DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED MAY 02 2012
VALID 021200Z - 031200Z
...THERE IS A MDT RISK OF SVR TSTMS FROM CNTRL NEB INTO CNTRL IA...
...THERE IS A SLGT RISK OF SVR TSTMS FROM NEB AND SD EWD ACROSS
LOWER MI AND INTO THE DELMARVA...
...SYNOPSIS...
A BROAD BELT OF SWLY FLOW ALOFT WILL EXTEND FROM THE NRN ROCKIES
ACROSS THE NRN PLAINS AND UPPER MS VALLEY. ONE LEAD SHORTWAVE WILL
EXIST OVER THE UPPER MS VALLEY AT 12Z WED...AND WILL QUICKLY MOVE
NEWD ACROSS THE GREAT LAKES AND INTO ONTARIO. BEHIND THIS
WAVE...HEIGHT MAY RISE BRIEFLY AHEAD OF THE NEXT SHORTWAVE TROUGH
WHICH WILL AFFECT WRN NEB AND THE DAKOTAS BY 00Z. A LOW LEVEL JET
WILL ALSO INCREASE DURING THE EVENING OVER THIS REGION...HELPING TO
FUEL COMPLEXES OF SEVERE THUNDERSTORMS FROM NEB INTO IA. ANOTHER
WEAK SHORTWAVE WILL EXIST FROM OH INTO THE MID ATLANTIC AND WILL
ENHANCE STORM CHANCES THERE.
AT THE SURFACE...A VERY LARGE AREA OF MOISTURE AND INSTABILITY WILL
BE PRESENT ACROSS THE PLAINS AND MIDWEST EWD ACROSS THE OH/TN
VALLEYS AND TO THE MID ATLANTIC. AS A RESULT...A VERY ACTIVE
CONVECTIVE DAY IS ANTICIPATED.
...NRN IA/SRN MN...SRN WI AND NRN IL AFTERNOON...
AN MCS ONGOING THIS EVENING WILL LIKELY LEAVE BEHIND A SLIGHTLY
COOLER AIR MASS OVER PORTION OF IA...MN...AND WI...REINFORCING THE
SYNOPTIC BOUNDARY. STRONG INSTABILITY AND A SWLY LOW LEVEL JET MAY
ALLOW FOR A CONTINUATION OF SOME ACTIVITY EARLY...FROM NRN MO INTO
ERN IA AND NRN IL WITH A MARGINAL THREAT OF WIND AND HAIL. DAYTIME
HEATING AND PERSISTENT SLY SURFACE FLOW SHOULD ALLOW RAPID
DESTABILIZATION ACROSS THE REGION WITH CAPE VALUES ON THE ORDER OF
2000-3000 J/KG. THE LOW LEVEL FLOW WILL NOT BE PARTICULARLY
STRONG...YET AS MASS FIELDS ADJUST TO THE NEXT TROUGH...BUT
HODOGRAPHS WILL BE LONG AND WILL STRONGLY FAVOR SUPERCELLS WITH VERY
LARGE HAIL FROM SERN SD EWD ACROSS NRN IA...PERHAPS SRN MN AND SWRN
WI.
...NEB...SERN SD...WRN IA EVENING/OVERNIGHT...
VERY STRONG INSTABILITY WILL BUILD OVER CNTRL AND ERN NEB...PRIOR TO
STORMS FORMING IN THE STRONG HEATING OVER W CNTRL NEB. CELLS SHOULD
QUICKLY BECOME SUPERCELLULAR WITH VERY LARGE HAIL AND DAMAGING
WINDS. MODELS ARE IN GOOD AGREEMENT DEPICTING A JETLET...POSSIBLY
RELATED TO CONVECTIVE FEEDBACK...MOVING FROM NEB INTO WRN IA. THIS
IS LIKELY DUE TO EXPLOSIVE RELEASE OF INSTABILITY WITH STEEP LAPSE
RATES AND HIGH PRECIPITABLE WATER CONTENT. THE INITIAL SUPERCELLS
WILL LIKELY MERGE DURING THE EVENING...BECOMING AN MCS CAPABLE OF
WIDESPREAD DAMAGING WINDS AS FAR E AS WRN IA.
...MD...ERN VA...ERN NC...
STRONG HEATING IS EXPECTED ACROSS THE AREA...PERHAPS IN THE WAKE OF
REMNANTS FROM THIS EVENINGS STORMS UPSTREAM OVER WV. FORECAST
SOUNDINGS INDICATE THAT 1500-2000 J/KG MLCAPE WILL BE PRESENT AND NO
CAPPING WILL EXIST. WITH WNWLY FLOW ALOFT...ANY STORMS THAT FORM
UPSTREAM WILL HAVE THE POTENTIAL TO GROW UPSCALE INTO AN MCS CAPABLE
OF BOTH WIND AND MARGINAL HAIL.
...CNTRL KS/WRN OK/NWRN TX DRYLINE...
A HIGHLY CONDITIONAL SEVERE THREAT WILL EXIST BY LATER AFTERNOON
ALONG THE DRYLINE. EXTREME INSTABILITY WILL BUILD UP ALONG THE
DRYLINE WHERE BOUNDARY LAYER DEWPOINTS WILL RISE INTO THE UPPER 60S
F BENEATH STEEP LAPSE RATES ALOFT. FORECAST SOUNDINGS SUGGEST THAT
TOTAL MIXING WILL OCCUR W OF THE DRYLINE THROUGH 500 MB...WHILE THE
AIR MASS E OF THE DRYLINE REMAINS CAPPED. THUS...A NARROW ZONE OF
UNCAPPED AND VERY UNSTABLE AIR WILL EXIST NEAR THE DRYLINE.
..JEWELL/GARNER.. 05/02/2012
