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000 FXUS62 KTAE 110821 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 250 AM EDT SAT OCT 11 2008 .SYNOPSIS... AT 2 AM EDT...FAIR SKIES DOMINATED THE FORECAST AREA. TEMPS RANGED FROM MID 60S NORTH TO AROUND 70 COAST. 24 HR TEMP/DEW POINT COMPARISON INDICATES THAT LOCAL AIRMASS SLIGHTLY WARMER AND WETTER THAN SAME TIME YESTERDAY. WINDS WERE GENERALLY NE AROUND 5 MPH. AT UPPER LEVELS... AMPLIFIED CONUS PATTERN TO CONTINUE HIGHLIGHTED BY A POSITIVELY TILTED TROF LOCATED ACROSS THE WRN CONUS AND A LARGE RIDGE BUILDING OVER ERN CONUS. TWO UPPER LOWS OF NOTE. STRONG LOW OVER GREAT BASIN TO DRIFT INTO CNTRL ROCKIES BY SUNDAY MORNING. CLOSER TO HOME... STACKED LOW DRIFTING EWD JUST OFF THE SC/GA COAST. MID LEVEL DRY AND STABLE AIR IS WRAPPING AROUND THIS LOW AND DOMINATING SE REGION. AS THE DEEP TROUGH AMPLIFIES OVER WRN CONUS AND RIDGE STRENGTHENS OVER THE ERN CONUS LATER TODAY...THE SC/GA LOW SEPARATES FROM MAIN FLOW AND BECOMES EMBEDDED IN THE EASTERLIES. THIS WILL FORCE IT TO RETROGRADE BENEATH RIDGE AND WWD ACROSS FL BEGINNING TODAY WITH A MINOR INCREASE IN PVA...MAINLY ERN ZONES. MODELS SHOW THAT LOW PROGGED TO SLOWLY FILL OVER THE NEXT 36 HRS...ENDING UP OVER THE ERN GOMEX BY SUNDAY EVENING AND WRN GULF ON WEDNESDAY. AT LOWER LEVELS... LOW LEVELS HIGHLIGHTED TODAY BY AN AREA OF HIGH PRESSURE MOVING FROM GREAT LAKES TO OVER NEW ENGLAND AND AN INVERTED TROF JUST OFF THE SOUTH CAROLINA COAST (AND JUST E OF H5 LOW) WITH NORTHEASTERLY FLOW DOMINATING THE SE REGION. AS UPPER RIDGE INTENSIFIES...SURFACE RIDGE OVER N ENGLAND WILL DROP S ALONG ERN SEABOARD THRU MONDAY. THIS WILL INDUCE THE TROUGH TO WEAKEN FURTHER AND SHIFT WSW UNDER RIDGE DURING THAT TIME. LOCALLY...THE COMBINATION OF THE SURFACE RIDGE SLIDING DOWN THE APPALACHIANS AND SWWD MOVING LOW WILL INCREASE LOW LEVEL CONVERGENCE AND GENERATE TIGHTER NE GRADIENTS MOST PRONOUNCED ON MONDAY. MOISTURE FIELD ALSO WRAPPING AROUND N SIDE OF LOW. LEADING EDGE OF SHOWERS/RAIN WILL MOVE SWWD INTO THE ERN ZONES SAT AFTERNOON THEN INCREASE IN COVERAGE ON SUN. THIS REFLECTED IN TIME HEIGHT X-SECTIONS AND MODEL SOUNDINGS. I.E. GFS TAE 1.18 PWAT AT 06Z SAT INCREASING TO 1.77 PWAT AT 00Z MON. ZFP WILL SHOW NE-SW POP AND WIND GRADIENT. AS STACKED LOW DECOUPLES...DEEP MOISTURE WILL BE LIMITED SO HEAVY RAIN NOT EXPECTED. MOSTLY CLOUDY SKIES WILL HELP TO KEEP TEMPERATURES CLOSE TO SEASONAL NORMS. HIGH PRESSURE WILL SHIFT S BY THE BEGINNING OF NEXT WEEK...WITH LIGHTER E FLOW AND DRIER CONDITIONS. .SHORT TERM (TODAY THROUGH MONDAY)... THIS MORNING...00Z KTAE SOUNDING CONTINUES TO SHOW A MOIST LOW LEVEL AROUND 890 MB WITH VERY DRY AIR NOTED ABOVE 815 MB. THE PRECIPITABLE WATER CAME IN AT 1.07. SREF PROBABILITIES FOR REDUCTION IN VISIBILITIES LESS THAN 3 MILES IS 30 TO 40 PERCENT WITH VALUES AROUND 25 PERCENT FOR CIGS LESS THAN 1500 FT. LATEST SATELLITE PIX SHOW FOG BEGINNING TO DEVELOP ALONG I-75 AND MOVING WWD. THINK WE WILL SEE AREAS OF FOG AND/OR STRATUS DEVELOP FURTHER TOWARDS SUNRISE...ESPECIALLY SE THIRD OF CWA. AND THIS REFLECTED IN GRIDS. REST OF TODAY...AFTER ANY LOW CLOUDS BURN OFF...DRY SINKING AIR ON WEST SIDE OF ABOVE LOW WILL ENCOURAGE SOME SUN. INLAND HIGHS IN LOW 80S. 0-30 PCT W-E