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000 FXUS62 KTAE 180646 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 245 AM EDT SAT OCT 18 2008 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS NOW SHOWING AN AMPLIFIED UPPER LEVEL PATTERN ACROSS NORTH AMERICA. LARGE AND DOMINANT UPPER LEVEL RIDGE COVERS MUCH OF THE WESTERN UNITED STATES WITH THE NORTHERN STREAM FLOW RIDING UP AND OVER INTO SOUTHWESTERN CANADA. THE FLOW THEN DIVES RAPIDLY BACK SOUTHWARD INTO LONGWAVE TROUGHING EXTENDING FROM EASTERN CANADA DOWN ACROSS THE EASTERN U.S. THIS TROUGH AXIS IS CURRENTLY PULLING TO THE EAST OF THE MISSISSIPPI RIVER VALLEY. OVERTOP OUR FORECAST AREA WE SEE THE UPPER RIDGE THAT BROUGHT SEVERAL DAYS OF WARM AND FAIR WEATHER TO THE AREA NOW PUSHED OFF TO THE SOUTH IN RESPONSE TO HEIGHT FALLS ASSOCIATED WITH THE UPPER TROUGH APPROACHING FROM THE NORTHWEST. AT THE SURFACE...COLD FRONT IS NOW MOVING SOUTHEAST ACROSS THE FORECAST AREA WITH THE FRONTS CURRENT POSITION RUNNING FROM NEAR THE SOUTH CAROLINA COAST SOUTHWEST TO NEAR VALDOSTA...TALLAHASSEE AND THEN OUT IN WESTERN COASTAL LEGS. THICK LOW/MID LEVEL CLOUD SHIELD ALONG AND JUST BEHIND THE FRONT IS ALSO WORKING ITS WAY EASTWARD ACROSS THE AREA WITH A SCATTERING OF MAINLY LIGHT SHOWERS AND SPRINKLES. TEMPERATURES STILL QUITE WARM AHEAD OF THE FRONT WITH UPPER 60S AND LOWER 70S COMMON...HOWEVER THESE WILL BEGIN TO FALL WITH THE FRONTS PASSAGE AS TEMPS BACK INTO SOUTHEAST ALABAMA ARE ALREADY FALLING THROUGH THE LOWER 60S AND UPPER 50S. && .SHORT TERM (SATURDAY THROUGH MONDAY)... SHORTWAVE ENERGY CONTINUES TO SHARPEN/AMPLIFY THE MID-LEVEL TROUGH AS IT PUSHES ACROSS THE SOUTHEASTERN STATES INTO THE AFTERNOON HOURS. SURFACE FRONT WILL CONTINUE RAPIDLY SOUTHEASTWARD AND EXIT THE FORECAST AREA THIS MORNING. MAIN LARGE SCALE SYNOPTIC LIFT/Q-G FORCING ASSOCIATED WITH THE MID-LEVEL HEIGHT FALLS RIDES TO OUR NORTH AND NORTHEAST THROUGH THE MORNING HOURS WITH WEAKER FORCING DOWN INTO THE EASTERN BIG BEND TO SUPPORT PERHAPS AN EARLY MORNING SHOWER OR SPRINKLE TOWARD PERRY OR CROSS CITY...HOWEVER QPF AMOUNTS WILL BE VERY LIGHT IF ANY. THE SURFACE FRONT AND ANY MID/ UPPER LEVEL SUPPORT WILL HAVE SHIFTED TO THE SOUTH AND EAST BY THE AFTERNOON HOURS SETTING THE STAGE FOR A VERY PLEASANT WEEKEND. GLOBAL MODELS SHOWING A VERY QUICK DRYING TREND FROM WEST TO EAST THROUGH EARLY AFTERNOON AS THE MID-LEVEL SHORTWAVE AXIS PASSES THE AREA. LATEST 00Z GFS FORECAST SOUNDINGS INDICATE PW VALUES AROUND KDHN DOWN TO LESS THAN 0.50" BY SUNRISE. TOWARD TALLAHASSEE PW VALUES FALL TO THESE LEVELS BY THE LATER MORNING HOURS AND DOWN TOWARD CROSS CITY THEY ARE ACHIEVED DURING THE AFTERNOON. THEREFORE WITH THE MOISTURE AND DYNAMICS MAKING