FXUS62 KTAE 041941
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
240 PM EST FRI DEC 4 2009
.SYNOPSIS...
19Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A HIGHLY AMPLIFIED
PATTERN ACROSS NORTH AMERICA. JUST ABOUT THE ENTIRE CONTINENT
REMAINS UNDER LONGWAVE TROUGHING WITH LOBES OF ENERGY EMBEDDED
WITHIN. MOST IMPORTANT TO OUR SHORT TERM FORECAST IS THE SHORTWAVE
ENERGY ROUNDING THE BASE OF THE TROUGH ACROSS THE SOUTHERN PLAINS
AND APPROACHING THE WESTERN GULF OF MEXICO. WV IMAGERY SHOWS
ABUNDANT SOUTHERN STREAM MOISTURE STREAMING NORTHEAST AHEAD OF THIS
SHORTWAVE INTO THE SOUTHEASTERN STATES.
AT THE SURFACE...COMPLEX SURFACE PATTERN EVOLVING ACROSS THE GULF OF
MEXICO THIS AFTERNOON...WITH ONE WEAK AREA OF LOW PRESSURE OVER THE
SOUTHEASTERN GULF...AND ANOTHER MORE DOMINANT AREA OF LOW PRESSURE
DEVELOPING IN THE WESTERN GULF BAROCLINIC ZONE UNDERNEATH THE
ADVANCING UPPER LEVEL ENERGY. THESE LOWS WILL CONSOLIDATE TONIGHT
ACROSS THE EASTERN GULF OF MEXICO/FL PENINSULA TO OUR SOUTH.
INCREASING ISENTROPIC UPGLIDE ACROSS THE EASTERN GULF IS RESULTING
IN AN EXPANDING AREA OF GENERALLY LIGHT RAIN ACROSS THE EASTERN
GULF. THIS AREA OF RAIN/SHOWERS HAS BEEN EXPANDING ONSHORE ACROSS
MAINLY THE FL BIG BEND REGION EARLY THIS AFTERNOON. SHOULD BE A
RATHER SHOWERY LATE AFTERNOON/EARLY EVENING EAST AND SOUTH OF A LINE
FROM AROUND PANAMA CITY TO QUINCY TO THOMASVILLE. COOL AFTERNOON
WITH TEMPERATURES HOLDING IN THE MIDDLE AND UPPER THE CLOUDS.
&&
.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...
STRONG SHORTWAVE TROUGH WILL TRANSLATE ALONG THE NORTHERN GULF
COAST OVERNIGHT WITH DECENT SWATH OF SYNOPTIC FORCING OVERSPREAD THE
REGION. ASSOCIATED SURFACE LOW WILL PASS SOUTH OF THE COASTAL WATERS
AND ACROSS THE FLORIDA PENINSULA AFTER MIDNIGHT. ISENTROPIC UPGLIDE
TO THE EAST AND NORTHEAST OF THE LOW TRACK WILL CONTINUE TO DEVELOP
AN AREA OF MAINLY LIGHT RAIN/SHOWERS INTO THE FLORIDA BIG
BEND/SOUTH-CENTRAL GA THIS EVENING. AS THE SYNOPTIC FORCING
INCREASES AFTER DARK...AND COMBINES WITH MODEST RRQ JET
DYNAMICS...WILL SEE RAIN CHANCES INCREASING FURTHER WEST INTO THE
REMAINDER OF THE PANHANDLE...SOUTHEAST ALABAMA AND SOUTHWEST
GEORGIA. AGAIN GENERALLY LOOKING FOR LIGHT PRECIP...HOWEVER GFS/NAM
BOTH SHOWING TWO DISTINCT BANDS OF LOWER LEVEL FRONTOGENETIC FORCING
AS THE LOW PASSES BY. THE FIRST WILL BE ACROSS THE SOUTHEAST BIG
BEND...AND THE OTHER CROSSING SOUTHERN/CENTRAL ALABAMA. NOT OUT OF
THE QUESTION TO SEE A BRIEF HEAVIER PERIOD OF RAIN ASSOCIATED WITH
THESE BANDS. EITHER WAY...WITH THE EXCEPTION OF POSSIBLY THE ZONE
FROM PERRY DOWN TO CROSS CITY...RAINFALL TOTALS SHOULD BE UNDER AN
INCH...WITH MOST LOCATIONS UNDER 1/2 INCH.
