Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 211145 AFDCAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 745 AM EDT MON APR 21 2014 .SYNOPSIS... A PRESSURE RIDGE WILL EXTEND THROUGH THE FORECAST AREA TODAY AND TONIGHT. A WEAK COLD FRONT WILL MOVE THROUGH THE AREA TUESDAY AFTERNOON AND EVENING. HIGH PRESSURE BEHIND THE FRONT WILL DOMINATE WEDNESDAY AND THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... A DRY SURFACE PRESSURE RIDGE WILL EXTEND THROUGH THE FORECAST AREA TODAY. AN H5 RIDGE WILL ALSO BE OVER THE AREA. IT WILL BE A SUNNY AND WARM DAY. THE TEMPERATURE GUIDANCE WAS CLOSE WITH HIGHS IN THE MIDDLE AND UPPER 70S. THE SURFACE PRESSURE RIDGE WILL WEAKEN IN THE AREA TONIGHT. ALOFT...AN UPPER TROUGH WILL APPROACH WITH AN INCREASE IN HIGH CLOUDINESS. OVERNIGHT LOW TEMPERATURES ARE FORECAST IN THE LOWER 50S. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... THE NAM AND GFS SHOW THE COLD FRONT MOVING THROUGH THE AREA TUESDAY AFTERNOON OR EVENING. THE NAM WAS A LITTLE SLOWER WITH THE TIMING. BOTH MODELS INDICATE H85 WESTERLY FLOW WITH GULF MOISTURE PARTLY CUT OFF. THE NAM AND GFS MOS POPS HAVE TRENDED HIGHER BUT ARE STILL IN THE CHANCE CATEGORY. KEPT CHANCE POPS BELIEVING COVERAGE WILL BE LIMITED BECAUSE OF A LACK OF DEEP MOISTURE AND WEAK CONVERGENCE ALONG THE FRONT. THE DIURNAL TIMING FAVORS THUNDERSTORMS. LIMITED MOISTURE WILL LIKELY KEEP INSTABILITY WEAK. THE NAM INDICATES SURFACE-BASED LI/S AROUND -3. THE MODELS INDICATE WEAK SHEAR WITH H85 WINDS NEAR 20 KNOTS. THEREFORE...THE CHANCE OF SEVERE THUNDERSTORMS IS LOW. DRYING BEHIND THE FRONT SHOULD DOMINATE LATE TUESDAY NIGHT. THE GUIDANCE TEMPERATURES WERE CONSISTENT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE MODELS WERE CONSISTENT SHOWING DRY RIDGING DOMINATING WEDNESDAY AND THURSDAY. THE GFS AND ECMWF SHOWED SOME MOISTURE INCREASE ASSOCIATED WITH A DIFFUSE FRONT FRIDAY. THE MODELS HAVE NOT BEEN CONSISTENT FOR SATURDAY AND SUNDAY. THE GFS SHOWED A COLD FRONT WITH LIMITED MOISTURE SATURDAY. THE ECMWF KEPT THE FRONT WELL NORTHWEST OF THE AREA THROUGH SUNDAY...ALTHOUGH PREVIOUS RUNS WERE MORE PROGRESSIVE. THE GFS...ECMWF...AND EKD MOS PLUS GFS ENSEMBLE MEAN POPS WERE VERY LOW THROUGH THE PERIOD. WE KEPT THE DRY FORECAST BUT CONFIDENCE IS LOW BECAUSE OF THE MODEL INCONSISTENCY. THE GFS...ECMWF...AND EKD MOS INDICATED NEAR OR ABOVE NORMAL TEMPERATURES DURING THE PERIOD. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... HIGH CONFIDENCE FOR VFR CONDITIONS THROUGH 12Z TUESDAY. AN UPPER RIDGE AND WEAK SURFACE HIGH PRESSURE WILL DOMINATE THE PATTERN TODAY PROVIDING MOSTLY SUNNY SKIES. WINDS WILL GENERALLY BE OUT OF THE NORTH THIS MORNING AND WILL ROTATE TO NORTHWESTERLY THIS AFTERNOON. INCREASING HIGH CLOUDS EXPECTED OVERNIGHT AS AN UPPER DISTURBANCE APPROACHES FROM THE WEST. LIGHT SOUTHWESTERLY WINDS OVERNIGHT. .EXTENDED AVIATION OUTLOOK...A WEAK FRONT WILL MOVE THROUGH TUESDAY AFTERNOON AND EVENING...WITH A CHANCE OF SHOWERS AND ASSOCIATED MVFR RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$

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