Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 012017
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
317 PM CDT SUN MAY 1 2016

.DISCUSSION...

LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LOW OVER SOUTHERN IOWA
CLOSED OFF FROM THE MAIN UPPER LEVEL TROUGH EXTENDING OVER MUCH OF
THE WESTERN CONUS. AT THE SURFACE...THE ASSOCIATED LOW WAS SITUATED
OVER ILLINOIS...WITH A COLD FRONT TRAILING SOUTHEASTWARD INTO
LOUISIANA. ACROSS THE LOCAL AREA...CLOUDY SKIES WERE KEEPING TEMPS
IN THE UPPER 70S. ONGOING CONVECTION TO OUR SOUTH...THAT DEVELOPED
ALONG A WEAK BOUNDARY...HAS INCREASED IN COVERAGE OVER THE LAST
SEVERAL HOURS. WITH AN EAST...NORTHEAST MOVEMENT...THE PRECIP WILL
ENTER THE SOUTHERN PORTION OF THE AREA WITHIN THE NEXT HOUR OR
SO...HOWEVER NOT EXPECTING MUCH PROGRESSION NORTH OF THE TN RIVER.
MEANWHILE...CONVECTION HAS INCREASED ALONG THE FRONT OVER THE LAST
COUPLE OF HOURS. THE SLOW PROGRESSION OF THE FRONT WILL KEEP THIS
ACTIVITY FROM REACHING OUR AREA DURING THE OVERNIGHT HOURS...EVEN AS
IT OUTRUNS THE MAIN FRONT. IN FACT...LATEST SHORT TERM HIRES
GUIDANCE HAS MUCH OF THE ACTIVITY ALONG THE FRONT...AND TO OUR SOUTH
DISSIPATING BEFORE IT REACHES INTO N AL. GIVEN THIS...ALONG WITH
SOME UNCERTAINTY...HAVE MAINTAINED A LOW END CHANCE FOR
THUNDERSTORMS DURING THE EARLY EVENING HOURS.

THE COLD FRONT WILL SLOWLY PUSH EAST DURING THE OVERNIGHT
HOURS...AND MAY REACH OUR WESTERN ZONES JUST BEFORE DAYBREAK.
AS STATED ABOVE...CONVECTION ALONG THE FRONT MAY DIMINISH
OVERNIGHT...GIVEN THE LOSS OF DAYTIME HEATING AND THE LACK OF STRONG
VERTICAL FORCING ALONG THE FRONT. THERE MAY BE SCATTERED SHOWERS
DEVELOPING AS IT ENTERS N AL...HOWEVER GUIDANCE SUGGESTS THAT THE
COVERAGE ALONG THE FRONT WILL INCREASE THROUGHOUT THE DAY AS OUR
INSTABILITY INCREASES. A 60 KT UPPER LEVEL JET WILL SUPPORT MODEST
WIND SHEAR...AND WITH FORECAST INSTABILITY APPROACHING...IF NOT
EXCEEDING...1000 J/KG...THERE MAY BE A FEW ORGANIZED UPDRAFTS WITHIN
STORMS THAT DEVELOP ALONG THE FRONT. HOWEVER...THE WEAK NATURE OF
THE UPPER LEVEL SUPPORT AND FORECAST INSTABILITY/SHEAR...NOT
EXPECTING WIDESPREAD SEVERE THUNDERSTORMS.

THE FRONT WILL MOVE THROUGH THE AREA DURING THE OVERNIGHT HOURS ON
TUESDAY...WITH MUCH OF PRECIP COMING TO AN END BY DAYBREAK. THERE
MAY BE LINGERING SHOWERS ACROSS THE EAST...BUT ANYTHING SHOULD BE
ISOLATED. NORTHERLY WINDS WILL HELP FILTER IN DRY AIR BEHIND THE
FRONT...WITH FORECAST DEWPOINTS DROPPING INTO THE UPPER 40S BY
MIDWEEK. THE MAIN UPPER TROUGH WILL FINALLY SHIFT ACROSS THE AREA
DURING THE DAY ON WEDNESDAY...WITH A SLIGHT CHANCE OF SHOWERS ACROSS
OUR TN COUNTIES AS IT MOVES THROUGH. TEMPERATURES WILL REALLY BEGIN
TO COOL AS THIS TROUGH SHIFTS EAST...AND AMPLIFIED RIDGING BEGINS TO
BUILD INTO THE FORECAST AREA. THE COOLEST TEMPS WILL BE ON
THURSDAY...WITH MAX TEMPS FORECAST TO REMAIN IN THE UPPER 60S.
THINGS BEGIN TO WARM UP THROUGH THE WEEKEND...AS THE RIDGE CONTINUES
TO MOVE EASTWARD.

73

&&

.AVIATION...
/ISSUED 1225 PM CDT SUN MAY 1 2016/
FOR 18Z TAFS...WILL CONTINUE WITH VFR/BORDERLINE MVFR CEILINGS AT HSV
AND MSL IN THE SHORT TERM PORTION OF THE FORECAST. HAVE KEPT IN A
TEMPO MVFR CEILING/VISIBILITY AT MSL FROM 21Z-01Z AND FROM 22Z-01Z
AT HSV. FROM 02Z-09Z WILL CONTINUE WITH HIGH END MVFR TO LOW END IFR
CEILINGS AT HSV AND MSL. EXPECT THAT LOWERING CEILINGS WILL BEGIN TO
OCCUR BY 09Z AT HSV AND MSL AND HAVE GONE PREDOMINANT WITH A MVFR
CEILING AROUND 2KFT THROUGH THE REST OF THE FORECAST. EXPECT TEMPO
5SM TSRA TO PREDOMINANT 5SM TSRA THROUGH THE REST OF THE FORECAST AT
HSV AND MSL.

TT

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    64  76  56  72 /  40  80  50  20
SHOALS        64  76  54  72 /  40  80  40  10
VINEMONT      62  75  54  71 /  40  80  60  20
FAYETTEVILLE  63  74  54  70 /  40  80  50  20
ALBERTVILLE   62  76  56  71 /  50  80  70  20
FORT PAYNE    60  76  56  71 /  50  80  70  30

&&

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

$$

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



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