Sunday, February 1, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 012000
SWODY1
SPC AC 011957

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0157 PM CST SUN FEB 01 2009

VALID 012000Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

EARLY AFTERNOON SURFACE/STREAMLINE ANALYSES SHOWED A BOUNDARY
EXTENDING NWWD THROUGH THE GULF TO THE UPPER TX COAST WHERE IT
INTERSECTED A NNE-SSW ORIENTED CONFLUENCE ZONE...WHICH EXTENDED FROM
THE WRN GULF INTO SE TX. REGIONAL RADAR/LIGHTNING DATA INDICATED
MORE SUSTAINED TSTMS OFFSHORE OVER THE NWRN GULF ALONG THE NW-SE
ORIENTED BOUNDARY. MEANWHILE...LOW LEVEL WAA REGIME/ ISENTROPIC
ASCENT N OF THIS BOUNDARY IS MAINTAINING AN AREA OF CLOUDS/
PRECIPITATION AND A MORE STABLE BOUNDARY NWD INTO LA. 12Z LCH
SOUNDING MODIFIED WITH CURRENT SURFACE TEMPERATURES IN THE MID
60S/DEWPOINTS IN THE UPPER 50S SUGGEST THE MORE RECENT TSTM
DEVELOPMENT JUST INLAND OF THE UPPER TX COAST INTO SWRN LA SHOULD BE
SURFACE BASED.

WEAK INSTABILITY COMBINED WITH EFFECTIVE BULK SHEAR UP TO 30 KT
SUGGEST INLAND STORMS SHOULD REMAIN MULTICELLULAR WITH AN ISOLATED
THREAT FOR GUSTY WINDS AND/OR HAIL. LOW LEVEL DIRECTIONAL SHEAR
WOULD BE SUPPORTIVE OF A TORNADO THREAT...BUT OVERALL WEAK
INSTABILITY SHOULD PRECLUDE A GREATER CONCERN FOR TORNADOES. GIVEN
THAT THE TORNADO THREAT IS NON-ZERO...THIS OUTLOOK AS RE-INTRODUCED
A LOW TORNADO PROBABILITY.

FOR THE EVENING/OVERNIGHT TSTMS/ISOLATED SEVERE WEATHER
POTENTIAL...PLEASE REFER TO THE PREVIOUS DISCUSSION.
...PETERS...

...PREVIOUS DISCUSSION... /ISSUED 1015 AM CST SUN FEB 01 2009/
...ARKLATEX...
CURRENT SATELLITE IMAGERY SHOWS AN UPPER TROUGH DIGGING INTO THE
PLAINS STATES...WHILE A SERIES OF SOUTHERN STREAM FEATURES TRAVERSE
NORTHERN MEXICO AND THE WESTERN GULF OF MEXICO. SOUTHERLY LOW LEVEL
WINDS ARE SLOWLY TRANSPORTING GULF MOISTURE NORTHWARD INTO THE LOWER
MS VALLEY...BUT RECENT COLD INTRUSIONS HAVE LEFT THAT PART OF THE
GULF RATHER COOL/STABLE. PRESENT INDICATIONS ARE THAT SURFACE
DEWPOINTS IN THE 60S WILL PRIMARILY REMAIN OFFSHORE THIS FORECAST
PERIOD...AND THAT SURFACE-BASED INSTABILITY WILL BE RESTRICTED TO
THE IMMEDIATE TX/LA GULF COAST AND OFFSHORE. MODEL GUIDANCE IS IN
FAIR AGREEMENT FOR THE DEVELOPMENT OF SCATTERED THUNDERSTORMS AFTER
DARK OVER EAST TX ALONG APPROACHING COLD FRONT. ELEVATED CAPE AND
RATHER STEEP LAPSE RATES SUGGEST SOME POTENTIAL FOR HAIL IN STRONGER
CORES...BUT OVERALL SEVERE THREAT APPEARS LOW. ALSO OVERNIGHT...
CLUSTERS OF THUNDERSTORMS MAY APPROACH THE LA COAST FROM THE
SOUTHWEST WHERE NEAR SURFACE-BASED INSTABILITY COULD POSE A THREAT
OF LOCALLY DAMAGING WINDS.
...HART...

..PETERS.. 02/01/2009

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