AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
340 PM EDT FRI MAY 24 2013
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS CONTINUE TO SHOW AN ACTIVE UPPER
LEVEL PATTERN IN PLACE OVER THE CONUS. LONGWAVE PATTERN IS DOMINATED
BY DEEP TROUGHS ALONG BOTH THE PACIFIC AND ATLANTIC COASTS WHILE A
LONGWAVE RIDGE AXIS BISECTS THE CONTINENT OVER THE CENTRAL PLAINS.
OUR FORECAST AREA RESIDES AT THE BASE OF THE EASTERN CONUS TROUGH.
A STRONG SHORTWAVE EMBEDDED WITHIN THIS TROUGH IS NOW DROPPING
SOUTHEASTWARD OVER THE MID-ATLANTIC/CAROLINAS. THIS ENERGY WILL NOT
ONLY ACT TO CLOSE OFF A POTENT UPPER LOW OFF THE NEW ENGLAND
COAST...BUT ITS MOMENTUM WILL ALSO HELP DRIVE A LATE SEASON COLD
FRONT DOWN AND THROUGH THE FLORIDA PENINSULA DURING THE NEXT 6-12
HOURS. 24/12Z KTBW SOUNDING PROFILE WAS DRY...BUT NOT UNSEASONABLY
DRY...JUST YET. HOWEVER LOOKING UPSTREAM TOWARD BIRMINGHAM AND
ATLANTA WE BEGIN TO SEE A MUCH DRIER AIRMASS ABOVE THE SURFACE WHICH
WILL BE SETTLING SOUTHWARD AND OVER OUR HEADS FOR THE HOLIDAY
WEEKEND.
AT THE SURFACE...AS MENTIONED ABOVE...A LATE SEASON COLD FRONT IS
READY TO ADVANCE THROUGH THE FORECAST AREA TONIGHT. THE FRONT IS
CURRENTLY ANALYZED JUST SOUTH OF THE I-10 CORRIDOR WITH A DISTINCT
DEWPOINT DISCONTINUITY FROM MUCH OF THE FLORIDA PENINSULA UP TO THE
FL PANHANDLE AND SOUTHERN PORTION OF AL/GA. THIS MORE COMFORTABLE
AIRMASS IS ON ITS WAY TO US FOR THE WEEKEND. SEEING JUST A FEW
ISOLATED SHOWERS DOWN TOWARD FT. MYERS LATE THIS AFTERNOON. A FEW
MORE ARE POSSIBLE TO THE SOUTH OF I-4 DURING THE NEXT FEW
HOURS...HOWEVER ANY SHOWERS WILL BE SMALL AND BRIEF IN NATURE WITH
VERY LOW OVERALL COVERAGE.
&&
.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...
TONIGHT...
SURFACE FRONT SLIPS SOUTH OF THE REGION FOLLOWED QUICKLY
BY STRONG CONTINENTAL HIGH PRESSURE RIDGING DOWN FROM THE NORTH. A
FAVORABLE NNE DRAINAGE FLOW WILL ALLOW SOME OF OUR NORTHERN AREAS
AROUND LEVY/CITRUS COUNTIES TO DROP INTO THE MID/UPPER 50S TOWARD
SUNRISE ON SATURDAY...WHILE THE REMAINDER OF THE REGION DROPS DOWN
INTO THE 60S. ANY ISOLATED EVENING SHOWERS OVER THE FAR SOUTHERN
ZONES WILL END WITH THE FRONTAL PASSAGE SETTING UP A DRY AND
PLEASANT OVERNIGHT PERIOD.
SATURDAY THROUGH SUNDAY NIGHT...
MID/UPPER LEVEL TROUGH AXIS WILL PUSH EAST OF THE SOUTHEAST CONUS
WITH BROAD SYNOPTIC SUPPRESSION IN ITS WAKE FOR THE WEEKEND. A VERY
DRY MID-LEVEL AIRMASS WITH THETA-E VALUES WELL BELOW 320K WILL BE
ARRIVING FROM THE NORTH PROVIDING A QUITE HOSTILE ENVIRONMENT FOR
DEEP CONVECTION. WITH THIS IN MIND...NEAR ZERO RAIN CHANCES ARE IN
THE FORECAST FOR BOTH SATURDAY AND SUNDAY OVER OUR ZONES. MAY STILL
BE JUST ENOUGH MOISTURE AND LOW LEVEL FORCING TO SUPPORT AN ISOLATED
SHOWER OVER FAR SOUTH FLORIDA...BUT SEEMS APPARENT THAT ANY ACTIVITY
WILL BE SOUTH OF OUR ZONES. LOW LEVEL FLOW WILL BE STRONG ENOUGH OUT
OF THE EAST THIS WEEKEND THAT WE ARE UNLIKELY TO EVEN SEE MUCH (IF
ANY) SEA-BREEZE DEVELOPMENT...ESPECIALLY ON SATURDAY.
LOW LEVEL TEMPERATURES WILL COOL OFF SOMEWHAT BEHIND THE
FRONT...HOWEVER DRY CONDITIONS AND EXCELLENT DIURNAL MIXING WILL
COMPENSATE...AND STILL KEEP US ENJOYING SEASONABLE TEMPERATURES.
UPPER 80S TO NEAR 90 WILL BE COMMON THE NEXT COUPLE OF DAY...EVEN
CLOSE TO THE BEACHES AS THE EASTERLY FLOW HOLDS THE SEA-BREEZE TO
THE COAST OR EVEN JUST OFFSHORE.
