Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 190101
SWODY1
SPC AC 190100

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0800 PM CDT FRI APR 18 2014

VALID 190100Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS THE SOUTHERN
FLORIDA PENINSULA AND KEYS...

...SUMMARY...
A FEW SEVERE STORMS ARE POSSIBLE OVERNIGHT ACROSS PARTS OF SOUTHERN
FLORIDA...ACCOMPANIED BY THE RISK FOR SEVERE WIND GUSTS AND SOME
HAIL...PERHAPS A COUPLE OF TORNADOES.

...FLORIDA...
RELATIVELY WARM AND DRY LOWER/MID TROPOSPHERIC CONDITIONS EVIDENT IN
19/00Z RAOBS FROM KEY WEST AND MIAMI HAVE INHIBITED DEEP CONVECTIVE
DEVELOPMENT TO THIS POINT ACROSS MUCH OF THE KEYS AND FAR
SOUTHEASTERN SECTIONS OF THE FLORIDA PENINSULA.  HOWEVER... MODELS
INDICATE A SIGNIFICANT PRE-FRONTAL MOISTURE SURGE ACROSS THIS REGION
OVERNIGHT...WITH PRECIPITABLE WATER LIKELY INCREASING IN EXCESS OF
1.75 INCHES.  THIS APPEARS LIKELY TO OCCUR COINCIDENT WITH AT LEAST
WEAK MID-LEVEL COOLING AHEAD OF THE PRIMARY MID-LEVEL COLD CORE
ASSOCIATED WITH CLOSED LOW/UPPER TROUGH DIGGING INTO THE
NORTHEASTERN GULF OF MEXICO OVERNIGHT.  SO...DESPITE THE LOSS OF
DAYTIME HEATING...THE BOUNDARY LAYER ACROSS SOUTHERN FLORIDA WILL
LIKELY REMAIN WEAK TO MODERATELY UNSTABLE AS A MID/UPPER JET NOSES
TOWARD THE REGION OVERNIGHT... STRENGTHENING DEEP LAYER VERTICAL
SHEAR.

THE LATEST RAPID REFRESH AND HIGH RESOLUTION RAPID REFRESH ARE
SUGGESTIVE THAT LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION WILL
CONTRIBUTE TO INCREASING STORM DEVELOPMENT WITHIN THIS BAND OF
MOISTENING BY THE 03-06Z TIME FRAME...MAINLY ALONG/AHEAD OF AN
INITIAL OUTFLOW BOUNDARY...ROUGHLY SOUTH OF MELBOURNE THROUGH THE
FORT MYERS AREA.  THE EVOLUTION OF A BROKEN LINE OF STORMS APPEARS
POSSIBLE...PERHAPS WITH DISCRETE SUPERCELL DEVELOPMENT WITHIN AND
AHEAD OF THE LINE...WHICH MAY IMPACT THE MIAMI METRO AREA BY 09-12Z.


...NORTHERN PLAINS...
FORCING ASSOCIATED WITH A VIGOROUS SHORT WAVE TROUGH WITHIN THE MAIN
BRANCH OF MID-LEVEL WESTERLIES...ACROSS THE NORTHERN TIER OF THE
U.S...HAS CONTRIBUTED TO ONGOING SUSTAINED VIGOROUS CONVECTIVE
DEVELOPMENT NOW ADVANCING ACROSS AND EAST OF THE GLASGOW MT AREA. AS
THIS ACTIVITY CONTINUES INTO A PROGRESSIVELY COOLER AND MORE STABLE
BOUNDARY LAYER ENVIRONMENT...TOWARD THE NORTH DAKOTA BORDER...THE
RISK FOR STRONG WIND GUSTS SHOULD BEGIN TO DIMINISH AS CONVECTION
WEAKENS DURING THE 01-03Z TIME FRAME.

ADDITIONAL WEAKER THUNDERSTORM DEVELOPMENT APPEARS POSSIBLE
OVERNIGHT WITHIN A STRENGTHENING DOWNSTREAM LOWER/MID TROPOSPHERIC
WARM ADVECTION REGIME ACROSS PARTS OF THE EASTERN DAKOTAS INTO
NORTHERN MINNESOTA.

...SIERRA NEVADA AND MOUNTAINS OF SRN CA INTO ROCKIES...
AREAS OF SCATTERED THUNDERSTORM ACTIVITY APPEAR GENERALLY LARGELY
DIURNAL IN NATURE...AND SHOULD BEGIN TO DIMINISH WITH THE LOSS OF
DAYTIME HEATING...BY AROUND 03-04Z.

..KERR.. 04/19/2014




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