WITH WINTRY PRECIPITATION FALLING WITH THIS SYSTEM OVER IN THE
HOUSTON TX AREA THIS AFTERNOON...THERE HAS BEEN ALOT OF QUESTIONS AS
TO THE SNOW/MIX POTENTIAL FOR OUR NECK OF THE WOODS. NO MATTER WHAT
GUIDANCE PACKAGE YOU LOOK AT...IT APPEARS THE CHANCES FOR ANY
WINTRY PRECIP IN OUR AREA IS VERY LOW. PARTIAL THICKNESSES HOLD
ABOVE TYPICAL VALUES UNTIL AFTER THE PRECIP HAS EXITED TO THE EAST.
THESE VALUES GET CLOSE TO WHAT WOULD BE LOOKED AT FOR A RAIN/SNOW
MIX TO THE NORTHWEST OF DOTHAN LATE TONIGHT...HOWEVER NAM/GFS
SOUNDINGS BOTH SHOW AT LEAST A 1200 FOOT ABOVE FREEZING LAYER UNTIL
AFTER THE PRECIP ENDS. THIS LAYER WILL BE PLENTY ENOUGH TO MELT ANY
FLAKES. THEREFORE...LOOKS LIKE JUST A COLD RAIN EVENT FOR ALL WITH
TEMPS IN THE 30S AND 40S.
SURFACE LOW MOVES OFF THE SOUTHEAST COAST SATURDAY MORNING WITH THE
SHORTWAVE AXIS CROSSING OVERHEAD SHORTLY THEREAFTER. DRIER AIR WILL
QUICKLY FILTER IN BEHIND THE LOW AND SHOULD END ANY LINGERING
SHOWERS ACROSS THE EASTERN HALF OF THE AREA WITHIN A FEW HOURS OF
SUNRISE. IMPROVING CONDITIONS ARE ANTICIPATED FOR THE LATE MORNING
AND AFTERNOON WITH PARTIAL CLEARING WORKING WEST TO EAST. RATHER
CHILLY LOW LEVEL AIRMASS WILL CONTINUE WITH 850MB TEMPS BETWEEN 0-4C.
HIGH TEMPS LOOK TO REACH AROUND 50 NORTH AND WEST OF DOTHAN TO THE
MIDDLE AND UPPER 50S ACROSS THE FLORIDA BIG BEND.
CONFIDENCE IS INCREASING IN OUR FIRST POTENTIAL SIGNIFICANT FREEZE
EVENT SATURDAY NIGHT/SUNDAY MORNING (ESPECIALLY FOR THE NW HALF OF
THE AREA). SURFACE HIGH PRESSURE WILL SLIDE TO OUR NORTH DURING THE
NIGHT WITH AN EXTENSION OF THE RIDGE DOWN INTO THE NE GULF. THIS
RIDGE EXTENSION SHOULD ALLOW OUR WINDS TO GO LIGHT AFTER SUNSET. ANY
LINGERING CLOUDS WILL EXIT TO OUR EAST DURING THE EVENING WITH
MOSTLY CLEAR SKIES THROUGH THE NIGHT. THE LIGHT WINDS/DRY LOW LEVEL
AIR...AND ALREADY CHILLY AIRMASS WILL SET UP DECENT RADIATIONAL
COOLING CONDITIONS. GUIDANCE CONSENSUS BRING MUCH OF THE AREA DOWN
INTO THE LOWER 30S FOR A COUPLE HOURS TOWARD SUNRISE SUNDAY MORNING.
