Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 231921
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
221 PM CDT SAT AUG 23 2014

.DISCUSSION...
ANOTHER HOT AND HUMID DAY IS UNDERWAY ACROSS THE TENNESSEE VALLEY,
WITH AFTERNOON TEMPS IN THE LOWER/MIDDLE 90S, DEWPOINTS IN THE LOWER
70S, AND HEAT INDEX VALUES CURRENTLY BETWEEN 100-105 DEGREES AS OF
2PM. AN H5 RIDGE IS PARKED JUST NORTHWEST OF THE ARKLAMISS THIS
AFTN, WITH THE SFC HIGH ANALYZED IN WEST CENTRAL MS. MOSTLY SUNNY
CONDITIONS PREVAIL ACROSS MUCH OF THE CWFA AS A RESULT, WITH THE
EXCEPTION OF OUR EASTERN ZONES. A SHORTWAVE ROTATING AROUND THE ERN
FLANK OF THE UPPER RIDGE HAS DROPPED SOUTH/SOUTHWEST FROM KY THIS
MORNING, WITH CONVECTION NOW FIRING UP TO THE E/NE OF KHTX.
ADDITIONAL SHOWERS AND STORMS ARE ALSO DEVELOPING TO THE WEST OF
NASHVILLE THIS AFTN, AND SHORT TERM MODELS ARE HANDLING THIS
DEVELOPMENT FAIRLY WELL. GUIDANCE SHOWS LESSER CONVECTION WEST/MORE
CONVECTION EAST, AND GIVEN RECENT RADAR TRENDS, HAVE OPTED TO
INCREASE POPS FOR THE REST OF THE AFTN (AND THROUGH MIDNIGHT). IN
ADDITION, CONVECTION IN THE EASTERN-MOST COUNTIES HAS FALLEN BELOW
CRITERIA, SO HAVE FORMALLY REMOVED JACKSON, DEKALB, MARSHALL IN AL,
AND FRANKLIN COUNTY TN.

THE FORECAST FOR TONIGHT ISN`T MUCH DIFFERENT THAN LAST NIGHT.
CONVECTION WILL EVENTUALLY FIZZLE OUT WITH THE LOSS OF DAYTIME
HEATING, THOUGH AN ISOLATED SHOWER/STORM CAN`T BE RULED OUT OVERNIGHT
WITH THE SHORTWAVE TRAVERSING THE AREA TO THE SW. PATCHY FOG WAS
INTRODUCED TO THE FCST TONIGHT, MAINLY CONFINED TO THE DEKALB VALLEY
IN NE AL, AS WELL AS ALONG THE TN RIVER.

OTHERWISE, MODELS ARE STILL IN GOOD AGREEMENT REGARDING A BACKDOOR
FRONT ARRIVING TOMORROW; THE ONLY DISCREPANCY BETWEEN THE MODELS IS
EXACTLY HOW MUCH CONVECTION WILL ACCOMPANY THIS FROPA. THIS FRONT IS
CURRENTLY ANALYZED OVER THE CAROLINAS THIS AFTN, AND WILL SLOWLY
ADVANCE WESTWARD THROUGH THE DAY TOMORROW. GIVEN THE AMPLE MOISTURE
IN PLACE, AND TRENDS OVER RECENT DAYS, HAVE OPTED TO INCREASE POPS
TOMORROW, ESPECIALLY ACROSS NE AL, BUT LATER SHIFTS MAY NEED TO
INCREASE THEM EVEN MORE DEPENDING ON MODEL TRENDS OVERNIGHT. DUE TO
THE INCREASED COVERAGE OF SHOWERS/STORMS ACROSS THE AREA TOMORROW,
WILL NOT BE ISSUING A HEAT ADVISORY FOR ANY PORTIONS OF THE CWFA. THE
ONLY LOCATIONS THAT *MAY* FLIRT WITH ADVISORY CRITERIA (105 DEGREES)
WOULD BE EXTREME NORTHWESTERN AL (WHERE CONVECTION WILL BE FEW/FAR
BETWEEN, ALLOWING FOR GREATER INSOLATION IN THESE LOCATIONS).

DRIER AIR WILL FILTER INTO THE AREA FROM THE EAST FOR THE MIDDLE OF
THE WEEK, WITH MORE COMFORTABLE CONDITIONS EXPECTED. AFTN HIGHS IN
THE MIDDLE TO UPPER 80S AND MORNING LOWS IN THE 60S ARE FORECAST
THROUGH WEDNESDAY, WITH A GRADUAL WARMING TREND EXPECTED THROUGH LATE
THIS WEEK. AT THIS TIME, THE TROPICAL SYSTEM OFF THE COAST OF FL WILL
BE GETTING ITS ACT TOGETHER AS IT TRAVELS UP THE EAST COAST. DURING
THE SAME TIME FRAME, BOTH THE GFS/ECMWF SHOW A COLD FRONT
APPROACHING OUR AREA FROM THE NW AS AN UPPER LOW DEVELOPS OVER THE
CENTRAL PLAINS AND HEADS NE TOWARD THE GREAT LAKES/NORTHEAST. THIS
WILL DRAG THE FRONT TOWARD THE AREA ON FRIDAY (GFS) OR SATURDAY
(ECMWF), SO WILL RETAIN THE CURRENT FORECAST DURING THIS TIME PERIOD
TO ACCOUNT FOR THE TIMING DISCREPANCY.

12

&&

.AVIATION...
/ISSUED 1252 PM CDT SAT AUG 23 2014/
FOR 18Z TAFS...
STRONG DAYTIME HEATING HAS RESULTED IN CUMULUS FORMING ACROSS THE
AREA. THERE IS A RISK OF ISOLATED SHOWER/T-STORM DEVELOPMENT THIS
AFTERNOON/EARLY EVENING...AS A WEAK BOUNDARY PUSHES TO THE SOUTH...
ESPECIALLY EAST OF I-65. SOMEWHAT DEEPER MOISTURE AND LONGER NIGHTS
UNDER MOSTLY CLEAR SKIES COULD LEAD TO PATCHY FOG FORMING BEFORE
DAYBREAK...MAINLY AT KMSL. TEMPO IFR VIS VALUES ARE POSSIBLE AT
KMSL EARLY SUN MORNING. VFR CONDITIONS SHOULD RETURN A FEW HOURS
AFTER DAYBREAK.

RSB

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    73  94  73  89 /  30  40  30  30
SHOALS        74  96  74  90 /  20  30  20  40
VINEMONT      73  94  72  89 /  20  40  30  30
FAYETTEVILLE  72  92  72  87 /  30  40  30  30
ALBERTVILLE   76  94  71  88 /  30  50  30  30
FORT PAYNE    73  93  71  89 /  30  60  30  30

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR ALZ001>007-016.

TN...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR TNZ076-096.

&&

$$

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



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