SWODY1
SPC AC 190445
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1145 PM CDT SUN OCT 18 2009
VALID 191200Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
LEAD SHORT WAVE TROUGH CURRENTLY OVER THE SIERRAS WILL WEAKEN TODAY
IN ADVANCE OF MORE SIGNIFICANT UPPER SYSTEM WHICH WILL UNDERGO
CONSIDERABLE AMPLIFICATION WHILE MOVING ON TO THE CA COAST AND
EVENTUALLY INTO THE LOWER CO VALLEY. AT THE SURFACE...SEPARATE LOW
CENTERS INITIALLY OVER THE NRN ROCKIES AND CNTRL HIGH PLAINS WILL
EVENTUALLY CONSOLIDATE OVER ERN CO/WRN KS LATER TONIGHT. PACIFIC
COLD FRONT ATTENDING WRN CONUS UPPER SYSTEM WILL PUSH EWD/SEWD
THROUGH THE NRN INTERMOUNTAIN REGION AND GREAT BASIN...LIKELY
SERVING AS THE FOCUS FOR ISOLATED/SCATTERED DEVELOPMENT.
...GREAT BASIN INTO NRN HIGH PLAINS...
PRE-FRONTAL AIR MASS WILL REMAIN RELATIVELY DRY WITH PW VALUES
GENERALLY LESS THAN 0.5-0.6 INCH. BUT...THE PRESENCE OF STEEP
MIDLEVEL LAPSE RATES AND DAYTIME HEATING WILL CONTRIBUTE TO POCKETS
OF WEAK CONVECTIVE INSTABILITY LATER TODAY. FORCING FOR ASCENT IN
EXIT REGION OF CYCLONIC UPPER JET STREAK COUPLED WITH THE WEAK AIR
MASS DESTABILIZATION ARE EXPECTED TO SUPPORT ISOLATED/SCATTERED TSTM
DEVELOPMENT ALONG PACIFIC FRONT THIS AFTERNOON INTO EVENING. A FEW
OF THE STRONGER STORMS WILL BE CAPABLE OF SMALL HAIL...THOUGH THE
PROSPECTS FOR ANY SEVERE WEATHER APPEAR QUITE LOW. ADDITIONAL
STORMS WILL BE POSSIBLE FARTHER E WITHIN ZONE OF LOWER TROPOSPHERIC
WAA FOCUSED INVOF INTENSIFYING WARM FRONT OVER THE NRN HIGH PLAINS.
...SRN ROCKIES...
INFLUX OF AN INCREASINGLY MOIST BOUNDARY LAYER OFF THE GULF OF CA IN
CONJUNCTION WITH DAYTIME HEATING WILL RESULT IN A WEAKLY UNSTABLE
AIR MASS ACROSS REGION TODAY. WHILE STRONGER FORCING FOR ASCENT
WILL REMAIN TO THE NW/W THROUGH THE DIURNAL HEATING CYCLE...GLANCING
INFLUENCE OF WEAKER LEAD IMPULSES IN CONCERT WITH OROGRAPHIC FORCING
WILL LIKELY YIELD ISOLATED TO SCATTERED TSTMS LATER TODAY. NO
SEVERE WEATHER IS EXPECTED.
..MEAD/GRAMS.. 10/19/2009
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