Saturday, March 7, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071302
SWODY1
SPC AC 071259

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0659 AM CST SAT MAR 07 2009

VALID 071300Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS E CNTRL PLNS INTO THE MID MS
AND OH VLYS...

...SYNOPSIS...
PROGRESSIVE SPLIT FLOW PATTERN WILL CONTINUE THROUGH SUN AS UT UPR
LOW CONTINUES ENE TO THE CNTRL PLNS/LWR MO VLY...AND NRN STREAM
IMPULSE NOW ON THE MB/ONTARIO BORDER MOVES GENERALLY E INTO WRN
QUEBEC. AT THE SFC...ELONGATED LOW OVER KS SHOULD CONSOLIDATE SWD
TO THE OK PANHANDLE THIS EVE. THE LOW SHOULD ACCELERATE NE INTO N
CNTRL MO TONIGHT/EARLY SUN AS ASSOCIATED STNRY FRONT REMAINS IN
PLACE ACROSS THE MID MS AND OH VLYS...AND TRAILING COLD FRONT SURGES
S INTO NW TX AND OK. STORMS THROUGH THE PERIOD SHOULD BE MOST
CONCENTRATED ALONG THE STNRY FRONT...ALTHOUGH INCREASING DEVELOPMENT
MAY OCCUR LATER IN THE PERIOD ALONG COLD FRONT.

...E CNTRL PLNS INTO MID MS/LWR OH VLYS...
SCTD CLUSTERS OF ELEVATED TSTMS EXPECTED TO PERSIST THROUGH THE
PERIOD ALONG AND N OF STNRY FRONT EXTENDING FROM THE CNTRL PLNS ENE
INTO PA/NY. THE FRONT SHOULD STRENGTHEN WITH TIME AS EWD MOVEMENT
OF MB/ONTARIO TROUGH MAINTAINS SFC RIDGE ACROSS THE UPR GRT
LKS...AND 45 KT WSWLY LLJ PERSISTS ACROSS THE MID MS/OH VLYS.
ASSOCIATED MOISTURE AVAILABILITY WILL REMAIN FAIRLY MODEST /PWS
AROUND 1.00-1.25 INCHES/...AND WEAK RIDGING WILL PREVAIL ALOFT
DOWNSTREAM FROM APPROACHING SRN STREAM TROUGH. BUT GIVEN 50+ KT
UNIDIRECTIONAL CLOUD LAYER SHEAR...STORMS WILL NEVERTHELESS HAVE THE
POTENTIAL TO PRODUCE OCCASIONAL BOUTS OF HAIL AS MUCAPE GRADUALLY
INCREASES TO NEAR 500 J/KG OVER IND/OH...AND REMAINS AOA 1000 J/KG
IN KS/MO.

FARTHER W...APPROACH OF UT TROUGH WILL ENHANCE UVV OVER THE CNTRL
PLNS THIS EVE...AND OVER THE MID MS VLY EARLY SUN. INCREASING
ASCENT/UPR DIFLUENCE AHEAD OF THE TROUGH...AND MODEST SFC HEATING
ALONG SWLY LLJ...COULD FOSTER DEVELOPMENT OF A MORE CONCENTRATED
AREA OR TWO OF STORMS ALONG STALLED FRONT OVER NRN PARTS OF KS AND
MO AND SE NEB/SRN IA BY EVE. IN THE PRESENCE OF STRENGTHENING DEEP
WSWLY SHEAR...COOL THERMODYNAMIC PROFILES AND GRADUALLY INCREASING
MOISTURE SUPPLY COULD YIELD ISOLD LOCALLY DMGG WIND GUSTS...IN
ADDITION TO LARGE HAIL.

CLOUDS WILL LIMIT WARM SECTOR SFC HEATING S OF STALLED FRONT. BUT
IF SUFFICIENT BREAKS DO DEVELOP...A CONDITIONAL RISK WILL EXIST FOR
ISOLD SFC-BASED STORMS NEAR THE FRONT/DRY LINE INTERSECTION
ACROSS S CNTRL/SE KS EWD INTO WRN MO LATE THIS AFTN/EARLY THIS EVE.
CLOCKWISE CURVED LOW-LVL HODOGRAPHS WILL ENLARGE AS LLJ INCREASES TO
AROUND 50 KTS. THUS...ANY SUSTAINED UPDRAFTS COULD DEVELOP LOW/MID
LVL ROTATION...INCREASING THE RISK FOR LARGE HAIL AND POSSIBLY A
TORNADO.

ADDITIONAL/MORE WIDESPREAD STORMS APPEAR LIKELY LATER TONIGHT EARLY
SUN AS UPR IMPULSE AND ASSOCIATED SFC LOW CONTINUE ENEWD. STORMS
COULD DEVELOP SWD ALONG COLD FRONT INTO SRN KS/NE OK...AND...MORE
LIKELY...EWD ACROSS MO AND IL. FAVORABLY-SHEARED ENVIRONMENT WITH
STEEP MID-LVL LAPSE RATES WILL SUPPORT A RISK FOR LARGE HAIL IN
STRONGER STORMS...AND POSSIBLY LOCALLY DMGG WINDS.

..CORFIDI/HURLBUT.. 03/07/2009

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