STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.
VALID 021200Z - 031200Z
THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
25 NE SBY RIC FAY 45 NW AYS DHN 10 WNW JAN GLH ELD SHV LFK AUS BWD
ABI SPS ADM PGO 40 SSW UNO DYR BNA CSV CRW LBE AVP PSF ORH
25 SW EWB.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 NNW DVL ATY FSD
10 SSE OLU RSL ICT 30 SSE CNU 45 NNW SGF 10 WSW BLV 10 ENE HUF IND
DAY ZZV DUJ 40 WSW GFL PWM ...CONT... 65 W MIA 25 NNE FMY
45 NE PIE 50 N PIE ...CONT... 40 SSE DRT 10 S SJT 55 W ABI
30 NE TCC ALS 20 SSE GUC 25 NE GJT CAG 30 W BFF 81V 15 ENE BIL
40 SE WEY 20 SW SLC 70 E TPH 50 NNE NID 20 SW LGB ...CONT...
25 S ONP 25 W PDX 10 SSW OLM 20 ENE CLM.
AS SHORT WAVE TROUGH DIGS SOUTH SOUTHEASTWARD ACROSS BRITISH
COLUMBIA...EVENTUALLY EVOLVING INTO A CLOSED LOW...MODELS SUGGEST
EASTERN PACIFIC CLOSED LOW WILL CONTINUE TO MIGRATE TOWARD THE
CENTRAL CALIFORNIA COAST...WITH CIRCULATION CENTER APPROACHING THE
SAN FRANCISCO BAY AREA TOWARD 03/12Z. DOWNSTREAM...SHORT WAVE
RIDGE WILL GRADUALLY SHIFT EASTWARD ACROSS THE CENTRAL/SOUTHERN
ROCKIES INTO THE PLAINS...WITH SLIGHT AMPLIFICATION OF UPPER FLOW
REGIME FROM RIDGE AXIS OVER THE PLAINS INTO DOWNSTREAM TROUGH OVER
THE LOWER OHIO/TENNESSEE VALLEY. MEANWHILE...HUDSON BAY CLOSED LOW
WILL MIGRATE EASTWARD INTO NORTHERN QUEBEC AS ANOTHER SHORT WAVE
ROTATES AROUND ITS SOUTHERN/EASTERN PERIPHERY.
...APPALACHIANS INTO ATLANTIC COAST...
STRONGER LOW/MID-LEVEL WESTERLY FLOW WILL BEGIN TO LIFT AWAY FROM
THE NORTHEAST STATES...BUT SUBSIDENT FLOW IN THE LEE OF THE
APPALACHIANS...AND IN THE WAKE OF ANOTHER SHORT WAVE TROUGH LIFTING
NORTHEASTWARD OFF THE MID ATLANTIC COAST...WILL ALLOW FOR
SUBSTANTIAL SURFACE HEATING/DESTABILIZATION. THIS WILL OCCUR
ALONG/SOUTH OF SURFACE FRONTAL ZONE...WHICH IS PROGGED FROM
SOUTHERN NEW ENGLAND INTO SOUTHERN PENNSYLVANIA BY MID DAY.
INSTABILITY AND LIFT ALONG FRONT IS EXPECTED TO SUPPORT FAIRLY
VIGOROUS CONVECTIVE LINE...IN THERMODYNAMIC ENVIRONMENT WHICH
SHOULD BE SUFFICIENT FOR AT LEAST MARGINALLY SEVERE HAIL/WIND GUSTS
ACROSS THE NEW YORK CITY/PHILADELPHIA AREAS...BEFORE FRONT
PROGRESSES OFF THE NORTH ATLANTIC COAST EARLY THIS EVENING.
OTHERWISE...SCATTERED THUNDERSTORM ACTIVITY IS EXPECTED BE
GENERALLY CONFINED TO THE VICINITY OF THE APPALACHIANS THROUGH THE
AFTERNOON HOURS...AIDED BY DIFLUENT UPPER FLOW REGIME DOWNSTREAM OF
LOWER OHIO VALLEY TROUGH. STRONGER STORMS MAY PRODUCE SOME HAIL/
GUSTY WINDS...PARTICULARLY NEAR PEAK HEATING...BUT ACTIVITY SHOULD
WEAKEN DURING THE EVENING HOURS AS IT DEVELOPS OFF THE HIGHER
TERRAIN.
