WARM FRONT IN MO REMAINS VERY FAVORABLE FOR ROTATING STORMS...POTENTIALLY SIGNIFICANT TORNADOES...AND DESTRUCTIVE HAIL. AN ENHANCED/PROLONGED TORNADIC THREAT MAY EXIST IN VICINITY OF THIS WEST-EAST ORIENTED WARM FRONT -- LOCATED FROM THE KC METRO AREA TO NEAR COLUMBIA MO AT 21Z. OTHERWISE...ADDITIONAL DEVELOPMENT APPEARS LIKELY LATE THIS AFTERNOON ALONG THE DRYLINE IN VICINITY OF AGITATED CU FIELD ACROSS SOUTHEAST KS.

Mesoscale Discussion #0262


CONCERNING...TORNADO WATCH 74...

   

VALID 122138Z - 122345Z

   

SUPERCELLS ARE EXPECTED TO INITIATE AND TRACK ENEWD ACROSS ERN OK INTO WRN AR LATE THIS AFTERNOON. THE INITIATION OF ISOLATED SUPERCELLS ARE ALSO POSSIBLE IN FAR NE TX BY EARLY EVENING. VERY LARGE HAIL AND WIND DAMAGE WILL BE LIKELY SHORTLY AFTER INITIATION WITH SIGNIFICANT TORNADOES POSSIBLE. A NEW TORNADO WATCH MAY BECOME NECESSARY SOUTH OF TORNADO WATCH 74 ACROSS SE OK AND NE TX LATE THIS AFTERNOON OR EARLY THIS EVENING.

   

SFC ANALYSIS CURRENTLY SHOWS A DRYLINE EXTENDING SSWWD ACROSS CNTRL OK INTO NCNTRL TX. OBJECTIVE ANALYSIS SHOWS A MODERATELY UNSTABLE AIRMASS EAST OF THE DRYLINE WITH STRONG VERTICAL SHEAR IN PLACE WHICH WILL BE FAVORABLE FOR SUPERCELLS UPON INITIATION. MODERATE CUMULUS IS EVIDENT ON VISIBLE IMAGERY JUST SOUTHEAST OF THE OKC METRO WITH OBJECTIVE ANALYSIS SHOWING THE CAPPING INVERSION GONE ACROSS ECNTRL OK. AS LOW-LEVEL CONVERGENCE CONTINUES TO INCREASE ALONG THE DRYLINE AND LARGE-SCALE ASCENT SPREADS NEWD AHEAD OF A SHORTWAVE TROUGH EVIDENT ON WATER VAPOR IMAGERY...RAPID SUPERCELL DEVELOPMENT APPEARS LIKELY BETWEEN 22Z AND 00Z. THE MOST LIKELY AREA FOR INITIATION WOULD BE EAST TO SOUTHEAST OF THE OKC METRO AREA WHERE THE CUMULUS FIELD APPEARS A BIT AGITATED. ADDITIONAL STORMS SHOULD DEVELOP SWD INTO FAR NE TX AS THE CAP WEAKENS SOUTH OF THE RED RIVER BY EARLY THIS EVENING. STRONG LOW-LEVEL SHEAR COMBINED WITH LOW LCL HEIGHTS WILL MAKE TORNADOES LIKELY WITH THE STRONGER SUPERCELLS THAT DEVELOP. SIGNIFICANT TORNADOES WILL BE POSSIBLE WITH VERY LARGE HAIL AND WIND DAMAGE LIKELY.

Mesoscale Discussion #0264


CONCERNING...TORNADO WATCH 73...

   

VALID 122306Z - 130030Z

   

CORRECTED FOR MCD GRAPHIC

   

TORNADO WATCH 73 CONTINUES UNTIL 04Z FROM FAR EASTERN KS INTO WESTERN/CENTRAL IL. ENHANCED POTENTIAL FOR DESTRUCTIVE TORNADOES/VERY LARGE HAIL IS SHIFTING EAST ACROSS EAST CENTRAL MO INTO WEST CENTRAL IL /POTENTIALLY NEAR THE ST LOUIS METRO/ EARLY THIS EVENING. FURTHER WEST...ADDITIONAL DEVELOPMENT IS ANTICIPATED ALONG THE DRYLINE IN SOUTHEAST KS.

   

THERE APPEARS TO BE ENHANCED POTENTIAL FOR SIGNIFICANT TORNADOES/DESTRUCTIVE HAIL ACROSS EAST CENTRAL MO INTO WEST CENTRAL IL THROUGH AT LEAST 02Z...POTENTIALLY NEAR/JUST NORTH OF THE ST LOUIS METRO AREA. SUPERCELLS WITH TORNADIC HISTORY ARE CURRENTLY MOVING ENE ALONG/JUST NORTH OF I-70 NEAR COLUMBIA MO. THESE STORMS ARE LIKELY TO CONTINUE TO RIDE THE ROUGHLY WEST-EAST ORIENTED BAROCLINIC ZONE ACROSS CENTRAL MO INTO CENTRAL IL AS DELINEATED VIA SURFACE MESOANALYSIS/VISIBLE SATELLITE IMAGERY. THESE STORMS SHOULD REACH THE MISSISSIPPI RIVER AROUND 0030Z.

