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May 12, 2014 1300 UTC Day 1 Convective Outlook

May 12, 2014

May 12, 2014 1300 UTC Day 1 Convective Outlook

day1otlk

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0739 AM CDT MON MAY 12 2014

VALID 121300Z – 131200Z

…THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF TX NNEWD INTO THE MID/UPR MS VLYS AND GRT LKS…

…SUMMARY…
CLUSTERS OF STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE TODAY FROM WISCONSIN AND LOWER MICHIGAN SOUTHWARD ACROSS PARTS OF THE MID-MISSISSIPPI VALLEY INTO THE SOUTHERN PLAINS.

…SYNOPTIC SETUP…
PATTERN WILL REMAIN AMPLIFIED OVER THE CONUS THROUGH TUE. TROUGH THAT AFFECTED THE CNTRL PLNS ON SUN WILL CONTINUE NNE AND BECOME ABSORBED WITHIN MORE SLOWLY MOVING SYSTEM OVER SK/MB…WHILE HEIGHTS CONTINUE TO RISE OVER THE FAR WEST AND OVER THE ERN GRT LKS/MID-ATLANTIC. A SERIES OF SHORTWAVE IMPULSES IN WAKE OF THE CNTRL PLNS SYSTEM WILL MAINTAIN CYCLONIC FLOW FROM THE FOUR CORNERS EWD INTO THE TX.

SFC LOW WITH THE CNTRL PLNS TROUGH…NOW CENTERED OVER SRN MN…SHOULD TRACK NNE INTO WRN WI BY THIS EVE AND INTO WRN ONT EARLY TUE AS TRAILING COLD FRONT ACCELERATES E ACROSS THE MID AND UPR MS VLYS. THE SRN PART OF FRONT SHOULD PROGRESS MORE SLOWLY E/SE ACROSS THE OZARKS…ERN OK…AND CNTRL/E TX TODAY/TNGT. THIS FRONT SHOULD BE THE MAIN FOCUS FOR STRONG TO SVR TSTMS LATER TODAY INTO TNGT.

…MID/UPR MS VLY TODAY INTO TNGT…
SFC HEATING…APPROACH OF WRN KS SHORTWAVE TROUGH…AND EWD ACCELERATION OF ASSOCIATED COLD FRONT SHOULD SUPPORT RENEWED TSTM DEVELOPMENT ALONG THE FRONT OVER THE MID AND UPR MS VLYS THIS AFTN. OTHER DEVELOPMENT MAY OCCUR ON OUTFLOW BOUNDARIES AHEAD OF THE BOUNDARY.

WITH 700 MB SSWLY FLOW INCREASING TO BETWEEN 40 AND 50 KTS…SOME RISK WILL EXIST FOR SUSTAINED STORMS/SUPERCELLS. THE DEGREE AND EXTENT OF DIURNAL DESTABILIZATION WILL…HOWEVER…BE COMPLICATED BY OVERNIGHT STORM OUTFLOW AND CLOUD DEBRIS. NEVERTHELESS…WITH EVEN MODEST INSTABILITY /MUCAPE AROUND 1500 J PER KG/…SETUP COULD YIELD POCKETS/CORRIDORS OF STORMS CAPABLE OF DMGG WIND AND SVR HAIL FROM SW/CNTRL MO NNE INTO THE ERN HALF OF IA…SW WI…AND PARTS OF IL. A COUPLE TORNADOES ALSO MAY OCCUR…ESPECIALLY IN IA/WI/NW IL…WHERE STRONGER SHEAR WILL EXIST. WEAKLY CAPPED ENVIRONMENT AND MODEST DEGREE OF LARGE-SCALE ASCENT SUGGEST THE STRONGEST STORMS WILL OCCUR THIS AFTN…WITH THE ACTIVITY WEAKENING/MERGING INTO CLUSTERS EARLY TNGT.

…ERN OK/AR/CNTRL…SRN…AND E TX THIS AFTN THROUGH TNGT…
TSTMS SHOULD INCREASE IN COVERAGE AND STRENGTH WITH SFC HEATING LATER TODAY ALONG AND AHEAD OF COLD FRONT FROM ERN OK/WRN AR SSW INTO CNTRL TX. BUOYANCY WILL BE GREATER RELATIVE TO POINTS N /MLCAPE OF 2000-2500 J/KG/…BUT DEEP SHEAR RELATIVELY WEAK /25-30 KTS/. STRONG MULTICELL STORMS SHOULD OCCUR…POSING SOME RISK FOR SVR HAIL AND STRONG WINDS. MOISTURE-RICH /PW TO 2 INCHES/ SSELY LOW-LVL FLOW AND MODEST INCREASE IN LARGE-SCALE ASCENT ASSOCIATED WITH DISTURBANCES IN CYCLONIC FLOW ALOFT MAY SUPPORT UPSCALE GROWTH INTO A LARGE MCS OVER S TX THIS EVE. SUCH A CONVECTIVE SYSTEM COULD PERSIST/MOVE SLOWLY SEWD THROUGH EARLY TUE WITH A CONTINUED RISK FOR ISOLD SVR WIND/HAIL.

…LWR MI/OH THIS AFTN…
DIFFUSE WARM FRONT EXTENDING NW-SE ACROSS LWR MI INTO OH MAY SERVE AS AN ADDITIONAL FOCUS FOR MAINLY DIURNAL TSTMS AS THE BOUNDARY DRIFTS SLOWLY NWD. DEEP W TO NWLY SHEAR WILL RANGE FROM AROUND 30 KTS IN CNTRL OH TO NEARLY 50 KTS IN NRN LWR MI…WITH MLCAPE AROUND 1000 J/KG. ISOLD SVR WIND GUSTS AND MARGINALLY SVR HAIL MAY OCCUR.

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