5/25/11 HIGH risk again in the mid-west and mid south
Wow, these folks need a break!
SPC AC 250557 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1257 AM CDT WED MAY 25 2011 VALID 251200Z - 261200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS EASTERN MISSOURI...EASTERN ARKANSAS...NORTHWEST MISSISSIPPI...WESTERN TENNESSEE...WESTERN KENTUCKY...CENTRAL AND SOUTHERN ILLINOIS...AND CENTRAL AND SOUTHERN INDIANA... ...THERE IS A SLGT RISK OF SVR TSTMS EXTENDING FROM THE LOWER GREAT LAKES REGION WWD ACROSS THE MIDWEST/OH VALLEY AND SWWD INTO AR/NERN TX/NRN LA... ...SYNOPSIS... A LARGE UPPER LOW OVER THE CENTRAL PLAINS AT THE START OF THE PERIOD IS PROGGED TO SHIFT STEADILY EWD WHILE WEAKENING SLOWLY WITH TIME. THIS LOW SHOULD REACH THE MID MS VALLEY LATE...AS THE MID-LEVEL JET ROTATES NEWD FROM THE BASE OF THE TROUGH INTO THE TN/OH VALLEYS THROUGH THE END OF THE PERIOD. FARTHER WEST...A LOW OVER THE ERN PACIFIC IS FORECAST TO MOVE ONSHORE...AND WILL WEAKEN AS IT PROGRESSES ACROSS THE PAC NW THROUGH THE PERIOD. AT THE SURFACE...A DEEP LOW INITIALLY OVER ERN KS IS EXPECTED TO REACH NRN INDIANA LATE...WITH A TRAILING COLD FRONT TO LIKEWISE ADVANCE EWD ACROSS MO/AR TOWARD THE OH VALLEY. IN THE WEST...A COLD FRONT AHEAD OF THE UPPER SYSTEM MOVING ONSHORE WILL CROSS THE PAC NW AND THE GREAT BASIN THROUGH 26/12Z. ...LOWER GREAT LAKES/OH VALLEY WWD INTO SERN IA/MO/AR/LA/E TX... A BROAD ZONE OF POTENTIALLY SIGNIFICANT SEVERE WEATHER -- INCLUDING VERY LARGE HAIL...WIDESPREAD DAMAGING WINDS...AND SCATTERED STRONG/DAMAGING TORNADOES -- IS FORECAST ACROSS A REGION CENTERED OVER THE MID MS/OH/TN VALLEYS TODAY. AT THE START OF THE PERIOD...GENERALLY SUB-SEVERE STORMS SHOULD BE CROSSING IA/IL...WITH ISOLATED/WEAKENING CONVECTION POSSIBLY ARCING SWD ACROSS THE MID MS VALLEY AND THEN SWWD INTO ERN TX. AS THE CONVECTION MOVES INTO THE SRN UPPER GREAT LAKES REGION AND ACROSS THE OH VALLEY STATES THROUGH MIDDAY...HEATING/DESTABILIZATION OF THE PRE-CONVECTIVE AIRMASS SHOULD PERMIT REINTENSIFICATION/EXPANSION OF STORMS ACROSS THIS REGION. STORM EXPANSION MAY POSSIBLY EXTEND AS FAR S AS WRN TN/NRN MS. MEANWHILE...STORM DEVELOPMENT IS FORECAST TO OCCUR BY EARLY AFTERNOON IN A SECOND BAND FARTHER W...DEVELOPING ACROSS MO JUST AHEAD OF THE UPPER SYSTEM...AND THEN EXPANDING SWD ALONG THE SURFACE FRONT. WITH A VERY MOIST WARM SECTOR AIRMASS...STRONG INSTABILITY IS EXPECTED TO DEVELOP BY AFTERNOON. WITH 70 KT MID-LEVEL SWLY JET ACROSS THE MID MS/LOWER OH VALLEY REGION ON SERN FRINGE OF THE ASSOCIATED LOW...SHEAR/INSTABILITY COMBINATION WILL FAVOR RAPID INTENSIFICATION OF STORMS -- WITH STORM MODE TO INCLUDE BOTH SUPERCELLS...AND RAPIDLY MOVING/BOWING CLUSTERS. IN ADDITION TO STRONG MID-LEVEL MESOCYCLONES... LOW-TROPOSPHERIC SHEAR WILL ALSO SUPPORT LOW-LEVEL ROTATION...AND THEREFORE POTENTIAL EXISTS FOR SEVERAL LARGE/STRONG TORNADOES. DAMAGING WINDS ARE LIKEWISE EXPECTED -- PARTICULARLY NEAR BOWING STORM CLUSTERS...AND LARGE HAIL IS ALSO LIKELY ACROSS THIS REGION. THE SECOND/FRONTAL BAND OF STORMS SHOULD CROSS THE MS VALLEY INTO EARLY EVENING...WITH SEVERE POTENTIAL ADVANCING ACROSS THE OH AND TN VALLEY REGIONS THROUGH LATE EVENING. GRADUAL DECREASE IN STORM SEVERITY IS EXPECTED OVERNIGHT...BUT LIMITED SEVERE THREAT MAY APPROACH THE WRN SLOPES OF THE APPALACHIANS -- AND SHIFT SWD TOWARD THE CENTRAL GULF COAST -- THROUGH THE END OF THE PERIOD. ..GOSS.. 05/25/2011
