Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 020220
AFDHUN

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
918 PM CDT SAT AUG 1 2015

.UPDATE...
NO CHANGES.

&&

.DISCUSSION...
AT 915 PM TEMPS WERE RANGING FROM THE LOWER 80S OVER NWRN AL TO THE
LOW 70S IN NERN AL. DEWPOINTS WERE MAINLY IN THE LOW TO MID 60S. STLT
SHOWS A FEW CI CLOUDS...CAUGHT UP IN NW FLOW...WILL MOVE ACROSS
PORTIONS OF THE TN VALLEY OVERNIGHT. AT THE SFC A LARGE AREA OF HIGH
PRESSURE COVERS THE REGION. SINCE THE 00Z U/A SOUNDING FROM OHX/BMX
ARE FAIRLY DRY...NOT EXPECTING ANY PCPN OR DENSE FOG OVERNIGHT.
OTHERWISE SEE NO REASON TO MAKE ANY CHANGES TO THE CURRENT FCST ATTM.

007

&&

.AVIATION...
/ISSUED 625 PM CDT SAT AUG 1 2015/
FOR 00Z TAFS...WITH HIGH PRESSURE AT THE SFC WELL ENTRENCHED ACROSS
THE REGION...VFR CONDS ARE XPCTED THROUGH THE FORECAST PERIOD. SOME
HIGH CLOUDS MAY WORK THEIR WAY SEWD INTO N CNTRL AL LATER THIS
EVENING...BEFORE DIMINISHING EARLY SUN.

09

&&

.PREV DISCUSSION...
/ISSUED 352 PM CDT SAT AUG 1 2015/
AN EXPANSIVE RIDGE CENTERED OVER THE SOUTHERN HIGH
PLAINS WILL REMAIN NEARLY STATIONARY OVER THE NEXT SEVEN DAYS. THE
RIDGE WILL EXPAND EASTWARD BRIEFLY INTO EARLY NEXT WEEK WITH TEMPS
GENERALLY INCREASING FOR THE TN VALLEY. THEN...AS HAS BEEN THE CASE
PERIODICALLY THIS SUMMER...A POTENTIAL TRAIN OF SHORT WAVE TROUGHS
WILL MOVE ACROSS THE REGION...BRINGING CHANCES FOR SHOWERS/STORMS
BEGINNING WEDNESDAY. NO SIGNIFICANT CHANGES WERE MADE TO THE
PREVIOUS FORECAST. HOWEVER...AFTERNOON HIGH TEMPS WERE GENERALLY
RAISED AND OVERNIGHT LOWS DECREASED A LITTLE OVER THE NEXT FEW DAYS
TO ACCOUNT FOR THE DRY AIRMASS WHICH IS EXPECTED TO LINGER INTO EARLY
NEXT WEEK.