   

FURTHER WEST...INCREASING STORM COVERAGE IS ANTICIPATED ACROSS SOUTHEAST KS OVER THE NEXT FEW HOURS...LEADING TO A RENEWED THREAT FOR TORNADOES/VERY LARGE HAIL THIS EVENING INTO WESTERN MO. CU FIELD REMAINS AGGRESSIVE ACROSS SOUTHEAST KS AMIDST NEGLIGIBLE CINH PER ADJUSTED RUC SOUNDINGS.

Mesoscale Discussion #0409


CONCERNING...SEVERE THUNDERSTORM WATCH 134...

   

VALID 030006Z - 030130Z

   

A LINE OF SUPERCELLS ONGOING ACROSS SE MO AND NE AR WILL CONTINUE TO HAVE A THREAT OF TORNADOES...LARGE HAIL AND WIND DAMAGE OVER THE NEXT FEW HOURS. A TORNADO WATCH WILL LIKELY BECOME NECESSARY EAST OF THE CURRENT TORNADO WATCHES.

   

LATEST SFC ANALYSIS SHOWS A LOW-LEVEL MOIST AXIS WITH SFC DEWPOINTS IN THE LOWER TO MID 60S F EXTENDING NWD ACROSS WRN TN AND WRN KY. THIS IS IN THE VICINITY OF A 40 KT LOW-LEVEL JET WHICH WILL CONTINUE TO INCREASE THIS EVENING. THIS COMBINED WITH STRONG LIFT AND VERTICAL SHEAR ASSOCIATED WITH THE NOSE OF A MID-LEVEL JET WILL CONTINUE TO MAKE THE ENVIRONMENT VERY FAVORABLE FOR SUPERCELLS AND TORNADOES. AS THE SUPERCELLS MOVE INTO THE LOW-LEVEL JET...LONG TRACK SIGNIFICANT TORNADOES WILL REMAIN POSSIBLE OVER THE NEXT HOUR. THE SEVERE THREAT SHOULD CONTINUE EWD INTO CNTRL TN AND CNTRL KY AS THE SUPERCELLS TRACK EWD. LARGE HAIL...WIND DAMAGE AND TORNADOES WILL CONTINUE TO BE POSSIBLE THROUGH LATE THIS EVENING.

Mesoscale Discussion #0410


CONCERNING...TORNADO WATCH 134...137...138...

   

VALID 030210Z - 030415Z

   

...MULTIPLE DISCRETE TORNADIC SUPERCELLS HAVE EVOLVED ACROSS THE REGION...

   

00Z SOUNDING FROM LZK SUGGESTS HIGH QUALITY LAPSE RATE/INSTABILITY ENVIRONMENT IS SPREADING DOWNSTREAM ACROSS THE TN VALLEY WHERE MULTIPLE DISCRETE TORNADIC SUPERCELLS PERSIST. SEVERAL OF THESE STORMS ARE LONG-LIVED AND HAVE YET TO EXHIBIT ANY SIGNIFICANT WEAKENING.  OVER THE LAST FEW HOURS...DIAGNOSTIC TRENDS ARE SHOWING RAPID RECOVERY INTO MIDDLE TN WHERE SIG TOR VALUES ARE NOW APPROACHING 8. TORNADIC THREAT REMAINS HIGH ACROSS THIS REGION FOR THE NEXT FEW HOURS...WITH THE POTENTIAL FOR STRONG TORNADOES.

Mesoscale Discussion #0435


CONCERNING...OUTLOOK UPGRADE 

   

VALID 061101Z - 061300Z

   

AFTER COLLABORATION WITH THE TOP/OAX/EAX WEATHER FORECAST OFFICES... THE STORM PREDICTION CENTER IS EXPECTED TO UPGRADE SERN NEB...NERN KS AND NWRN MO TO A CATEGORICAL HIGH RISK AT 13Z.

   

H5 12-HR HEIGHT FALLS OF 210 METERS WILL SPREAD ENEWD ACROSS THE CNTRL PLAINS THIS AFTN.  TSTMS ARE EXPECTED TO DEVELOP BY EARLY AFTN ALONG THE DRYLINE/SFC LOW FROM SCNTRL NEB INTO CNTRL KS AS INHIBITION IS ERODED.  STORMS SHOULD QUICKLY ORGANIZE INTO SUPERCELLS GIVEN STRONG VERTICAL SHEAR PROFILES /H5 FLOW OF 105 KTS OVER OKLA...WITH AOA 60 KTS INTO ERN KS/. 

