Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 190447
SWOMCD
SPC MCD 190446
FLZ000-190645-

MESOSCALE DISCUSSION 0369
NWS STORM PREDICTION CENTER NORMAN OK
1146 PM CDT FRI APR 18 2014

AREAS AFFECTED...SOUTHERN FLORIDA PENINSULA AND THE KEYS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 190446Z - 190645Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO INCREASE IN AREAL COVERAGE
OVER THE DISCUSSION AREA THROUGH THE OVERNIGHT HOURS WITH AN
ASSOCIATED RISK FOR LOCALLY DAMAGING WINDS AND PERHAPS A TORNADO OR
TWO. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WATCH.

DISCUSSION...RECENT TRENDS IN RADAR DATA INDICATE A STEADILY
STRENGTHENING CLUSTER OF TSTMS APPROXIMATELY 60NM WSW OF KEY WEST
WITH OTHER DEEPENING SHOWERS OBSERVED TO THE NORTH AND WEST OF THE
INITIAL STORMS. CONTINUED LOW-LEVEL MOISTENING ALONG THE SRN
EXTENSION OF A 30-40 KT SLY LLJ COUPLED WITH GRADUAL HEIGHT
FALLS/DCVA ASSOCIATED WITH A MID TO UPPER-LEVEL LOW CURRENTLY
CENTERED ALONG THE CNTRL GULF COAST APPEAR TO BE MECHANISMS
CONTRIBUTING TO THIS CONVECTIVE DEVELOPMENT. AND LATEST
CONVECTION-ALLOWING MODEL GUIDANCE SUGGESTS THAT THIS INCIPIENT TSTM
DEVELOPMENT WILL INCREASE IN AREAL COVERAGE WHILE EXPANDING EWD/NEWD
THROUGH THE LOWER/MIDDLE KEYS AND PORTIONS OF THE SOUTHERN FL
PENINSULA DURING THE OVERNIGHT HOURS.

CURRENT VAD DATA FROM MELBOURNE SWD/SWWD THROUGH MIAMI AND KEY WEST
INDICATE A NOTABLE STRENGTHENING IN SLY WINDS IN THE LOWEST 1-2 KM
IN ASSOCIATION WITH THE RECENT LLJ DEVELOPMENT. MOREOVER...MIDLEVEL
FLOW HAS STRENGTHENED TO 45-50 KT WHICH IS RESULTING IN SUFFICIENT
DEEP-LAYER SHEAR TO SUPPORT ORGANIZED/ROTATING UPDRAFTS. GIVEN THE
PRESENCE OF A MOIST AND MODERATELY UNSTABLE AIR MASS...THE
ENVIRONMENT WILL REMAIN SUPPORTIVE OF SUPERCELL AND BOWING
STRUCTURES OVERNIGHT WITH THE PRIMARY HAZARD BEING LOCALLY DAMAGING
WIND GUSTS. A TORNADO OR TWO REMAIN POSSIBLE...ESPECIALLY WITH ANY
STORMS THAT CAN FAVORABLY INTERACT WITH A WEAK W-E-ORIENTED OUTFLOW
BOUNDARY WHICH EXTENDS ROUGHLY JUST NORTH OF A FMY-PBI LINE WHERE
LOW-LEVEL SHEAR/VORTICITY MAY REMAIN LOCALLY AUGMENTED.

..MEAD.. 04/19/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MFL...KEY...

LAT...LON   24538252 25398195 26328145 26798054 26788007 26207986
            25118038 24528117 24238210 24538252




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