THE IMPACT OF THE FRONT WILL BE FELT MORE AT NIGHT WITH BELOW NORMAL
LOW TEMPERATURES. MAY LOCATIONS AWAY FROM THE IMMEDIATE COAST WILL
LIKELY DIP INTO THE MID/UPPER 50S AROUND SUNRISE SUNDAY MORNING.
ALONG THE COAST FROM TAMPA BAY SOUTHWARD LOWER TO MIDDLE 60S WILL BE
MORE COMMON. SUNDAY NIGHT LOW TEMPERATURES WILL BE UP A FEW DEGREES
FROM THOSE ON SATURDAY NIGHT...BUT REMAIN BELOW NORMAL FOR LATE MAY.
&&
.LONG TERM (MONDAY THROUGH NEXT FRIDAY)...
MODEL SOLUTIONS REMAIN IN GOOD AGREEMENT SHOWING HIGH PRESSURE RIDGE
AXIS REMAINING NORTH OF THE FORECAST AREA THROUGH THE LONG TERM
PERIODS...KEEPING AN EASTERLY BOUNDARY LAYER FLOW IN PLACE. MOISTURE
WILL REMAIN LIMITED THROUGH MONDAY NIGHT...WITH RAIN FREE CONDITIONS
EXPECTED. BOUNDARY LAYER MOISTURE WILL THEN SLOWLY INCREASE THROUGH
THE REMAINDER OF THE WEEK...SO WILL CARRY SLIGHT CHANCE/LOW CHANCE
POPS IN MOST AREAS TUESDAY THROUGH FRIDAY FOR AFTERNOON/EARLY
EVENING SHOWERS AND THUNDERSTORMS.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL WITH FEW-SCT CLOUDS THROUGH THE
AFTERNOON. THERE MAY BE SOME ISOLD TSRA NEAR PGD/FMY/RSW BUT NOT
CLOSE ENOUGH TO CARRY IN THE TAF. NORTHWEST AND GUSTY WINDS DIMINISH
SOME OVER NIGHT AS THEY SHIFT TO NORTH THEN NE...BECOMING ROBUST
AFTER SUNRISE.
&&
.MARINE...
ROUGH BOATING CONDITIONS ARE EXPECTED AT TIMES OVER THE EASTERN GULF
OF MEXICO THIS HOLIDAY WEEKEND. A COLD FRONT WILL CROSS THE FORECAST
WATERS THROUGH TONIGHT ALLOWING STRONG HIGH PRESSURE TO RIDGE DOWN
FROM THE NORTH IN ITS WAKE. WINDS WILL SHIFT NORTHEAST OVERNIGHT AND
INCREASE TO CAUTIONARY LEVELS INTO SATURDAY MORNING. A BRIEF
REDUCTION IN THE WINDS IS POSSIBLE SATURDAY AFTERNOON...BUT EXPECT
EASTERLY FLOW WILL QUICKLY INCREASE ONCE AGAIN TO ADVISORY LEVELS
SATURDAY EVENING AND REMAIN ELEVATED THROUGH SUNDAY MORNING. THE
RIDGE POSITION WILL SUPPORT OVERNIGHT AND MORNING EASTERLY WIND
SURGES THROUGH THE EARLY PORTION OF NEXT WEEK.
&&
.FIRE WEATHER..
A DRY AIRMASS WILL ARRIVE ACROSS THE REGION FOR THE UPCOMING HOLIDAY
WEEKEND. THIS DRY AIRMASS WILL ALLOW RELATIVE HUMIDITY VALUES TO
DROP BELOW 35 PERCENT OVER MUCH OF THE AREA SATURDAY AFTERNOON. THE
LOW RELATIVE HUMIDITY IS ANTICIPATED TO COMBINE WITH GUSTY EAST TO
NORTHEAST WINDS AND ENERGY RELEASE COMPONENT VALUES OF 27 OR HIGHER
TO PRODUCE CRITICAL FIRE WEATHER CONDITIONS FOR LOCATIONS CURRENTLY
WITHIN THE FIRE WEATHER WATCH. DRY CONDITIONS ARE ALSO ANTICIPATED
FOR SUNDAY WITH THE BEST CHANCES OF CRITICAL RELATIVE HUMIDITY
VALUES BEING ALONG AND NORTH OF THE I-4 CORRIDOR. WINDS ARE NOT
EXPECTED TO BE AS STRONG DURING SUNDAY AND ANY POTENTIAL RED FLAG
CONDITIONS LOOK TO BE DEPENDENT ON HOW ERC VALUES FLUCTUATE DURING
THE WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 71 90 65 88 / 10 0 0 0
FMY 69 92 66 87 / 20 10 0 0
GIF 68 89 61 87 / 10 0 0 0
SRQ 70 90 65 88 / 10 0 0 0
BKV 64 88 56 88 / 10 0 0 0
SPG 74 89 68 87 / 10 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH
SATURDAY EVENING FOR CITRUS-DESOTO-HARDEE-HERNANDO-
HILLSBOROUGH-MANATEE-PASCO-PINELLAS-POLK-SARASOTA-
SUMTER.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/FIRE WEATHER...MROCZKA
MARINE...MROCZKA/MCMICHAEL
AVIATION/DECISION SUPPORT...RUDE
LONG TERM...JELSEMA