   

THE 2-8KM SHEAR VECTORS REMAIN SUFFICIENTLY NORMAL TO THE INITIATING BOUNDARY TO SUPPORT DISCRETE CELLS...THOUGH ACTIVITY WILL TEND TO EVOLVE INTO A MIXED MODE OF LEWPS/BOWS WITH TIME.  NONETHELESS...BACKED SELY LOW-LEVEL FLOW E/NE OF THE SFC LOW/WARM FRONT WILL BE FAVORABLE FOR TORNADOES...SOME STRONG...AS THE STORMS MOVE ENEWD AT 30-40 KTS ACROSS NERN KS...SERN NEB AND NWRN MO. VERY LARGE HAIL CAN ALSO BE EXPECTED GIVEN STEEP MID-LEVEL LAPSE RATES AND 2000-2500 J/KG MLCAPE.

Mesoscale Discussion #0448


CONCERNING...TORNADO WATCH 155...157...

   

VALID 070053Z - 070230Z

   

...HIGH POTENTIAL FOR TORNADOES AND LARGE HAIL WITH DISCRETE SUPERCELLS NOW MOVING ACROSS ERN OK....

   

LATEST RADAR IMAGERY SHOWS SEVERAL SUPERCELL TSTMS EXTENDING FROM FAR SE KS TO SE OK. ENVIRONMENTAL PARAMETERS ARE VERY FAVORABLE FOR STORM ROTATION...WITH 0-1 SRH NEAR 400 M2/S2. HASKELL OK PROFILER AND VAD DATA FROM BOTH TULSA AND FORT SMITH SHOW VERY IMPRESSIVE DIRECTION/SPEED SHEAR WITH 50 KT OBSERVED NEAR 1 KM. LAMONT AND PURCELL PROFILER DATA ALSO SHOW 100KT DOWN TO 3KM...INDICATING THE EXTREMELY STRONG WINDS...ASSOCIATED WITH EJECTING JET STREAK. SEVERAL OF THESE STORMS HAVE ALREADY PRODUCED BRIEF TORNADOES...INCLUDING A RECENT REPORT OF A TORNADO WEST OF EUFAULA DAM IN HASKELL CO JUST BEFORE 730PM. STORM SIGNATURES DO INDICATE THAT STORMS ARE FEELING THE EFFECTS OF THE EXTREME SHEAR. 

   

HOWEVER...THE STORMS /BY MAINTAINING SOME SPACE BETWEEN CELLS/ ARE NOT DESTRUCTIVELY INTERFERING...WHICH DOES INCREASE THE POTENTIAL FOR TORNADOES. BEST POTENTIAL APPEARS TO BE ACROSS SE OK INTO WCNTRL AR. AIRMASS IS SLIGHTLY MORE STABLE ACROSS NW AR...BUT MOISTURE IS RAPIDLY RETURNING IN A SLIGHTLY ELEVATED FASHION. STRENGTH OF SHEAR SUGGESTS SEVERE THREAT WILL SPREAD INTO PORTIONS OF WW 157 /INTO NRN AND WRN AR/ THROUGH LATER THIS EVENING.

Mesoscale Discussion #0457


CONCERNING...TORNADO WATCH 162...163...

   

VALID 071922Z - 072115Z

   

THREAT FOR A FEW STRONG LONG TRACK TORNADOES IS EXPECTED TO PERSIST WITH STORMS MOVING THROUGH WRN AND MIDDLE TN INTO WRN AND CNTRL KY NEXT FEW HOURS. ISOLATED TORNADOES REMAIN POSSIBLE FROM SRN IL INTO SRN IND. OTHER STORMS ARE EXPECTED TO DEVELOP FARTHER S ACROSS PARTS OF SERN AR...NRN LA INTO MS AND AL THIS AFTERNOON AND EVENING. THESE STORMS WILL POSE A THREAT FOR A FEW STRONG TORNADOES AND VERY LARGE HAIL ONCE THEY DEVELOP.

   

THE ATMOSPHERE REMAINS MODERATELY UNSTABLE OVER THE LOWER MS VALLEY AND PARTS OF THE SERN U.S. WITH MLCAPE FROM 1500 TO 2000 J/KG FROM NERN LA...SERN AR INTO CNTRL AND NRN MS AND NRN AL. THE 18Z RAOB FROM JACKSON STILL SHOWED SOME CONVECTIVE INHIBITION IN THE 850 MB-700 MB LAYER. WARMING AND MIXING WITHIN THE BOUNDARY LAYER AND HEIGHT FALLS ASSOCIATED WITH SEWD ADVANCING UPSTREAM VORT MAX SUGGEST THE POTENTIAL FOR INITIATION WILL BECOME INCREASINGLY LIKELY WITHIN ZONE OF MODEST WARM ADVECTION OVER THE LOWER MS VALLEY. THE STRONG MID LEVEL JET ASSOCIATED WITH THE UPSTREAM SHORTWAVE TROUGH WILL SHIFT SLOWLY SEWD AND REMAIN IN A FAVORABLE POSITION RELATIVE TO THE LOW LEVEL JET FOR VERTICAL SHEAR CONDUCIVE FOR SUPERCELLS WITH STRONG LOW LEVEL MESOCYCLONES. NEW STORMS THAT DEVELOP WILL LIKELY REMAIN DISCRETE FOR SEVERAL HOURS. KINEMATIC AND THERMODYNAMIC PROFILES WILL CONTINUE TO SUPPORT A THREAT FOR VERY LARGE HAIL AND STRONG TORNADOES.