TRANQUIL WEATHER CONDITIONS ARE LIKELY OVER THE NEXT SEVERAL DAYS AS
GENERALLY SUBSIDENT AND DIFFLUENT LOW-LVL FLOW CONTINUE ACROSS MUCH
OF THE TN VALLEY REGION. FOR TONIGHT...THE FEW CLOUDS THAT HAVE
MANGED TO FORM TODAY WILL BEGIN TO DISSIPATE AS THE BOUNDARY LAYER
SETTLES. WINDS THAT HAVE BEEN AROUND 10-15 MPH WITH HIGHER GUSTS
WILL ALSO RELAX AS MIXING RAPIDLY DECREASES. DUE TO THE LOW DEW
POINTS IN THE AREA...FOG DEVELOPMENT TONIGHT (AS LAST NIGHT) IS
UNLIKELY. THE ONLY LOCATIONS PERHAPS SUSCEPTIBLE WOULD BE THE PAINT
ROCK VALLEY WHERE EFFICIENT COOL AIR DRAINAGE AND SLIGHTLY HIGHER
SOIL MOISTURE VALUES COULD LEAD TO SOME SHALLOW GROUND FOG. NONE WAS
ADDED TO THE FORECAST FOR NOW THOUGH. OTHERWISE...THE MAIN FORECAST
CONCERN OVER THE NEXT FEW DAYS WILL BE THE HOT TEMPERATURES. AS A
LOW/MID LEVEL RIDGE EXPANDS AND CROSSES THE AREA BY
TUESDAY...TEMPERATURES WILL GRADUALLY TREND HIGHER. THE HOTTEST DAYS
FOR THE PERIOD ARE LIKELY TO BE ON MONDAY AND/OR TUESDAY WHEN VALUES
REACH THE MID TO UPPER 90S ACROSS A GOOD PORTION OF THE AREA. A 100F
TEMPERATURE WOULD NOT BE TOO SURPRISING IN A FEW OF OUR NORMALLY
HOTTER LOCATIONS BY TUESDAY. HUMIDITY VALUES WILL BE LOW AGAIN ON
SUNDAY AND MONDAY...BUT WILL BEGIN TO CLIMB BY TUESDAY AS WINDS
SHIFT FROM THE SOUTH-WEST AND BRING HIGHER LOW-LVL MOISTURE BACK
INTO THE REGION. CURRENT FORECAST HEAT INDICES FOR TUESDAY REACH
JUST OVER 100F IN A FEW SPOTS WHICH IS BELOW HEAT ADVISORY CRITERIA.
HOWEVER...ANY UPWARD ADJUSTMENTS IN TEMPS OR DEW POINTS MAY
NECESSITATE A HEAT ADVISORY FOR TUESDAY (WHICH WOULD BE THE MOST
LIKELY DAY DURING THE FORECAST PERIOD).

A SHORT WAVE TROUGH WILL ROUND THE NORTHERN FLANK OF THE SOUTHERN
RIDGE BY TUESDAY AND BEGIN TO ENTER THE TN VALLEY LATE TUESDAY OR ON
WEDNESDAY. FOR NOW...POPS/WX WERE KEPT OUT OF THE FORECAST FOR
TUESDAY NIGHT AND RETAINED FOR WED WITH TIMING TO BE REFINED OVER THE
NEXT FEW DAYS. ANYWAY...THE VORT MAX WILL LARGELY PASS JUST TO OUR
NORTH ACROSS TN/KY. HOWEVER...CONVECTION AND ASSOCIATED COLD POOLS
WILL INTERACT WITH A VERY WARM AND INCREASINGLY HUMID AIRMASS TO
GENERATE DOWNSTREAM SHOWERS/STORMS IN OUR AREA LIKELY ON WED. GFS
BUFR SOUNDINGS MODIFIED WITH MODEL-BLENDED BOUNDARY LYR DEW POINTS
YIELDS ARND 1500-2000 J/KG OF SBCAPE WED AFTERNOON. SHEAR IS WEAK
HOWEVER WITH GENERALLY 30-35 KTS OR LOWER FLOW THROUGHOUT THE ENTIRE
TROP COLUMN. FLOW IS ALSO UNIDIRECTIONAL. NEVERTHELESS...DRY MID-LVL
AIR AND STEEP LOW-LVL LAPSE RATES SUGGEST A STRONG WIND GUST THREAT
WITH ANY STRONGER STORM CELLS. AS ELUDED TO ABOVE...A TRAIN OF SHORT
WAVES EMBEDDED IN THE NWRLY UPR-LVL FLOW WILL BRING PERHAPS REPEATED
BOUTS OF SHOWERS/STORMS TO THE AREA FOR THURSDAY AND FRIDAY. TIMING
IS STILL QUITE DIFFICULT WITH THESE FEATURES...BUT AFTERNOON/EVENING
PERIODS WOULD GENERALLY BE MORE FAVORED GIVEN BOUNDARY LAYER HEATING
CONSIDERATIONS. SHEAR MAY INCREASE BY LATE IN THE WEEK...BUT SHOULD
STILL BE FAIRLY WEAK FOR SIGNIFICANT STORM ORGANIZATION. GIVEN
THERMODYNAMIC PROFILES....STRONG WIND GUSTS WOULD CONTINUE TO BE THE
MAIN THREAT WITH STORMS DURING THE PERIOD.

KDW

&&

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

$$

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



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