Last edited by dkmac; 05-25-2011 at 05:44 AM.
"The ultimate judge of your swing is the flight of the ball." - Ben Hogan
An area of significant severe weather, including very large hail, widespread wind damage and scattered strong to violent tornadoes, is forecast across eastern Missouri, eastern Arkansas, northwestern Mississippi, western Tennessee, western Kentucky, central and southern Illinois and central and southern Indiana; this includes the cities of Peoria, Indianapolis, Evansville, Memphis, Little Rock, and Saint Louis.
Thunderstorm activity is forecast to track across the southern Great Lakes and Ohio Valley this morning and by midday, the airmass ahead of this thunderstorm activity will become quite unstable causing this thunderstorm activity to strengthen this afternoon and expand southward into western Tennessee and northern Mississippi. At the same time this afternoon, a second area of thunderstorms are forecast to develop across Missouri and Arkansas and will track into southern Illinois, southern Indiana, western Kentucky, western Tennessee, and northern Mississippi later this afternoon. The airmass across this entire region with both areas of thunderstorm activity is forecast to be very moist and very unstable. In addition, very strong vertical wind shear profiles will exist across this area and all of these parameters will lead to rapid strengthening of thunderstorm activity with both supercells and bow echoes expected. Strong low-level rotation is forecast and several large and strong to violent tornadoes are possible across this entire area. In addition, widespread wind damage is expected with any bow echoes and large hail is also likely across this area. The highest risk area for large violent tornadoes given the forecast parameters will be across Northwest Tennessee, Western Kentucky, Southern Illinois and Southwest Indiana.
The NAM model may be doing the best in forecasting the potential instability parameters with substantially backed winds ahead of the frontal system. The forecast sounding for Paducah, Kentucky for late this afternoon and this evening is troubling as it’s showing storm relative helicity values of 500+ and EHI values of 6.6. Now, an EHI value of greater than 4 would be supportive of EF-4 and EF-5 tornadoes and the NAM is forecasting a 6.6!!I strongly suspect that the current moderate risk area that the Storm Prediction Center has out will be upgraded to a High Risk either with the 9 am Eastern/8 am Central or the 12:30 pm Eastern/11:30 am Central Time update.
If you have a Facebook or Twitter account, I highly recommend that you follow us to get the latest information, especially during fast-breaking events like Tornado Warnings. Our Facebook Page address is: [Uown-Weather-Services/137527286264871"]httk.com/pages/Crown-Weather-Services/137527286264871[/URL]. To follow us on Twitter, just go to our Twitter page at http://wwwcrownweather/ and click follow.
Please take the time this morning to think about what you will do if a Tornado Warning is issued for your location across the Mid-Mississippi, Ohio and Tennessee Valleys.
Make sure you have more than one source of local weather warnings and information; whether it be local media outlets, e-mail weather warning alerts or your favorite internet website. DO NOT rely on tornado sirens as you may not be able to hear them while indoors, especially if heavy rain and hail are pounding on your roof.