   

TORNADOES CONTINUE TO BE CONFIRMED WITH SUPERCELLS MOVING THROUGH WRN AND MIDDLE TN AS WELL AS PORTIONS OF WRN AND CNTRL KY. THIS ACTIVITY WILL LIKELY PERSIST AND SHIFT ENEWD NEXT SEVERAL HOURS.

Mesoscale Discussion #0458


CONCERNING...TORNADO WATCH 164...

   

VALID 072056Z - 072230Z

   

GREATEST TORNADIC THREAT SHOULD BE CONFINED TO THE FAR SRN PORTION OF WW164. ADDITIONAL TSTMS SHOULD CONTINUE TO DEVELOP ALONG SWD MOVING COLD FRONT ACROSS NRN PORTION OF WW164. LARGE HAIL WILL BE THE MAIN THREAT WITH ALL STORMS.

   

SEVERAL CLUSTERS OF MULTICELLS AND SUPERCELLS TSTMS HAVE DEVELOPED IN A MODERATELY UNSTABLE AIRMASS WITH MLCAPES OF 1000 TO 2000 J/KG AND STRONG MID/UPPER-LEVEL SPEED SHEAR. STEEP MID-LAPSE LEVEL RATES AS EVIDENCED BY REGIONAL 18Z RAOBS WILL CONTINUE TO SUPPORT LARGE HAIL...SOME OF WHICH WILL BE SIGNIFICANT GIVEN THE DEGREE OF MID-LEVEL COOLING THAT HAS OCCURRED. LOW-LEVEL WIND FIELDS ARE SUPPORTIVE OF TORNADIC STORMS ALONG THE SRN PERIPHERY OF WW164 AND FURTHER S WHERE NEAR-SURFACE BACKING EXISTS. FURTHER N...THE IND VAD PROFILER SHOWS A UNIDIRECTIONAL WSW LOW-LEVEL SIGNATURE WITH ONLY MODEST SPEED SHEAR.

   

ADDITIONAL CONVECTIVE DEVELOPMENT WILL LIKELY CONTINUE ALONG THE SWD-MOVING COLD FRONT IN VICINITY OF DEC TO MIE AT 20Z. THE STEEP LAPSE RATES ALOFT WILL SUPPORT LARGE HAIL...HOWEVER WEAK AND UNIDIRECTIONAL LOW-LEVEL WIND FIELDS AS EVIDENCED BY ILX AND LSX VAD PROFILERS SUPPORT A DIMINISHING TORNADIC THREAT ACROSS CNTRL IL.

Mesoscale Discussion #0461


CONCERNING...TORNADO WATCH 163...

   

VALID 072212Z - 072345Z

   

THROUGH 00Z...THE GREATEST POTENTIAL FOR TORNADOES /SOME OF THEM SIGNIFICANT/ IS EXPECTED IN A SW-NE CORRIDOR FROM SE OF GLH TO NEAR TUP TO NE MSL.

   

SW-NE ORIENTED BAND OF TSTMS CONTINUE TO BECOME BETTER ORGANIZED EARLY THIS EVENING FROM THE ARKLAMS NEWD ACROSS NRN MS WITH SEVERAL STORM SPLITS...SUGGESTING UNIDIRECTIONAL VERTICAL SHEAR PROFILES.  THIS NOTION IS CONFIRMED BY CURRENT OKOLONA MS PROFILER DATA WHICH EXHIBIT RELATIVELY STRONG VERTICAL SPEED SHEAR WITH AROUND 60 KTS OF DEEP-LAYER SHEAR AND 0-1 KM SRH OF 100-150 M2/S2.  21Z JAN SOUNDING SHOWED THE PRESENCE OF STEEP MID-LEVEL LAPSE RATES ATOP A LOW-LEVEL MEAN MIXING RATIO OF 10-11 G/KG...WHICH WERE CONTRIBUTING TO MLCAPES OF 1000-1500 J/KG.  THIS SOUNDING ALSO EXHIBITED A MODERATELY HIGH LCL /1800 M/ OWING TO BOUNDARY-LAYER TEMPERATURE-DEWPOINTS SPREADS OF AROUND 25 F.