POP GRADIENT WITH LIGHT RAIN. INCREASING BOUNDARY LAYER WINDS AND CLOUD COVER SHOULD HELP PRECLUDE WIDESPREAD FOG FROM FORMING TONIGHT AND KEEP INLAND LOWS IN MID 60S. SUNDAY...20-50 PCT W-E POP GRADIENT...ISOLD TSTMS POSSIBLE ESPECIALLY E HALF OF CWA. INLAND HIGHS IN FROM AROUND 80 N TO MID 80S S. E WINDS INCREASE TO MODERATE. MONDAY...20 PCT POPS ACROSS CWA. INLAND HIGHS IN LOW 80S. LOCALLY BREEZY EAST WINDS. .LONG TERM (TUESDAY THROUGH SATURDAY)...AFTER SEVERAL RUNS SHOWING GOOD AGREEMENT BETWEEN THE GFS AND 12 UTC ECMWF...THEIR LONG RANGE SOLUTIONS ARE BEGINNING TO DIVERGE. BOTH MODELS SHOW AN UPPER RIDGE HANGING ON OVER THE SE U.S ON TUESDAY. THE GFS THEN RETROGRADES THE HIGH TO THE WESTERN GULF BY THURSDAY WITH A ZONAL PATTERN DEVELOPING ACROSS MUCH OF THE CONUS WHICH STALLS A WEAK SURFACE FRONT WELL NORTH OF THE LOCAL REGION. THE UPPER RIDGE THEN BUILDS DURING THE REMAINDER OF THE PERIOD WITH AXIS THROUGH THE NATIONS MID SECTION WHICH INDUCES WEAK TROUGHING ALONG THE EASTERN U.S. THE ECMWF SOLUTION SHOWS THE UPPER RIDGE LINGERING OVER THE SE CORNER OF THE U.S WEDNESDAY. THE RIDGE THEN WEAKENS AND RETREATS TO THE EAST AS A DEEPENING TROUGH SWINGS FROM THE PLAINS ON THURSDAY AND OFF THE SE U.S COAST ON SATURDAY. AT THE SURFACE...THIS SENDS A COLD FRONT INTO AND ACROSS OUR CWA LATE FRIDAY/EARLY SATURDAY WITH A MUCH DRIER AIRMASS FILTERING IN ON SATURDAY. THE ECMWF SHOWS ONLY LIGHT QPF AMOUNTS WITH THIS FRONT. EITHER SOLUTION...TUESDAY THROUGH THURSDAY SHOULD BE DRY. THE ONLY DAYS IN QUESTION FOR POPS WILL BE FRIDAY AND SATURDAY. DUE TO THE UNCERTAINTY...WILL LEAVE OUT ANY MENTION OF POPS FOR NOW. TEMPS WILL CONTINUE TO BE ABOVE CLIMO WITH MAX READINGS GENERALLY IN THE MID TO UPPER 80S AND MIN TEMPS IN THE LOWER TO MID 60S. && .AVIATION...THE FOG PRODUCT (11U-3.9U SATELLITE IMAGERY) AND DOWNSTREAM METARS ARE SHOWING A BLANKET OF STRATUS RAPIDLY SPREADING INTO THE REGION FROM THE EAST. BY DAYBREAK...MOST OR ALL OF OUR TAF SITES SHOULD BE EXPERIENCING IFR/LIFR CIGS/VSBYS. LIKE YESTERDAY... IT MAY TAKE UNTIL LATE MORNING OR EARLY AFTERNOON FOR CONDITIONS TO IMPROVE TO VFR LEVELS. A FEW SHOWERS WILL DEVELOP IN THE AFTERNOON OVER NE FLORIDA AND SE GEORGIA AND MOVE WEST. SOME OF THIS ACTIVITY MAY REACH" onClick="return popup(this, 'notes')">REACH VLD IN THE EVENING. WENT WITH A PROB30 GROUP FOR SHOWERS AT VLD FROM 00Z TO 06Z TO COVER THIS POSSIBILITY. && .MARINE...GRADIENT WILL REMAIN WEAK THIS MORNING BEFORE SLOWLY TIGHTENING DURING THE DAY AS TROUGH OF LOW PRESSURE/INVERTED TROUGH SLIDES WEST AND HIGH PRESSURE BUILDS DOWN THE EAST SIDE OF APPALACHIANS. EXERCISE CAUTION CONDITIONS POSSIBLE BY TONIGHT WITH ADVISORY CONDITIONS BY LATE SUNDAY. THE TIGHT GRADIENT IS EXPECTED TO KEEP WINDS NEAR ADVISORY LEVELS THROUGH EARLY NEXT WEEK...ESPECIALLY OVER THE OFFSHORE LEGS. && .FIRE WEATHER...AMPLE LOW LEVEL MOISTURE WILL KEEP AFTERNOON RH VALUES ABOVE CRITICAL LEVELS THROUGH THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 82 67 83 68 / 10 20 40 20 PANAMA CITY 82 69 84 70 / 05 10 20 20 DOTHAN 80 65 79 65 / 10 20 30 20 ALBANY 79 66 80 67 / 20 30 50 20 VALDOSTA 81 66 81 67 / 30 40 50 20 CROSS CITY 84 67 85 68 / 20 20 40 20 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ BLOCK/BARRY