Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 261038
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
538 AM CDT SUN APR 26 2015

.DISCUSSION...
LATEST WATER VAPOR SATELLITE ANIMATION SUGGESTS THAT A WEST-NORTHWEST
FLOW ALOFT HAS NOW BECOME ESTABLISHED ACROSS THE CENTRAL TENNESSEE
VALLEY...AS THE REGION REMAINS BETWEEN A SUBTROPICAL HIGH LOCATED
ACROSS THE CARIBBEAN SEA AND A BROAD UPPER LOW CENTERED OFF THE
COAST OF NORTHERN NEW ENGLAND. THIS TREND WILL PERSIST THROUGH FIRST
HALF OF THE SHORT TERM PERIOD...AS 500-MB HEIGHTS RISE ACROSS THE
CENTRAL PLAINS DOWNSTREAM FROM AN AMPLIFIED TROUGH PUSHING SLOWLY
EASTWARD ACROSS THE WESTERN CONUS. AT THE SURFACE...AN INITIAL SURGE
OF COOLER/DRIER AIR WILL CONTINUE TO PUSH SOUTHWARD THIS MORNING --
WITH A STRONGER SURGE EXPECTED TO ARRIVE DURING THE AFTERNOON. A
GUSTY NORTH-NORTHWEST WIND WILL STEADILY ADVECT COOLER AIR INTO THE
REGION AND WORK IN CONJUNCTION WITH ABUNDANT LOW-LEVEL STRATUS CLOUDS
TO KEEP TEMPERATURES 5-10 DEGREES COLDER THAN VALUES OBSERVED
YESTERDAY. BASED ON EXPECTED TIMING OF SECONDARY COLD FRONT AND
ARRIVAL OF THICKER STRATUS...A PRONOUNCED N-S ORIENTED TEMPERATURE
GRADIENT WAS INDICATED IN THE MAX T GRID FOR TODAY. OVERALL...EXPECT
MOSTLY CLOUDY SKIES AND COOLER TEMPERATURES TODAY WITH A GUSTY NORTH
WIND AT TIMES. A FEW LIGHT SHOWERS MAY ACCOMPANY PASSAGE OF SECONDARY
COLD FRONT ACROSS SOUTHERN TN AND NORTHEAST AL...BUT COVERAGE APPEARS
TO BE VERY LOW AT THIS POINT. LOW CLOUDS WILL LIKELY CLEAR THE REGION
EARLY THIS EVENING...BUT HIGH CLOUDS SHOULD RETURN BY EARLY MONDAY
MORNING AND THIS -- ALONG WITH A STEEP PRESSURE GRADIENT AND WELL
MIXED PBL -- SHOULD LIMIT THE THREAT FOR NOCTURNAL FOG. LOWS TONIGHT
WILL BE IN THE MID/UPPER 40S...OR AROUND 5-10 DEGREES BELOW NORMAL.

