Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 221129
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
529 AM CST MON DEC 22 2014

.DISCUSSION...

CURRENT WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW ACROSS THE
NORTHERN PLAINS...WITH UPPER LEVEL RIDGING JUST OFF THE SOUTHEAST
COAST. WINDS HAVE BEGUN TO VEER MORE TOWARDS THE SOUTH...AND WITH
EXTENSIVE CLOUD COVER...TEMPERATURES HAVE RISEN BY A DEGREE OR TWO
OVER THE LAST COUPLE OF HOURS. THIS TREND WILL CONTINUE AS WAA RAMPS
UP IN ADVANCE OF THE NEXT SYSTEM THAT WILL MOVE THROUGH THE FORECAST
AREA. A WEAK UPPER LEVEL SHORTWAVE IS EXPECTED TO ROUND THE BASE OF
THE BROAD UPPER LEVEL TROUGH...WHICH IS CURRENTLY SITUATED OVER MUCH
OF THE CENTRAL CONUS. AS THIS SHORTWAVE MOVES NORTHEAST OVER THE
AREA...SCATTERED LIGHT RAIN WILL DEVELOP...WITH COVERAGE INCREASING
DURING THE AFTERNOON AND EVENING HOURS.

THE MAIN UPPER LEVEL TROUGH WILL CONTINUE TO AMPLIFY AND DIG SOUTHWARD
INTO THE ARKLATEX BY 06Z ON TUESDAY...AS A STRONG UPPER RIDGE BEGINS
TO PUSH EAST ONTO THE WEST COAST. A COLD FRONT WILL MOVE INTO THE
MISSISSIPPI VALLEY BY DAYBREAK ON TUESDAY...BEFORE STALLING JUST TO
OUR WEST. SOUTHERLY FLOW WILL CONTINUE TO PUSH IN DEEP GULF
MOISTURE...ALONG WITH THE WARMER TEMPERATURES. THIS WILL LEAD TO THE
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS LATE MONDAY NIGHT...CONTINUING
THROUGH TUESDAY.

THE UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN ON TUESDAY...WITH A
STRONG CUT OFF LOW DEVELOPING OVER OKLAHOMA. MEANWHILE...SURFACE
CYCLOGENESIS WILL OCCUR ALONG THE LOUISIANA GULF COAST ALONG THE
STALLED SURFACE COLD FRONT. THIS LOW WILL MOVE TO THE NORTHEAST
OVERNIGHT TUESDAY...ALMOST PARALLEL TO THE INTERSTATE 59
CORRIDOR...WITH A WARM FRONT THAT IS CURRENTLY ALONG THE GULF
COAST...PUSHING TO THE NORTH AS WELL. AS THE LOW RACES NORTH
WEDNESDAY MORNING...THE SURFACE COLD FRONT WILL EXIT TO THE
EAST...WITH MUCH OF THE PRECIPITATION COMING TO AN END WEDNESDAY
AFTERNOON.

THE SEVERE THREAT STILL APPEARS TO BE VERY MINIMAL ACROSS THE
FORECAST AREA. ALTHOUGH EXTENSIVE CLOUD COVER COULD HELP KEEP THE
INSTABILITY LOW ACROSS THE AREA...THE STRONG WAA MAY BE ENOUGH TO
OFFSET THE CLOUD COVER AND PRECIPITATION. FORTUNATELY...CURRENT
GUIDANCE SUGGESTS THAT THE WARM FRONT WILL NOT QUITE MAKE IT THIS FAR
NORTH...BEFORE THE LOW EXITS THE AREA. MID LEVEL LAPSE RATES WILL BE
DECENT...THUS THE CONTINUED MENTION OF THUNDERSTORMS...AND THERE
COULD BE THE POTENTIAL FOR SMALL HAIL AND SUBSEVERE WIND GUSTS. THE
BIGGER IMPACT MAY BE THE AMOUNT OF RAINFALL EXPECTED. STORM TOTAL
AMOUNTS COULD REACH ABOVE 2 INCHES IN LOCALIZED AREAS...THOUGH THIS
LOOKS TO OCCUR OVER THE COURSE OF ABOUT 24 HOURS. HOWEVER...WITH
MOISTENING GROUND CONDITIONS AHEAD OF THE CONVECTION TUESDAY
EVENING...THERE IS THE POTENTIAL FOR STREAMS TO REACH BANKFULL BY
WEDNESDAY MORNING. HOWEVER...THE FLOODING THREAT APPEARS TO BE TOO
LOW TO MENTION ANYTHING IN THE HWO AT THIS POINT.

THE UPPER LEVEL TROUGH WILL FINALLY MOVE ACROSS THE FORECAST AREA
WEDNESDAY EVENING THROUGH THURSDAY MORNING...WITH LINGERING MOISTURE
ENOUGH TO WARRANT SCATTERED LIGHT SHOWERS ACROSS OUR NORTHEASTERN
COUNTIES. THE ENTIRE SYSTEM LOOKS TO BE SLIGHTLY SLOWER THAN
PREVIOUS GUIDANCE SUGGESTED...WITH HIGH TEMPERATURES REACHING INTO
THE UPPER 50S WEDNESDAY AFTERNOON. CLOUD COVER WILL REMAIN IN PLACE
ACROSS THE AREA...THEREFORE OVERNIGHT LOWS DO NOT LOOK TO DROP AS
MUCH AS PREVIOUSLY FORECAST. FORECAST SOUNDINGS SUGGEST THAT MUCH OF
THE MOISTURE OCCURS WHILE TEMPS AND DEWPOINTS ARE ABOVE FREEZING.
THEREFORE...TOOK OUT MENTION OF ANY FROZEN PRECIP.

CHRISTMAS DAY WILL BE PLEASANT ACROSS THE REGION...AS HIGH PRESSURE
BUILDS BRIEFLY INTO THE AREA. DID NOT MAKE TOO MANY CHANGES TO THE
EXTENDED...GIVEN THE GENERAL DISAGREEMENT AMONG GUIDANCE.

&&

.AVIATION...
/ISSUED 1138 PM CST SUN DEC 21 2014/
FOR 06Z TAFS...
FLYING CONDITIONS WILL GRADUALLY DETERIORATE THROUGH THE PERIOD...AS
MOISTURE INCREASES ACROSS THE REGION. A DECK OF MAINLY MVFR STRATUS
OVER THE REGION...WILL LOWER INTO THE IFR RANGE DURING THE OVERNIGHT.
LIGHT DRIZZLE/RAIN...MOSTLY NEAR/EAST OF KHSV LATE TONIGHT WILL ADD
TO THE WEATHER COMPLEXITY. RAIN CHANCES WILL INCREASE DURING MON...AS
A SYSTEM NEARS FROM THE SW. CIG LEVELS COULD LOWER TO LIFR LATE MON
AFTERNOON/EVENING. WINDS EAST OF I-65 WILL BE FROM THE SE 10-15KT.
LIGHT WINDS WEST OF I-65 WILL BECOME SE 5-10KT AFTER DAYBREAK.

RSB

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    54  52  61  50 /  50  60  80  90
SHOALS        56  54  60  44 /  50  70  80  90
VINEMONT      52  50  62  50 /  50  60  80  90
FAYETTEVILLE  54  52  58  50 /  50  60  80  90
ALBERTVILLE   52  50  59  54 /  50  60  80  90
FORT PAYNE    52  50  57  52 /  50  50  80  90

&&

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

$$

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


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