   

DESPITE THE MODEST LOW-LEVEL SHEAR AND LCL HEIGHTS...POTENTIAL WILL EXIST FOR TORNADOES WITH ALL RIGHT MOVING SUPERCELLS ACROSS WW 163 AREA.  COOLING/MOISTENING OF BOUNDARY-LAYER COUPLED WITH INCREASING LOW-LEVEL SHEAR AFTER 00Z...SUGGEST THAT THE POTENTIAL FORT A FEW SIGNIFICANT TORNADOES MAY INCREASE AT THIS TIME.

Mesoscale Discussion #0640


CONCERNING...TORNADO WATCH 244...

   

VALID 242009Z - 242115Z

   

THREAT FOR SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND A FEW TORNADOES APPEARS TO BE INCREASING OVER NWRN THROUGH N CNTRL OK NEXT FEW HOURS.

   

THIS AFTERNOON A CONVECTIVE OUTFLOW BOUNDARY EXTENDS FROM NERN OK NWWD THROUGH NWRN OK JUST S OF ENID TO E OF WOODWARD. WRN PART OF THIS OUTFLOW BOUNDARY ACROSS NWRN OK IS SLOWING AND IS IN THE PROCESS OF MODIFYING WHERE SURFACE HEATING IS OCCURRING IN THE WAKE OF EARLIER CONVECTIVE DEBRIS. STORMS ARE JUST BEGINNING TO DEVELOP ALONG THE OUTFLOW BOUNDARY NEAR ENID. THE ATMOSPHERE IN THE VICINITY OF THIS BOUNDARY IS VERY UNSTABLE WITH VERY STEEP LAPSE RATES. STORMS SHOULD INTENSIFY AS THEY MOVE NEWD OVER THE BOUNDARY WHERE DEEP LAYER SHEAR AND LOW LEVEL HODOGRAPHS ARE FAVORABLE FOR SUPERCELLS WITH LOW LEVEL MESOCYCLONES CAPABLE OF PRODUCING VERY LARGE HAIL AND A FEW TORNADOES.

Mesoscale Discussion #0973


CONCERNING...TORNADO WATCH 393...

   

VALID 251950Z - 252115Z

   

...THREAT FOR TORNADOES APPEARS TO BE INCREASING ACROSS SRN INDIANA...

   

A BROKEN LINE OF SUPERCELLS HAS FORMED FROM SERN IL ACROSS SRN PORTIONS OF INDIANA...WITH VERY STRONG ROTATIONAL COUPLETS NOTED FROM INDIANAPOLIS AND LOUISVILLE KY RADARS. ADDITIONAL STRONG CELLS ARE DEVELOPING SOUTH AND EAST OF INDIANAPOLIS WITH 2 INCH HAIL REPORTED RECENTLY JUST SOUTH OF MUNCIE INDIANA IN HENRY COUNTY. OBJECTIVE ANALYSIS AND SFC OBSERVATIONS INDICATE THE ENVIRONMENT HAS BECOME VERY UNSTABLE WITH LATEST MLCAPE VALUES EXCEEDING 2500 J/KG. WITH SFC DEWPOINTS IN THE LOWER 70S AND STRONG DIRECTIONAL SHEAR/PER VWP DATA/...THERE IS AN INCREASING CONCERN FOR TORNADOES.

Mesoscale Discussion #0976


CONCERNING...TORNADO WATCH 393...

   

VALID 252144Z - 252315Z

   

THE POTENTIAL EXISTS FOR A STRONG TORNADO OR TWO LATE THIS AFTERNOON AND EARLY THIS EVENING ACROSS FAR SRN IND AND WRN KY. ALSO...LARGE HAIL AND WIND DAMAGE WILL BE LIKELY WITH THE STRONGER STORMS. A TORNADO WATCH WILL BE ISSUED SHORTLY ACROSS WRN KY.

   

LATEST SFC ANALYSIS SHOWS A MOIST AXIS EXTENDING NWD ACROSS WRN TN INTO WRN KY WHERE DEWPOINTS ARE IN THE UPPER 60S F TO LOWER 70S F. AS A RESULT...THE AIRMASS IS MODERATELY UNSTABLE SOUTH OF A LINE OF SEVERE STORMS MOVING SEWD THROUGH SRN IND ATTM. REGIONAL WSR-88D VWPS CURRENTLY SHOW MODERATE VERTICAL SHEAR IN PLACE WITH STRONG LOW-LEVEL SHEAR PROFILES. THIS COMBINED WITH RELATIVELY LOW-LCL HEIGHTS WILL BE FAVORABLE FOR TORNADOES WITH SUPERCELLS THAT MOVE SEWD ACROSS FAR SRN IND AND WRN KY NEAR THE OH RIVER THROUGH EARLY EVENING. A STRONG TORNADO OR TWO WILL BE POSSIBLE ESPECIALLY AS THE LOW-LEVEL JET STRENGTHENS EARLY THIS EVENING. LARGE HAIL AND WIND DAMAGE WILL BE LIKELY WITH THE STRONGER STORMS IN THE LINE. IN ADDITION...THE THREAT FOR SUPERCELLS WITH TORNADOES...LARGE HAIL AND WIND DAMAGE SHOULD EXPAND SWD ACROSS MOST OF WRN KY THIS EVENING AS STORM COVERAGE INCREASES AND A LARGE LINEAR MCS DEVELOPS ACROSS THE REGION.

