SWODY2
SPC AC 020541
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT WED MAY 02 2007
VALID 031200Z - 041200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
MID/UPPER LEVEL TROUGH IS EXPECTED TO SHIFT FARTHER INLAND ACROSS
THE INTERMOUNTAIN WEST TOWARD THE ROCKIES ON THURSDAY AS HEIGHTS
RISE OVER THE NERN PACIFIC. A SERIES OF SHORT WAVE TROUGHS WILL
TRAVERSE THE SRN AND ERN PERIPHERIES OF THIS TROUGH. ONE SUCH
IMPULSE IS PROGGED TO TRACK FROM THE GREAT BASIN TO WY BY LATE
THURSDAY AFTERNOON...AND THEN MOVE NWD ACROSS THE REST OF THE NRN
HIGH PLAINS.
FARTHER EAST...SPLIT FLOW REGIME IS EXPECTED TO BECOME ENHANCED AS
AN UPPER RIDGE STRENGTHENS AND BUILDS NWD ACROSS THE UPPER MS VALLEY
TO HUDSON BAY. MODELS TEND TO AGREE WITH EWD PROGRESSION OF A MID
LEVEL IMPULSE THROUGH ERN TX TO THE LOWER MS VALLEY...BUT DIFFER
WITH HOW QUICKLY THIS FEATURE WEAKENS DURING DAY 2 FORECAST PERIOD.
..PARTS OF CENTRAL/ERN TX TO WRN LA...
AT 12Z THURSDAY...A CLUSTER OF TSTMS...POTENTIAL MCS...SHOULD BE
ONGOING ACROSS PARTS OF CENTRAL TX WITH MODELS SUGGESTING CLOUDINESS
FROM THIS ACTIVITY SPREADING DOWNSTREAM ACROSS ERN TX AND LIMITING
THE DEGREE OF SURFACE HEATING. IN ADDITION TO LIMITED SURFACE
HEATING...MID LEVEL LAPSE RATES ARE EXPECTED TO WEAKEN AS 500 MB
TEMPERATURES WARM IN WAKE OF PROGRESSIVE IMPULSE. THUS...
INSTABILITY MAY TEND TO BE SOMEWHAT WEAK WHERE STRONGEST ASCENT
AHEAD OF SRN STREAM IMPULSE WILL BE SUPPORTIVE OF CONVECTIVE
DEVELOPMENT ACROSS ERN TX INTO LA. EFFECTIVE BULK SHEAR AROUND 25
KT SHOULD RESULT IN MULTICELLS WITH A THREAT FOR ISOLATED SEVERE.
GIVEN UNCERTAINTY WITH AMOUNT OF INSTABILITY AVAILABLE FOR
STRONG/SEVERE TSTM DEVELOPMENT AND MODEL DIVERGENCE IN WEAKENING OF
SRN STREAM SYSTEM...THIS OUTLOOK WILL MAINTAIN LOW SEVERE
PROBABILITIES ACROSS CENTRAL/ERN TX TO WRN LA.
..NRN/CENTRAL HIGH PLAINS...
ASCENT SPREADING NEWD ACROSS THE NRN HIGH PLAINS AHEAD OF
APPROACHING GREAT BASIN MID LEVEL SHORT WAVE TROUGH IS EXPECTED TO
SUPPORT TSTM DEVELOPMENT ALONG STRENGTHENING LEE TROUGH OVER ERN MT
SWD TO NERN CO. DESPITE STEEP LAPSE RATES AND STRONG SURFACE
HEATING...LIMITED MOISTURE RETURN WILL TEND TO RESULT IN WEAK
INSTABILITY...WITH TSTMS BEING HIGH BASED. EFFECTIVE BULK SHEAR
WILL BE SUPPORTIVE OF ORGANIZED TSTMS PRODUCING STRONG GUSTY WINDS
AND HAIL. HOWEVER...WEAK INSTABILITY IS EXPECTED TO LIMIT SEVERE
COVERAGE...AND THUS MAINTAIN LOW SEVERE PROBABILITIES FOR THIS
OUTLOOK.
STRENGTHENING SLY LLJ OVER THE CENTRAL HIGH PLAINS THURSDAY EVENING
IS EXPECTED TO AID DEVELOPMENT OF TSTM CLUSTER EWD ACROSS WRN PARTS
OF DAKOTAS/NEB WITHIN WAA REGIME ALONG NOSE OF LLJ. PLUME OF STEEP
LAPSE RATES ATOP LOW LEVEL WAA SHOULD SUPPORT A FEW SEVERE STORMS
WITH HAIL THURSDAY NIGHT.
.PETERS.. 05/02/2007
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