FXUS62 KFFC 230126 AAB AFDFFC AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 826 PM EST THU JAN 22 2015 .UPDATE... REALLY NO CHANGE TO THE FORECAST. RAIN CHANCES INCREASING TONIGHT ACROSS THE ENTIRE AREA. FORECAST LOW TEMPERATURES RUNNING 8-11 DEGREES ABOVE NORMAL. && .PREV DISCUSSION... /ISSUED 617 PM EST THU JAN 22 2015/ SHORT TERM /TONIGHT THROUGH SATURDAY/... ANOTHER COMPLICATED FORECAST FOR THE SHORT TERM...BUT ACTUALLY MADE SOMEWHAT EASIER IN THAT GUIDANCE IS ALL TRENDING WARMER. IN A NUTSHELL...DEEP TROUGH IN THE SOUTHERN PLAINS WITH SURFACE LOW IN THE NORTHERN GULF WILL SPREAD MOISTURE ACROSS THE AREA STARTING TONIGHT...WITH THE MOISTURE OVERRUNNING A HYBRID DAMMING SURFACE HIGH PRESSURE. WIDESPREAD RAIN EXPECTED DURING THE DAY TOMORROW WITH PERHAPS BRIEF DRYSLOTTING BEHIND THE MAIN RAIN SHIELD BEFORE THE WRAPAROUND/DEFORMATION AXIS PRECIP MOVES ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY MORNING. RAPID CLEARING SATURDAY AFTERNOON BEHIND THE SYSTEM AS MUCH DRIER AIR PUSHES INTO THE SOUTHEAST. NOW FOR THE DETAILS...STARTING WITH WINTRY POTENTIAL. NOTE THAT MOST OF THIS PARAGRAPH PERTAINS ONLY TO THE MOUNTAINS. NO WINTRY PRECIP EXPECTED IN ANY OTHER LOCATIONS. NEW GUIDANCE IS DELAYING ONSET OF PRECIP IN THE NORTHEAST MOUNTAINS UNTIL A BIT LATER THAN PREVIOUSLY ADVERTISED DUE TO THE LOW LEVEL DRY AIR IN PLACE. BY THE TIME THE COLUMN SATURATES...IT MIGHT NOT BE TILL AROUND SUNRISE IN THE MOUNTAINS. BOTH NAM AND GFS BUFR SOUNDINGS STILL INDICATING A DECENT WARM NOSE ALOFT DUE TO THE WAA ON TOP OF THE COOL DOME AND IN GENERAL LOOKS LIKE WE WILL BE HARD PRESSED TO SEE ANYTHING BUT LIQUID ACROSS THE AREA TONIGHT. CANNOT RULE OUT A STRAY ICE PELLET OR SOMETHING IN THE MOUNTAINS...ESPECIALLY THE MOUNTAIN VALLEYS WHERE COOLER/DRIER AIR IS ABLE TO TRAP...BUT OVERALL A LIQUID EVENT TONIGHT. DAYTIME TEMPERATURES ON FRIDAY SUPPORT LIQUID EVERYWHERE. FRIDAY NIGHT IS STILL A BIT IFFY. STARTING ABOUT 00Z SATURDAY...LOW LEVEL TEMPERATURES START DROPPING OFF WHILE STRONG WARM NOSE REMAINS IN PLACE. SURFACE WINDS SWING AROUND TO SOUTHWEST AND THEN NORTHWEST AFTER MIDNIGHT SATURDAY MORNING AND STRONG CAA RAPIDLY ERODES THE COLD NOSE...BUT SURFACE TEMPERATURES CONTINUE TO LAG SOMEWHAT. BY 09- 12Z SATURDAY MORNING...DRY AIR ALOFT STARTS MOVING IN BUT THE REST OF THE PROFILE IS SUPPORTIVE OF AT LEAST A MIX IF NOT FROZEN PRECIP. WE QUICKLY LOSE SATURATION AT THE CRITICAL -10C LEVEL BUT WITH NORTHWEST FLOW PICKING UP THINK THAT OROGRAPHIC LIFT WILL BE ABLE TO LIFT THE MOISTURE TO THE DENDRITIC GROWTH LEVEL...RESULTING IN THE POTENTIAL FOR A BRIEF RAIN/SNOW MIX. BUT WITH THAT AND THE WARMING TREND IN GUIDANCE...HAVE REALLY PULLED BACK ON WINTRY POTENTIAL WITH ONLY ISOLATED TRACE/DUSTING ACCUMULATIONS POSSIBLE AND ONLY AT THE HIGHEST ELEVATIONS. NEXT UP IS CONVECTIVE POTENTIAL. BUT LIKE ABOVE...THIS IS REALLY LIMITED TO JUST THE SOUTHEAST CORNER. WITH THE WARMING TREND IN GUIDANCE ALSO COMES AN EVER SO SLIGHT INCREASE IN INSTABILITY. NAM BRINGS SBCAPE VALUES OF BETWEEN 200-300 J/KG INTO SOUTHEAST ZONES WHILE GFS KEEPS SBCAPE GENERALLY UNDER 100 J/KG. BUT DEEP LAYER SHEAR OF 50-60KT AND LOW LEVEL SHEAR OF 30-40KT IS ENOUGH TO BE SOMEWHAT CONCERNED