Mesoscale Discussion #2008


CONCERNING...TORNADO WATCH 786...787...788...

   

VALID 222000Z - 222130Z

   

THE POTENTIAL FOR SUPERCELLS CAPABLE OF TORNADOES IN ADDITION TO LARGE HAIL AND DAMAGING WINDS WILL CONTINUE ACROSS REGION THROUGH THE REMAINDER OF THE AFTERNOON.  AN ENHANCED THREAT OF POTENTIALLY SIGNIFICANT TORNADOES EXISTS ACROSS CNTRL/SRN MO INTO NRN AR...FAR WRN TN AND PERHAPS FAR ERN OK.

   

AS OF 1945Z...REGIONAL RADAR IMAGERY SHOWED A CLUSTER OF SUPERCELLS OVER FRANKLIN...CRAWFORD...WASHINGTON...IRON AND REYNOLDS COUNTIES MO NEAR AND JUST TO THE NE OF WARM FRONT WHICH EXTENDED FROM N OF SGF TO JUST N OF POF INTO NWRN TN /N OF DYR/.  ANOTHER INTENSE STORM CLUSTER /WITH EMBEDDED SUPERCELLS/ WAS LOCATED OVER FULTON...IZARD AND STONE COUNTIES IN N-CNTRL AR.

   

MODIFICATION OF EARLY AFTERNOON OBSERVED SOUNDINGS FROM LIT AND SGF INDICATES THAT AIR MASS ACROSS SRN MO...AR INTO ERN OK HAS BECOME MODERATE TO STRONGLY UNSTABLE WITH MLCAPES OF 2000-3000 J/KG. ACCOMPANYING WIND PROFILES INDICATED LONG HODOGRAPHS WITH 45-60 KTS OF 0-6 KM SHEAR AND 0-1 KM SRH OF 150-250 M2/S2.  THIS LOW-LEVEL SHEAR IS LIKELY LARGER INVOF WARM FRONT OVER SRN MO WHERE 0-1 KM SRH LIKELY EXCEEDS 250-300 M2/S2.  DESPITE THE ABSENCE OF ANY APPRECIABLE LARGE-SCALE FORCING FOR ASCENT...THIS COMBINATION OF SHEAR AND INSTABILITY SUGGESTS THE POTENTIAL FOR SIGNIFICANT SUPERCELLS CAPABLE OF STRONG TORNADOES.  THIS THREAT IS GREATEST ACROSS NRN AR INTO SRN MO.

   

EXPECT OTHER STORMS CURRENTLY INTENSIFYING OVER NWRN AR INTO SWRN MO TO EVOLVE SIMILARLY...WITH ADDITIONAL SUPERCELL DEVELOPMENT LIKELY FROM NEAR LIT NEWD TO NEAR DYR WITHIN THE NEXT COUPLE OF HOURS.

Mesoscale Discussion #2011


CONCERNING...TORNADO WATCH 788...790...

   

VALID 222208Z - 230015Z

   

CLUSTER OF TORNADIC SUPERCELLS /SOME LIKELY SIGNIFICANT/ WILL CONTINUE TO MOVE EWD AROUND 40 KTS ACROSS MUCH OF THE SRN HALF OF WW 788 /SCENTRAL/SERN MO AND SRN IL/ AND ACROSS WRN KY AND EVENTUALLY SWRN IND /WW 790/ OVER THE NEXT 2 HRS.

   

RECENT RADAR IMAGERY FROM STL AND PAH INDICATED SEVERAL STRONGLY ROTATING SUPERCELLS. ENVIRONMENT OVER THE REGION REMAINS EXTREMELY FAVORABLE FOR TORNADOES /0-1 KM SRH UP TO 350 M2/S2/ WITH A FEW DMGG TORNADOES POSSIBLE. MOST FAVORABLE LOCATION OF SIG TORNADO POTENTIAL APPEARS TO BE OVER FAR WRN KY AND SRN IL WHERE STRONGEST LOW LEVEL SHEAR /0-1 KM SRH AROUND 350 M2/S2 AND PRESSURE FALLS /2-3 MB/2 HR/ EXIST. AS SUPERCELLS CONTINUE TO MOVE FAIRLY RAPIDLY EWD THROUGH WRN KY AND INTO SWRN IND/SERN IL...THEY WILL ENCOUNTER MORE STABLE AIRMASS NORTH OF A WARM FRONT EXTENDING FROM NEAR MVN TO SOUTH OF EVV TO NEAR BWG. THIS BOUNDARY SHOULD CONTINUE TO LIFT SLOWLY NWD AND SUPPORT A DEVELOPING TORNADO THREAT INTO SERN IL/SWRN IND IN THE NEXT FEW HRS AS LOW LEVEL JET INCREASES. HOWEVER THE SVR THREAT IS ANTICIPATED TO REMAIN LIMITED INTO CENTRAL KY AND THE REST OF SRN IND.

