Area Forecast Discussion
Issued by NWS

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936 FXUS62 KTAE 181346 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 946 AM EDT SAT APR 18 2015 .NEAR TERM [THROUGH TODAY]...
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PREVIOUS FORECAST IS ON TRACK WITH ONLY MINOR CHANGES MADE. CURRENTLY IN A BRIEF PERIOD OF MID- LEVEL DRYING FOR OUR CWA BEFORE DEEP LAYER MOISTURE RETURNS AS A LARGE MESOSCALE COMPLEX CURRENTLY OVER SOUTHERN LA APPROACHES THIS AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL SPREAD INTO THE WESTERN ZONES THIS AFTERNOON WHERE POPS ARE HIGHEST (40-60%). POPS FOR THE EASTERN ZONES HAVE BEEN TRIMMED BACK INTO THE LOWER CHANCE CATEGORY (30%). ENHANCED UPPER RIDGING OVER THE REGION AHEAD OF A DEEP TROUGH ALONG WITH SOME BREAKS IN THE CLOUD COVER WILL PUSH TEMPS INTO THE MID TO UPPER 80S FOR MOST OF THE CWA.
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&& .HYDROLOGY...
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RAINFALL THIS WEEK HAS RESULTED IN A RISE OF AREA RIVERS WITH MANY REACHING ACTION OR BANK FULL STAGE. THE CHOCTAWHATCHEE RIVER IS FORECAST TO REACH MINOR FLOOD STAGE AT CARYVILLE ON SUNDAY NIGHT AND AT BRUCE ON MONDAY. WITH AN ADDITIONAL 1 TO 2 INCHES OF RAIN EXPECTED THROUGH TUESDAY, OTHER RIVERS MAY APPROACH MINOR FLOOD STAGE BY THE END OF THE WEEK.
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&& .PREV DISCUSSION [506 AM EDT]...
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.SHORT TERM [TONIGHT THROUGH MONDAY]... BY LATE TONIGHT OR EARLY SUNDAY A LOBE OF MID-UPPER LEVEL VORTICITY, ASSOCIATED WITH A SUBTLE SHORTWAVE, IS EXPECTED TO REACH ALABAMA AND THE WESTERN FLORIDA PANHANDLE. COINCIDING WITH THIS WILL BE THE RAPID DEVELOPMENT AND STRENGTHENING OF A 100-120 KNOT UPPER LEVEL (250MB) JET STREAK FROM ALABAMA INTO EASTERN KENTUCKY. THIS WOULD PLACE OUR FORECAST AREA IN A REGION OF POSITIVE DCVA AND THE RIGHT FRONT QUADRANT OF AN UPPER LEVEL JET STREAK. IN OTHER WORDS, THE STAGE WILL BE SET FOR VERTICAL MOTION BY SUNDAY MORNING, AND WE SHOULD SEE SHOWERS AND STORMS EITHER PERSIST IN A NORTHEASTWARD TRAJECTORY FROM THE GULF OF MEXICO, OR DEVELOP ACROSS PORTIONS OF ALABAMA, GEORGIA, AND NORTH FLORIDA. MODELS ARE ACTUALLY IN EXCELLENT AGREEMENT WITH THE MAJORITY OF THE CONVECTIVE DEVELOPMENT TAKING PLACE BETWEEN AROUND 09 UTC AND 15 UTC SUNDAY MORNING. HI-RES MODELS INDICATE THAT WHILE INITIAL CONVECTIVE MODES MAY BE MORE CELLULAR, GROWTH INTO A LINEAR SYSTEM IS EXPECTED WITH TIME WITH STORMS EVENTUALLY PUSHING EAST THROUGH MUCH OF THE AREA. GIVEN THE AGREEMENT, POPS WERE BUMPED UP TO AROUND 80 PERCENT FOR MUCH OF THE AREA. ALTHOUGH IT SHOULDN`T RAIN FOR MORE THAN A FEW HOURS AT A GIVEN LOCATION IT SEEMS QUITE LIKELY THAT MUCH OF THE AREA WILL SEE RAIN. MODEL FORECAST SOUNDINGS INDICATE A FAVORABLE OVERLAP OF AROUND 40-50 KNOTS OF DEEP LAYER SHEAR AND 1000-1500 J/KG OF SBCAPE, EVEN IN THE EARLY MORNING HOURS, ACROSS THE AREA. GIVEN THE FAVORABLE ENVIRONMENT, WE INCLUDED SEVERE THUNDERSTORM WORDING IN THE FORECAST. HOWEVER, SOME UNCERTAINTIES REMAIN, LARGELY CENTERED AROUND WHETHER OR NOT THIS INITIAL ROUND OF STORMS WILL BE ABLE TO ROOT QUICKLY IN THE BOUNDARY LAYER OR WILL ACTUALLY BE REALIZING LESS INSTABILITY THAN WHAT MODELS ARE PROJECTING. PRECIPITABLE WATER VALUES SHOULD BE AROUND THE 99TH PERCENTILE FOR THIS TIME OF YEAR, SO HEAVY RAIN WILL ALSO BE POSSIBLE. