Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 180553
SWODY1
SPC AC 180551

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT FRI APR 18 2014

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY ACROSS PARTS OF THE
CENTRAL AND NORTHERN FLORIDA PENINSULA....

...SUMMARY...
A FEW SEVERE STORMS ARE POSSIBLE TODAY ACROSS CENTRAL AND NORTHERN
SECTIONS OF THE FLORIDA PENINSULA...ACCOMPANIED BY THE RISK FOR
DAMAGING WIND GUSTS...PERHAPS A COUPLE OF TORNADOES...AND SOME HAIL.

...SYNOPSIS...
SHORT WAVES WITHIN A COUPLE OF BELTS OF MID-LATITUDE WESTERLIES
TRAVERSING THE U.S. DURING THIS FORECAST PERIOD APPEAR LIKELY TO
REMAIN GENERALLY PROGRESSIVE.  THIS INCLUDES A PAIR OF LARGER SCALE
TROUGHS ASSOCIATED WITH THE WEAKER BUT MORE AMPLIFIED SOUTHERN
STREAM...ACROSS THE SOUTHERN TIER STATES...WHICH IS INTERACTING WITH
ANOTHER BELT OF WESTERLIES EMERGING FROM THE SUBTROPICAL EASTERN
PACIFIC.

WHILE ONE TROUGH PROGRESSES INLAND ACROSS PARTS OF THE SOUTHWESTERN
U.S. AND NORTHWESTERN MEXICO...CONTRIBUTING TO AREAS OF WIDELY
SCATTERED THUNDERSTORM ACTIVITY ACROSS THE SIERRA
NEVADA/INTERMOUNTAIN WEST AND ROCKIES...THE OTHER IS FORECAST TO DIG
ACROSS CENTRAL/EASTERN GULF COASTAL AREAS AND THE NORTHEASTERN GULF
OF MEXICO THROUGH 12Z SATURDAY.  WITH MUCH MORE SUBSTANTIVE MOISTURE
AND POTENTIAL INSTABILITY AVAILABLE TO THE LEAD IMPULSE...HIGHEST
THUNDERSTORM PROBABILITIES FOR TODAY AND TONIGHT APPEAR TO EXIST
ACROSS THE EASTERN GULF OF MEXICO THROUGH PORTIONS OF THE FLORIDA
PENINSULA AND ADJACENT WESTERN ATLANTIC.

OTHER ISOLATED TO WIDELY SCATTERED THUNDERSTORM ACTIVITY MAY NOT BE
OUT OF THE QUESTION FROM PARTS OF THE NORTHERN ROCKIES EAST-
NORTHEASTWARD THROUGH THE NORTHERN PLAINS.  THIS IS WHERE MOISTURE
RETURN WILL BE SEASONABLY WEAK TO MODEST...BUT LAPSE RATES RATHER
STEEP...ON THE SOUTHERN PERIPHERY OF A SIGNIFICANT NORTHERN-STREAM
SHORT WAVE IMPULSE PROGRESSING EASTWARD ALONG THE CENTRAL
CANADIAN/U.S. BORDER AREA.

...FLORIDA...
VARIABILITY DOES EXIST AMONG THE MODELS CONCERNING THE SMALLER SCALE
PERTURBATIONS WITHIN THE EVOLVING APPROACHING UPPER TROUGH...AND
ASSOCIATED SURFACE FRONTAL-WAVE DEVELOPMENT ACROSS THE EASTERN GULF
OF MEXICO.  THIS COULD HAVE A SUBSTANTIVE IMPACT ON THE CONVECTIVE
EVOLUTION FOR THIS PERIOD.  HOWEVER...THERE DOES APPEAR A GENERAL
CONSENSUS OF POTENTIAL FOR AT LEAST SCATTERED THUNDERSTORM
DEVELOPMENT ALONG AN INLAND-ADVANCING SEA BREEZE ACROSS INTERIOR
CENTRAL SECTIONS OF THE PENINSULA FROM LATE MORNING INTO AFTERNOON.
THEN GUIDANCE GENERALLY SUGGESTS THAT A PRE-FRONTAL MESOSCALE
CONVECTIVE SYSTEM WILL EVOLVE WHILE PROGRESSING INLAND OFF THE GULF
OF MEXICO THROUGH THE FLORIDA PENINSULA DURING THE LATE AFTERNOON
AND EVENING.

ALTHOUGH MID/HIGH LEVEL LAPSE RATES ACROSS THE REGION ARE EXPECTED
TO REMAIN WEAK...LIMITING THE MAGNITUDE OF
DESTABILIZATION...SEASONABLY HIGH MOISTURE CONTENT ACROSS AT LEAST
THE CENTRAL PENINSULA IS EXPECTED TO CONTRIBUTE TO MIXED- LAYER CAPE
AT OR ABOVE 1000 J/KG WITH DAYTIME HEATING.  COUPLED WITH MODEST
LOW/MID-LEVEL WIND FIELDS...VEERING WITH HEIGHT...BENEATH 30-40+ KT
SOUTHWESTERLY 500 MB FLOW...SEA-BREEZE CONVECTION MAY INCLUDE A FEW
SUPERCELL STRUCTURES CAPABLE OF PRODUCING SEVERE HAIL...LOCALLY
STRONG WIND GUSTS...AND THE RISK FOR AT LEAST SHORT-LIVED TORNADOES.

OTHERWISE...DAMAGING WIND GUSTS WILL PROBABLY BE THE PRIMARY SEVERE
THREAT WITH THE SUBSEQUENT SQUALL LINE...MOSTLY AIDED BY HEAVY
PRECIPITATION LOADING.

..KERR/MOSIER.. 04/18/2014



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