DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 291251
SWODY1
SPC AC 291249

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT MON OCT 29 2007

VALID 291300Z - 301200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...
A STRONG SHORT WAVE TROUGH WILL MOVE ACROSS NRN/CNTRL CA THROUGH
TODAY BEFORE SHEARING EWD OVER THE GREAT BASIN...AND GRADUALLY
PHASING WITH A LOWER AMPLITUDE IMPULSE SPREADING INLAND ACROSS THE
PACIFIC NORTHWEST. MEANWHILE...BROAD UPPER RIDGE ENCOMPASSING MUCH
OF THE CNTRL U.S. WILL SHIFT EAST TO THE GREAT LAKES AND OH VALLEY.
EXTENSIVE SURFACE ANTICYCLONE ASSOCIATED WITH THE RIDGE ALOFT WILL
PERSIST FROM THE NORTHEAST TO THE MIDWEST TO THE SRN PLAINS. THE
TIGHT PRESSURE GRADIENT BETWEEN THE LARGE SURFACE HIGH AND LOWER
PRESSURE OVER THE CARIBBEAN WITH TROPICAL STORM NOEL WILL MAINTAIN
HIGH ONSHORE WINDS ALONG THE EAST COAST AND OVER THE ERN GULF OF
MEXICO.

..CA/ORE...
STRENGTHENING SYNOPTIC SCALE ASCENT SHOULD LEAD TO AN INCREASE IN
SHOWERS AND TSTMS OVER PORTIONS OF NRN CA/SRN ORE TODAY. GPS WATER
VAPOR DATA INDICATED A STEADY INCREASE IN MOISTURE AHEAD OF THE
TROUGH WITH PW VALUES GENERALLY OVER 1 INCH. RECENT SHORT-TERM
FORECAST SOUNDINGS ALSO SUGGEST STEEP 850-500MB LAPSE RATES IN THE
RANGE OF 7.5-8 C/KM ABOVE A STABLE BOUNDARY LAYER. MOISTENING AND
LIFT WITHIN/BENEATH LEFT EXIT REGION OF STRONG UPPER JET TRANSLATING
INLAND ACROSS THE CNTRL SIERRA THIS AFTERNOON COULD SUPPORT POCKETS
OF MUCAPE AROUND 500 J/KG IF RUC AND NAM FORECASTS ARE CORRECT.
GIVEN STRENGTH OF LARGE SCALE FORCING AND POSSIBILITY OF SOME
DESTABILIZATION...A FEW STRONGER STORMS WITH HAIL APPEAR POSSIBLE.

..FL...
STRONG LOW LEVEL ELY FLOW AND MASS CONVERGENCE FOCUSED ALONG
RESIDUAL FRONTAL ZONE ON THE SRN PERIPHERY OF ERN STATES ANTICYCLONE
WILL MAINTAIN THE CHANCE FOR SHOWERS AND STORMS OVER SECTIONS OF
NRN/CNTRL FL EAST COAST TODAY. WIDESPREAD CLOUDS AND SHOWERS WILL
RESULT IN DEEPLY SATURATED THERMODYNAMIC PROFILES AND GENERALLY WEAK
LAPSE RATES NOT CONDUCIVE TO STRONG STORM UPDRAFTS. GIVEN STRENGTH
OF LOW LEVEL SHEAR...AND THE POTENTIAL FOR THIS SHEAR TO INCREASE
FARTHER SOUTH TOWARD POTENTIALLY MORE UNSTABLE AIR MASS WITH
TIME...AN ISOLATED TORNADO/WATERSPOUT CANNOT BE COMPLETELY RULED
OUT. HOWEVER...THE PROBABILITY OF THIS THREAT STILL APPEARS QUITE
LOW AT THIS TIME.

.CARBIN.. 10/29/2007

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