Check the weather often throughout the day. If you will be traveling or have outdoor activities planned, be sure you can get the latest weather information and keep up with developing severe weather.
If severe thunderstorms threaten you, remember these basic safety guidelines:
Severe thunderstorms produce large hail and damaging winds. If you are under a Severe Thunderstorm Warning, seek shelter in a sturdy building and stay away from doors and windows. If you are driving, think about finding substantial shelter to avoid being caught in large hail and strong winds. Always remember that every thunderstorm produces lightning and no place outdoors is safe.
If you are under a Tornado Warning, you need to act quickly to save your life!! An underground shelter or a safe room is the safest place. If no underground shelter is available, take cover in a sturdy building. Go to the lowest floor and stay away from doors, windows and outside walls. The goal is to put as many walls between you and the tornado as you can. You should protect yourself from flying and falling debris with pillows or blankets. We cannot emphasize enough that mobile homes and vehicles are not safe in a tornado, so plan ahead and be sure you have plenty of time to get to a sturdy shelter. Finally, I want to stress and emphasize that large violent tornadoes are likely this afternoon and this evening across the Mid-Mississippi, Ohio and Tennessee Valleys. If you live across this area, please take this very seriously and heed all watches and warnings today. If you have relatives, friends or colleagues that live across this area, please contact them and inform them of this significant severe weather threat.
Stay tuned for further updates concerning this potential significant severe weather event.
Last edited by dkmac; 05-25-2011 at 06:13 AM.
"The ultimate judge of your swing is the flight of the ball." - Ben Hogan
The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi...mid mississippi...and lower ohio valleys this afternoon and tonight.... Please read the latest public statement about this event.
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0755 AM CDT WED MAY 25 2011
VALID 251300Z - 261200Z
...THERE IS A HIGH RISK OF SVR TSTMS OVER PARTS OF NORTHEAST
ARKANSAS...SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...SOUTHWEST
INDIANA...WESTERN KENTUCKY...AND WESTERN TENNESSEE...
...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK
AREA...FROM PARTS OF THE LWR AND MID MS VLYS INTO THE LWR OH VLY...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ABOVE
AREAS...FROM SE TX NORTHEAST TO THE LWR GRT LKS...
...SVR WEATHER OUTBREAK EXPECTED FROM THE OZARKS AND MID/LWR MS VLY
INTO THE OH VLY TODAY THROUGH TONIGHT...
POTENT KS UPR LOW WILL CONTINUE EAST INTO WRN MO LATE TODAY...AND
INTO WRN IL EARLY THU...AS ASSOCIATED BELT OF 70+ KT MID LVL FLOW
SWEEPS E/NE FROM THE SRN PLNS/OZARKS INTO THE LWR MS/LWR TN VLYS.
AT THE SAME TIME...SFC LOW NOW OVER ERN KS SHOULD TRACK E INTO CNTRL
MO BY TNGT...AND INTO CNTRL IL EARLY THU. A SERIES OF CONFLUENCE
AXES/WEAK COLD FRONTS IN THE SRN QUADRANT OF THE LOW WILL MOVE
STEADILY E ACROSS THE OZARKS AND MID/LWR MS VLYS TODAY THROUGH EARLY
THU. E OF THE LOW...FRONT NOW EXTENDING EWD ACROSS CNTRL IL/IND
SHOULD ADVANCE N/NEWD AS A WARM FRONT INTO SRN MI AND THE LWR GRT
LKS.
...OZARKS INTO THE MID/LWR MS AND OH VLYS TODAY/TONIGHT...
STRONG SFC-BASED INSTABILITY WILL DEVELOP TODAY WITHIN DRY SLOT OF
SYSTEM UPR LOW AS THAT SYSTEM CONTINUES STEADILY EWD. BY EARLY TO
MID AFTN...SBCAPE SHOULD BE AOA 2500 J/KG OVER A BROAD CORRIDOR S OF
WARM FRONT FROM CNTRL IL/IND SWD INTO THE LWR MS... WITH HIGHER
VALUES POSSIBLE IN AXIS OF RICHEST BOUNDARY LAYER MOISTURE OVER THE
MS DELTA REGION OF AR/MS/TN.
