Area Forecast Discussion
Issued by NWS Columbia, SC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KCAE 020707 AFDCAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 307 AM EDT THU APR 2 2015 .SYNOPSIS... A WEAK WARM FRONT EXTENDING THROUGH GEORGIA TODAY WILL DISSIPATE TONIGHT. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL MOVE THROUGH THE FORECAST AREA SATURDAY MORNING. DRY HIGH PRESSURE BEHIND THIS FRONT WILL DOMINATE SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... HIGH PRESSURE OFF THE COAST WILL CIRCULATE LOW-LEVEL MOISTURE INTO THE FORECAST AREA. THE NAM AND GFS DISPLAY A WEAK WARM FRONT IN GEORGIA WITH ISENTROPIC UPGLIDE IN THE FORECAST AREA. THE MODELS SHOW THE GREATER LIFT IN THE WEST PART OF THE FORECAST AREA. THERE WILL ALSO BE AN INCREASE IN MOISTURE AND INSTABILITY ASSOCIATED WITH A MID-LEVEL SHORTWAVE TROUGH SHOWN BY THE WATER VAPOR IMAGERY IN THE LOWER MISSISSIPPI RIVER VALLEY WHICH SHOULD AFFECT THE FORECAST AREA THIS AFTERNOON INTO THE EVENING. THIS SUPPORT PLUS HEATING SHOULD LEAD TO SHOWERS AND THUNDERSTORMS. THE MODELS SHOW MOISTURE REMAINING SOMEWHAT SHALLOW WHICH SHOULD LIMIT COVERAGE. WE KEPT POPS IN THE CHANCE CATEGORY WITH THE GREATEST CHANCE IN THE WEST PART. THE SPC WRF AND ARW DISPLAY THE GREATEST SHOWER OR THUNDERSTORM COVERAGE IN THE WEST PART OF THE FORECAST AREA DURING THE 500 PM TO 900 PM TIME FRAME. THE LATEST ANALYSIS SHOWED H5 TEMPERATURES -15 TO -16. THE MODELS INDICATED MODERATE TO STRONG INSTABILITY THIS AFTERNOON. THE NAM HAD A TOTAL TOTALS AROUND 52 AND SURFACE-BASED LI -2 TO -5 WITH THE GREATEST INSTABILITY IN THE SOUTH PART. THE MODEL INDICATED A WET BULB ZERO HEIGHT OF 8000 TO 9000 FEET. SHEAR WAS MARGINAL WITH H85 WINDS AROUND 25 KNOTS. BASED MAINLY ON THE INSTABILITY...SEVERE THUNDERSTORMS MAY OCCUR...BUT THE THREAT APPEARS LIMITED BY SHALLOW MOISTURE AND THE MODEL FORECAST SOUNDINGS INDICATE SKINNY CAPE. THE SHOWER AND THUNDERSTORM CHANCE SHOULD DIMINISH OVERNIGHT WITH THE LOSS OF HEATING AND UPPER-LEVEL LIFT SHIFTING EAST OF THE AREA. WE USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST TODAY AND TONIGHT. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... THE NAM AND GFS INDICATE LESS ISENTROPIC LIFT FRIDAY. MOISTURE APPEARS SHALLOW IN THE WAKE OF A MID-LEVEL SHORTWAVE TROUGH. FORCING ASSOCIATED WITH THE APPROACHING COLD FRONT SHOULD REMAIN NORTHWEST OF THE AREA. THE NAM...GFS...AND ECMWF MOS HAVE POPS LESS THAN 20 PERCENT. WE KEPT THE FORECAST DRY. IT WILL BE WARM JUST AHEAD OF THE COLD FRONT AND THE WARMER TEMPERATURE GUIDANCE IS USUALLY BEST WITH THIS PATTERN. CONVERGENCE AHEAD OF THE COLD FRONT SUPPORTS A CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY NIGHT. THE MODELS HAVE BEEN CONSISTENT HOLDING BACK THE DEEPER MOISTURE ASSOCIATED WITH THE FRONT UNTIL TOWARD MORNING. SHEAR WILL BE STRONG. THE MODELS SHOW H85 WINDS 40 TO 50 KNOTS. HOWEVER...A LACK OF SIGNIFICANT INSTABILITY SHOULD LIMIT THE SEVERE THUNDERSTORM THREAT. THE NAM KEEPS SURFACE-BASED LI/S ABOVE ZERO AND THIS APPEARS REASONABLE BASED ON JUST WEAK UPPER-LEVEL LIFT AND NOCTURNAL COOLING. USED THE WARMER TEMPERATURE GUIDANCE FRIDAY NIGHT BECAUSE OF MIXING AHEAD OF THE FRONT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... CONVERGENCE ASSOCIATED WITH THE COLD FRONT SUPPORTS A CONTINUED SHOWER OR THUNDERSTORM CHANCE SATURDAY MORNING. DRYING BEHIND THE FRONT SHOULD DOMINATE DURING THE AFTERNOON. USED THE WARMER TEMPERATURE GUIDANCE SATURDAY BECAUSE OF A RELATIVELY WARM START AND DOWNSLOPE FLOW DURING THE AFTERNOON. THE HIGH PRESSURE CENTER BEHIND THE FRONT SHOULD BE NEAR THE FORECAST AREA BY LATE SATURDAY NIGHT. EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS WITH STRONG NOCTURNAL COOLING. THE GFS AND ECMWF MOS HAVE LOWS IN THE UPPER 30S TO AROUND 40. THE DRY AIR MASS SHOULD REMAIN IN PLACE THROUGH SUNDAY AND THE MOS HAS HIGHS NEAR 70. THE HIGH WILL BE OFF THE COAST MONDAY THROUGH WEDNESDAY. THE MODELS INDICATE AN ASSOCIATED ONSHORE FLOW PLUS ISENTROPIC LIFT IN THE FORECAST AREA. THE GFS HAS TRENDED WITH MORE MOISTURE MONDAY WITH LESS ISENTROPIC LIFT TUESDAY AND WEDNESDAY. AN AVERAGE OF THE GFS AND ECMWF MOS POPS PLUS GFS ENSEMBLE MEAN SUPPORT POPS OF 20 TO 30 PERCENT MONDAY THROUGH WEDNESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... VFR CONDITIONS EXPECTED EARLY THIS MORNING. POSSIBLE MVFR CEILINGS ACROSS THE AREA TOWARDS SUNRISE. THE FRONTAL BOUNDARY REMAINS JUST SOUTH OF THE CENTRAL SAVANNAH RIVER AREA EARLY THIS MORNING. MODELS BEGIN TO INDICATE RETURN MOISTURE ALONG THE CSRA TOWARDS SUNRISE...WITH SCTD/PSBL BKN CLOUDS AROUND 2000-3000 FT BY SUNRISE. BY 14Z...VFR ACROSS THE AREA UNTIL LATE AFTERNOON. WARM FRONT WILL APPROACH FROM THE SW LATER TODAY WITH SHOWERS POSSIBLE LATE AFTERNOON INTO THE EARLY EVENING. MVFR CIGS POSSIBLE. SHOWERS SHOULD END BY LATE EVENING. LIGHT EASTERLY WINDS EARLY WINDS EARLY THIS MORNING WILL VEER TO SOUTHERLY BY LATE AFTERNOON. EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE THURSDAY NIGHT THROUGH FRIDAY NIGHT AS FRONTAL BOUNDARIES MOVE THROUGH THE REGION DURING THE PERIOD. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.