Flash Flood Watch 1, NWS Tampa Bay, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
1015 AM EDT FRI SEP 26 2014

.UPDATE (REST OF TODAY AND TONIGHT)...
14Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A HIGHLY AMPLIFIED AND
UNPROGRESSIVE NORTHERN STREAM FLOW OVER NORTH AMERICA. MAIN FLOW
ARRIVES WITHIN A DEEP TROUGH OVER THE CALIFORNIA COAST BEFORE
QUICKLY RIDGING WELL NORTH INTO CENTRAL CANADA. THE FLOW THEN
FLATTENS OUT DOWNSTREAM AND BECOMES MORE ZONAL BY THE TIME IT
REACHES THE CANADIAN MARITIMES. SOUTH OF THIS MAIN FLOW WE FIND A
WEAK SHORTWAVE DROPPING SOUTHEAST OUT OF NEW ENGLAND OVERTOP AN
UPPER RIDGE CENTERED OFF THE SOUTHEAST CONUS COAST. OUR FORECAST
REGION REMAINS ON THE VERY WESTERN PERIPHERY OF THIS RIDGE
CIRCULATION...ALTHOUGH THE 26/12Z KTBW SOUNDING PROFILE DOES NOT
SHOW MUCH CONSISTENCY WITH THE WIND DIRECTION THROUGH ANY DEPTH OF
THE COLUMN.

ONCE AGAIN WE HAVE STARTED THE DAY WITH A VERY SHALLOW STABLE LAYER
RESULTING IN AREAS OF STRATUS. THIS STABLE LAYER PER THE KTBW
SOUNDING IS MAYBE 1-2KFT THICK...AND WE SHOULD BE ABLE TO MIX IT OUT
BY LATE IN THE MORNING. AS ADVERTISED BY THE MODELS...THE PW HAS
BEEN RISING AND IS NOW OVER 2.2" AT KTBW...AND APPROACHING 2.4" AT
KMFL. AS WOULD BE EXPECTED WITH SUCH A MOIST PROFILE...LAPSE RATES
ARE FAIRLY POOR...GENERALLY IN THE VICINITY OF MOIST ADIABATIC
THROUGH MUCH OF THE COLUMN. THEREFORE...THE COLUMN IS VERY FAVORABLE
FOR CONVECTION...BUT UNFAVORABLE FOR SEVERE TYPE UPDRAFTS. THIS IS
NOT TO SAY THAT A FEW STRONGER STORMS ARE NOT POSSIBLE GIVEN PROPER
LOW LEVEL MOISTURE POOLING TO INCREASE THE CAPE POTENTIAL...
HOWEVER...OVERALL THESE TYPE OF STORMS SHOULD BE FEW AND FAR BETWEEN
TODAY. THE GREATER THREAT FROM TODAYS STORMS (AND WE DO THINK
OVERALL COVERAGE THROUGH THE AFTERNOON AND EARLY EVENING WILL BE ON
THE HIGH SIDE) WILL BE THE POTENTIAL FOR LOCALLY VERY HEAVY
RAINFALL. SOME SPOTS HAVE SEEN CONSIDERABLE RAINFALL ALREADY THIS
WEEK...AND WILL NEED TO BE WATCHED CLOSELY SHOULD ANOTHER HEAVY
RAINFALL EVENT OCCUR NEARBY. HIGHLANDS COUNTY IS ONE PLACE THAT WILL
NEED TO BE WATCHED AS FLOODING HAS ALREADY BEEN A FACTOR IN THE PAST
COUPLE OF DAYS.

AT THE SURFACE...PRESSURE GRADIENT IS PROVIDING A SHALLOW LAYER OF
NORTHEAST TO EAST FLOW BETWEEN A LARGE RIDGE OF HIGH PRESSURE OVER
THE DEEP SOUTH AND AN INVERTED TROUGH ALONG THE FLORIDA EAST COAST.
THIS TROUGH WILL BE MIGRATING WESTWARD ACROSS THE PENINSULA TODAY
AND ALONG WITH A FEEBLE SEA-BREEZE WILL PROVIDE THE FOCUS FOR
POTENTIALLY A LOT OF SHOWERS AND STORMS AFTER 18-20Z.

REGIONAL RADARS ARE QUIET ACROSS THE FORECAST AREA THIS MID-MORNING
AND EXPECT THINGS TO REMAIN QUIET FOR SEVERAL MORE HOURS. SO...NO
REAL CONCERNS FOR OUTDOOR ACTIVITIES INTO THE EARLY AFTERNOON.
THEREAFTER RAIN CHANCES WILL BE QUICKLY INCREASING. LOCAL AND
NATIONAL HIRES CONVECTION ALLOWING GUIDANCE ARE JUST ABOUT ALL
AGGRESSIVE WITH THE STORM COVERAGE DURING THE SECOND HALF OF THE
DAY. THE GENERAL EVOLUTION SHOWN THROUGH THE GUIDANCE SUITE IS
TYPICAL OF AN EASTERLY FLOW REGIME. SHOWERS AND STORMS WILL FIRST
BREAK OUT OVER THE SOUTHERN ZONES BY MID AFTERNOON AND THEN MIGRATE
NORTHWEST WITH TIME REACHING THE TAMPA BAY AND NATURE COAST ZONES
FOR THE LATE AFTERNOON OR EARLY EVENING TIME PERIOD. THIS IS STILL A
SUMMER-LIKE SCENARIO WHERE IT LIKELY WILL NOT RAIN FOR A LONG TIME
AT MOST SPOTS...BUT THAT MOST SPOTS WILL LIKELY SEE RAIN. RAINFALL
CHANCES RANGE FROM 40-50% UP AROUND CHIEFLAND TO 60-70% BY THE TIME
YOU REACH BROOKSVILLE AND ALL THE WAY SOUTH FROM THERE TO FORT MYERS
AND SEBRING.

