Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 272118
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
318 PM CST SAT DEC 27 2014

.DISCUSSION...

CURRENT SURFACE ANALYSIS SHOWS A SURFACE COLD FRONT EXTENDING FROM
ITS PARENT LOW OVER NORTHERN MICHIGAN...TRAILING SOUTHWESTWARD
THROUGH THE ARKLATEX. AHEAD OF THIS FRONT...SOUTHERLY FLOW HAS
ADVECTED WARM AND MOIST GULF AIR ACROSS MUCH OF THE LOWER MISSISSIPPI
AND TENNESSEE VALLEY REGIONS. RAIN WAS ALSO CONTINUING TO MOVE TO THE
NORTHEAST AHEAD OF THIS SURFACE FRONT...WITH ISOLATED EMBEDDED
THUNDERSTORMS OBSERVED ACROSS NORTHERN MISSISSIPPI AND MORE
WIDESPREAD THUNDERSTORMS ACROSS SOUTHER ALABAMA.

AS THE COLD FRONT MOVES SLOWLY TO THE EAST OVER THE NEXT DAY OR
TWO...SEVERAL WEAK SHORTWAVES AND SURFACE LOWS ARE EXPECTED TO
DEVELOP AND MOVE ALONG THE FRONT. THIS WILL BRING MULTIPLE WAVES OF
SHOWERS ACROSS THE FORECAST AREA...WITH THE FIRST ROUND OCCURRING
THIS MORNING...AND THE NEXT ROUND JUST ON THE WESTERN BOUNDARY OF THE
FORECAST AREA. RAIN WILL BEGIN TO OVERSPREAD THE AREA BY SUNSET AND
THEN MOVE NORTHEASTWARD THROUGH THE EVENING. MID LEVEL LAPSE RATES
APPEAR TO BE STEEP ENOUGH TO ALLOW FOR ELEVATED INSTABILITY ACROSS
THE WESTERN COUNTIES...AND AN ISOLATED THUNDERSTORM OR TWO WILL BE
POSSIBLE. THOUGH NOT EXPECTING ANYTHING IN THE WAY OF STRONG OR
SEVERE THUNDERSTORMS...LOCALLY HEAVY RAINFALL WILL BE LIKELY. ACROSS
THE EASTERN PORTION OF THE FORECAST AREA...MORE WIDESPREAD HEAVY
RAINFALL IS EXPECTED...HOWEVER CURRENTLY THERE DOES NOT APPEAR TO BE
ENOUGH ELEVATED INSTABILITY TO WARRANT THUNDERSTORMS.

WIDESPREAD SHOWERS WILL CONTINUE THROUGH THE DAY ON SUNDAY...WITH A
BRIEF LULL IN ACTIVITY POSSIBLE DURING THE AFTERNOON. THE FINAL
ROUND OF PRECIPITATION WILL MOVE THROUGH LATE SUNDAY
EVENING...THROUGH MONDAY MORNING AS THE LAST UPPER LEVEL SHORTWAVE
SWEEPS THE AREA WITH ENOUGH ENERGY TO PUSH THE COLD FRONT TO THE
EAST OF THE AREA. STORM TOTAL QPF WILL APPROACH 2 INCHES...AND
POSSIBLY EXCEED THAT ACROSS THE EAST. LOCALLY HIGHER AMOUNTS ARE
POSSIBLE IN THE HEAVIER BANDS. WITH THE RECENT RAINFALL OF OVER 1.5
INCHES...LOCALIZED FLASH FLOODING IS A DISTINCT POSSIBILITY...AND
HAVE EXTENDED THE PREVIOUS FLASH FLOOD WATCH TO INCLUDE THE ENTIRE
AREA. MUCH OF THE PRECIPITATION SHOULD PUSH EAST OF THE AREA BY
MIDNIGHT MONDAY...AND THE WATCH WILL EXPIRE THEN.

ZONAL FLOW ALOFT WILL OVERTAKE THE WEATHER PATTERN ACROSS THE
SOUTHEAST BY MONDAY AFTERNOON...WITH STRONG SURFACE HIGH PRESSURE
BUILDING IN BEHIND THE COLD FRONT. NORTHERLY FLOW WILL ADVECT COLD
ARCTIC AIR ACROSS MUCH OF THE CONUS...WITH SEVERAL DAYS OF DRY
CONDITIONS. BY MIDWEEK...TEMPERATURES WILL DROP BELOW NORMAL FOR THIS
TIME OF YEAR AND THANKFULLY NO PRECIP IS EXPECTED.

HIGH PRESSURE WILL PROPAGATE EASTWARD THROUGH THE END OF THE
WORKWEEK...AS THE NEXT SYSTEM BEGINS TO TAKE SHAPE TO THE WEST. WHILE
MODELS HAVE SOME TIMING DISAGREEMENTS...THE OVERALL SETUP IS SOMEWHAT
CONSISTENT. SOUTHERLY FLOW WILL RETURN TO THE REGION BY FRIDAY...WITH
MOISTURE INCREASING THROUGH THE DAY. AN UPPER LEVEL CLOSED LOW WILL
PUSH EAST OF THE ROCKIES AND SWIFTLY MOVE TO THE NORTHEAST FRIDAY
EVENING. MEANWHILE...A SURFACE LOW WILL DEVELOP AND PUSH ANOTHER
COLD FRONT THROUGH THE AREA DURING THE LATTER PART OF THE EXTENDED.
TEMPERATURES ARE EXPECTED TO WARM ABOVE FREEZING PRIOR TO THE ONSET
OF PRECIPITATION...THEREFORE...ONLY LIQUID PRECIPITATION IS EXPECTED.

73

&&

.AVIATION...
/ISSUED 1157 AM CST SAT DEC 27 2014/
FOR 18Z TAFS...MVFR STRATUS HAS ALREADY DEVELOPED ACROSS MOST OF
NW/NC ALABAMA...WITH RADAR DATA INDICATING THAT -RA WILL CONTINUE
TO LIFT NWD INTO TN. EXPECT LITTLE CHANGE IN CIGS THIS AFTN...BUT
WILL MAINTAIN A PERSISTENT THREAT FOR -RA AT MSL BASED ON EWD MOTION
OF ACTIVITY IN NRN MISS. A HEAVIER/MORE WIDESPREAD AREA OF RA --
CURRENTLY ACROSS SRN MISS/AL -- WILL PUSH NEWD REACHING THE TERMINALS
BY LATE AFTN. THIS ACTIVITY WILL PERSIST THRU THE EVENING/OVERNIGHT
AND INTO SUNDAY MORNING BEFORE SFC LOW LIFTS NEWD AND AWAY FROM THE
TERMINALS BTWN 28/14-16Z. EXPECT PREVAILING IFR CIGS DURING THIS
PERIOD ALONG WITH MVFR VSBY REDUCTIONS. SE/SSE FLOW OF 8-12 KTS WILL
CONTINUE THRU THIS EVENING...BEFORE BCMG LGT/VRBL. A NNW WIND OF 8-12
KTS WILL DEVELOP BY END OF TAF PERIOD.

70/DD

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    50  53  40  53 / 100 100  90  10
SHOALS        50  50  37  52 / 100 100  90  10
VINEMONT      51  54  41  51 / 100 100  90  20
FAYETTEVILLE  49  52  40  51 / 100 100  90  10
ALBERTVILLE   51  56  44  53 / 100 100  90  20
FORT PAYNE    51  57  44  55 / 100 100  90  20

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH SUNDAY EVENING
     FOR ALZ001>010-016.

TN...FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH SUNDAY EVENING
     FOR TNZ076-096-097.

&&

$$

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



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