HOWEVER...OUR INLAND PANHANDLE ZONES... SOUTHEAST ALABAMA AND
NORTHERN GA ZONES WILL HAVE THE POTENTIAL TO DROP INTO THE UPPER 20S
FOR A TIME. WILL HOLD OFF ON THIS SHIFT...BUT FREEZE WATCHES MAY BE
REQUIRED FOR PORTIONS (IF NOT ALL) OF THE AREA WITH TONIGHT'S
FORECAST PACKAGE.
FAIR AND QUIET WEATHER FOR SUNDAY AFTER THE COLD START. SURFACE HIGH
PRESSURE WILL BE IN CONTROL WITH AFTERNOON HIGH TEMPS UP ABOUT 5
DEGREES FROM SATURDAY. DO EXPECT AN INCREASE IN HIGH LEVEL CIRRUS...
ESPECIALLY THE SECOND HALF OF THE DAY AS OUR NEXT POTENTIAL WEATHER
SYSTEM ORGANIZES TO OUR WEST.
&&
.LONG TERM...(MONDAY-THURSDAY).
MODELS APPEAR TO BE IN DECENT AGREEMENT THROUGH MUCH OF THE EXTENDED
FORECAST. THE PERIOD BEGINS WITH A WEAK SHORT WAVE TROUGH LIFTING
EAST-NORTHEAST ACROSS THE SERN REGION. THIS WILL RESULT IN
INCREASING DEEP LAYER MOISTURE AND RAIN CHANCES ACROSS THE REGION
THROUGH THE DAY MONDAY AS COLD A FRONT APPROACHES FROM THE WEST.
ANOTHER IMPULSE WITHIN THE SOUTHWEST FLOW ALOFT QUICKLY FOLLOWS THE
PREVIOUSLY MENTIONED ONE ABOVE AND LIFTS NORTHEAST ACROSS THE AREA
TUESDAY AND TUESDAY NIGHT. THIS WILL KEEP THE RAIN CHANCES UP
THROUGH WEDNESDAY AS ANOTHER WAVE ALONG THE FRONTAL BOUNDARY AT THE
SURFACE DEVELOPS AND LIFTS NORTHEAST ACROSS THE GULF COAST.
MEANWHILE...GFS/ECMWF INDICATE A STRONGER SHORT WAVE TROUGH DROPPING
SOUTHEAST OVER THE CENTRAL PLAINS...THEN EAST AND NORTHEAST ACROSS
THE GREAT LAKES REGION WEDNESDAY THROUGH THURSDAY. SURFACE COLD
FRONT ASSOCIATED WITH THIS FEATURE WILL SWEEP THROUGH THE REGION
FROM WEST TO EAST THROUGH THIS TIME WITH A MUCH DRIER AND COOLER
AIRMASS FOLLOWING ITS PASSAGE INTO THE SECOND HALF OF THE UPCOMING
WEEK. TEMPERATURES ARE EXPECTED TO REMAIN ABOVE NORMAL MONDAY
THROUGH WEDNESDAY...THEN BACK TOWARD AVERAGE THROUGH THE SECOND HALF
OF THE WEEK.
&&
.AVIATION...
A RATHER CHILLY DAY IS UNDERWAY WITH SUBSTANTIAL MID-LEVEL
CLOUDINESS OVER THE FORECAST AREA. VFR CONDITIONS CONTINUE IN THE
MIDST OF A SOLID CLOUD DECK. EXPECT VFR CONDITIONS FOR MUCH OF THE
DAY WITH ON AND OFF LIGHT RAIN SHOWERS THROUGH THE DAY AND INTO THE
OVERNIGHT HOURS. AS A LOW DEVELOPS IN THE GULF...LOW CLOUDS WILL
MOVE INTO THE REGION. LOW CIGS/VSBYS WILL CREATE PERIODS OF MVFR/IFR
CONDITIONS THROUGH THE EVENING AND THROUGH THE OVERNIGHT. AS THE LOW
MOVES NORTHEAST...WINDS WILL INCREASE TO 10 T0 15KT WITH HIGHER
GUSTS AT PFN. TOMORROW...EXPECT LOW CIGS DURING THE MORNING HOURS
WITH GUSTY WINDS. CLOUDS SHOULD BEGIN TO CLEAR OUT TOMORROW
AFTERNOON USHERING IN VFR CONDITIONS THROUGH TOMORROW NIGHT.