SCTD TSTMS SHOULD FORM IN WEAKLY CAPPED ENVIRONMENT ON LEAD WIND
SHIFT/COLD FRONT OVER THE MO/AR OZARKS BY EARLY AFTN...WITH OTHER
STORMS LIKELY TO FORM AROUND THE SAME TIME OR PERHAPS A BIT LATER
ALONG LOW LVL CONFLUENCE AXIS EXTENDING FROM THE SRN IL SSW INTO SE
MO/ERN AR/WRN TN. ISOLD DEVELOPMENT ALSO MAY OCCUR LATE THIS AFTN
AND EVE SWWD ALONG COLD FRONT INTO SE TX AND LA.
STORM DEVELOPMENT FROM AR/TN NWD WILL BE AUGMENTED BY ASCENT/MID LVL
COOLING ASSOCIATED WITH VORT LOBE NOW ENTERING NW AR. AS THIS
FEATURE CONTINUES PIVOTING NEWD...ASSOCIATED BAND OF 50+ KT WSWLY TO
SWLY 700 MB FLOW WILL OVERSPREAD MUCH OF AR...SE MO...SRN
IL/IND...AND WRN PORTIONS OF KY/TN...ENHANCING CLOUD LAYER SHEAR.
AT THE SAME TIME...BROAD CURRENT OF SSWLY LOW LVL FLOW WILL PERSIST
AHEAD OF THE SFC LOW...MAINTAINING WIDESPREAD AREA WITH PW AOA 1.25
INCHES FROM THE WRN GULF CST WELL INTO THE OH VLY/LWR GRT LKS.
COMBINATION OF BROAD...MOISTURE-RICH...WEAKLY-CAPPED UNSTABLE
ENVIRONMENT WITH SUBSTANTIAL DEEP SHEAR SHOULD SUPPORT NUMEROUS
SUSTAINED SUPERCELLS WITH VERY LARGE HAIL AND HIGH WINDS. SOME OF
THE STORMS...ESPECIALLY THOSE ALONG IL/MO/AR CONFLUENCE BAND...COULD
YIELD STRONG/VIOLENT TORNADOES. STRONG TORNADOES ALSO MAY OCCUR
ALONG W/E WARM FRONT IN IL/IND. WIND PROFILES AND WEAKLY LINEAR LOW
LVL FORCING SUGGEST THAT THE ACTIVITY WILL EVOLVE INTO BROKEN LINE
SEGMENTS. EMBEDDED BOWING SEGMENTS/SUPERCELLS WITHIN THESE
STRUCTURES LIKELY WILL POSE A CONTINUED RISK FOR TORNADOES IN
ADDITION TO DMGG WIND/SVR HAIL INTO THE NIGHT. AN EXTENSIVE QLCS
MAY EVOLVE OVER PARTS OF THE OH AND TN VLYS BY EARLY THU AS THE BAND
OF STRONGEST...LARGELY UNIDIRECTIONAL DEEP SSWLY FLOW ON ERN SIDE OF
MO/IL UPR TROUGH APPROACHES THE WRN SLOPES OF THE APPALACHIANS.
MESOSCALE DISCUSSION 0953
NWS STORM PREDICTION CENTER NORMAN OK
1018 AM CDT WED MAY 25 2011
AREAS AFFECTED...PORTIONS OF SERN MO...NERN AR...SRN IL/IND...WRN
KY/TN
CONCERNING...OUTLOOK UPGRADE
VALID 251518Z - 251615Z
AN EXPANSION OF THE CATEGORICAL HIGH RISK WILL OCCUR WITH THE
UPDATED DAY 1 CONVECTIVE OUTLOOK AT 1630Z FOR A POTENTIAL MAJOR
TORNADO OUTBREAK. THIS WILL LIKELY INCLUDE ADDITIONAL PORTIONS OF
SERN MO...NERN AR...SRN IL/IND...AND WRN KY/TN. PLEASE SEE THE
FORTHCOMING DAY 1 OUTLOOK THAT WILL BE ISSUED BY 1630Z FOR FURTHER
METEOROLOGICAL DISCUSSION.
Note: The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.
