SWODY1
SPC AC 111249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT THU OCT 11 2007
VALID 111300Z - 121200Z
..NO SVR TSTM AREAS FORECAST...
..SRN/CENTRAL HIGH PLAINS AREA TODAY INTO TONIGHT...
A CONTINENTAL POLAR AIR MASS HAS BACKED WWD ONTO THE
CAPROCK...THOUGH LITTLE ADDITIONAL WWD PROGRESS OF THIS RELATIVELY
COOL/DRY AIR IS EXPECTED TODAY. A CORRIDOR OF 55-60 F BOUNDARY
LAYER DEWPOINTS WILL BE MAINTAINED ACROSS W CENTRAL TX AND ERN NM
..AND THE MOISTURE SHOULD SPREAD NWD TOWARD EXTREME SW KS AND SE CO
BY THIS EVENING TO THE E OF A WEAK LEE CYCLONE. DAYTIME
HEATING/MIXING BENEATH MODERATELY STEEP MID LEVEL LAPSE RATES WILL
SUPPORT AFTERNOON MLCAPE VALUES OF 1000-2000 J/KG...WITH ONLY WEAK
CONVECTIVE INHIBITION.
A WEAK MID LEVEL TROUGH AND LOW-LEVEL WAA WILL CONTINUE TO SUPPORT A
FEW CLUSTERS OF ELEVATED THUNDERSTORMS THIS MORNING ACROSS THE ERN
TX PANHANDLE AND NW TX. A SEPARATE SRN WAVE WILL MOVE OVER THE BIG
BEND/MIDDLE RIO GRANDE VALLEY THIS AFTERNOON...SUPPORTING SCATTERED
THUNDERSTORMS IN CONJUNCTION WITH INSOLATION. BY THIS
AFTERNOON...THE WEAK MID LEVEL TROUGH OVER THE TX PANHANDLE WILL
MOVE TO THE SE OF THIS AREA...LEAVING THE POTENTIAL FOR WEAK LARGE
SCALE SUBSIDENCE OVER THE INSTABILITY AXIS FROM W CENTRAL TX NWD.
IF DEEP CONVECTION DOES DEVELOP THIS AFTERNOON/EVENING...THE
MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR IN EXCESS OF 30 KT
COULD AGAIN SUPPORT ISOLATED SUPERCELLS IMMEDIATELY E OF THE LEE
CYCLONE/TROUGH.
A ROUGHLY 35 KT NOCTURNAL LLJ IS FORECAST TO DEVELOP FROM W TX INTO
WRN KS BY 03-06Z. LOW-LEVEL WAA ON THE NOSE OF THE LLJ...ALONG WITH
STEEP MID LEVEL LAPSE RATES AND INCREASING LOW-LEVEL MOISTURE...MAY
SUPPORT A FEW ELEVATED THUNDERSTORMS CAPABLE OF PRODUCING ISOLATED
LARGE HAIL ACROSS EXTREME ERN CO AND WRN KS LATE TONIGHT.
..SRN NEW ENGLAND LATER TODAY AND TONIGHT...
A MID LEVEL LOW OVER JAMES BAY WILL DIG SWD TOWARD THE GREAT LAKES
REGION...WHILE THE SEPARATE CLOSED LOW OVER ERN OH EVOLVES GRADUALLY
INTO MORE OF AN OPEN WAVE WHILE MOVING EWD TO THE ATLANTIC COAST BY
TONIGHT...AND THEN NEWD TO JUST OFF THE SE NEW ENGLAND COAST BY
12/12Z. AN ASSOCIATED SURFACE CYCLONE NEAR THE DE COAST WILL DEEPEN
AND PROGRESS NNEWD INTO SRN NEW ENGLAND IN RESPONSE TO THE
APPROACHING MID LEVEL WAVE. A NARROW PORTION OF THE WARM
SECTOR...WITH BOUNDARY LAYER DEWPOINTS IN THE 60S AND AT LEAST WEAK
INSTABILITY...MAY OVERSPREAD THE SRN/SERN NEW ENGLAND COAST TONIGHT
AS THE DEEPENING SURFACE CYCLONE BEGINS TO OCCLUDE. THE RELATIVELY
WEAK INSTABILITY AND THE POTENTIAL FOR MAINTENANCE OF A SHALLOW
NEAR-SURFACE STABLE LAYER OVER SRN/ERN NEW ENGLAND TONIGHT WILL
TEMPER ANY SEVERE STORM THREAT...THUS WILL REFRAIN FROM ADDING ANY
SEVERE PROBABILITIES IN THIS UPDATE.
.THOMPSON/GRAMS.. 10/11/2007
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