&&
.MARINE...
LOW PRESSURE WILL SLIDE SOUTH OF THE COASTAL WATERS OVERNIGHT AND
THEN OFF THE SOUTHEAST COAST SATURDAY MORNING. THE GRADIENT WILL
TIGHTEN THROUGH THE EVENING WITH NORTHERLY WINDS REACHING SMALL
CRAFT ADVISORY LEVELS ACROSS THE WESTERN LEGS BY LATE EVENING AND
SHORTLY AFTER MIDNIGHT FOR THE REMAINDER OF THE FORECAST WATERS.
THESE WINDS WILL SHIFT TO THE NORTHWEST SATURDAY MORNING WITH WINDS
AND SEAS REMAINING AT ADVISORY LEVELS THROUGH MUCH OF THE DAY. HIGH
PRESSURE WILL SLIDE NORTH OF THE WATERS SATURDAY NIGHT. WINDS AND
SEAS WILL FALL BELOW ADVISORY LEVELS...BUT SHOULD HOLD AT CAUTIONARY
LEVELS INTO SUNDAY MORNING. WINDS AND SEAS SHOULD FALL BELOW
HEADLINE CRITERIA FOR SUNDAY AFTERNOON THROUGH MONDAY.
&&
.FIRE WEATHER...
WET WEATHER PATTERN WILL CONTINUE. A LOW IS LOCATED IN THE WESTERN
GULF OF MEXICO. AS THIS LOW MOVES NORTHEASTWARD...IT WILL BRING
LIGHT RAIN SHOWERS AND CLOUDY CONDITIONS THROUGH SATURDAY MORNING. A
DRIER AIRMASS WILL MOVE INTO THE REGION LATER SATURDAY INTO SUNDAY.
AT THIS TIME...HIGH TEMPERATURES ARE NOT FORECAST TO BE ELEVATED
ENOUGH TO LOWER RELATIVE HUMIDITY TO CRITICAL LEVELS...THUS NO FIRE
WEATHER CONCERNS ARE ANTICIPATED THROUGH THE EARLY PART OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 41 57 31 59 42 / 90 20 0 0 10
PANAMA CITY 41 56 35 60 47 / 80 10 0 0 20
DOTHAN 37 51 28 57 41 / 90 10 0 10 10
ALBANY 40 52 28 58 40 / 90 20 0 0 10
VALDOSTA 42 54 31 60 42 / 90 30 0 0 10
CROSS CITY 46 59 32 65 44 / 100 40 0 0 10
APALACHICOLA 43 58 36 61 46 / 100 10 10 0 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST SATURDAY
FOR THE FOLLOWING ZONES: APALACHEE BAY OR COASTAL WATERS
FROM KEATON BEACH TO OCHLOCKONEE RIVER FL OUT TO 20 NM...
COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL
OUT TO 20 NM...COASTAL WATERS FROM SUWANNEE RIVER TO KEATON
BEACH OUT 20 NM...COASTAL WATERS FROM APALACHICOLA TO
DESTIN FL OUT 20 NM...WATERS FROM SUWANNEE RIVER TO
APALACHICOLA FL FROM 20 TO 60 NM...WATERS FROM APALACHICOLA
TO DESTIN FL FROM 20 TO 60 NM.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
AVIATION/FIRE WEATHER...BARRY/AUSTIN
LONG TERM...GIBBS
