Wet weather for the rest of the afternoon as the overrunning light to at times moderate rainfall returns to the area. I'm not expecting problems this afternoon or evening across the area. It's later tonight when we could see some serious issues.
First issue... Severe storms possible late. Shortwave energy and the associated sfc system will lift northeast into the Ohio Valley late. Increasing instability, an intensifying low level jet, and strong shear will give any storms to acquire rotating updrafts. Damaging winds, hail, and isolated tornadoes will be possible with the storms. Greatest threat for severe weather will arrive late tonight in our area. Here's SPCs svr outlook:
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1131 AM CDT SAT MAY 01 2010 VALID 011630Z - 021200Z ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PORTIONS OF FAR NRN LA...ERN AND SRN AR...NWRN MS...WRN TN AND THE MO BOOTHEEL... ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK ACROSS PORTIONS OF AR...LA...MS...SERN MO...FAR SRN IL...SWRN IN...WRN KY...WRN TN...NWRN AL AND NRN/CENTRAL MS... ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY NEWD INTO OH VALLEY... TORNADO OUTBREAK IS POSSIBLE LATER THIS AFTERNOON AND TONIGHT... ESPECIALLY ACROSS FAR NORTHERN LOUISIANA...SOUTHERN AND EASTERN ARKANSAS...THE MISSOURI BOOTHEEL...FAR WESTERN TENNESSEE...AND NORTHWESTERN MISSISSIPPI. ...SYNOPSIS... BROAD HIGH AMPLITUDE TROUGH EXTENDING FROM THE INTERMOUNTAIN WEST INTO THE CENTRAL STATES WILL MOVE ONLY SLOWLY EWD THROUGH THIS PERIOD. WITHIN THIS LARGE TROUGH...A STRONG UPPER IMPULSE...WILL EJECT RAPIDLY NEWD FROM SWRN TX INTO SERN KS/SWRN MO...ALONG WITH AN ACCOMPANYING 90-100 KT MID LEVEL JET. THIS FEATURE IS EXPECTED TO BE A MAJOR CONTRIBUTOR TO AN ENHANCED SEVERE WEATHER THREAT LATER TODAY AND TONIGHT. AT THE SURFACE...MAIN FRONTAL BOUNDARY WILL REMAIN QUASI-STATIONARY FROM LOWER MI SWWD INTO ERN TX. A WEAK SURFACE LOW WILL TRACK NEWD ALONG THE FRONT...FROM NERN TX INTO AR THIS EVENING...AND INTO MO/IL OVERNIGHT. ...ERN TX...LOWER MS VALLEY...LWR TN AND OH VALLEYS... AT MID MORNING...AN AREA OF THUNDERSTORMS EXTENDED FROM TN WWD INTO PORTIONS OF NRN MS/SERN AR...AND VERY MOIST SLY FLOW MAY MAINTAIN THIS QUASI-STATIONARY MCS THE AFTERNOON HOURS. THERE WILL BE A POTENTIAL FOR A TORNADO OR TWO...ESPECIALLY WITH THE STORMS ON THE SOUTH END OF THE COMPLEX...THOUGH TRAINING STORMS SUGGEST HEAVY RAINS SHOULD BE THE PRIMARY THREAT INTO THE AFTERNOON HOURS. OTHER STORMS WILL ALSO BE DEVELOPING SOUTH OF THESE BAND OF STORMS ACROSS PORTIONS OF ERN LA...MS AND NWRN AL...WITH ENVIRONMENTAL CONDITIONS FAVORABLE FOR TORNADOES. HOWEVER...AS UPPER WAVE APPROACHES FROM THE WEST...STORMS ARE EXPECTED TO REDEVELOP NEAR THE FRONT/SURFACE LOW IN THE ARKLATEX REGION BY EARLY/MID AFTERNOON. THESE STORMS SHOULD THEN DEVELOP/SPREAD NEWD AHEAD OF THE NEWD MOVING SURFACE LOW. THESE STORMS WILL DEVELOP IN A VOLATILE ENVIRONMENT WITH VERY STRONG INSTABILITY...MLCAPES NEAR 3000 J/KG AND 60-70 KT OF DEEP LAYER SHEAR. THESE ENVIRONMENT WILL BE SUPPORTIVE FOR INTENSE SUPERCELLS. THE DEGREE OF INSTABILITY...EXTREME LOW/DEEP LAYER SHEAR FAVORS LONG LIVED AND VERY DAMAGING TORNADOES WITH THESE STORMS. THE GREATEST THREAT FOR THE VERY DAMAGING TORNADOES WILL BE IN THE ARKLATEX BY MID/LATE AFTERNOON AND THEN SPREAD NEWD ACROSS THE REMAINDER OF THE HIGH RISK AREA LATE THIS AFTERNOON AND INTO THE NIGHTTIME HOURS. THE STORMS ARE LIKELY TO ADVANCE NEWD INTO WRN TN/LOWER OH VALLEY OVERNIGHT WITH A THREAT FOR TORNADOES...SOME POSSIBLY STRONG. HOWEVER...SOME COOLING OF THE BOUNDARY LAYER AND WEAKER ENVIRONMENTAL INSTABILITY SUGGESTS THE OVERALL THREAT WILL BE LOWER THAN ACROSS THE HIGH RISK AREA. ..IMY/STOPPKOTTE.. 05/01/2010
Second issue... very heavy, flash flooding rainfall. A 50 to 60 kt low level jet will continue to transport an airmass indicative of pwats on the order of 2 inches plus. Any training of thunderstorms will easily produce several inches of rainfall in a short time. A flash flood watch is in effect across the region. Greatest heavy rain threat will be later tonight into early Sunday morning.
We'll keep you posted,
Jay
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