503 FXUS64 KHUN 011558 AAA AFDHUN AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HUNTSVILLE AL ISSUED BY NATIONAL WEATHER SERVICE JACKSON MS 1058 AM CDT WED AUG 1 2012 .DISCUSSION...MORNING STRATUS HAS CLEARED IN MOST LOCATIONS AND TEMPERATURES HAVE WARMED INTO THE UPPER 80S ACROSS THE AREA. AS THE TENNESSEE VALLEY REMAINS ON THE EASTER PERIPHERY OF THE UPPER RIDGE...LOW LEVEL TEMPERATURES WILL BE WARM ALLOWING FOR ANOTHER HOT DAY WITH HIGHS IN THE UPPER 90S...NEAR AROUND 100. ENOUGH LOW LEVEL MOISTURE SHOULD LINGER AND THIS WILL ALLOW HEAT INDICES TO REACH 105 OR GREATER FOR WESTERN COUNTIES. THE GOING HEAT ADVISORY THROUGH THIS EVENING LOOKS GOOD AND NO ADJUSTMENTS NEEDED. AFTERNOON SHOWERS AND THUNDERSTORMS LOOK POSSIBLE GIVEN A WEAK SHORTWAVE MOVING ACROSS PORTIONS OF THE REGION. MADE SOME MINOR UPDATES TO ACCOUNT FOR CURRENT TRENDS BUT OTHERWISE THE GOING FORECAST IS IN GOOD SHAPE. /28/ && .AVIATION... FOR 18Z TAFS...LOW CLOUDS AND FOG HAVE MOSTLY DISSIPATED WITH ONLY A FEW AREAS LINGERING...INCLUDING FEW015 AT KHSV. THIS SHOULD CONTINUE TO IMPROVE TO VFR CONDITIONS OVER THE NEXT FEW HOURS. ISOLATED TSRA POSSIBLE THIS AFTERNOON BUT CONFIDENCE IN AFFECTING A SPECIFIC SITE TOO LOW TO INCLUDE AT THIS TIME. MVFR CONDTIONS ONCE AGAIN POSSIBLE TOMORROW BY 10Z. /28/ && .PREV DISCUSSION... /ISSUED 440 AM CDT WED AUG 1 2012/ MUCH QUIETER CONDITIONS PREVAIL THIS MORNING ACROSS THE TN VALLEY... THOUGH THINGS ARE NOT COMPLETELY DRY. A SHORTWAVE/MCV RESPONSIBLE FOR SOME ISLTD SEVERE CONVECTION OVER ERN IL/WRN IN HAS GENERATED A FEW ROGUE STORMS ACROSS MID TN...BUT THESE HAVE HAD LIMITED SUCCESS MOVING INTO THE HUN CWFA. 11-3.9 MICRON IMAGERY SHOWS LOW CLOUDS/FOG ACROSS THE ERN HALF OF THE AREA...WHICH IS SUPPORTED BY THE 1-3 MILE VIS AND 500-1000 FT CEILING REPORTS FROM AREA ASOS/AWOS SITES. CONDITIONS ARE NEARLY IDEAL FOR FOG FORMATION WITH SUCH HIGH SURFACE MOISTURE...NEARLY CLEAR SKIES AND LT/VAR WINDS. VIS REPORTS ARE NOT LOW ENOUGH TO WARRANT AN ADVISORY ATTM BUT THEY HAVE BEEN GENERALLY TRENDING DOWN FOR MUCH OF THE MORNING. THE OTHER CONCERN FOR TODAY IS THE HEAT...AS SHORTWAVE RIDGING ROUNDS THE ERN FLANK OF THE UPPER HIGH PERPETUALLY CENTERED OVER WRN TX AND LOW-LVL TEMPS HEAT UP. ASSUMING THE STRATUS BREAKS UP IN A TIMELY MANNER... UPPER 90S APPEAR ATTAINABLE FOR A LARGE PART OF THE AREA. A FEW 100S ARE POSSIBLE...BUT TODAY IT WILL BE MORE THE HUMIDITY THAN THE HEAT. LOW-LVL MOISTURE WILL EVENTUALLY MIX OUT BUT HEAT INDICES SHOULD STILL BE ABLE TO GET TO 105+ OVER PARTS OF NW AL...WITH 100-105 COMMON ELSEWHERE. THUS WILL BE ISSUING A HEAT ADVISORY FOR THE SHOALS AREA THIS AFTN. OTHERWISE...A WEAK SHORTWAVE TRACKING NE OF THE AREA THIS AFTN AND TONIGHT WILL HELP SPARK OFF A FEW SHOWERS AND STORMS. MID-LVL DRYING NOTED ON GOES WATER VAPOR IMAGERY...COMBINED WITH STEEP LOW-LVL LAPSE RATES...MAY BE SUPPORTIVE OF MICROBURSTS WITHIN ANY STORMS THAT DO GET GOING. THE THEME FOR THE REST OF THE FCST PERIOD IS SUMMED UP IN TWO WORDS: NORTHWEST FLOW. THE UPPER HIGH CENTERED OVER NM/TX/OK WILL MOVE VERY LITTLE OVER THE ENTIRE 7 DAY PERIOD. MED-RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SUGGESTING A RELATIVELY ACTIVE WEEKEND. A MORE ROBUST SHORTWAVE WILL IMPACT THE AREA FRIDAY. WHILE SUBTLE RIDGING IS EXPECTED TO BRIEFLY BUILD EWD FOR THE WEEKEND...IT WILL BE SHORT- LIVED AS A DEEP TROUGH OVER THE GREAT LAKES HELPS DRIVE ANOTHER WEAK FRONT INTO THE AREA SUNDAY AND MONDAY. NOTHING JUMPS OUT IN TERMS OF SEVERE POTENTIAL...BUT IT WILL BE A PERSISTENT ISSUE WITH THE ADDITIONAL FORCING AND TYPICAL HEAT/HUMIDITY. FLASH FLOODING MAY EVENTUALLY BECOME AN ISSUE IF BOUNDARIES PERSISTENTLY FOCUS STORMS OVER THE SAME AREAS...PARTICULARLY WITH 2+ INCH PRECIP WATER VALUES FOR MUCH OF THE WEEKEND. THIS FAVORS A SOMEWHAT COOLER /GENERALLY NO MORE THAN 5 DEGREES ABOVE NORMAL/ BUT MORE HUMID PATTERN ONCE WE GET PAST TODAY'S HEAT CONCERNS. HIGH TEMPS THRU THE EXTENDED SHOULD STAY IN THE LOW-MID 90S BUT LOWS WILL BE CONSISTENTLY IN THE LOW-MID 70S. THE GFSX MOS HAS GOOD SUPPORT FROM THE ECMWF AND ENSEMBLES AND IS ACCEPTABLE. BCC && .HUN WATCHES/WARNINGS/ADVISORIES... AL...HEAT ADVISORY UNTIL 6 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: ALZ001>004. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.