FXUS62 KTAE 071851
AFDTAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
151 PM EST MON DEC 7 2009
...ISOLATED STRONG STORMS POSSIBLE WEDNESDAY...
.SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)...WEATHER PATTERN
ACROSS THE NATION WILL BE DOMINATED BY MASSIVE CENTRAL CONUS WINTER
STORM OVER THE NEXT FEW DAYS. OFFENDING UPPER TROUGH IS CURRENTLY
DIGGING INTO THE INTER-MOUNTAIN WEST WITH SFC LOW DEEPENING OVER
THE GREAT BASIN. THIS LOW WILL MOVE INTO THE PLAINS TUESDAY AND
RAPIDLY DEEPEN AS IT LIFTS NORTHEAST TOWARDS THE GREAT LAKES.
IN RESPONSE TO THE DEEPENING LOW...SOUTHERLY FLOW WILL INCREASE
OVER THE FORECAST AREA TONIGHT AND TUESDAY WITH A WARM FRONT
DEVELOPING ALONG THE GULF COAST TUESDAY MORNING AND LIFTING NORTH
THROUGH THE DAY. THE BEST LIFT AND JET DYNAMICS ARE FORECAST TO
REMAIN NORTH OF THE FORECAST AREA THROUGHOUT THIS EVENT.
HOWEVER...SHOULD BE ENOUGH OVERRUNNING AND SYNOPTIC SCALE LIFT FOR
LIKELY POPS OVER THE NORTH TAPERING TO CHANCE OVER THE
SOUTHEASTERN ZONES. ATMOSPHERE IS FORECAST TO REMAIN STABLE OVER
THE ENTIRE AREA THROUGH TUESDAY AFTERNOON SO NO THUNDER EXPECTED.
QPF IS FORECAST TO BE MODEST WITH AMOUNTS GENERALLY LESS THAN ONE
HALF INCH THROUGH WEDNESDAY.
BY TUESDAY NIGHT...FOCUS WILL SHIFT TO THE APPROACHING COLD FRONT.
GUIDANCE DOES INDICATE A MODESTLY UNSTABLE ATMOSPHERE PUSHING
INLAND BY THE PREDAWN HOURS WEDNESDAY. SHEAR WILL BE MORE THAN
SUFFICENT FOR SEVERE STORMS...BUT BEST LIFT AND FORCING WILL BE
PULLING AWAY TO THE NORTH. WILL HAVE THUNDER IN THE FORECAST
TUESDAY NIGHT FOR SE ALABAMA...SPREADING SOUTHEAST THROUGH THE DAY
WEDNESDAY. WIDESPREAD SEVERE WEATHER NOT EXPECTED BUT CANNOT RULE
OUT ISOLATED STRONG TO SEVERE STORMS ALONG AND AHEAD OF THE FRONT.
.LONG TERM (THURSDAY THROUGH SUNDAY)...THE MEDIUM RANGE GUIDANCE
AGREES THAT THE RATHER AMPLIFIED H5/H2 TROUGH FROM NRN CANADA SEEN
DURING THE MID WEEK PERIOD WILL MOVE EWD AND TREND TOWARDS A
BROADER/FLATTER PATTERN BY THE UPCOMING WEEKEND...WITH LARGELY
ZONAL FLOW ACROSS SRN HALF OF CONUS. AT SAME TIME WE SEE EVIDENCE
OF UPSTREAM RIDGING OVER WRN CONUS. STILL...SRN STREAM REMAINS
SUFFICIENTLY ACTIVE THRU MUCH OF EXTENDED TO CONTINUE SENDING A
SERIES OF SRN STREAM SHORTWAVES DOWNSTREAM TO GENERATE SURFACE
WAVES LIFTING STALLED FRONT(S) BACK NORTH AND PUSHING COLD FRONTS
INTO SE REGION IN A REPEAT OF RECENT EL NINO PATTERN.
AT LOWER LEVELS...AS ABOVE TROUGH MOVES EWD...ASSOCIATED COLD
FRONT MOVES ACROSS LOCAL REGION EXITING CWA LATE WED NIGHT.
ALTHOUGH UPPER SUPPORT REMAINS WELL NORTH OF THE FORECAST
AREA...FRONT MAY BRING A CHANCE OF TSTMS BEFORE STALLING ACROSS
S/CNTRL GULF LATE WED NIGHT INTO EARLY THURS. IN ITS WAKE...HIGH
PRESSURE BUILDS OVER SE CONUS BRIDGING THE FRONT WITH A RETURN TO
LOW LEVEL NNE FLOW YIELDING A MODESTLY DRIER AND COOLER AIRMASS.