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE IN THE SHORT TERM PERIOD, LIKELY EITHER LATER SUNDAY NIGHT OR MONDAY. SUBSIDENCE IN THE WAKE OF THE MORNING MCS COULD LEAD TO A LULL IN THE LATE AFTERNOON AND EVENING BEFORE A SURFACE COLD FRONT AND ANOTHER UPPER LEVEL SHORTWAVE BEGIN TO APPROACH. FORCING WILL NOT BE AS STRONG OR FOCUSED FROM SUNDAY NIGHT INTO MONDAY, SO RAIN CHANCES ARE NOT AS HIGH. HOWEVER, INSTABILITY IS LIKELY TO BE HIGHER WITH CONTINUED MODERATE-STRONG DEEP LAYER SHEAR AND STEEPER MID LEVEL LAPSE RATES AS AN EML PLUME ARRIVES RELATIVELY IN TACT FROM THE HIGH PLAINS. THEREFORE, ADDITIONAL STRONG TO SEVERE STORMS WILL BE POSSIBLE. GIVEN LOWER OVERALL LIKELIHOOD OF STORMS, SEVERE WORDING WAS NOT INCLUDED IN THE FORECAST AT THIS TIME. .LONG TERM [MONDAY NIGHT THROUGH SATURDAY]... THE SURFACE COLD FRONT SHOULD PUSH THROUGH THE AREA ON MONDAY NIGHT WITH HIGH PRESSURE SETTLING INTO THE GULF COAST REGION THROUGH WEDNESDAY MORNING. ALTHOUGH THE FRONT SHOULD NOT MAKE HIGH TEMPERATURES SIGNIFICANTLY COOLER, IT SHOULD BRING IN A SLIGHTLY DRIER AIR MASS THEREBY ALSO LEADING TO SLIGHTLY COOLER OVERNIGHT LOWS. SOME SMALL RAIN CHANCES ENTER THE FORECAST AGAIN ON THURSDAY AS THE SURFACE HIGH ERODES. .AVIATION... [THROUGH 12Z SUNDAY] CEILINGS WILL FALL TO IFR/LIFR LEVELS AT ALL TERMINALS BY DAYBREAK. THE POTENTIAL EXISTS FOR LIFR VISIBILITIES AS WELL, BUT CONFIDENCE REMAINS LOWER WRT FOG. FOR NOW, IFR VISIBILITIES ARE ADVERTISED. CEILINGS WILL BE SLOW TO SCATTER TOMORROW MORNING. SCATTERED CONVECTION WILL DEVELOP AND SPREAD FROM WEST TO EAST LATER TODAY BECOMING WIDESPREAD LATE TONIGHT THROUGH SUNDAY MORNING. .MARINE... SOUTHERLY WINDS WILL SLOWLY INCREASE THIS WEEKEND AND COULD REACH SCEC LEVELS OF 15-20 KNOTS OVER PARTS OF THE COASTAL WATERS LATE TONIGHT OR EARLY SUNDAY. LIGHTER WINDS WILL RETURN BEHIND THE COLD FRONT ON TUESDAY AND WEDNESDAY. SHOWERS AND STORMS WILL BE POSSIBLE AHEAD OF THE FRONT FROM TODAY THROUGH MONDAY. SOME STORMS ON SUNDAY COULD BE SEVERE WITH STRONG WINDS. .FIRE WEATHER... NO RED FLAG CONDITIONS ARE EXPECTED AT LEAST THROUGH THE MIDDLE OF NEXT WEEK.
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&& .PRELIMINARY POINT TEMPS/POPS...
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TALLAHASSEE 88 70 81 68 84 / 40 30 80 20 30 PANAMA CITY 83 73 78 72 79 / 50 50 80 20 30 DOTHAN 82 68 80 67 82 / 50 70 80 20 30 ALBANY 83 69 81 67 82 / 40 70 80 20 30 VALDOSTA 87 69 84 67 83 / 30 30 80 20 30 CROSS CITY 86 69 84 68 83 / 30 20 70 20 40 APALACHICOLA 84 73 78 73 80 / 40 30 80 20 30
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&& .TAE WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AL...NONE. GM...NONE. && $$ NEAR TERM...WESTON/BARRY SHORT TERM...LAMERS LONG TERM...LAMERS AVIATION...BARRY MARINE...LAMERS FIRE WEATHER...BARRY HYDROLOGY...WESTON

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