354 FXUS64 KHUN 010207 AAB AFDHUN AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HUNTSVILLE AL 907 PM CDT TUE APR 30 2013 .UPDATE... ADDED MOSTLY CLOUDY SKY COVER PERCENTAGE TO FORECAST GRIDS. && .DISCUSSION... A FAN OF HIGH CS/CI (UAH CEILOMETER INDICATING 30-40KFT) WAS ARCHING ANTI-CYCLONICALLY FROM THE MCS IN THE CENTRAL GULF THRU THE SHORTWAVE RIDGE POSN IN THE SE. THIS HAS KEPT A BKN OPAQUE SKY CONDITION IN PLACE THIS EVENING, SO HAVE ADJUSTED SKY GRIDS ACCORDINGLY. TEMPS ARE DECLINING AS FORECAST INTO THE 60S THIS EVENING, WITH NO CHGS NEEDED. THE THREAT OF BR/FG APPEARS TO BE MORE LIMITED DUE TO THE CI CANOPY IN PLACE. AK && .AVIATION... /ISSUED 541 PM CDT TUE APR 30 2013/ FOR 00Z TAFS... VFR CONDITIONS WILL PREVAIL MOST OF THIS PERIOD, WITH THE EXCEPTION OF SOME BRIEF LIGHT BR (MVFR) BETWEEN 10-13Z. SOUTHEASTERLY WINDS WILL INCREASE RAPIDLY WED MORNING WITH SUSTAINED WINDS ~15KT AND GUSTS ~22KT. AK && .PREV DISCUSSION... /ISSUED 300 PM CDT TUE APR 30 2013/ WENT WITH A BLEND OF NAM/GFS/ECMWF FOR THIS FCST...BUT WILL LEAN A LITTLE MORE TOWARDS THE GFS. MODELS ARE IN A LITTLE BETTER AGREEMENT WITH UPPER LOW TRACK FOR THIS FCST PERIOD. ATTM THE SVR WX THREAT LOOKS LOW THRU THE ENTIRE FCST PERIOD. WITH SCT CU ACROSS THE TN VALLEY...TEMPS WERE WERE IN THE MID/UPPER 70S WITH DEWPOINTS IN THE LOWER 50S. AT 5H THERE IS SHORT WAVE OVER THE SRN MS RIVER VALLEY WHILE A RIDGE EXTENDED ALONG THE ERN HALF OF THE COUNTRY. TONIGHT...THE SHORT WAVE OVER THE SRN MS RIVER VALLEY WILL CONTINUE TO SLOWLY MOVE EAST...INCREASING CLOUDS LATE TONIGHT ACROSS THE CWA. THERE SHOULD BE ENOUGH INFLUENCE FROM RIDGING TO KEEP THE CHC OF PCPN OUT OF THE FCST. WEDNESDAY...THERE SHOULD BE ENOUGH SUBSIDENCE ACROSS THE CWA TO KEEP ONLY A LOW POP OF SHRA AND A FEW TSRA ACROSS THE CWA...WITH THE BEST CHC OVER OUR SWRN ZONES. WILL KEEP WEDNESDAY NIGHT DRY FOR NOW SINCE MODELS ARE NOT PRINTING OUT ANY PCPN DUE TO THE INFLUENCE OF RIDGING. THURSDAY...MAY HAVE A LITTLE HIGHER CHC OF SHRA/TSRA...AS THE RIDGE ALONG THE EAST COAST WEAKENS. WILL CONTINUE THE HIGHER POPS IN OUR SWRN ZONES WITH THE LOWER POPS IN THE NERN ZONES. THE PREVIOUSLY MENTIONED SHORT WAVE WILL BEGIN TO MERGE/PHASE WITH A DEVELOPING UPPER LOW OVER THE MIDWEST BY LATE IN THE PERIOD ON THURSDAY. FRIDAY THRU SUNDAY...BY FRIDAY AFTN THE CENTER OF THE CLOSE UPPER LOW WILL BE OVER OK ACCORDING TO THE GFS WITH ECMWF PLACING THE LOW IN ERN KS. SATURDAY MRNG GFS/ECMWF ARE STILL IN PRETTY GOOD AGREEMENT WITH THE UPPER LOW...SOMEWHERE OVER SW MO OR NW AR. AHEAD OF THE LOW WILL BE A BAND MOISTURE THAT WILL KEEP THE TN VALLEY IN A GOOD CHC OF SHRA AND A FEW TSRA. ATTM THINKING THE BEST CHC OF PCPN WILL BE FRIDAY NIGHT AND SATURDAY MRNG. THE GFS AND ECMWF BEGINS TO DIVERGE A LITTLE BY SUNDAY...WITH THE ECMWF TAKING THE UPPER LOW NORTH INTO THE UPPER MIDWEST AND THE GFS KEEPS IT MORE SOUTH...OVER THE STL AREA. MAY SEE A BREAK IN THE PCPN ON SUNDAY BUT WILL PLAY IT SAFE FOR NOW AND KEEP A LOW POP IN FOR SHRA ONLY. MONDAY/TUESDAY...DEPENDING ON WHICH MODEL IS CORRECT THIS PERIOD MAY BE DRY...BUT WITH MODEL UNCERTAINTY WILL KEEP A LOW POP IN FOR SHRA AND A FEW STORMS. 07 && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT WEATHER.GOV/HUNTSVILLE.