BUT...AS HIGH MOVES E OF CWA...AHEAD OF NEXT UPSTREAM LOW...FLOW
QUICKLY BECOMES ONSHORE THURS/FRI. THIS LOW DEVELOPS IN THE LWR MS
VALLEY TO MOVE RAPIDLY ACROSS THE SOUTHEAST U.S. FRIDAY NIGHT
REACHING THE MID- ATLC COAST LATER ON SAT. INITIALLY THIS STRONGER
LOW (WITH UPPER DYNAMICS FURTHER S THAN PREVIOUS SYSTEM) WILL HELP
LIFT STALLED GULF BOUNDARY BACK NWD FOR INCREASING CLOUDS AND
POSSIBLY LIGHT RAIN THURS AFTN AND EVE (ESPECIALLY SRN THIRD OF
CWA) FOLLOWED BY GOOD CHANCE OF SHWRS/ISOLD TSTMS OVERSPREADING
CWA FRI-SAT AHEAD OF COLD FRONT. THIS FRONT WILL APPROACH CWA BY
EARLY SAT AND EXIT RAPIDLY SEWD TO N/CNTRL FL BY SAT EVE AND SHOW
MORE UPPER SUPPORT THAN EARLIER SYSTEM. IN ITS WAKE...EXPECT DRIER
AND COOLER AIR ADVECTING SEWD INTO THE LOCAL AREA LATE SAT NIGHT
THRU SUNDAY.
WITH INITIAL COLD FRONT EXITING LOCAL REGION EXTENDED PERIOD
COMMENCES...LINGERING 20 PCT POPS WED NIGHT. IN WAKE OF THIS
FRONT/LOW...NIL POPS THURS INTO EARLY FRI MORN...THEN AHEAD AND
ALONG NEXT WX SYSTEM...HI SCT POPS FRI AFTN-FRI NIGHT
DECREASING TO SCT SAT THEN ISOLD-WDLY SCT SAT NIGHT AND NO POPS ON
SUN. AS FAR AS TEMPS...PERIOD BEGINS WITH MOISTURE/CLOUDS FROM
EXITING COLD FRONT KEEPING MIN TEMPS WED NIGHT 8-13 DEGREES ABOVE
CLIMO (CLIMO IS LOW 40S) WHILE MAX TEMPS ON THURS DROP TO LOW 60S OR
SLIGHTLY BELOW CLIMO (CLIMO IN MID 60S). THEN...WITH COOL DRY
AIRMASS BRIEFLY BUILDING IN...MIN TEMPS AROUND CLIMO THURS NIGHT
BEFORE INCHING UP TO AROUND 8 DEGREES ABOVE CLIMO BY SAT NIGHT
AHEAD OF NEXT WX SYSTEM. IN WAKE OF STRONGER FRONT...INLAND MIN
TEMPS DROP INTO UPPER 30S ON SUNDAY.
&&
.AVIATION...EXPECT VFR CONDITIONS CONTINUE AT ALL TERMINALS THROUGH
INTO EVENING TONIGHT BUT OVERNIGHT CEILINGS AND VISBY WILL LOWER
RELATIVELY RAPIDLY AS LOW LEVEL WINDS VEER TO MORE EASTERLY BRINGING
AN INCREASE IN MOISTURE. IFR AND LIFR CONDTIONS POSSIBLE AT INLAND
TERMINALS BY LATE NIGHT AND CONTINUING INTO TUESDAY MORNING.
&&
.MARINE...SOUTHERLY FLOW WILL INCREASE OVER THE WATERS THROUGH
WEDNESDAY...REACHING SMALL CRAFT CRITERIA TUESDAY NIGHT. OFFSHORE
FLOW CLOSE TO 20 KNOTS EXPECTED THROUGH THURSDAY MORNING BEHIND
THE FRONT. WINDS AND SEAS WILL REMAIN ELEVATED BUT VEER TO THE
EAST THROUGH THE END OF THE WORK WEEK.
&&
.FIRE WEATHER...HIGH LEVEL MOISTURE IN THE LOW LEVELS THROUGH
TUESDAY AND INTO WEDNESDAY BEFORE COLD FRONT EXPECTED TO PASS
THROUGH. NO RED FLAG CONDITIONS ARE ANTICIPATED AT LEAST THROUGH
WEDNESDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TALLAHASSEE 52 71 61 77 50 / 10 50 30 60 20
PANAMA CITY 55 70 65 75 51 / 10 50 40 60 10
DOTHAN 50 67 61 74 41 / 10 70 50 50 10
ALBANY 48 67 60 76 44 / 10 70 50 60 10
VALDOSTA 51 71 61 78 51 / 10 60 30 50 30
CROSS CITY 53 76 62 77 55 / 10 40 20 50 40
APALACHICOLA 56 69 65 76 53 / 10 50 30 50 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.
&&
$$
CAMP/GOREE/BLOCK
