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000
FXUS64 KHUN 100324 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
924 PM CST TUE FEB 9 2010

.UPDATE...
ADDED FLURRIES TO TENNESSEE AND FAR NE ALABAMA FOR THE OVERNIGHT.

&&

.DISCUSSION...
A POWERFUL UPPER LEVEL LOW...NOW SPINNING OVER THE OHIO VALLEY
CONTINUED TO MOVE EAST. DRIER AIR CIRCULATING AROUND THIS LOW HAS
BROUGHT CLEARING SKIES ACROSS THIS PART OF THE TENNESSEE VALLEY
DURING THE LATE AFTERNOON. DESPITE THE RETURN OF MORE COLDER THAN
SEASONAL AIR...THE SUN MADE A BRIEF APPEARANCE FOR MOST OF THE
WESTERN AND CENTRAL LOCALITIES...A FIRST TIME IN ALMOST A WEEK. MORE
AREAS SHOULD RECEIVE SUN TOMORROW...DESPITE PERIODS OF HIGHER CLOUDS
MOVING IN FROM THE WSW.

DESPITE GENERAL DOWNGLIDING OF REMAINING MOISTURE IN THE LOWER
ATMOSPHERE...ENOUGH TERRAIN LIFTING OVER THE CUMBERLAND PLATEAU AND
HIGHER TERRAIN OF NE ALABAMA HAS RESULTED IN A FEW FLURRIES. THE
FOG/LOW CLOUD SATELLITE VIEW SHOWED MORE LOWER ALTITUDE MOISTURE
OVER MISSOURI/SOUTHERN ILLINOIS. THIS MOISTURE...SHOULD IT HOLD
TOGETHER WILL CONTINUE TO PROVIDE A SLIM CHANCE FOR MORE FLURRIES
DURING THE OVERNIGHT AND EARLY WED MORNING...PRIMARILY OVER NE
ALABAMA AND THE SOUTHERN CUMBERLAND PLATEAU OF MIDDLE TENNESSEE.

OTHERWISE...CHILLY LOW TEMPERATURES IN THE LOWER 20S LOOK OK.
CONSIDERING COLD AIR ADVECTION CONTINUING THROUGH THE NIGHT...WILL
LEAVE THEM AS IS. BRISK WINDS MOSTLY IN THE 10-25 MPH RANGE...WITH
15-25 MPH WINDS OVER NE ALABAMA AND IN THE MOUNTAINS WILL RESULT IN
WIND CHILL TEMPERATURES NEARING ZERO BY DAYBREAK WED...ESPECIALLY IN
THE MORE EXPOSED LOCATIONS.

ALL ELSE FROM THE DAY CREW LOOKS FINE. UPDATES WILL BE SHIPPED SOON.

&&


.AVIATION...    /00Z ISSUANCE/
AN UPPER LEVEL LOW OVER THE WESTERN OHIO VALLEY HAS BROUGHT MUCH
DRIER AIR TO THE REGION. THIS HAS SCOURED MVFR CLOUDINESS EASTWARD
TO THE AL/GA BORDER...WITH MOSTLY CLEAR SKIES NOW OVER THIS REGION.
THERE IS A CHANCE FOR MORE MVFR CEILINGS FOR AREAS MAINLY EAST OF
THE I-65 CORRIDOR AS WRAP AROUND MOISTURE MOVES OVER THE AREA. THE
OTHER ISSUE WILL BE WINDS...WITH SUSTAINED WINDS IN THE 10-15KT
RANGE FROM WNW. WINDS SHOULD INCREASE TO THE 15-25KT RANGE BEFORE
DAYBREAK... WITH SOME GUSTS NEARING 30KTS FROM THE NW WED AFTERNOON.
WINDS SHOULD SLOWLY SUBSIDE TO AROUND 10KTS TOWARD DUSK.

&&

.PREV DISCUSSION...  /ISSUED 302 PM CST TUE FEB 9 2010/

SYNOPSIS...A STRONG SUBTROPICAL JET STREAM CONTINUES ACROSS MUCH OF
THE SOUTHERN HALF OF THE U.S. THE CUTOFF LOW SITUATED OVER THE
MIDWEST IS GRADUALLY SHIFTING NORTHEAST TAKING THE CLOUDS AND PRECIP
WITH IT. THIS SAME SYSTEM HAS SENT A COLD AIR MASS ACROSS MUCH OF
THE SOUTHEAST INCLUDING THE TN VALLEY.

A SMALL CUTOFF LOW EJECTED FROM THE MAIN NORTHERN JET OVER THE
EASTERN PACIFIC IS SLIDING SOUTHWARD JUST OFF THE COAST OF CA. THE
PROGRESSION OF THIS FEATURE WILL BE ESPECIALLY IMPORTANT FOR WEATHER
ON FRIDAY.

SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)...THE MAIN STORY FOR
TONIGHT WILL BE THE RAPID CLEARING OF CLOUDS AND THE COLD AIR MASS
COMING RIGHT OFF THE SNOWPACK JUST TO THE NORTHWEST. THIS COLD AND
DRY AIR WILL QUICKLY BLAST THROUGH THE TN VALLEY WITH TEMPS AND
DEWPOINTS DROPPING RAPIDLY BEHIND THE CLEARING. HAVE LOWERED TEMPS
NEAR 20 EXCEPT FOR NE AL WHERE MORE TIME UNDER CLOUD COVER MAY
TEMPER THE DROP. ANOTHER FACTOR TO CONSIDER IS THAT THE WINDS WILL
GUST EVEN MORE BEHIND THE FRONT WITH GUSTS TO 15-20 MPH POSSIBLE AT
LEAST INITIALLY TONIGHT. WIND GUSTS WILL THEN PICK UP AGAIN BY
WEDNESDAY MORNING UNDER CLEAR SKIES AS MOMENTUM FROM AN UPPER JET
STREAK MIXES DOWNWARD. FOR EXAMPLE...MODEL GUIDANCE IS INDICATING
WINDS OF BTWN 40-45 KTS AROUND 850 HPA ON WEDNESDAY MORNING.
HOWEVER...NOT EXPECTING WIND GUSTS TO VENTURE MORE THAN AROUND 20-25
MPH FOR THE MAJORITY OF THE AREA WITH SOME ELEVATED AREAS RISING UP
TO 30 MPH.

WITH THE STRONG CAA IN PLACE...TEMPS WILL LIKELY ONLY RISE TO NEAR
40 DESPITE THE PARTLY CLOUDY CONDITIONS. AFTER SUNSET...TEMPS WILL
DROP AGAIN BELOW FREEZING INTO THE LOW TO MID 20S.

WITH A GENERAL ZONAL FLOW PATTERN ACROSS MUCH OF THE SOUTHERN TIER
STATES...SHORTWAVES ARE MARCHING DOWN THE FLOW WITH EASE. IN
FACT...THE AFOREMENTIONED SMALL CUTOFF LOW PROCEEDING OFF THE COAST
OF CA WILL BE ENTERING W TX BY WEDNESDAY NIGHT INTO THURSDAY MORNING
WITH ITS SPEED COURTESY OF THE SUBTROPICAL JET STREAM.

AS THE CUTOFF LOW PROCEEDS EASTWARD...SFC CYCLOGENESIS WILL RESULT
OVER THE WESTERN GULF OF MEXICO NEAR BROWNSVILLE TX BY THURSDAY
NIGHT. CLOUDS WILL BEGIN TO INCREASE AGAIN WITH CIRRUS BLOW OFF FROM
THE CUTOFF LOW MOVING ACROSS THE AREA BY LATE THURSDAY AFTERNOON
INTO THURSDAY EVENING.

LONG TERM (FRIDAY THROUGH TUESDAY)...THE MODELS ARE QUITE DIFFERENT
WITH SOLUTIONS FOR THE PROGRESSION OF THE SFC LOW. THE CUTOFF LOW
SEEMS TO OPEN UP AS A WAVE AND PROCEED EAST/SOUTHEAST ACROSS THE
REGION. GFS CONTINUES TO HAVE ITS SOUTHERLY TRACK WITH THE SFC LOW
NOW PROGGED TO PROCEED SOUTHWARD TOWARDS CUBA. MEANWHILE...THE ECMWF
IS STILL HOLDING TO A MORE NORTHERLY TRACK WITH BOTH THE TROUGH AND
THE SFC LOW. IF THE MORE NORTHERLY TRACK ACTUALLY TAKES
PLACE...COULD SEE SOME SNOWFALL MAINLY OVER THE SOUTHERN PORTIONS OF
THE CWA. SOME SNOWFALL MAY ALSO COME FROM THE TROUGH PASSING
OVERHEAD. HOWEVER...GIVEN THAT THE DRY AIR MASS WILL BE IN PLACE AND
LITTLE IN THE WAY OF MOISTURE ADVECTION...NOT EXPECTING MUCH IN THE
WAY OF ACCUMULATIONS. ALSO...GROUND TEMPS WILL PROBABLY BE HOVERING
IN THE MID 30S BY THAT TIME AND THE LIGHT INTENSITY OF THE SNOW
KEEPING ACCUMULATIONS MINIMAL.

ONCE THE WAVE PASSES TO THE EAST...CLOUDS SHOULD CLEAR OVERNIGHT ON
FRIDAY NIGHT WITH PARTLY CLOUDY CONDITIONS EXPECTED FOR SATURDAY
(FOR THE FIRST TIME IN A WHILE). TEMPS ON SATURDAY MAY ACTUALLY
CLIMB BACK INTO THE MID 40S AGAIN. MEANWHILE...ANOTHER REINFORCING
SHOT OF COLD AIR...IN THE FORM OF A SHORTWAVE EJECTED OFF THE MAIN
UPPER TROUGH OVER THE EASTERN U.S...IS DEPICTED BY ECMWF CHARGING
SOUTHWARD BY LATE SATURDAY NIGHT. IT LOOKS AS IF THIS SHOULD BE JUST
SOME CLOUDS FOR EARLY SUNDAY MORNING WITH SOMEWHAT COOLER TEMPS ON
SUNDAY AFTERNOON.

BUT...THERE MAY BE SOME LINGERING CLOUDS ON MONDAY MORNING FROM THE
MAIN UPPER TROUGH. OTHERWISE...BELOW NORMAL TEMPS WILL PREVAIL FOR
BOTH MONDAY AND TUESDAY.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

UPDATE/AVIATION...RSB
PREV DISCUSSION...SL.77