A QUICK EXIT THIS MORNING...WILL BE EXPECTING A RAIN FREE DAY AFTER THE POSSIBLE EARLY MORNING SPRINKLES ACROSS THE SE BIG BEND. MORNING CLOUDS ALONG THE FRONT OVER THE SOUTHEAST HALF OF THE AREA WILL BEGIN TO CLEAR WITH SKIES BECOMING PARTLY TO MOSTLY SUNNY BY AFTERNOON. A COOLER AIRMASS WILL ALSO ARRIVE DURING SATURDAY BEHIND THE FRONT WITH 850MB TEMPS DROPPING TO BETWEEN 7 AND 11C FROM NORTH TO SOUTH BY SUNSET. THE COOLER AND DRIER AIR COMBINED WITH A 10-15 MPH NORTHERLY FLOW WILL PROVIDE A MORE FALL-LIKE FEEL THIS AFTERNOON. HIGH TEMPERATURES RANGING FROM THE MIDDLE AND UPPER 70S NORTHWEST TO AROUND 80 IN THE SOUTHEAST. MID-LEVEL SHORTWAVE ENERGY EXITS WELL OFF THE SOUTHEAST COAST TO NIGHT. STRONG 1025-1030MB SURFACE RIDGE ACROSS THE OHIO/MIDDLE MS VALLEYS WILL BEGIN TO BUILD SOUTH AND EAST KEEPING THE GRADIENT TIGHT ACROSS THE AREA. DESPITE THE DRIER AIR AND MOSTLY CLEAR SKIES...THIS GRADIENT SHOULD KEEP THE LOW LEVEL FLOW UP A BIT AND NOT LET RADIATIONAL COOLING TAKE CONTROL AND REALLY PLUMMET TEMPERATURES. HOWEVER...WILL STILL BE A COOL NIGHT WITH LOWS RANGING FROM THE UPPER 40S WELL INLAND (GENERALLY NORTH OF THE I-10 CORRIDOR TO THE LOWER 50S AND MIDDLE 50S FURTHER SOUTH. SUNDAY THROUGH THE MONDAY WILL FEATURE FAIR AND PLEASANT FALL WEATHER FOR THE AREA. UPPER LEVEL RIDGING WILL RE-BUILD ALONG THE NORTHERN GULF COAST WHILE AT THE SAME TIME SURFACE RIDGING CONTINUES TO BUILD SOUTH AND EAST TO ALONG THE EASTERN SEABOARD. DESPITE PLENTY OF SUNSHINE...850MB TEMPS BETWEEN 8 AND 10C ON SUNDAY AFTERNOON WILL ALLOW TEMPERATURES TO ONLY CLIMB TO THE MIDDLE AND UPPER 70S FOR MOST LOCATIONS. SUNDAY NIGHT...MODELS PROGS STILL SHOWING A DECENT GRADIENT ACROSS THE AREA...HOWEVER WITH THE RIDGE AXIS A BIT CLOSER WE MAY STILL BE ABLE TO DE-COUPLE THE BOUNDARY LAYER LATE AT NIGHT...ESPECIALLY ACROSS THE NORTHERN AND WESTERN ZONES. FOR THIS REASON STILL FEEL A BIT MORE CONFIDENT GOING WITH WIDESPREAD MID AND UPPER 40S AWAY FROM THE IMMEDIATE COAST ON SUNDAY NIGHT AS OPPOSED TO SATURDAY NIGHT. TEMPERATURES BEGIN TO MODERATE JUST A BIT ON MONDAY BACK TO NEAR CLIMO WITH UPPER 70S NORTH TO LOWER 80S SOUTH UNDER PARTLY TO MOSTLY SUNNY SKIES. && .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY). STRONG HIGH PRESSURE WILL DOMINATE MOST OF THE EASTERN U.S. INCLUDING THE SOUTHEAST THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. HOWEVER...AFTER THAT THERE CONTINUES TO BE A SIGNIFICANT DIFFERENCE BETWEEN THE GFS AND THE EURO MODELS...FUNDAMENTALLY IN THE WAY THEY HANDLE THE NEXT SIGNIFICANT SHORT WAVE THAT IS FORECAST TO DROP INTO THE CENTRAL U.S. BY MID WEEK. THE EURO HAS CONSISTENTLY FORECAST THIS SYSTEM TO ROUND THE BOTTOM OF THE MEAN TROUGH AND EXIT RAPIDLY