ABOUT...AND SPC DAY2 OUTLOOK DOES INCLUDE THE SOUTHEAST CORNER IN THE MARGINAL OUTLOOK. REFLECTIVITY FORECASTS REALLY DO TRY TO DEVELOP WHAT LOOKS LIKE SOME SEMI-DISCRETE CELLS MORPHING INTO SOME SORT OF LINE LATE FRIDAY AFTERNOON AND EVENING. RIGHT NOW NOT REALLY EXPECTING SEVERE BUT CANNOT RULE OUT ISOLATED STRONG STORMS. ADDED SLIGHT CHANCE THUNDER TO THE GRIDS FROM 18Z FRIDAY TO 00Z SATURDAY. MIGHT BE MORE LIKE 21Z FRIDAY TO 00Z SATURDAY BUT WE CAN REFINE THAT...AS WELL AS ANY INCREASE IN SEVERE POTENTIAL...LATER. OTHERWISE...A COLD RAINY DAY ON FRIDAY. QPF VALUES OVER 2 INCHES STORM TOTAL FOR PORTIONS OF CENTRAL GEORGIA SO DID ADD HEAVY RAIN WORDING TO LINE UP WITH HIGHEST QPF. HOPEFULLY THAT COVERED EVERYTHING OF SIGNIFICANCE. KEEP IN MIND THAT FORECASTS ARE CONSTANTLY CHANGING AND WE WILL CONTINUE TO LOOK AT UPDATED...HIGH RESOLUTION GUIDANCE THROUGH THE EVENING AND OVERNIGHT TO MONITOR LATEST TRENDS. LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... EXTENDED FORECAST PERIOD CONTINUES TO START OUT UNSETTLED AS FIRST STORM SYSTEM EXITS AND PRECIPITATION ENDS. NEXT SYSTEM STILL ON TRACK FOR LATE SUNDAY THROUGH MONDAY AS NORTHWESTERLY UPPER FLOW DOMINATES THE BEGINNING OF THE NEW WEEK. ALTHOUGH ALL OF THE MEDIUM RANGE MODELS ARE RELATIVELY SIMILAR CONCERNING THE LARGER SCALE UPPER FLOW PATTERN WITH A LARGE...DEEPENING UPPER TROUGH OVER THE EASTERN CONUS...THE SMALLER SCALE DETAILS REMAIN NOTICEABLY DIFFERENT. ALL BRING AT LEAST THE TAIL-END OF A STRONG SHORT WAVE THROUGH THE SOUTHERN APPALACHIANS. TREND TOWARD WARMER SURFACE TEMPERATURES ALSO CONTINUES WITH ALL BUT THE HIGHEST ELEVATIONS OF THE NORTH GEORGIA MOUNTAINS REMAINING ABOVE FREEZING THROUGH MONDAY EVENING. COLD AIR IN THE MID AND UPPER LEVELS IS STILL MUCH MORE FAVORABLE WITH THIS SYSTEM FOR AT LEAST A MIX OF RAIN AND SNOW. MOISTURE ALSO REMAINS SOMEWHAT LIMITED BUT DYNAMICS AND COLD ADVECTION COMBINED WITH SOME OROGRAPHIC ASSISTANCE SHOULD RESULT IN SCATTERED RAIN/SNOW SHOWERS ACROSS FAR NORTH GEORGIA. STILL MUCH UNCERTAINTY WITH THIS SYSTEM. THE REMAINDER OF THE EXTENDED FORECAST PERIOD IS DOMINATED BY WEAKENING NORTHWEST UPPER FLOW KEEPING THE REGION BASICALLY DRY WITH AT OR SLIGHTLY BELOW SEASONAL NORMAL TEMPERATURES THROUGH THE MAJORITY OF THE PERIOD. 20 AVIATION... 00Z UPDATE... VFR CEILINGS LOWERING TO LIFR/IFR CONDITIONS LATE TONIGHT/EARLY FRIDAY WITH INCREASING RAIN ACROSS THE AREA. LIGHT AND VARIABLE WINDS BECOMING ENE 10-15KTS AND GUSTS AROUND 20KTS LATE TONIGHT AND FRIDAY. //ATL CONFIDENCE...00Z UPDATE... MEDIUM TO HIGH CONFIDENCE THROUGH TONIGHT. LOW TO MEDIUM CONFIDENCE ON TIMING OF LOWER CONDITIONS. BDL && .PRELIMINARY POINT TEMPS/POPS... ATHENS 41 43 38 51 / 100 100 70 20 ATLANTA 43 46 37 48 / 100 100 70 20 BLAIRSVILLE 38 42 36 43 / 90 100 70 30 CARTERSVILLE 40 45 37 47 / 100 100 60 20 COLUMBUS 47 52 42 51 / 100 100 60 10 GAINESVILLE 41 42 36 47 / 100 100 70 20 MACON 46 50 43 53 / 100 100 70 20 ROME 39 45 37 47 / 100 100 60 20 PEACHTREE CITY 43 47 39 49 / 100 100 60 10 VIDALIA 49 59 50 56 / 90 100 100 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BDL daculaweather
Posted on: Fri, 23 Jan 2015 01:26:53 +0000
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