Area Forecast Discussion
Issued by NWS Huntsville, AL

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FXUS64 KHUN 071104 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
504 AM CST SUN FEB 7 2016

.UPDATE...
FOR 12Z TAFS

&&

.DISCUSSION...
/ISSUED 152 AM CST SUN FEB 7 2016/
AT 07Z, A SURFACE RIDGE OF HIGH PRESSURE WAS SITUATED FROM SOUTHEAST
TX THRU MIDDLE TN AND INTO PA. WATER VAPOR IMAGERY SHOWED A RATHER
STRONG TROF OVER THE SOUTHEAST, JUST PASSING EAST OF OUR FORECAST
AREA THIS MORNING. IMAGERY ALSO SHOWS SEVERAL WAVES WITHIN NW FLOW
ENTERING THE UPPER MS VALLEY AND NORTHERN PLAINS.

ANOTHER NICE WX DAY IS EXPECTED TODAY WITH SEASONAL HIGHS IN THE
L-M50S. CLOUDS WILL RAPIDLY INCREASE FROM THE NW THIS EVENING AS THE
INITIAL SHORTWAVE AND LFQ OF POLAR JET AXIS ARRIVES. DIVERGENCE ALOFT
INCREASES LATE TONIGHT WHICH SHOULD ENHANCE UVVS TO SUPPORT PRECIP.
THE QUESTION IS LOW LEVEL MOISTENING. THE NAM IS EXTREMELY DRY AND
FORECASTS NO PRECIP TONIGHT. EVEN THE GFS MOS IS QUITE LOW WITH POPS,
ALTHOUGH THE RAW FIELDS WOULD SUGGEST OTHERWISE. FIRST "WAVE" OF
PRECIP OR VIRGA WILL SLIDE SE OF THE AREA QUICKLY EARLY MONDAY
MORNING WITH THE PRE-FRONTAL SFC TROF. THEN THE STRONGER COLD FRONT
ARRIVES WITH STRONG COLD ADVECTION AND LOW LEVEL LAPSE RATES
GENERATING SOME LIMITED CAPE FOR SHOWERY PRECIP. OROGRAPHIC UPSLOPE
FLOW WILL ALSO ENHANCE THE POTENTIAL FOR BANDS OF SHOWERY PRECIP
ALONG THE CUMBERLAND PLATEAU IN SRN TN AND FAR NERN AL. PRECIP
SHOULD MIX WITH OR CHANGE TO -SHSN ATOP THE PLATEAU MONDAY AFTN. A
SECONDARY VORT LOBE DROPS SE RAPIDLY MONDAY EVENING INTO KY/MIDDLE
TN. THIS ALONG WITH UPSLOPE FLOW ALONG THE PLATEAU MAY PRODUCE
PERSISTENT -SHSN IN SOME AREAS. BUT PINNING THE AREAL COVERAGE
REMAINS A QUESTION MARK AT THIS POINT. SO HAVE MAINTAINED CHC POPS
FOR NOW. WE MAY NEED TO INTRODUCE ACCUMULATIONS TO THE PLATEAU IN
LATER UPDATES IF THE CONFIDENCE IN POP GOES UP, PARTICULARLY WITH
AREAL COVERAGE.

AFTER A COLD DAY ON WEDNESDAY, THE UPPER TROF RETREATS ITS GRIP OVER
THE TN VALLEY BY THURSDAY. TEMPS SHOULD MODERATE BACK INTO THE 40S TO
L50S AT LEAST ON THURSDAY (THE ECMWF SUGGESTS EVEN WARMER). LIGHT
OVERRUNNING PRECIP MAY DEVELOP EARLY FRIDAY AS A NWLY FLOW
SHORTWAVE COMBINES WITH A W-SW SURGE OF WARM AIR AHEAD OF THE ARCTIC
FRONT. THE GFS DOES INDICATE SOME POTENTIAL FOR -SN/FZRA INITIALLY,
BUT SIDING WITH THE WARMER ECWMF AT THIS POINT, ESPECIALLY WITH A
BLENDED POP OF ONLY AROUND 20 PERCENT. THE NEW ECWMF SHOWS -SHSN
POTENTIAL WITH THE MODIFIED ARCTIC FRONT FRIDAY NIGHT, BUT HAVE
OPTED TO LEAVE OUT FOR NOW.

&&

.AVIATION...
FOR 12Z TAFS...

VFR CONDITIONS ARE EXPECTED ACROSS N AL/S MIDDLE TN FOR THE NEXT 24
HOURS. -RA MAY BE POSSIBLE AT KHSV/KMSL BTWN 09Z-12Z AND THEN ESPECIALLY
AFTER 12Z AS A COLD FRONT APPROACHES.

SL.77

&&

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

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.


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