Note: Click for Watch Status Reports.
SEL9
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 369
NWS STORM PREDICTION CENTER NORMAN OK
1040 AM CDT WED MAY 25 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHERN ARKANSAS
FAR EASTERN KANSAS
CENTRAL AND SOUTHERN MISSOURI
EFFECTIVE THIS WEDNESDAY MORNING AND EVENING FROM 1040 AM UNTIL
600 PM CDT.
TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTH SOUTHWEST OF
FLIPPIN ARKANSAS TO 60 MILES NORTH NORTHWEST OF COLUMBIA
MISSOURI. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 367...WW 368...
DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY LATE THIS MORNING INTO AFTERNOON IN ADVANCE OF POTENT
MIDLEVEL VORTICITY MAXIMUM MOVING OUT OF THE CNTRL PLAINS. STORMS
WILL LIKELY BE FOCUSED ALONG SURFACE COLD FRONT WITH ADDITIONAL
ACTIVITY POSSIBLE DOWNSTREAM WITHIN OPEN WARM SECTOR. AMBIENT AIR
MASS IS ALREADY MODERATELY UNSTABLE WITH MLCAPE OF 1000-2500
J/KG...AND FURTHER DESTABILIZATION WILL OCCUR THROUGH THE AFTERNOON.
WHEN COUPLED WITH DEEP-LAYER SHEAR OF 40-45 KT AND EFFECTIVE SRH OF
200-300 M2/S2...SETUP WILL FAVOR THE DEVELOPMENT OF SUPERCELLS
CAPABLE OF TORNADOES...SOME OF WHICH COULD BE SIGNIFICANT.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24035.
DISCRETE SUPERCELLS SHOULD FORM BY MID-AFTERNOON WITH A POTENTIAL
THREAT OF LONG-TRACKED/STRONG TORNADOES. A PDS TORNADO WATCH WILL BE
REQUIRED...MOST LIKELY BY 18Z.
RECENT VISIBLE SATELLITE IMAGERY INDICATES A DEEPENING CU FIELD AND
CLOUD STREETS ACROSS MUCH OF AR DOWNSTREAM OF A COLD FRONT THAT
EXTENDED FROM FAR SWRN MO INTO NERN TX AS OF 16Z. 12Z WRF-NMM
DEPICTS DISCRETE CELLS EMANATING OUT OF THIS CU FIELD BY 19Z...WITH
RECENT HRRR RUNS FASTER WITH TSTM INITIATION BUT SIMILAR IN
CONVECTIVE MODE. ENVIRONMENT IS PRIMED FOR RAPID EVOLUTION TO
SUPERCELLS GIVEN VERY FAVORABLE LOW/MID-LEVEL HODOGRAPHS PER
PROFILER AND VWP DATA...AMIDST A BROAD ZONE OF STRONG INSTABILITY
WITH MLCAPE AROUND 2500 J/KG. ANY SUPERCELLS DEVELOPING WITHIN A
BROAD AXIS OF A 45-55 KT LLJ...POTENTIAL FOR LONG-LIVED/STRONG
TORNADOES WILL INCREASE GREATLY TOWARDS MID-AFTERNOON.
Note: The expiration time in the watch graphic is amended if the watch is replaced, cancelled or extended.
Note: Click for Watch Status Reports.
SEL1
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 371
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT WED MAY 25 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL AND EASTERN ARKANSAS
MISSOURI BOOTHEEL
NORTHERN MISSISSIPPI
WESTERN TENNESSEE
EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL
1000 PM CDT.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...
DESTRUCTIVE TORNADOES...LARGE HAIL TO 3 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 50 MILES NORTHWEST OF LITTLE
