SWODY1
SPC AC 121955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0155 PM CST SAT DEC 12 2009
VALID 122000Z - 131200Z
...NO SVR TSTM AREAS FORECAST...
...SERN LA/MS/AL REGION...
ONGOING FORECAST LOOKS ON TRACK AS WEAK WARM FRONT/WARM SECTOR WILL
MOVE INLAND INTO EXTREME SERN LA THIS AFTERNOON AND FURTHER INLAND
ACROSS THE MS DELTA REGION OVERNIGHT. BAND OF ONGOING CONVECTION
FROM SOUTH OF LA INTO SRN MS APPEARS TO BE ASSOCIATED WITH
CONFLUENCE ZONE SITUATED AT 850 MB. WHILE STRONGER INSTABILITY OVER
THE GULF WATERS MAY SUPPORT AN ISOLATED STRONGER STORM OR TWO IN
SERN LA THIS AFTERNOON...THE STRONGEST LOW LEVEL CONVERGENCE IS
FORECAST TO SHIFT FROM SRN/CENTRAL MS NEWD INTO WEST CENTRAL AL
BEFORE WEAKENING. THE DISLOCATION BETWEEN THE MORE MOIST BOUNDARY
LAYER AND STRONGER LIFT...ALONG WITH POOR MID LEVEL LAPSE
RATES...SUGGEST THE SEVERE POTENTIAL IS LOW.
...CA...
AT 19Z...EXTENSIVE CLOUDS AND PCPN COVERED THE CENTRAL 2/3RDS OF THE
STATE...AHEAD OF STRONG SHORTWAVE TROUGH APPROACHING THE WEST
CENTRAL COAST. WHILE NO LIGHTNING HAS BEEN OCCURRING INLAND...
LIGHTNING STRIKES WERE NOTED WITHIN CORE COLD OF UPPER TROUGH...
ROUGHLY 200 NM WEST OF SFO. EVEN AS LAPSE RATES IMPROVE DUE TO
UVV/COLDER AIR ALOFT SPREADING INTO THE STATE...THE SEVERE THREAT
WILL BE VERY LOW DUE TO LACK OF ANY APPRECIABLE HEATING AND VERY
WEAK INSTABILITY.
..IMY.. 12/12/2009
.PREV DISCUSSION... /ISSUED 1025 AM CST SAT DEC 12 2009/
...LOWER MS RIVER VALLEY INTO THE SOUTHEAST...
SURFACE FRONT WILL CONTINUE TO LIFT SLOWLY NWD AND POSSIBLY COME
ASHORE ACROSS THE MS RIVER DELTA REGION LATE TODAY/TONIGHT AS WEAK
SURFACE LOW DEVELOPS INTO CENTRAL LA. THIS WILL OCCUR AS LOW
AMPLITUDE SHORTWAVE TROUGHS EJECTS ACROSS THE CENTRAL U.S...LEAVING
BROAD VEERING LOW LEVEL WIND FIELDS EVOLVING ACROSS THE GULF COAST
REGION. LOW LEVEL WAA REGIME WILL LIKELY MAINTAIN ELEVATED MOIST
CONVECTION AND SCATTERED THUNDERSTORM DEVELOPMENT FROM FAR ERN
TX/AR/LA ENEWD THROUGH THE PERIOD. FORECAST SOUNDINGS WITHIN WEAK
WARM SECTOR OVER FAR SERN LA/CENTRAL GULF COAST INDICATE SHALLOW
STABLE LAYER TOPPED BY WEAK LAPSE RATES...DESPITE INFLUX OF NEAR 70F
SURFACE DEW POINTS. THIS COMBINED WITH THE GENERAL VEERING WIND
PROFILES/WEAKENING SHEAR SHOULD LIMIT OVERALL SEVERE THREAT.
...CENTRAL CA COAST INTO THE INTERIOR VALLEYS...
INTENSE...FAST MOVING SHORTWAVE TROUGH NOW OFF THE CENTRAL CA COAST
WILL OVERSPREAD THE REGION TODAY AS IT SHIFTS ESEWD. SHEAR WILL
REMAIN QUITE STRONG ALONG NOSE OF 80+ KT MID LEVEL JET NOSING INTO
THE CENTRAL CA VALLEYS...ALTHOUGH REGION WILL LIKELY REMAIN
SOCKED-IN WITH CLOUDS/PRECIPITATION SUGGESTING VERY LIMITED
INSTABILITY. ALTHOUGH A FEW EMBEDDED THUNDERSTORMS CAN BE
EXPECTED...ACTIVITY WILL LIKELY REMAIN ELEVATED ATOP STABLE NEAR
SURFACE LAYER WITH MINIMAL SEVERE POTENTIAL.
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