   

FURTHER NORTH...THERE APPEARS TO BE A LIMITED SHORT TERM THREAT OF SVR WEATHER IN THE IMMEDIATE STL AREA/ECENTRAL MO...AS VIS SAT IMAGERY SHOWS NO APPARENT TOWERING CU ALONG THE SFC CONFLUENCE BOUNDARY EXTENDING ACROSS CENTRAL MO. HOWEVER ISOLATED SUPERCELLS WILL CONTINUE TO DEVELOP ALONG THE CONFLUENCE TROUGH OVER CENTRAL IL. SOMEWHAT WEAKER LOW LEVEL SHEAR /0-1 KM SRH AROUND 250 M2/S2/ WILL STILL BE SUPPORTIVE OF TORNADIC POTENTIAL.

Mesoscale Discussion #2018


CONCERNING...TORNADO WATCH 792...794...

   

VALID 230323Z - 230530Z

   

03Z MESOANALYSIS PLACES A COMPOSITE OUTFLOW BOUNDARY SITUATED FROM THE CONFLUENCE OF THE OH/MS RVRS SWWD TO ALONG THE AR/MO BORDER THEN INTO ECNTRL OK VCNTY KMKO.  THE DRYLINE WAS RETREATING INTO CNTRL AND SWRN OK.  

   

WEAKEST INHIBITION APPEARS TO EXIST ACROSS SERN OK AND IN A NARROW CORRIDOR VCNTY THE OUTFLOW BOUNDARY ACROSS THE NRN TWO ROWS OF COUNTIES IN AR.  WITHIN THIS ZONE...SEVERAL SUPERCELL TSTMS CONTINUE WITH RIGHT-MOVING MEMBERS EXPERIENCING 0-1KM SRH RANGING FROM 200 M2/S2 OVER SERN OK TO OVER 400 M2/S2 ACROSS NRN AR.  STORMS IN THIS REGION WILL HAVE THE HIGHEST POTENTIAL FOR TORNADOES THROUGH EARLY SAT MORNING...ESPECIALLY IF THEY CAN REMAIN ROOTED INTO THE BOUNDARY LAYER. 

   

CONVECTION HAS BEEN INCREASING FROM EXTREME SWRN MO SWWD INTO ECNTRL OK AS MOISTURE BEGINS TO SLOSH BACK WEST IN ADVANCE OF AN APPROACHING UPPER LEVEL TROUGH.  TSTMS SHOULD CONTINUE TO DEVELOP FARTHER W WITH TIME INTO CNTRL OK AFTER 06Z AS THE LLJ INCREASES AND LARGE SCALE ASCENT SPREADS EWD.  STRONGER INHIBITION ACROSS CNTRL/NERN OK INTO SWRN MO SUGGESTS THAT THE PRIMARY SEVERE THREAT WILL BE LARGE HAIL AS STORMS REMAIN ROOTED ABOVE THE BOUNDARY LAYER.

Mesoscale Discussion #2203


CONCERNING...TORNADO WATCH 850...851...

   

VALID 150532Z - 150630Z

   

SEVERE TSTMS WITH LARGE HAIL/HIGH WINDS AND TORNADOES ARE EXPECTED TO BECOME EVEN MORE WIDESPREAD ACROSS THE ARKLATEX AND MS THROUGH LATE TONIGHT. LATEST ANALYSIS DEPICTS A MODESTLY DEEP SURFACE LOW LOCATED NEAR DURANT OKLAHOMA WITH A WARM FRONT EXTENDING EAST ACROSS SCNTRL AR. VIGOROUS TSTM DEVELOPMENT HAS OCCURRED ALONG AND NORTH OF THE INTENSIFYING WARM FRONT OVER THE PAST COUPLE OF HOURS. MOST OF THIS CONVECTION HAS BEEN ROOTED ABOVE THE BOUNDARY LAYER AND CONTINUES TO POSE A THREAT OF LARGE HAIL. HOWEVER... SITUATION NOW APPEARS TO BE CHANGING QUICKLY ALONG THE SRN EDGE OF THIS CONVECTION WHERE INTENSE FORCING IS BEGINNING TO ACT ON INCREASINGLY MOIST AND UNSTABLE AIR MASS FROM NERN TX ACROSS SRN AR AND NRN LA. RESULTANT BOUNDARY LAYER MODIFICATION AND LOW LEVEL SHEAR AND FORCING ALONG THE WARM FRONT COULD SUPPORT INTENSE AND LONG-LIVED MESOCYCLONES...AND POSSIBLY STRONG TORNADOES OVERNIGHT.

