Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 011257
SWODY1
SPC AC 011255

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0655 AM CST SUN MAR 01 2015

VALID 011300Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL BE POSSIBLE ACROSS
PARTS OF CENTRAL AND SOUTHERN CALIFORNIA...FROM PARTS OF ARKANSAS
AND MISSISSIPPI TO THE WESTERN GULF COAST...AND CENTRAL FLORIDA.

...SYNOPSIS...
IN MID/UPPER LEVELS...SPLIT-FLOW PATTERN WILL PERSIST ALOFT THROUGH
PERIOD...AS TROUGHING PERSISTS OVER SRN PAC COAST AND GREAT BASIN.
LEADING PERTURBATION -- NOW MANIFEST AS ELLIPTICAL CYCLONE WITH
SW-NE LONG AXIS OVER NV AND S-CENTRAL CA AND ADJOINING PAC -- IS
FCST TO DRIFT SEWD WHILE REORIENTING TOWARD LESS POSITIVE TILT.
THIS FEATURE MAY BECOME OPEN-WAVE IN CHARACTER OVER SRN CA NEAR END
OF PERIOD AS SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE-CHANNEL
IMAGERY OVER NWRN BC -- DIGS SEWD TO COASTAL PAC NW.
MEANWHILE...NRN-STREAM SHORTWAVE TROUGH NOW OVER DAKOTAS AND NERN WY
WILL ACCELERATE EWD OVER UPPER MS VALLEY THIS EVENING...REACHING
LOWER GREAT LAKES BY 12Z.

AT SFC...12Z ANALYSIS SHOWED QUASISTATIONARY FRONTAL-WAVE LOW
OFFSHORE TX COASTAL BEND W OF MARINE STATION KBBF...N OF BUOY 42020
AND E OF CRP...WITH QUASISTATIONARY FRONT SWD ACROSS EXTREME WRN
GULF WATERS.  WARM FRONT WAS DRAWN ESEWD ACROSS NRN GULF TO S
FL...ARCHING NWD OVER GULF STREAM AND OFFSHORE SC.  SECONDARY/WEAKER
WARM-FRONTAL ZONE WAS ANALYZED FROM LOW NEWD ACROSS NRN LA AND MID
TN.  WRN GULF FRONTAL SEGMENT SHOULD MOVE SLOWLY NWD TO NEAR LA
COAST...WHILE PORTION NEAR FL SHIFTS WWD/NWWD ACROSS ERN/SRN FL
PENINSULA TODAY.

...CENTRAL FL...
WIDELY SCATTERED TO SCATTERED TSTMS ARE POSSIBLE THIS AFTN AS
CONTINUATION OF LOW-LEVEL DIABATIC SFC HEATING AND CONVERGENCE
JUXTAPOSE INVOF OLD FRONTAL ZONE AND SEA-BREEZE.  ACTIVITY MAY BE
GREATER IN COVERAGE NEAR I-75 CORRIDOR THAN INVOF E COAST AS
CONVERGENCE/CONVECTIVE REGIME SHIFTS WWD DURING MOST BUOYANT WINDOW
OF TIME THIS AFTN.  MLCAPE ONLY IN 700-1200 J/KG RANGE...WEAK
LOW-LEVEL SHEAR...AND SHALLOWNESS OF MOIST LAYER NEAR SFC SUGGEST
SVR POTENTIAL WILL BE TOO MINIMAL/DISORGANIZED FOR AOA 5% WIND/HAIL
PROBABILITIES.

...LOWER MS VALLEY...WRN GULF COAST...
SPORADIC TSTMS ARE POSSIBLE THROUGHOUT PERIOD...INITIALLY NEAR GULF
COAST WITH GRADUAL EXPANSION INLAND/NEWD ACROSS LOWER MS VALLEY OVER
TIME.  HEIGHTS ALOFT ARE FCST TO INCREASE ACROSS THIS AREA
THROUGHOUT PERIOD AS GREAT LAKES TROUGH PASSES WELL N AND NNE OF
AREA...AND AS RIDGING AMPLIFIES OVER ROCKIES E OF CA PERTURBATION.
AS SUCH...MID/UPPER-LEVEL FORCING FOR ASCENT WILL BE MINUSCULE AT
BEST...AND FCST SOUNDINGS SUGGEST SLGT MID/UPPER-LEVEL PROFILE
WARMING OVER AREA THROUGH TONIGHT.  AS SUCH...DEEP-LAYER LAPSE RATES
ABOVE STABLE BOUNDARY LAYER WILL REMAIN ONLY MRGLLY UNSTABLE...WITH
WAA AND CONCURRENT MOISTURE TRANSPORT CONTRIBUTING JUST ENOUGH
THETAE TO YIELD BUOYANT PROFILES ACROSS MIDLEVEL STABLE LAYERS...AS
EVIDENT IN 12Z LCH RAOB.  ELEVATED MUCAPE 500-1000 J/KG WILL SUPPORT
THUNDER POTENTIAL.

...PORTIONS CENTRAL/SRN CA...
ISOLATED TO WIDELY SCATTERED TSTMS SHOULD DEVELOP AGAIN TODAY INVOF
TROUGH AND RELATED POCKETS OF DCVA/COOLING ALOFT...WHERE LAPSE RATES
ARE OPTIMALLY STEEPENED.  MLCAPE SHOULD REMAIN BELOW 250 J/KG IN
MOST AREAS...BUT CAN EXTEND WELL INTO THERMAL LAYERS SUPPORTING LTG
GENERATION.  ISOLATED OVERNIGHT TSTMS ALSO WILL BE POSSIBLE INVOF
COASTAL SRN CA AS PERTURBATION ALOFT AND RELATED COLD-CORE
DESTABILIZATION/WEAK-CINH REGIME SHIFT SEWD.

..EDWARDS/GLEASON.. 03/01/2015



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