FXUS62 KTAE 232005
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
304 PM EST WED DEC 23 2009
.SYNOPSIS...SYNOPTIC FEATURES THIS THIS AFTERNOON INCLUDE A 1036 MB
HIGH PRESSURE SYSTEM CENTERED IN SOUTHERN CANADA NORTH OF LAKE
SUPERIOR WITH RIDGING EXTENDING DOWN INTO THE CAROLINAS. A 1002 MB
LOW PRESSURE CENTER ASSOCIATED WITH THE UPPER LOW IS NOW IN WEST
TEXAS. A WIDE SWATH OF MOIST RETURN FLOW IS OCCURRING EAST OF THE LOW
INTO A STATIONARY FRONT ACROSS THE MISSOURI AND OHIO VALLEYS. UPSLOPE
FLOW IS OCCURRING NORTH OF THE FRONT FROM THE TEXAS PANHANDLE TO
MONTANA. MAJOR UPPER AIR FEATURES INCLUDE THE DEEP COMPLEX TROUGH IN
THE WEST. AHEAD OF THE TROUGH...RIDGING IS BUILDING FROM THE GREAT
LAKES SOUTHWARD TO THE FLORIDA EAST COAST. A DEEP UPPER LOW IS
LOCATED IN NEW ENGLAND...AND A UNUSUAL UPPER TROUGH IS LOCATED ACROSS
CUBA DOWN INTO THE CENTRAL CARIBBEAN.
CLOSER TO HOME...AT 19Z SURFACE TEMPS WERE IN THE LOW TO MID 60S...
DEWPOINTS WERE MOSTLY IN THE MID TO UPPER 40S. WINDS WERE EASTERLY...
EAST SOUTHEAST OFFSHORE. A MIDDLE DECK AND CIRRUS COVERS MUCH OF THE
AREA.
&&
.SHORT TERM (TONIGHT THROUGH FRIDAY NIGHT)...MODELS ARE SOMEWHAT IN
AGREEMENT. FIRST...THE SHORTWAVE IN NEW MEXICO WILL BOTTOM OUT
TOMORROW MORNING IN TEXAS ACCORDING TO THE GFS...AS THE SECOND
SHORTWAVE DROPS DOWN ACROSS MONTANA. THE TWO IMPULSES APPEAR TO DO
A FUJIWARA EFFECT AS THE FIRST MOVES NORTH AND THE OTHER DRIVES
SOUTH...AND FINALLY...COMBINING INTO ONE UPPER LOW OVER IOWA ON
FRIDAY. THE NAM IS SIMILAR. HOWEVER...THE LATEST ECMWF IS SOMEWHAT
DISTURBING WITH FIRST UPPER SHORT WAVE MUCH FARTHER SOUTH IN NORTHERN
LOUISIANA THURSDAY EVENING...BEFORE MAKING A BEELINE NORTHWARD.
THIS SOLUTION WILL POSSIBLY BRING MORE SEVERE WEATHER TO THE
NORTHERN GULF COAST. EACH MODEL IS SLIGHTLY DIFFERENT ON FRONTAL
PASSAGE...THE ECMWF SLIGHTLY FASTER THAN GFS...WITH THE NAM SLIGHTLY
SLOWER THAN THE GFS. AS TO CONVECTION...THE BULK OF THE FORCING
APPEARS TO WEST OF OUR CWA. IT APPEARS THAT WE WILL HAVE SUITABLE
BULK SHEARS...50 KNOTS OR SO...BUT MARGINAL INSTABILITY. HAVE GONE
WITH THE GFS. HAVE ADDED T+ IN THE GRIDS STARTING AT 00Z TOMORROW
EVENING.
.LONG TERM (SATURDAY THROUGH WEDNESDAY)...
A POTENT COLD FRONT WILL SWEEP ACROSS THE AREA BY FRIDAY BRINGING
IN ANOTHER RUSH OF COLD WEATHER FOR THE HOLIDAY WEEKEND. A DRY
AIRMASS WILL MOVE IN BEHIND THE FRONT MAKING FOR PLEASANT WEATHER
THROUGH THE BEGINNING OF NEXT WEEK. THE GFS SHOWS THE DEVELOPMENT OF
A WEAK DISTURBANCE IN THE WESTERN GULF SUNDAY NIGHT INTO MONDAY.