MEANWHILE...A VORT MAX WITHIN THE BASE OF PREVIOUSLY MENTIONED
WESTERN CONUS TROUGH IS FORECAST TO COMPLETELY CLOSE OFF ACROSS THE
SOUTHERN ROCKIES LATER TODAY AND SHIFT SLOWLY EASTWARD ACROSS THE
SOUTHERN HIGH PLAINS BY MONDAY AFTERNOON. SOLUTIONS FROM VARIOUS
GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT THIS FEATURE WILL BEGIN
TO ACCELERATE INTO THE OZARKS REGION BY TUESDAY AFTERNOON...WITH FLOW
ALOFT BECOMING INCREASINGLY DIFFLUENT ACROSS THE FORECAST AREA.
SURFACE PRESSURE FALLS ASSOCIATED WITH THE APPROACH OF THIS
DISTURBANCE WILL BECOME CONCENTRATED OVER THE NORTHWESTERN GULF ON
MONDAY NIGHT...WITH A DEEPENING LOW FORECAST TO TRACK NORTHEASTWARD
INTO THE CENTRAL GULF COAST ON TUESDAY. THE NET RESULT OF THIS CAN BE
SEEN IN POINT FORECAST SOUNDINGS...WITH RAPIDLY STRENGTHENING LOWER
TROPOSPHERIC VEERING DURING THE DAY TUESDAY. THIS WILL ENHANCE LARGE
SCALE ASCENT ALREADY IN PLACE FROM DIFFLUENT FLOW ALOFT AND SHOULD
TRANSLATE TO A FAIRLY WIDESPREAD COVERAGE OF LIGHT RAIN SHOWERS BY
LATE AFTERNOON AS PWATS RISE TO AROUND 1 INCH. THE ONLY EXCEPTION TO
THIS WILL BE ACROSS THE FAR NORTHEASTERN ZONES...WHERE LINGERING DRY
AIR BELOW 700-MB WILL BE MORE DIFFICULT TO SATURATE. DUE TO THE ONSET
OF CLOUDS AND PRECIPITATION DURING THE DAY ON TUESDAY...HIGHS WILL
ONLY REACH THE MID 60S -- OR AROUND 10 DEGREES BELOW NORMAL.

VERTICAL MOTIONS WILL INCREASE EVEN FURTHER ON TUESDAY NIGHT AND
WEDNESDAY MORNING...AS THE OZARKS MID-LEVEL LOW OPENS INTO A WAVE
AND SHIFTS EAST-NORTHEASTWARD ACROSS THE REGION -- AND EVENTUALLY
INTO THE CAROLINAS BY WEDNESDAY AFTERNOON. THE LOCAL AREA WILL REMAIN
IN THE COOL SECTOR OF SURFACE LOW TRACKING NORTHEASTWARD ACROSS
SOUTHERN GA/AL AND THE FLORIDA PANHANDLE...AND WITH SOUNDINGS
INDICATING LITTLE TO NO ELEVATED INSTABILITY WE SIMPLY EXPECT
WIDESPREAD SHOWERS TO CONTINUE THROUGH THE NIGHT BEFORE SLOWLY ENDING
FROM NW-TO-SE ON WEDNESDAY MORNING. A COUPLE OF STRONGER NORTHERN
STREAM WAVES WILL DIG SOUTHEASTWARD DURING THE REMAINDER OF THE WORK
WEEK...MAINTAINING DRY BUT UNSEASONABLY COOL CONDITIONS ACROSS THE
REGION. HIGHS WILL REMAIN IN THE 60S WITH LOWS IN THE 40S. EXTENDED
RANGE GEM/GFS/ECMWF GUIDANCE DOES OFFER EVIDENCE OF A GRADUAL
WARMING TREND NEXT WEEKEND AS MID-LEVEL RIDGING SETS UP ACROSS THE
SOUTHEASTERN CONUS.

70/DD

&&

.AVIATION...
/ISSUED 1214 AM CDT SUN APR 26 2015/
FOR 06Z TAFS...A COLD FRONT WILL DROP SOUTH DURING THE NEXT FEW
HOURS WITH ISOLD TO SCT SHRA/TSRA STILL PSBL. THESE SHOULD EXIT THE
AREA BY 10Z AT THE LATEST. VFR CIGS ARE EXPECTED ALTHOUGH WE HAVE
INCLUDED A PERIOD FROM 12-15Z WHEN MVFR CIGS ARE PSBL. NORTHERLY FLOW
WILL CLEAR THE SKY BY SUNDAY AFTERNOON AS DRIER AIR FILTERS INTO THE
REGION.

AK

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    72  48  70  49 /  10  10  10  20
SHOALS        72  49  70  50 /  10  10  10  30
VINEMONT      74  49  70  50 /  10  10  10  30
FAYETTEVILLE  68  44  66  45 /  10  10  10  20
ALBERTVILLE   74  49  67  49 /  10  10  10  30
FORT PAYNE    72  45  68  46 /  20  10  10  20

&&

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

&&

$$

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



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