Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 220520
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1220 AM CDT FRI AUG 22 2014

.UPDATE...
FOR 06Z TAFS

&&

.DISCUSSION...
/ISSUED 919 PM CDT THU AUG 21 2014/

A SFC HIGH PRESSURE SYSTEM AND ACCOMPANYING UPPER RIDGE IS BUILDING
NORTHWARD FROM THE GULF OF MEXICO. AS A RESULT, SHOWERS AND
THUNDERSTORMS THAT HAD BEEN LINGERING EARLIER THIS AFTERNOON HAVE ALL
DISSIPATED AND HAVE REMOVED MENTION OF THUNDERSTORMS FROM THE
FORECAST TONIGHT. TEMPERATURES HAVE GENERALLY COOLED OFF INTO THE
UPPER 70S TO LOW 80S WITH DEWPOINTS HOLDING OR RISING INTO THE LOW
70S. AS A RESULT, DEWPOINT DEPRESSIONS LOOK TO BE LOW ENOUGH TO
SUPPORT PATCHY FOG DEVELOPMENT TONIGHT MAINLY ALONG
RIVERS...LAKES...AND VALLEYS.

DEWPOINTS LOOKED TO BE UNDERDONE FOR TOMORROW ESPECIALLY WITH NEW
MODEL GUIDANCE SHOWING LOW 70S DURING PEAK HEATING. THE MAIN
REASONING IS THAT WITH SFC RIDGING AND LITTLE IN THE WAY OF MOMENTUM
MIXING, THERE SHOULD NOT BE MUCH IN THE WAY OF DRY AIR MIXING DOWN.
IN FACT, BY 15-18Z, IF ANYTHING MOISTURE ADVECTION FROM THE MS RIVER
DELTA REGION MAY ACTUALLY KEEP DEWPOINTS IN THE LOW 70S AS WELL. THUS,
WITH THE ADJUSTMENTS MADE TO THE DEWPOINTS BASED OFF THE MODEL
GUIDANCE AND VERY SLIGHT ADJUSTMENTS TO ONGOING DAYTIME HIGHS
TOMORROW, HEAT INDEX VALUES SHOULD RISE BETWEEN 100-107 DEGREES.

THE HOTTEST PORTIONS OF THE AREA ARE FORECAST TO BE FROM THE
INTERSTATE 65/565 CORRIDOR WESTWARD INCLUDING MADISON, LIMESTONE,
CULLMAN, MORGAN, LAWRENCE, LAUDERDALE, COLBERT, AND FRANKLIN COUNTIES
IN ALABAMA. THESE AREAS WILL LIKELY EXPERIENCE HEAT INDEX VALUES
BETWEEN 104-107. THUS, HAVE ISSUED A HEAT ADVISORY FOR THOSE AREAS IN
EFFECT TOMORROW AFTERNOON FROM 11AM-7PM CDT.

SL.77

&&

.AVIATION...
FOR 06Z TAFS...

VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS N AL/S MIDDLE TN FOR
THE NEXT 24 HOURS. FOG FORMATION IS POSSIBLE NEAR RIVERS, VALLEYS,
AND LAKES OF N AL/S MIDDLE TN THAT WILL ACT TO LOWER VIS CLOSE TO
MVFR BTWN 09-13Z ESPECIALLY NEAR KMSL.

SL.77

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...HEAT ADVISORY FROM 11 AM TO 7 PM CDT FRIDAY FOR ALZ001>007-016.

TN...NONE.
&&

$$

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



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