...LOWER OHIO VALLEY INTO GULF COAST...
WHILE ISOLATED STRONG STORMS ARE POSSIBLE ALONG FRONTAL BOUNDARY
ACROSS THE LOWER OHIO VALLEY...MOST WIDESPREAD CONVECTIVE
DEVELOPMENT IS EXPECTED BY MID TO LATE AFTERNOON ACROSS THE
NORTHERN GULF STATES. CONFLUENT LOW-LEVEL FLOW REGIME NEAR OLD
OUTFLOW BOUNDARY IS EXPECTED TO PROVIDE FOCUS FOR ACTIVITY...
BENEATH DIFLUENT REGIME BETWEEN ONE BELT OF WESTERLIES ACROSS THE
OHIO VALLEY...AND ANOTHER BELT INTO TROUGH OFF THE ATLANTIC COAST.
VERTICAL SHEAR PROFILES WILL BE RATHER WEAK...BUT INSTABILITY
RATHER STRONG WITH HEATING OF BOUNDARY LAYER WITH DEW POINTS NEAR
70F. RELATIVELY STEEP LOW/MID-LEVEL LAPSE RATES WILL SUPPORT MEAN
MIXED LAYER CAPE IN EXCESS OF 2000 J/KG...CONTRIBUTING TO POTENTIAL
FOR LARGE HAIL/DAMAGING WIND GUSTS IN MORE INTENSE STORMS.
...TEXAS...
ALTHOUGH LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION WILL BE
WEAK...MID-LEVEL CAP MAY BE WEAK ENOUGH FOR INTENSE CONVECTIVE
DEVELOPMENT NEAR/SHORTLY AFTER PEAK HEATING...IN THE VICINITY OF
DRY LINE/SURFACE FRONT INTERSECTION ACROSS NORTH CENTRAL/NORTHEAST
TEXAS. MODERATELY STRONG WEST NORTHWESTERLY MID-LEVEL FLOW WILL
PROVIDE SUFFICIENT SHEAR FOR SUPERCELLS IN THERMODYNAMIC
ENVIRONMENT WITH STEEP LAPSE RATES AND MEAN MIXED LAYER CAPE OF
2000 TO 4000 J/KG. ACTIVITY WILL CONTINUE INTO THE MID EVENING
HOURS BEFORE DIMINISHING WITH LOSS OF HEATING...
...CENTRAL PLAINS...
ALTHOUGH SIGNIFICANT NORTHWARD RETURN OF LOW-LEVEL MOISTURE IS NOT
LIKELY INTO THE NORTH CENTRAL HIGH PLAINS TODAY...MODELS SUGGEST
DEVELOPMENT OF SURFACE BASED INSTABILITY MAY OCCUR ACROSS PARTS OF
SOUTHWEST NEBRASKA FOR A BRIEF PERIOD LATE THIS AFTERNOON. LOW-
LEVEL WARM ADVECTION WILL BECOME FOCUSED ACROSS THIS REGION...NEAR
CREST OF AMPLIFYING SHORT WAVE RIDGE. ISOLATED STORMS APPEAR
POSSIBLE...AND WHILE NOT STRONG...HODOGRAPHS WILL BE SUPPORTIVE OF
UPDRAFT ROTATION...ENHANCING POTENTIAL FOR HAIL IN ENVIRONMENT WITH
MEAN MIXED LAYER CAPE OF 500 TO 1000 J/KG.
SURFACE BASED THUNDERSTORMS SHOULD DIMINISH THIS EVENING WITH LOSS
OF DAYTIME HEATING...BUT INCREASING THERMAL/MOISTURE ADVECTION
ABOVE BOUNDARY LAYER MAY SUPPORT ADDITIONAL SCATTERED THUNDERSTORMS
TONIGHT...NEAR STRENGTHENING SOUTHERLY NOCTURNAL LOW-LEVEL JET.
..KERR/JEWELL.. 05/02/03
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1300Z
|