SWODY2
SPC AC 201720
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM CDT WED OCT 20 2010
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM EXTREME ERN NM INTO A
LARGE PART OF WRN TX...
...SYNOPSIS...
SYNOPTIC REGIME WILL REMAIN DOMINATED BY AMPLIFIED SPLIT FLOW
THURSDAY. A STRONG JET STREAK APPROACHING THE UPPER MS VALLEY WILL
DROP SEWD THROUGH THE BASE OF ERN U.S. UPPER TROUGH AND INTO THE MID
ATLANTIC...CONTRIBUTING TO CYCLOGENESIS ACROSS NEW ENGLAND. AT THE
SURFACE A COLD FRONT WILL ACCOMPANY THIS IMPULSE AND ADVANCE SEWD
THROUGH THE NERN STATES AND THE OH VALLEY DURING THE DAY.
FARTHER WEST...THE UPPER LOW CURRENTLY SITUATED OVER NRN BAJA WILL
EJECT THROUGH THE SRN ROCKIES AND SRN HIGH PLAINS IN RESPONSE TO AN
UPSTREAM TROUGH THAT WILL MOVE ONTO THE WRN U.S. COAST.
...EXTREME ERN NM THROUGH WRN TX...
SELY LOW-LEVEL FLOW WILL PERSIST ACROSS THE SRN HIGH PLAINS WITHIN
ZONE OF HEIGHT FALLS DOWNSTREAM FROM EWD ADVANCING UPPER TROUGH.
PARTIALLY MODIFIED GULF AIR WITH 50S TO NEAR 60F DEWPOINTS WILL BE
ADVECTED NWWD THROUGH WRN TX AND ERN NM BENEATH STEEPER LAPSE RATES
WITH 1000-1500 J/KG MLCAPE POSSIBLE AS THE BOUNDARY LAYER WARMS. A
FEW THUNDERSTORMS WILL LIKELY BE IN PROGRESS OVER A PORTION OF ERN
AND NERN NM INTO THE TX PANHANDLE IN ASSOCIATION WITH INITIAL
IMPULSE ROTATING THROUGH UPPER LOW. ADDITIONAL STORMS WILL LIKELY
DEVELOP SOUTH OF THIS ACTIVITY WITHIN THE DESTABILIZING AIR MASS
ACROSS WRN TX AS THE CAP WEAKENS AND AS ANOTHER LOBE OF VORTICITY
ROTATES NWD THROUGH UPPER TROUGH. EFFECTIVE VERTICAL SHEAR WILL
INCREASE TO 40-45 KT SUPPORTING POTENTIAL FOR ORGANIZED STORMS.
SUPERCELLS...CLUSTERS AND LINE SEGMENTS WILL BE POSSIBLE WITH
ISOLATED LARGE HAIL AND DAMAGING WIND THE MAIN THREATS THROUGH MID
EVENING.
...NERN STATES...
COLD TEMPERATURES ALOFT WITHIN EXIT REGION OF CYCLONICALLY CURVED
UPPER JET WILL PROMOTE A CORRIDOR OF STEEPER /7-7.5 C/KM/ 700-500 MB
LAPSE RATES. HOWEVER...LOW-LEVEL MOISTURE WILL REMAIN LIMITED WITH
DEWPOINTS IN THE UPPER 40S TO NEAR 50F IN PRE-FRONTAL WARM SECTOR
WHICH SHOULD KEEP MLCAPE BELOW 500 J/KG. DEEP LAYER FORCING WILL BE
AUGMENTED ALONG AND AHEAD OF THAT PORTION OF THE FRONT LOCATED
WITHIN EXIT REGION OF UPPER JET ACROSS PARTS OF NEW ENGLAND...AND
STORMS ARE EXPECTED TO DEVELOP WITHIN THIS ZONE DURING THE DAY. SWLY
UNIDIRECTIONAL SHEAR INCREASING TO 40+ KT ALONG WITH STEEP LAPSE
RATES AND COLD AIR ALOFT WILL SUPPORT A MODEST THREAT FOR MARGINALLY
SEVERE HAIL AND STRONG WIND GUSTS. THE ANTICIPATED WEAK INSTABILITY
WILL SERVE AS THE LIMITING FACTOR FOR A MORE ROBUST SEVERE THREAT.
..DIAL.. 10/20/2010
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