FIRST PART OF THE NIGHT / EVENING HOURS SHOULD STILL SEE SOME SCT
STORMS ALONG THE I-75 CORRIDOR AND TOWARD THE COAST WITH THE
ACTIVITY SLOWLY MIGRATING OFFSHORE INTO THE EASTERN GULF. THE SECOND
HALF OF THE OVERNIGHT SHOULD BE MAINLY DRY OVER THE LAND ZONES WITH
CONTINUED SHOWERS/STORMS ONGOING OVER THE COASTAL WATERS. LOW
TEMPERATURES BY SUNRISE SATURDAY WILL BE IN THE LOWER 70S NORTH AND
LOWER TO MIDDLE 70S SOUTH. HAVE A GREAT FRIDAY AND KEEP THOSE
UMBRELLAS HANDY LATER TODAY.

&&

.AVIATION...
AN AREA OF LOWE STRATUS FROM KSRQ UP INTO THE TAMPA BAY TERMINALS IS
SHRINKING FAST THIS MID-MORNING AND EXPECT CONDITIONS TO RETURN TO
VFR FOR ALL STATION BY 15-16Z. APPEARS AS THOUGH STORMS WILL BE
QUITE ACTIVE LATER TODAY AND HAVE INCLUDED TEMPOS FOR THUNDER AT ALL
TERMINALS AFTER 19Z. STORMS MIGRATE OFF THE COAST WITHIN A FEW HOURS
OF SUNSET AND PREVAILING VFR IS THEN EXPECTED THROUGH THE REMAINDER
OF THE OVERNIGHT.

&&

.MARINE...
LITTLE CHANGE FROM YESTERDAY AS A SURFACE TROUGH REMAINS IN PLACE
OVER THE EASTERN GULF WATERS AND DEEP TROPICAL MOISTURE REMAINS OVER
THE AREA. SCATTERED TO NUMEROUS THUNDERSTORMS OVER THE FLORIDA EAST
COAST WILL MOVE SLOWLY WEST AND BE A THREAT TO THE COASTAL WATERS
TOWARD THE LATE AFTERNOON AND EVENING HOURS. LIGHT OFFSHORE WINDS
AGAIN TODAY WITH A MILD SEA BREEZE AFFECT FOR THE SECOND HALF OF THE
DAY. THE MAIN HAZARDS WILL CONTINUE TO BE HIGHER WINDS AND SEAS IN
THE VICINITY OF THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
TPA  85  75  88  76 /  70  40  60  40
FMY  86  75  88  74 /  70  30  50  20
GIF  86  74  88  74 /  60  20  50  20
SRQ  86  75  88  74 /  70  50  60  40
BKV  86  73  88  72 /  60  30  60  40
SPG  86  77  87  77 /  70  50  60  40

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.

&&

UPDATE/AVIATION...MROCZKA
MARINE...DOUGHERTY

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
431 AM EDT FRI SEP 26 2014

FLZ043-050-052-056-057-061-139-142-148-149-151-155-160-162-165-
239-242-248-249-251-255-260-262-265-GMZ830-836-850-853-856-870-
873-876-270845-
SUMTER-PINELLAS-POLK-HARDEE-HIGHLANDS-DESOTO-COASTAL LEVY-
COASTAL CITRUS-COASTAL HERNANDO-COASTAL PASCO-
COASTAL HILLSBOROUGH-COASTAL MANATEE-COASTAL SARASOTA-
COASTAL CHARLOTTE-COASTAL LEE-INLAND LEVY-INLAND CITRUS-
INLAND HERNANDO-INLAND PASCO-INLAND HILLSBOROUGH-INLAND MANATEE-
INLAND SARASOTA-INLAND CHARLOTTE-INLAND LEE-TAMPA BAY WATERS-
CHARLOTTE HARBOR AND PINE ISLAND SOUND-
TARPON SPRINGS TO SUWANNEE RIVER OUT 20 NM-
ENGLEWOOD TO TARPON SPRINGS OUT 20 NM-
BONITA BEACH TO ENGLEWOOD OUT 20 NM-
TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM-
ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-
BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-
431 AM EDT FRI SEP 26 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL AND SOUTHWEST
FLORIDA.

.DAY ONE...TODAY AND TONIGHT.

...THUNDERSTORM IMPACT...
SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED...WITH THE
HIGHEST CHANCES DURING THE AFTERNOON AND EARLY EVENING HOURS. THE
THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF PRODUCING STRONG
GUSTY WINDS...HEAVY RAINFALL...AND FREQUENT LIGHTNING STRIKES.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

...THUNDERSTORM IMPACT...
SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED EACH DAY...MAINLY
DURING THE AFTERNOON AND EARLY EVENING HOURS. THE THUNDERSTORMS
WILL BE CAPABLE OF PRODUCING STRONG GUSTY WINDS...HEAVY
RAINFALL...AND FREQUENT LIGHTNING STRIKES.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS SHOULD MONITOR THE WEATHER AND SELF ACTIVATE IF NEEDED.

JELSEMA