Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 242350
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
650 PM CDT SUN MAY 24 2015

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 225 PM CDT SUN MAY 24 2015/
WATER VAPOR IMAGERY AND RAP H5 ANALYSIS INDICATED A DEPARTING UPPER
RIDGE SHIFTING EASTWARD OFF THE FL COAST, WITH A RATHER EXPANSIVE
UPPER LOW CHURNING OVER THE INTERMOUNTAIN WEST. BETWEEN THESE
FEATURES WAS A LARGE PLUME OF MOISTURE EXTENDING NORTHWARD FROM THE
WRN GOMEX AS FAR NORTH AS THE HIGH PLAINS. SEVERAL SHORTWAVES WERE
EMBEDDED IN THIS SSW/NNE FLOW ACROSS THE MIDDLE OF THE COUNTRY, WHICH
IS SLOWLY MAKING ITS WAY EASTWARD THIS AFTERNOON. AT THE SFC, HIGH
PRESSURE REMAINED ANCHORED OVER THE CAROLINAS, WITH ANOTHER
DEVELOPING SFC LOW OVER THE CENTRAL PLAINS. CONVECTION IS FIRING UP
TO OUR SW ALONG/AHEAD OF THE APPROACHING SHORTWAVE, IN CONJUNCTION
WITH A BOUNDARY SPRAWLED SE TO NW ACROSS SRN AL/MS AT H85. THIS
ACTIVITY WILL GRADUALLY SHIFT NORTHWARD THROUGH THE AFTERNOON/
EVENING, WITH MOISTURE AND LOW/MID-LEVEL FLOW INCREASING THROUGH THE
NIGHT. AS SUCH, MORNING LOWS/DEWPOINTS WILL BE SEVERAL DEGREES
HIGHER OVER NW AL AS COMPARED TO THE DRIER CONDITIONS EXPECTED IN NE
AL (UPPER 60S/70 VS LOWER/MIDDLE 60S).

THE SHORTWAVE CURRENTLY TO OUR WEST TO MAKE ITS ARRIVAL IN THE TN
VALLEY TOMORROW, WITH SEVERAL ROUNDS OF SHOWERS AND STORMS EXPECTED
THROUGH THE DAY. THIS THINKING HASN`T CHANGED MUCH WITH THE PAST FEW
MODEL RUNS OVER RECENT DAYS. GENERALLY, GUSTY WINDS TO 30-40MPH AND
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE IN ANY STRONGER STORMS, WITH
PWATS APPROACHING 1.75". HIGHS WILL TOP OUT AROUND 80 DEGREES, WITH
MANY LOCATIONS A COUPLE OF DEGREES LESS IN NW AL DUE TO REDUCED
INSOLATION EXPECTED THERE.

TWO ADDITIONAL SHORTWAVES ARE EXPECTED TUESDAY, ONE DURING THE EARLY
MORNING TO START THE DAY, AND A MORE ROBUST ONE WILL ARRIVE BY
TUESDAY AFTERNOON. THE GREATER THREAT FOR SEVERE STORMS WILL EXIST
TUESDAY AFTERNOON, WITH DAMAGING WINDS IN EXCESS OF 60MPH THE PRIMARY
THREAT. LOCALLY HEAVY RAINFALL WILL STILL BE A THREAT (AGAIN, WITH
PWATS APPROACHING/EXCEEDING 1.75" AND DIVERGENT FLOW ALOFT). TRAINING
OF CELLS WILL ENHANCE THE RISK FOR FLASH FLOODING AS WELL DURING
THIS TIME FRAME. WE`RE CURRENTLY INCLUDED IN A DAY 3 SLIGHT RISK FROM
SPC, AND AS SUCH, THESE RISKS HAVE BEEN ADVERTISED IN THE HWO.

A RATHER UNSETTLED PATTERN WILL EXIST FOR THE REST OF THE WEEK,
REALLY, WITH SEVERAL SHORTWAVES TRAVERSING THE AREA DURING THIS TIME.
WEDNESDAY AFTERNOON/EVENING MAY BE THE DRIEST OF THE FORECAST PERIOD,
WITH ONE SHORTWAVE DEPARTING AND ANOTHER WEAK BOUNDARY APPROACHING
FROM THE NW. BOTH THE GFS/ECMWF HAVE THIS FEATURE WASHING OUT SW TO
NE ACROSS THE AREA TO END THE WEEK, WITH SEVERAL ROUNDS OF SHOWERS
AND STORMS EXPECTED TO PUSH ACROSS THE CWFA DURING THIS TIME. GIVEN
THIS THINKING, TEMPS WERE ADJUSTED DOWNWARD FROM PREVIOUS THINKING
(WITH A MUCH WETTER SOLUTION LOOKING LIKELY TO PLAY OUT). IF BOTH
MODELS ARE CORRECT FOR EARLY NEXT WEEK, AN UPPER LOW WILL WOBBLE
SOUTHEASTWARD FROM THE CENTRAL PLAINS AND BECOME PSEUDO-CUTOFF,
KEEPING A WETTER PATTERN IN PLACE ACROSS THE SOUTHEAST AS WE HEAD
INTO THE NEW WORK WEEK. FOR NOW, WILL ONLY INCREASE CLOUD COVER AND
ADJUST POPS UPWARD PENDING FURTHER MODEL RUNS/AGREEMENT.

12

&&

.AVIATION...
FOR 00Z TAFS...AN UPPER DISTURBANCE MOVING ACROSS PORTIONS OF SRN MS
RVR VALLEY WAS PRODUCING SCT SHRA WITH A FEW EMBEDDED TSRA ACROSS
NRN AL ATTM. THUS EXPECT MAINLY SCT SHRA WITH AN OCCASIONAL TSRA THRU
02Z AT BOTH TAF SITES. AFTER 02Z THE SHRA ACTIVITY WILL BEGIN TO
TAPER OFF. MORE SHRA AND TSRA WILL BE POSSIBLE MONDAY AFTN AS AN UPPER
TROF EDGES CLOSER TO THE TN VALLEY. MAINLY VFR CONDITIONS ARE
EXPECTED THRU 11Z. A PERIOD OF MVFR CONDITIONS ARE POSSIBLE BETWEEN
11Z AND 19Z...AFTER 19Z VFR CONDITONS ARE EXPECTED (EXCEPT MVFR IN
TSRA).

07

&&

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

$$

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


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