[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 140546
SWODY1
SPC AC 140543

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1143 PM CST WED DEC 13 2006

VALID 141200Z - 151200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
FAST-MOVING WAVE TRAIN WILL CONTINUE ACROSS THE NRN STATES THIS
PERIOD AS A LEAD IMPULSE...CURRENTLY MOVING ACROSS THE NRN
PRAIRIES...SPREADS EWD AND AMPLIFIES OVER THE GREAT LAKES THROUGH
EARLY FRIDAY. ANOTHER STRONG STORM SYSTEM...NOW MAKING STEADY EWD
PROGRESS ACROSS THE ERN PACIFIC...WILL MAKE IT TO THE NORTHWEST
COAST TODAY WITH STRONG MID LEVEL HEIGHT FALLS DEVELOPING INLAND TO
THE NRN GREAT BASIN AND NRN ROCKIES THROUGH LATE TONIGHT.

SOUTH OF THE FASTER MID LEVEL FLOW...A BROAD UPPER TROUGH AND MID
LEVEL SHEAR ZONE IS FORECAST TO EVOLVE ACROSS MEXICO AND THE NWRN
GULF. WEAK DISTURBANCES EMANATING FROM THIS TROUGH WILL TRANSLATE
EWD OVER THE ERN GULF AND FL TODAY...LIKELY ENHANCING ASCENT NEAR
AND SOUTH OF RESIDUAL DEEP-LAYER FRONTAL ZONE.

...FL...
LOW LEVEL ELY FETCH OFF THE ATLANTIC WILL MAINTAIN 65-70F DEWPOINTS
ACROSS CNTRL AND SRN FL TODAY. DIURNAL HEATING SHOULD CONTRIBUTE TO
THE DEVELOPMENT OF INSTABILITY WITH FORECAST SOUNDINGS DEPICTING
MUCAPE OF 800-1200 J/KG POSSIBLE. GIVEN WEAK CAP AND POSSIBILITY OF
MODEST BACKGROUND ASCENT FROM SRN STREAM IMPULSES...EXPECT AT LEAST
SCATTERED TSTM DEVELOPMENT THROUGH THE AFTERNOON. EFFECTIVE BULK
SHEAR MAGNITUDES OF AROUND 30KT COULD SUPPORT ISOLATED PERSISTENT
MULTICELLULAR STORMS...PERHAPS GENERATING GUSTY WINDS...BUT LAPSE
RATES AND LACK OF STRONGER LOW LEVEL FLOW SHOULD NEGATE HIGHER
PROBABILITY SEVERE THREAT.

...PAC NW...
ONSHORE FLOW AND WARM AIR ADVECTION WILL INTENSIFY THROUGH THE DAY
FROM NRN CA ACROSS WRN WA AHEAD OF THE NEXT STRONG SHORT WAVE TROUGH
APPROACHING THE COAST. INSTABILITY WILL LIKELY REMAIN TOO MARGINAL
TO SUPPORT CG LIGHTNING UNTIL AFTER THE PASSAGE OF THE STRONGER
DYNAMIC FORCING ASSOCIATED WITH THE UPPER TROUGH. STRONG OROGRAPHIC
FORCING AND LOWERING STATIC STABILITY ASSOCIATED WITH MID LEVEL COLD
AIR ADVECTION IN THE WAKE OF THE STRONGER HEIGHT FALLS SHOULD LEAD
TO AT LEAST WIDELY SCATTERED TSTM ALONG THE COAST AND INTO THE COAST
RANGES THROUGH TONIGHT.

...UPPER MS VALLEY TO GREAT LAKES...
A FAST-MOVING POCKET OF STRONG DYNAMIC FORCING AND WEAK
DESTABILIZATION ON THE NOSE OF NARROW BUT INTENSE JET STREAK WILL
CONTINUE TO SWEEP EAST FROM SD TO MN THROUGH DAYBREAK. THIS FEATURE
HAS SPAWNED SPORADIC LIGHTNING WITH A FEW HIGH WIND GUSTS OBSERVED
AT THE SURFACE. NAM-WRF HINTS THAT ISOLATED CONVECTION MAY PERSIST
AS THIS SYSTEM MOVES EAST AND AMPLIFIES THROUGH THE DAY.
HOWEVER...LACK OF GREATER INSTABILITY AND FAST MOVEMENT OF THE
IMPULSE SHOULD LIMIT LIGHTNING COVERAGE TO LESS THAN 10 PERCENT
ACROSS THE REGION.

..CARBIN.. 12/14/2006