ROCK ARKANSAS TO 50 MILES EAST SOUTHEAST OF JACKSON TENNESSEE.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
DISCUSSION...TSTM INITIATION IS EXPECTED WITHIN THE NEXT ONE TO TWO
HOURS WITHIN BROADLY CONFLUENT LOW-LEVEL FLOW REGIME IN PLACE ACROSS
AR. HERE...AIR MASS IS ALREADY MODERATELY UNSTABLE WITH MLCAPE OF
2500 J/KG WITH FURTHER DESTABILIZATION EXPECTED THIS AFTERNOON.
THIS INSTABILITY AXIS COINCIDES WITH A 60-70 KT MIDLEVEL JET STREAK
AND 40-50 KT LLJ...RESULTING IN VERY STRONG LOW AND DEEP-LAYER SHEAR
ACROSS THE BROAD WARM SECTOR. CURRENT INDICATIONS ARE THAT ONE OR
MULTIPLE FAST-MOVING BANDS OF SUPERCELLS ARE LIKELY THIS AFTERNOON
INTO EVENING WITH A THREAT FOR TORNADOES...SOME POTENTIAL STRONG TO
VIOLENT AND LONG-TRACKED...VERY LARGE HAIL AND DAMAGING WINDS.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 25040.
IWX: 1 Nne Hicksville [Defiance Co, OH] emergency mngr reports FLASH FLOOD at 02:52 PM EDT -- water affecting hicksville community hospital. sandbagging underway with water into lab areas.
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 371 CONTINUES.
...THREAT INCREASING FOR DISCRETE SUPERCELLS CAPABLE OF PRODUCING
LONG-TRACK/STRONG TORNADOES ACROSS WW 371...
INITIAL DISCRETE SUPERCELL THAT PROGRESSED ACROSS SHARP COUNTY AR
HAS RECENTLY SHIFTED INTO SERN MO. ADDITIONAL DISCRETE CELLS ARE
FORMING SW OF THIS TSTM WITHIN A CONFLUENCE AXIS THAT STRETCHED
TOWARDS TXK. ENVIRONMENT ACROSS CNTRL/ERN AR IS EXTREMELY CONDUCIVE
TO RAPID SUPERCELL EVOLUTION. MODIFIED 18Z LZK RAOB SUGGESTS MLCAPE
HAS NOW REACHED 3500 TO 4000 J/KG WITH 0-1 KM SHEAR AROUND 30 KT.
LARGE HODOGRAPHS...STRONG INSTABILITY AND A DISCRETE CONVECTIVE MODE
WILL ALL REMAIN HIGHLY FAVORABLE FOR LONG-TRACKED SUPERCELLS
PRODUCING STRONG TORNADOES AND VERY LARGE HAIL.
ALTHOUGH THE SEVERE THREAT WILL UNDOUBTEDLY INCREASE INTO THIS
EVENING AND LIKELY REQUIRE A TORNADO WATCH ISSUANCE...SUBSTANTIAL
UNCERTAINTY EXISTS OVER THE TIMING OF SUSTAINED TSTM INITIATION E/S
OF WW/S 370/371 ACROSS MIDDLE TN INTO NRN AL.
SMALL CB/SHOWER DEVELOPMENT HAS RECENTLY OCCURRED ACROSS PARTS OF
SWRN TN/NRN MS WITHIN A LONG-LIVED BUT DIMINISHING STRATOCU DECK
THAT ARCS FROM WRN TN INTO NRN LA. WITH STRONGER FORCED ASCENT
LIKELY HOLDING WEST OF THIS REGION...APPARENT WEAK LOW-LEVEL
CONVERGENCE AND THE LACK OF SIGNAL IN CONVECTION-ALLOWING
HRRR/WRF-NMM GUIDANCE SUGGEST UPDRAFTS MAY STRUGGLE TO BECOME
SUSTAINED DESPITE A VERY BUOYANT AND UNCAPPED AIR MASS PER MODIFIED
18Z BNA RAOB. HOWEVER...IF TSTMS DO BECOME SUSTAINED...THE
COMBINATION OF STRONG INSTABILITY AND SHEAR WILL BE FAVORABLE FOR
SUPERCELLS WITH ALL MODES OF SEVERE WEATHER POSSIBLE...AND
NECESSITATE A WW ISSUANCE PERHAPS AS EARLY AS 21-22Z.
OTHERWISE...THE EVENTUAL NEWD PROGRESSION OF ONGOING SUPERCELLS OVER
CNTRL AR WILL LIKELY LEAD TO A WW ISSUANCE LATER THIS EVENING.
5/25/11 HIGH risk again in the mid-west and mid south
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Originally Posted by ROLLTIDE
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