Tuesday, February 19, 2008

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 190829
SWODY3
SPC AC 190827

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CST TUE FEB 19 2008

VALID 211200Z - 221200Z

..THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF E CNTRL THROUGH
SERN TX INTO THE LOWER MS VALLEY...

..SYNOPSIS...

SPLIT FLOW REGIME WILL CONTINUE THURSDAY WITH MODELS SIMILAR IN
EVOLUTION OF PATTERN...BUT DIFFERENCES IN DETAILS REMAIN. THE GFS IS
SLOWER AND LESS AMPLIFIED THAN THE NAM...ECMWF AND SREF MEAN WITH
SHORTWAVE TROUGH THAT WILL ADVANCE INTO SRN PLAINS. SURGE OF ARCTIC
HIGH PRESSURE WILL MOVE SEWD THROUGH THE ERN TWO THIRDS OF THE
COUNTRY. THE MAIN THRUST OF THE COLD AIR WILL EXTEND FROM THE CNTRL
AND NRN PLAINS THROUGH THE OH VALLEY...MID ATLANTIC AND NERN STATES.
COLD FRONT DEMARCATING THE LEADING EDGE OF COLDER AIR SHOULD EXTEND
FROM NRN FL WWD INTO THE WRN GULF COAST AREA...THROUGH CNTRL AND
SWRN TX BY EARLY THURSDAY. HOWEVER...THE TRUE ARCTIC FRONT WILL
LIKELY EXTEND FROM NRN PARTS OF THE SRN PLAINS THROUGH THE TN VALLEY
AND MID ATLANTIC REGION. WRN PORTIONS OF COLD FRONT WILL CONTINUE TO
SETTLE SLOWLY SWD THROUGH TX. HOWEVER...COASTAL FRONT MAY ADVANCE
INLAND THROUGH PARTS OF SRN LA.

..CNTRL AND SERN TX THROUGH THE LOWER MS VALLEY AREA...

SWD ADVANCE OF COLD FRONT WILL LIMIT THE SIZE OF THE QUALITY WARM
SECTOR. EARLY THURSDAY THE WARM SECTOR WITH UPPER 60S DEWPOINTS
SHOULD EXTEND FROM ROUGHLY SRN AND SERN TX INTO THE NWRN GULF. SWLY
FLOW ASSOCIATED WITH EWD ADVANCING UPPER TROUGH WILL ADVECT AN EML
AND STEEPER MID LEVEL LAPSE RATES OVER THE MOIST WARM SECTOR DURING
THE DAY. WHILE THIS WILL CONTRIBUTE TO DESTABILIZATION...IT MAY ALSO
SERVE TO CAP THE WARM SECTOR TO SURFACE BASED STORMS.
DESTABILIZATION WILL ALSO BE POSSIBLE IN COOL SECTOR FROM PARTS OF W
CNTRL THROUGH N CNTRL TX AS THE LOW LEVEL JET TRANSPORTS MOISTURE
ABOVE THE STABLE LAYER AND BENEATH STEEPENING MID LEVEL LAPSE RATES.
ELEVATED CONVECTION WILL LIKELY BE ONGOING WITHIN WARM ADVECTION
REGIME NORTH OF COASTAL FRONT FROM PARTS OF ERN TX INTO THE LOWER MS
VALLEY REGION. Q-G FORCING ACCOMPANYING THE EWD ADVANCING SHORTWAVE
TROUGH WILL LIKELY RESULT IN AN INCREASE IN THUNDERSTORMS INITIALLY
IN POST FRONTAL REGION ACROSS PARTS OF CNTRL THROUGH N CNTRL TX
THURSDAY EVENING. MUCAPE AND LAPSE RATES MAY BE SUFFICIENT FOR A
THREAT OF HAIL WITH THIS ACTIVITY. STORMS MAY EVENTUALLY DEVELOP
CLOSER TO LEADING EDGE OF SURFACE POSITION OF FRONT AS DEEPER
FORCING ADVANCES EWD.

POTENTIAL WILL EXIST FOR UNSTABLE WARM SECTOR TO RECOVER INLAND
ACROSS PARTS OF SERN TX INTO SRN LA OVERNIGHT AS THE LOW LEVEL JET
INCREASES AND COASTAL FRONT LIFTS NWD. HEIGHT FALLS AND
STRENGTHENING LOW LEVEL JET ASSOCIATED WITH EWD ADVANCING SHORTWAVE
TROUGH MIGHT EVENTUALLY SUPPORT SURFACE BASED STORMS IN THIS REGION.
IF STORMS MANAGE TO DEVELOP IN WARM SECTOR...VERTICAL SHEAR PROFILES
WOULD SUPPORT SUPERCELLS WITH AN ATTENDANT THREAT FOR ISOLATED
TORNADOES AND DAMAGING WIND. OTHERWISE LARGE HAIL WILL BE POSSIBLE
WITH ANY SUPERCELLS DEVELOPING ABOVE THE SURFACE STABLE LAYER NORTH
OF COASTAL FRONT.

.DIAL.. 02/19/2008

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