FXUS62 KTBW 211911
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
311 PM EDT TUE MAY 21 2013
.SHORT TERM (TONIGHT - THURSDAY)...WEAK MID-LEVEL LOW OVER NORTH 
FLORIDA IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH TONIGHT THEN 
MOVE SLOWLY NORTHEAST ON WEDNESDAY. DRIER AIR HAS MOVED IN BEHIND 
THE LOW TO THE SOUTH OF TAMPA...BUT THE AIRMASS IS NOT DRY ENOUGH TO 
INHIBIT THUNDERSTORM DEVELOPMENT THIS AFTERNOON. COUNTER-CLOCKWISE 
FLOW AROUND THE LOW WILL LIKELY ALLOW STORMS NORTH OF TAMPA TO MOVE 
BACK TOWARD THE COAST WHILE STORMS TO THE SOUTH PUSH FARTHER INLAND. 
WEAK STEERING FLOW IN THE MIDDLE MEANS STORM MOTION WILL BE DICTATED 
BY OUTFLOW BOUNDARIES AND THEREFORE QUITE UNPREDICTABLE.
 
SHOWERS AND STORMS WIND DOWN TONIGHT WITH SOME PATCHY FOG 
DEVELOPING...ESPECIALLY WHERE THE GROUND REMAINS WET FROM PREVIOUS 
SHOWERS.
 
ON WEDNESDAY...A WEAK AREA OF HIGH PRESSURE AT THE SURFACE WILL BE 
IN PLACE OVER FLORIDA AND THE EASTERN GULF. THIS SHOULD ALLOW 
AFTERNOON SEA BREEZES TO PENETRATE WELL INLAND AND FOCUS THE STORMS 
ALONG THE SPINE OF THE PENINSULA. STEERING LEVEL FLOW WILL BE NEXT 
TO NOTHING...SO ONCE AGAIN OUTFLOW BOUNDARIES WILL DICTATE WHERE 
STORMS MOVE/DEVELOP DURING THE LATE AFTERNOON AND EVENING HOURS.
 
THURSDAY WILL BE SIMILAR...BUT THE ATMOSPHERE BETWEEN 700 AND 850 
MBS DRIES CONSIDERABLY. THIS WILL DELAY DEVELOPMENT AS WELL AS LIMIT 
THE OVERALL EXTENT OF STORMS. AFTER A COUPLE OF DAYS OF SCATTERED TO 
NUMEROUS SHOWERS AND STORMS...IT LOOKS LIKE THURSDAY WILL JUST HAVE 
ISOLATED STORMS...AND THEN MAINLY INLAND.
.LONG TERM (THURSDAY NIGHT-MONDAY)...
HIGH AMPLITUDE PATTERN WILL PERSIST WITH A L/W TROUGH OVER THE 
EASTERN U.S. WITH A STRONG CUT-OFF LOW DEVELOPING FRIDAY OVER THE
MID ATLANTIC. AS THE TROUGH AXIS PUSHES EAST OF FLORIDA ON
FRIDAY...A COLD FRONT WILL MOVE ACROSS REGION WITH A SLIGHT CHANCE
OF THUNDERSTORMS. SURFACE HIGH PRESSURE WILL BUILD OVER THE
FORECAST AREA FRIDAY NIGHT AND SATURDAY WITH SLIGHTLY DRIER AIR
ADVECTING ACROSS THE REGION. HIGH PRESSURE WILL MOVE TO THE MID
ATLANTIC COAST SUNDAY AND OVER THE WESTERN ATLANTIC MONDAY...WHILE
U/L RIDGING OVER THE CENTRAL U.S. WILL BEGIN TO GRADUALLY EDGE
EAST. THIS WILL KEEP BROAD EASTERLY BOUNDARY LAYER FLOW ACROSS THE
FORECAST AREA WITH SUBSIDENCE ALOFT AND A LOW CHANCE OF RAIN EACH
DAY.
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE
THROUGH ABOUT 22/02Z. MAJORITY OF THIS CONVECTION WILL BE OVER
INLAND AREAS AND SHOULD STAY EAST OF TPA...PIE AND SRQ...BUT COULD
IMPACT LAL...PGD...FMY AND RSW CAUSING SOME MVFR/LOCAL IFR
CONDITIONS. OTHERWISE...VFR CONDITIONS ARE EXPECTED.
&&
.MARINE...NO ISSUES THROUGH FRIDAY AS A WEAK AREA OF HIGH PRESSURE 
KEEPS WINDS LIGHT WITH SOME ENHANCEMENT TO ONSHORE WINDS NEAR THE 
COAST DURING THE AFTERNOON SEA BREEZES EACH DAY. A STRONG AREA OF 
HIGH PRESSURE WILL BUILD NORTH OF THE WATERS BY SATURDAY MORNING 
WHICH WILL PUSH A SHEAR LINE THROUGH THE REGION. THE PRESSURE 
GRADIENT WILL TIGHTEN SIGNIFICANTLY RESULTING IN ROBUST EAST TO 
NORTHEAST FLOW OVER THE WEEKEND...POSSIBLY REQUIRING SMALL CRAFT 
ADVISORIES AT TIMES.
&&
.FIRE WEATHER...NO HUMIDITY PROBLEMS EXPECTED. LIGHT TRANSPORT WINDS 
ON WEDNESDAY WILL LEAD TO RATHER POOR DISPERSIONS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA  71  87  72  88 /  30  20  20  10 
FMY  71  90  71  90 /  30  30  20  10 
GIF  69  89  70  91 /  30  60  20  20 
SRQ  69  87  70  87 /  30  20  20  10 
BKV  64  88  65  89 /  30  30  20  10 
SPG  74  86  75  86 /  30  20  20  10 
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...JILLSON
LONG TERM...OGLESBY
AVIATION...CLOSE