THIS MAY BRING IN SOME MID TO UPPER-LEVEL CLOUDS BUT RAIN CHANCES
APPEAR LOW AT THIS TIME...THUS SILENT 10% POPS HAVE BEEN INTRODUCED
FROM THIS TIME THROUGH WEDNESDAY. THE FORECAST BECOMES A BIT TRICKY
BY WEDNESDAY NIGHT REGARDING AN APPROACHING FRONTAL SYSTEM. THE GFS
SOLUTION DEVELOPS A SURFACE LOW OVER THE CENTRAL GULF WEDNESDAY
NIGHT AND BRINGS IT OVER OUR AREA THROUGH 1200Z THURSDAY. THE ECMWF
DEPICTS A SURFACE LOW FORMING OVER THE NORTHWESTERN GULF BY
WEDNESDAY MORNING AND ACCELERATES THE SYSTEM NORTH OF OUR AREA WITH
A TRAILING COLD FRONT PUSHING THROUGH BY THURSDAY MORNING. BOTH
SOLUTIONS WOULD SUGGEST THAT POPS MAY NEED TO BE RAISED IN FUTURE
FORECASTS...BUT DUE TO UNCERTAINTY AND THE LONG-TERM NATURE OF THE
PREDICTION...WILL MAINTAIN SILENT 10% POPS FOR NOW. TEMPS WILL
AVERAGE BELOW CLIMO THROUGH MID-WEEK WITH LOWS APPROACHING THE
FREEZING MARK SEVERAL NIGHTS NEXT WEEK AND HIGHS AVERAGING AROUND 60
DEGREES. DEPENDING ON THE TIMING OF THE NEXT FRONTAL
SYSTEM...TEMPERATURES WILL BEGIN INCREASING BY THURSDAY AHEAD OF THE
NEXT DISTURBANCE.
&&
.AVIATION...PATCHY HIGH CLOUDS WILL GRADUALLY THICKEN AND LOWER FROM
WEST TO EAST ACROSS THE TRI-STATE AREA THIS EVENING. AFTER 06Z...
EXPECT WIDESPREAD IFR CEILINGS AND MVFR VISIBILITIES TO DEVELOP AND
PERSIST INTO THE MORNING HOURS THURSDAY...AS SHOWERS AND ISOLATED
THUNDERSTORMS BEGIN TO SPREAD EASTWARD INTO WESTERN PORTIONS OF THE
AREA BY 12Z...AND ACROSS THE REST OF THE AREA DURING THE DAY. A
COLD FRONT WILL MOVE EASTWARD ACROSS THE AREA THURSDAY NIGHT AND
FRIDAY MORNING...ACCOMPANIED BY GUSTY SHIFTING WINDS...AND THE
POTENTIAL FOR SOME STRONG THUNDERSTORMS WITH DAMAGING WINDS AND LIFR
CONDITIONS.
&&
.MARINE...WINDS THIS AFTERNOON AT THE BUOYS ARE RUNNING 18-22
KNOTS WITH SEAS JUST UNDER 6 FEET. CONDITIONS ARE EXPECTED TO WORSEN
OVER THE MARINE AREA TONIGHT AS WINDS INCREASE OUT OF THE SOUTHEAST
AHEAD OF AN APPROACHING STORM SYSTEM. WINDS COULD EVEN APPROACH 30
KNOTS OR SO AHEAD OF THE COLD FRONT THURSDAY AFTERNOON. HAVE
ADJUSTED THE BEGIN TIME FOR THE SCA TO 00Z TONIGHT. SEAS SHOULD
REMAIN ELEVATED THROUGH FRIDAY AFTERNOON.
&&
.FIRE WEATHER...MOISTURE IS INCREASING AND ANOTHER WIDESPREAD RAIN
EVENT IS EXPECTED THURSDAY INTO FRIDAY. A COLD FRONT WILL SWEEP
ACROSS THE AREA THURSDAY NIGHT AND FRIDAY MORNING...BRINGING AN END
TO THE RAINFALL...AND USHERING IN COLDER AND DRIER AIR FOR THE
WEEKEND. CONDITIONS WILL NEED TO BE MONITORED FOR THE POSSIBILITY OF
LONG DURATIONS OF LOW RELATIVE HUMIDITY ON SATURDAY AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 48 67 55 63 37 / 10 60 90 30 10
PANAMA CITY 54 67 54 61 40 / 10 80 90 20 10
DOTHAN 48 63 50 60 34 / 10 70 80 20 10
ALBANY 44 65 52 61 35 / 10 50 90 30 10
VALDOSTA 46 69 56 68 41 / 10 30 100 40 10
CROSS CITY 46 72 57 70 40 / 10 30 90 40 10
APALACHICOLA 54 67 56 62 40 / 10 70 90 30 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST FRIDAY
FOR THE FOLLOWING ZONES: COASTAL WATERS FROM OCHLOCKONEE
RIVER TO APALACHICOLA FL OUT TO 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.
&&
$$
AVIATION/FIRE WEATHER...DUVAL
LONG TERM...AUSTIN/GODSEY
REST OF DISCUSSION...WATSON
