SWODY2
SPC AC 181729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST MON JAN 18 2010
VALID 191200Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT A VERY STRONG...GENERALLY ZONAL...UPPER JET NOW
APPROACHING SOUTHERN CALIFORNIA/NORTHERN BAJA...WILL CONTINUE TO
NOSE EASTWARD INTO THE SOUTHERN BRANCH OF THE PREVAILING SPLIT UPPER
FLOW REGIME ACROSS NORTH AMERICA. THE EXIT REGION OF THIS FEATURE
MAY SPREAD ACROSS THE LOWER RIO GRANDE VALLEY INTO WESTERN GULF
COASTAL AREAS AS EARLY AS 12Z WEDNESDAY. WITHIN THIS REGIME A
SERIES OF SHORT WAVE IMPULSES ARE PROGGED TO ADVANCE INLAND OFF THE
PACIFIC. BUT GUIDANCE IS SUGGESTIVE THAT THEY WILL TEND TO SPLIT
APART PRIOR TO REACHING THE COAST...WITH NORTHERN PORTIONS LIFTING
NORTH NORTHEASTWARD AND WEAKENING WITHIN BROADER SCALE NORTHERN
BRANCH RIDGING...AND SOUTHERN PORTIONS MIGRATING EASTWARD WITHIN
BROAD TROUGHING DEVELOPING ACROSS THE SOUTHERN PLATEAU INTO PORTIONS
OF THE LOWER MISSISSIPPI VALLEY. THE SOUTHERN IMPULSES ARE PROGGED
TO SUPPORT SURFACE CYCLOGENESIS ACROSS THE SOUTH CENTRAL HIGH PLAINS
TUESDAY...ALONG WITH AN INCREASINGLY SOUTHERLY COMPONENT TO THE
LOW-LEVEL FLOW FROM THE GULF OF MEXICO INTO PARTS OF THE SOUTHERN
PLAINS/LOWER MISSISSIPPI VALLEY.
...CALIFORNIA...
VARIABILITY EXISTS AMONG THE MODELS CONCERNING THE TIMING OF THE
INLAND PROGRESSION OF ONE SHORT WAVE TROUGH DURING THIS
PERIOD...WHICH WILL IMPACT CONVECTIVE POTENTIAL. CURRENTLY...IT
APPEARS A POSSIBILITY THAT MID-LEVEL COOLING ASSOCIATED WITH A -24
TO -28C 500 MB THERMAL TROUGH COULD BECOME JUXTAPOSED WITH THE WARM
SECTOR OF A WEAKENING/OCCLUDING FRONTAL WAVE...NEAR COASTAL AREAS
NORTH OF POINT CONCEPTION THROUGH THE LOS ANGELES BASIN...TUESDAY
AFTERNOON AND EVENING. IF THIS OCCURS... DESTABILIZATION COULD
BECOME SUFFICIENT FOR VIGOROUS LOW-TOPPED THUNDERSTORMS...IN THE
PRESENCE OF SUFFICIENT SHEAR FOR THE EVOLUTION OF SUPERCELLS.
...OZARK PLATEAU/UPPER PORTIONS OF THE LWR MS VALLEY...
GULF BOUNDARY LAYER RECOVERY IN THE WAKE OF THE PASSAGE OF A
SIGNIFICANT UPPER TROUGH OVER THE WEEKEND HAS BEEN TEMPORARILY
SUPPRESSED. AND IT APPEARS PROBABLE THAT INLAND MOISTURE RETURN
THROUGH THIS PERIOD WILL BE RELATIVELY WEAK. COUPLED WITH
INHIBITIVE LOWER/MID TROPOSPHERIC WARMING FROM THE SOUTHWEST...
POTENTIAL FOR DEEP CONVECTIVE DEVELOPMENT IS A BIT UNCERTAIN.
HOWEVER...IT DOES NOT APPEAR OUT OF THE QUESTION THAT SCATTERED
STORMS COULD FORM WITHIN A STRENGTHENING LOW-LEVEL WARM ADVECTION
REGIME LATE TUESDAY EVENING OR OVERNIGHT. IF THIS OCCURS... CLOUD
BEARING LAYER SHEAR IN THE PRESENCE OF COOL THERMODYNAMIC PROFILES
WITH STEEPENING LAPSE RATES MAY BE SUFFICIENT FOR SMALL TO PERHAPS
MARGINALLY SEVERE HAIL.
..KERR.. 01/18/2010
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