SWOMCD
SPC MCD 291946
CAZ000-292115-
MESOSCALE DISCUSSION 2139
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT MON OCT 29 2007
AREAS AFFECTED...SIERRA NEVADA RANGE
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 291946Z - 292115Z
TSTMS ARE EXPECTED TO INCREASE IN COVERAGE ACROSS DISCUSSION AREA
THIS AFTERNOON WITH THE POTENTIAL FOR SOME MARGINALLY SEVERE HAIL
WITH THE MOST INTENSE CORES. A WW IS NOT ANTICIPATED.
A PLUME OF RELATIVELY STEEP MID-LEVEL LAPSE RATES OF 7-8 C/KM
COUPLED WITH DAYTIME HEATING ARE CONTRIBUTING TO AIR MASS
DESTABILIZATION OVER THE SACRAMENTO VALLEY EWD INTO SIERRA NEVADAS
WHERE MUCAPES HAVE INCREASED TO 500-1000 J/KG. RECENT TRENDS IN
RADAR...SATELLITE AND LIGHTNING DATA SETS INDICATE TSTMS SLOWLY
INCREASING IN AREAL COVERAGE OVER THE SACRAMENTO VALLEY...NAMELY
GLENN...TEHAMA AND MORE RECENTLY SACRAMENTO COUNTIES. FORCING FOR
ASCENT ATTENDANT TO MOBILE UPPER TROUGH APPROACHING THE CA COAST
APPEARS TO BE THE PRIMARY MECHANISM SUPPORTING THIS MORE RECENT
STORM DEVELOPMENT.
AS THIS SYSTEM CONTINUES EWD...EXPECT AN INCREASE IN STORM COVERAGE
OVER PORTIONS OF THE SACRAMENTO INTO SAN JOAQUIN VALLEYS...AND
EVENTUALLY THE HIGHER TERRAIN OF THE SIERRAS. RUC PROXIMITY
FORECAST SOUNDINGS SUGGEST THAT AMBIENT THERMODYNAMIC ENVIRONMENT
OVER THE SIERRAS WILL BE MOST FAVORABLE FOR THE DEVELOPMENT OF A
COUPLE MARGINALLY SEVERE STORMS CAPABLE OF SOME HAIL. THIS THREAT
SHOULD TEND TO DIMINISH BY MID TO LATE EVENING AS BOUNDARY LAYER
COOLS AND STABILIZES.
.MEAD.. 10/29/2007
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...VEF...REV...HNX...STO...
36751987 38852153 39722187 39982194 40372155 40282084
38321964 37241862 36541904
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