National Weather Service Forecast for Lawrenceville and Gwinnett County
Lat: 33.95N, Lon: 83.99W Wx Zone: GAZ034
Area Forecast Discussion000 FXUS62 KFFC 222342 AAA AFDFFC AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 640 PM EST WED FEB 22 2012 .SHORT TERM /TONIGHT THROUGH FRIDAY/... HAVE FINALLY SEEN SOME BREAKS IN THE CLOUDS ACROSS THE FORECAST AREA SO SOME DAYTIME HEATING THIS AFTERNOON. EXPECT BEST CHANCE OF PRECIP FROM 00Z TO 06Z TONIGHT ACROSS NORTH GEORGIA. ALTHOUGH SPC SHOWS A SLIGHT RISK FOR ABOUT HALF OF THE CWA...DECIDED TO LIMIT THUNDERSTORMS TO THE ATLANTA AREA AND NORTHWARD. GIVEN LACK OF PRECIP ACROSS THE METRO ATLANTA AREA AND SOUTHWARD...THINK THAT ANY ISOLATED SEVERE STORMS THAT DEVELOP WILL BE ACROSS FAR NORTH GEORGIA...GENERALLY NORTH OF A ROME TO GAINESVILLE LINE. NAM IS MUCH MORE AGGRESSIVE WITH INSTABILITY TONIGHT. GFS LIMITS MUCAPE TO 300J/KG ACROSS THE NORTH WHEREAS THE NAM SHOWS ALMOST 1000 J/KG. THINK THE NAM IS PROBABLY OVERDOING THE CAPE VALUES. AS FAR AS 0-1KM SHEAR VALUES...BOTH SHOW VALUES OF 30-35KTS AT 06Z. CAPE VALUES ARE EVEN BETTER FURTHER SOUTH...BUT WILL BE HARDER TO GET STORMS ACROSS THAT AREA WITH SUCH LIMITED PRECIP EXPECTED. WILL DRY OUT FOR THURSDAY BEFORE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A FRONT MOVE INTO THE CWA ON THURSDAY NIGHT. PARENT SFC LOW IS WELL NORTH OF THE AREA ACROSS THE OHIO VALLEY WHILE THE UPPER LEVEL LOW IS EVEN FURTHER NORTH ACROSS THE GREAT LAKES REGION. MUCAPE VALUES ARE DECENT IN BOTH THE GFS AND NAM WITH 1000 J/KG THURSDAY NIGHT. 0-1KM SHEAR VALUES ARE ALSO GOOD WITH 40-45KTS. GIVEN THESE PARAMETERS AND GOOD MOISTURE...THERE IS A CHANCE OF SEVERE STORMS WITH THIS SYSTEM THURSDAY NIGHT. .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... NO CHANGES TO THE EXTENDED FORECAST GRIDS. ONLY REMOVED MENTION OF FRIDAY DURING THE DAY FROM THE PREVIOUS EXTENDED FORECAST DISCUSSION. /ISSUED 358 AM EST WED FEB 22 2012/ CLEARING IS EXPECTED FRIDAY NIGHT UNDER STRONG HIGH PRESSURE INFLUENCE. SHOULD BE BREEZY AND COOL FRIDAY NIGHT BEHIND THE COLD FRONT. STILL HOLDING ONTO A DRY FORECAST OVER THE WEEKEND...ALTHO BOTH GFS AND ECMWF ARE SHOWING STRONG ISENTROPIC LIFT SPREADING RAIN SHOWERS INTO THE STATE BY EARLY MONDAY MORNING. THE GFS IS MUCH FASTER AND CLEANER WITH THE NEXT COLD FRONT SWEEPING THROUGH MONDAY NIGHT WHILE THE ECMWF HOLDS OFF UNTIL TUESDAY. WITH MUCH UNCERTAINTY... WILL TAKE A COMPROMISING APPROACH AND SHOW A CHANCE TO SLIGHT CHANCE POP FROM SUNDAY NIGHT THROUGH TUESDAY... BUT ALL SHOWERS WITH NO THUNDER MENTIONED FOR NOW. 39 && .AVIATION... 00Z UPDATE... CONVECTION ACROSS NORTHERN ALABAMA IS EXPECTED TO MOVE INTO NORTH GEORGIA BETWEEN 00Z AND 06Z...BUT IS EXPECTED TO REMAIN NORTH OF THE TAF SITES FOR NOW. VFR CONDITIONS CURRENTLY WILL TRANSITION TO MVFR ACROSS THE TAF SITES BETWEEN 02Z AND 04Z...AND EVENTUALLY IFR BY 08Z. CONDITIONS SHOULD BEGIN IMPROVING AFTER 12Z WITH MVFR CONDITIONS BECOMING WIDESPREAD AFTER 15Z AND VFR PREVAILING AFTER 18Z. WINDS WILL REMAIN SOUTHWESTERLY BETWEEN 3-8KT THROUGH 14Z... INCREASING TO 9-12KT WITH GUSTS OVER 20KT BY 18Z. 20 //ATL CONFIDENCE...00Z UPDATE... HIGH CONFIDENCE ON WIND SPEED AND DIRECTION...MEDIUM ON ALL OTHER ELEMENTS. 20 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 53 77 57 60 / 40 5 60 50 ATLANTA 57 75 52 56 / 20 5 70 50 BLAIRSVILLE 48 70 46 53 / 60 5 70 30 CARTERSVILLE 53 75 50 58 / 50 5 70 30 COLUMBUS 58 79 61 65 / 20 5 50 60 GAINESVILLE 51 75 53 62 / 60 5 70 30 MACON 57 79 64 66 / 20 5 50 60 ROME 51 76 50 58 / 60 5 70 30 PEACHTREE CITY 50 76 55 59 / 20 5 60 60 VIDALIA 61 81 65 69 / 20 5 50 70 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 11 |