Friday, July 4, 2008

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 040733
SWODY3
SPC AC 040730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI JUL 04 2008

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS E-CENTRAL NEB TO LS...

...SYNOPSIS...
MID-UPPER LEVEL PATTERN ACROSS CONUS IS FCST TO BECOME LESS
AMPLIFIED THROUGH PERIOD...AS ERN CONUS TROUGHING DEVOLVES INTO VERY
BROAD/WEAK AREA OF HEIGHT WEAKNESS FROM MID ATLANTIC TO LOWER MS
VALLEY. SEVERAL WEAK SHORTWAVE PERTURBATIONS ARE FCST TO MOVE EWD
BETWEEN NERN CONUS AND CENTRAL/NRN GREAT PLAINS IN WAKE OF MORE
WELL-DEFINED TROUGH DISCUSSED IN DAY-2 OUTLOOK. DETERMINISTIC AND
ENSEMBLE GUIDANCE IS INCONSISTENT WITH DETAILS OF THESE
FEATURES...HOWEVER SOME CONFIDENCE IS EVIDENT IN WEAK SHORTWAVE
TROUGHS OVER CENTRAL PLAINS AND OVER NRN GREAT BASIN REGION BY ABOUT
7/00Z.

AT SFC...COLD FRONT FROM DAY-2 PERIOD WILL MOVE SEWD ACROSS MN NORTH
WOODS AND LS...BUT WILL BECOME QUASISTATIONARY FARTHER SW ACROSS NEB
AND CENTRAL HIGH PLAINS OF CO/KS. LEE/PREFRONTAL TROUGHING WILL
PERSIST THROUGH THIS PERIOD FROM SSW-NNE ACROSS CENTRAL HIGH
PLAINS...S OF FRONTAL ZONE.

...CENTRAL PLAINS TO LS REGION...
ATTM...POTENTIAL FOR ORGANIZED SVR APPEARS RELATIVELY MAXIMIZED
DURING AFTERNOON INVOF SFC COLD FRONT...FROM LS SWWD AT LEAST INTO
ERN/CENTRAL NEB. RICHEST SFC MOISTURE SHOULD BE ACROSS THIS REGION
AS EVAPOTRANSPIRATIVE PROCESSES AND MOIST ADVECTION CONTRIBUTE TO
DEW POINTS MID 60S TO ISOLATED LOW 70S F...BENEATH STEEP ENOUGH
MIDLEVEL LAPSE RATES TO SUPPORT MLCAPES 2500-4000 J/KG. DEEP-LAYER
SHEAR PROFILES ALSO ARE FCST TO INCREASE WITH NEWD EXTENT UP FRONTAL
ZONE...SUPPORTING SOME POTENTIAL FOR ORGANIZED MULTICELL...BOW AND
ISOLATED SUPERCELLULAR ORGANIZATION.

FARTHER SW...DEEP-LAYER WIND PROFILES AND VERTICAL SHEAR EACH ARE
FCST TO WEAKEN...LENDING GREATER UNCERTAINTY REGARDING
LONGEVITY/ORGANIZATION OF AFTERNOON/EVENING TSTMS. HOWEVER...GIVEN
HOT AND VERY WELL MIXED SUBCLOUD LAYER LIKELY...ALONG WITH CINH
FURTHER WEAKENED BY CONVERGENCE INVOF FRONT...TROUGH AND
UPSLOPE/OROGRAPHIC REGIMES...AT LEAST ISOLATED SVR IS LIKELY.

...SERN CONUS TO MID ATLANTIC...
ANOTHER ROUND OF MULTICELLULAR/PULSE TSTMS IS POSSIBLE ACROSS WIDE
SWATH OF ERN CONUS THIS PERIOD...ALONG AND S OF RESIDUAL FRONTAL
ZONE DESCRIBED IN DAY-2 OUTLOOK. PRIMARY FOCI FOR CONCENTRATED
CONVECTIVE POTENTIAL WILL BE OLD FRONT...SEA BREEZES...AND ANY
SIGNIFICANT OUTFLOWS FROM DAY-2 ACTIVITY. DEEP-LAYER WINDS AND
SHEAR APPEAR TOO WEAK -- AND MESOSCALE FORCING TOO UNCERTAIN -- TO
JUSTIFY CATEGORICAL RISK FOR ORGANIZED SVR ATTM.

..EDWARDS.. 07/04/2008

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