ZCZC SPCSWOMCD ALL ACUS11 KWNS 180554 SPC MCD 180554 FLZ000-180800- MESOSCALE DISCUSSION 0077 NWS STORM PREDICTION CENTER NORMAN OK 1154 PM CST TUE FEB 17 2015 AREAS AFFECTED...SRN FLORIDA COASTAL AREAS/KEYS CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 180554Z - 180800Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...STORMS DEVELOPING ACROSS THE COASTAL WATERS AND KEYS COULD EVENTUALLY BE ACCOMPANIED BY A FEW STRONG SURFACE GUSTS...MAINLY TOWARD 09-12Z. HOWEVER...THE NEED FOR A SEVERE WEATHER WATCH IS NOT CURRENTLY ANTICIPATED. DISCUSSION...SCATTERED THUNDERSTORM DEVELOPMENT IS NOW WELL UNDERWAY ACROSS THE LOWER KEYS...LIKELY IN RESPONSE TO FORCING ASSOCIATED WITH WEAK PRE-FRONTAL WARM ADVECTION...AND PERHAPS A WEAK SHORT WAVE IMPULSE WITHIN BROADLY CYCLONIC MID/UPPER FLOW. VARIOUS MODEL FORECAST OUTPUT IS SUGGESTIVE THAT THIS INITIAL ACTIVITY WILL CONTINUE TO SPREAD NORTHEASTWARD TOWARD SOUTHERN PENINSULA COASTAL AREAS...AND THE UPPER KEYS...WITH ADDITIONAL STORM DEVELOPMENT OCCURRING ACROSS SOUTHERN COASTAL AREAS AND THE KEYS...ALONG THE APPROACHING COLD FRONT...LATER TONIGHT. BOUNDARY-LAYER BASED INSTABILITY APPEARS MOSTLY CONFINED TO THE COASTAL WATERS AND KEYS...IN ASSOCIATION WITH THE 70F+ SURFACE DEW POINTS. WHILE CAPE IS LIKELY TO REMAIN RELATIVELY WEAK /GENERALLY LESS THAN 1000 J PER KG/...DEEP LAYER SHEAR BENEATH 50-60 KT WESTERLY 500 MB FLOW IS STRONG...AND MAY CONTRIBUTE TO MID-LEVEL UPDRAFT ROTATION IN STRONGEST CELLS. THE EVOLUTION OF AN INCREASINGLY ORGANIZED CONVECTIVE LINE DOES NOT APPEAR OUT OF THE QUESTION TOWARD 09-12Z...WHEN PRE-FRONTAL 850 MB FLOW IS FORECAST TO VEER FROM SOUTHERLY TO SOUTHWESTERLY...WHILE STRENGTHENING TO 40+ KT OR SO. THIS COULD BE ACCOMPANIED BY AT LEAST SOME RISK FOR STRONG CONVECTIVE GUSTS. HOWEVER...UNTIL THEN...SEVERE WEATHER POTENTIAL APPEARS MINIMIZED BY WEAK LOW-LEVEL WIND FIELDS AND SHEAR...IN ADDITION TO THE MARGINAL THERMODYNAMIC ENVIRONMENT. ..KERR/THOMPSON.. 02/18/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MFL...KEY... LAT...LON 24508217 24938161 25238073 25538014 25187995 24768054 24328180 24508217 NNNN