NORTHEAST... WHILE THE GFS CONTINUES TO DIG THE SYSTEM MUCH FURTHER SOUTH MOVE IT MUCH MORE SLOWLY EASTWARD. THESE DIFFERENCES HAVE SIGNIFICANT IMPLICATIONS FOR THE FORECAST TOWARD THE END OF NEXT WEEK...BECAUSE BOTH MODELS HAVE PERSISTED IN FORECASTING THE DEVELOPMENT OF A TROPICAL LOOKING LOW OVER THE NORTHWEST CARIBBEAN BY THURSDAY. GIVEN THAT THE EURO HAS BEEN MORE CONSISTENT...AND THAT THE ENSEMBLE MEAN CONTINUED TO FAVOR MORE OF A EURO TYPE SOLUTION...WILL LEAN HEAVILY TOWARD THE EURO FORECAST...AND GO WITH A MUCH LESS CLOUDY FORECAST WITH LESS WIND THAN THE GFS WOULD IMPLY BY THE END OF THE WEEK. TEMPERATURES WILL START OUT A LITTLE BELOW CLIMO AND SHOULD GRADUALLY TREND UPWARD TO NEAR CLIMO BY THE MIDDLE TO END OF THE WEEK. && .MARINE... COLD FRONT WILL EXIT TO THE EAST OF THE FORECAST WATERS LATER THIS MORNING WITH WINDS SHIFTING BEHIND THE FRONT TO THE NORTH AND NORTHWEST AND INCREASING. CAUTIONARY LEVEL WINDS OVER THE WESTERN LEGS EARLY IN THE MORNING WILL SPREAD EAST TO ENCOMPASS THE ENTIRE MARINE AREA BY THIS AFTERNOON. STRONG HIGH PRESSURE WELL TO THE NORTH BEGINS TO BUILD SOUTH LATER TODAY INTO SUNDAY TIGHTENING THE GRADIENT OVER THE FORECAST WATERS. A PERIOD OF ADVISORY LEVEL WINDS AND SEAS IS POSSIBLE TONIGHT INTO EARLY SUNDAY AS FLOW BECOMES NORTHEAST. THE SURFACE HIGH WILL SETTLE SLOWLY SOUTH INTO THE EARLY PART OF NEXT WEEK...HOWEVER WITH THE RIDGE AXIS REMAINING TO THE NORTH...AN EXTENDED PERIOD OF NEAR OR SLIGHT ABOVE CAUTIONARY LEVEL WINDS AND OFFSHORE SEAS IS LIKELY INTO MONDAY OR TUESDAY. && .AVIATION... A BAND OF LIGHT RAIN AND PATCHY FOG...ACCOMPANIED BY MVFR TO IFR CEILINGS...ASSOCIATED WITH A WEAK COLD FRONT...WILL CONTINUE TO MOVE EAST ACROSS THE TRI STATE AREA EARLY THIS MORNING...AND EXIT TO THE EAST OF THE AREA BY MID TO LATE MORNING. BEHIND THE FRONT...SOME PATCHY FOG AND IFR CEILINGS WILL LINGER UNTIL AFTER SUNRISE...MAINLY OVER PORTIONS OF SOUTHEAST ALABAMA... THE EASTERN FLORIDA PANHANDLE AND SOUTH CENTRAL GEORGIA. SKIES WILL CLEAR RAPIDLY BY MID TO LATE MORNING ACROSS MOST OF THE AREA...AND VFR CONDITIONS WILL PREVAIL THROUGH THE REMAINDER OF THE FORECAST PERIOD AND BEYOND. BEHIND THE FRONT WINDS WILL SHIFT TO THE NORTH 8 TO 12 MPH THROUGH THE AFTERNOON BEFORE DIMINISHING AFTER SUNSET. && .FIRE WEATHER... ...COMING SOON... && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 80 50 78 47 80 / 05 0 0 0 0 PANAMA CITY 78 55 79 53 81 / 0 0 0 0 0 DOTHAN 76 48 76 47 78 / 0 0 0 0 0 ALBANY 78 48 76 45 77 / 0 0 0 0 0 VALDOSTA 79 50 78 47 80 / 10 0 0 0 0 CROSS CITY 80 52 79 50 81 / 20 0 0 0 0 .TAE WATCHES/WARNINGS/ADVISORIES... ...COMING SOON... && $$ AVIATION/LONG TERM/FIRE WEATHER...DUVAL SYNOPSIS/SHORT TERM/MARINE...MROCZKA