   

FARTHER SOUTHEAST...STORMS CONTINUE TO INCREASE IN A BAND OF MOIST CONFLUENCE FROM SRN LA INTO MS. SHEAR AND FORCING WILL CONTINUE TO INCREASE ACROSS THIS REGION AS POWERFUL TROUGH DIGS ACROSS NORTH TX AND 60-70KT MID LEVEL FLOW OVERSPREADS THE REGION. ENVIRONMENT WILL BECOME INCREASINGLY FAVORABLE FOR UPDRAFT ROTATION ACROSS THESE AREAS THROUGH THE REST OF TONIGHT AND EXPECT TORNADO... HAIL...AND DAMAGING WIND POTENTIAL TO INCREASE IN THESE AREAS AS WELL THROUGH EARLY WEDNESDAY.

Mesoscale Discussion #2205


CONCERNING...TORNADO WATCH 850...

   

VALID 150816Z - 151015Z

   

POTENTIAL EXISTS FOR A COUPLE STRONG TORNADOES ACROSS WW 850.

   

SURFACE ANALYSIS CONTINUES TO SHOW DEEPENING LOW CENTERED NEAR DEQUEEN AR...AHEAD OF A SURGING COLD FRONT NOW THROUGH MUCH OF NRN TX. SYNOPTIC WARM FRONT EXTENDS ACROSS CNTRL AR INTO CNTRL MS WHERE RAPID WARM/MOIST ADVECTION CONTINUES. 06Z SHV RAOB SHOWS STRONG INSTABILITY IN PLACE WITH MLCAPES AROUND 1500 J/KG AND ONLY WEAK CAPPING AROUND 850 MB.

   

SATELLITE IMAGERY CONTINUES TO SHOW VERY STRONG UPPER VORTICITY CENTER MOVING ESEWD ACROSS NRN TX/SRN OK. DPVA/LIFT AND COOLING ALOFT ASSOCIATED WITH THIS FEATURE AND SURGING COLD FRONT WILL PROVIDE SUFFICIENT LIFT FOR THUNDERSTORMS TO FORM 09-12Z...MAINLY ACROSS SRN AR AND NRN LA. STORMS MAY FORM ALONG OR JUST AHEAD OF THE COLD FRONT AND/OR IN FREE WARM SECTOR ACROSS SRN AR/NRN LA. STORMS WILL BE SUPERCELLS WITH LIKELIHOOD OF TORNADOES UNTIL THEY EVENTUALLY GET UNDERCUT BY COLD FRONT. DQU PROFILER AND SHV VWP SHOW 0-1 SRH OF 350-450 M2/S2 INDICATING POTENTIAL FOR STRONG TORNADOES.

Mesoscale Discussion #2214


CONCERNING...TORNADO WATCH 858...

   

VALID 151848Z - 151945Z

   

THE THREAT FOR TORNADOES WILL CONTINUE ACROSS SE AL AND EXPAND EWD INTO SW GA AND THE FL PANHANDLE OVER THE NEXT FEW HOURS. STRONG TORNADOES WILL BE POSSIBLE WITH THE MORE PERSISTENT ROTATING STORMS.

   

LATEST SFC ANALYSIS SHOWS A SFC LOW IN NW MS WITH STRONG PRESSURE FALLS LOCATED ACROSS THE WARM SECTOR WITH THE FALL CENTER IN SE AL ATTM. A LINE OF STRONG TO SEVERE THUNDERSTORMS IS ONGOING JUST TO THE WEST OF THE FALL CENTER AND IS LOCATED VERY CLOSE TO THE AXIS OF A 70 KT LOW-LEVEL JET. WSR-88D VWPS JUST AHEAD OF THE LINE IN THE DOTHAM AREA OF FAR SE AL SHOW IMPRESSIVE LOW-LEVEL SHEAR PROFILES WITH 0-1 KM SHEAR VALUES AROUND 50 KT AND 0-3 KM HELICITY VALUES EXCEEDING 500 M2/S2. THIS SUGGESTS TORNADOES WILL BE VERY LIKELY WITH ROTATING STORMS AS THE LINE MOVES EWD THIS AFTERNOON ACROSS THE FL PANHANDLE AND INTO SW GA OVER THE NEXT FEW HOURS. A FEW STRONG TORNADOES MAY OCCUR WITH THE MORE PERSISTENT ROTATING SUPERCELLS THIS AFTERNOON.