Area Forecast Discussion
Issued by NWS Charleston, SC

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000 FXUS62 KCHS 261128 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 728 AM EDT Sun Mar 26 2017 .SYNOPSIS... Atlantic high pressure will weaken early this week. A weak cold front will stall over the area during the middle of the week, then shift back north as a warm front Friday. Another cold front should move through Saturday or Saturday night followed by drier high pressure Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 725 AM: Regional radar indicated a fading band of showers across GA. KCLX radar detected a few areas of light returns across the coastal plain, associated with bird roost rings. I will adjust PoPs to slow the arrival of any remaining showers later today. As of 6 AM: Composite radar showed a weak line of showers from the SC foothills south to the GA/FL border. These showers have been weakening as they move east into a less supportive environment. It still appears likely that a weak line or clusters of showers will move across the inland GA counties today. I will update the forecast update the near term sky trends to recent satellite images. As of 325 AM, regional radar composite indicated a weak band of showers near the AL/GA border, sliding slowly east. Coastal GA/SC will remain of the western edge of H5 ridging this morning, slowly weakening as a broad H5 S/W ripples over the lower Savannah River Valley this afternoon. Forecast soundings indicate that a significant inversion will remain across the forecast area, centered around H75. In addition, afternoon dewpoint depressions are forecast to remain greater than 20 degrees. Given the thermal and moisture profiles, SBCAPEs values will remain limited to around 500 J/kg across inland GA, to less than 100 J/kg near the SC coast. The fading band of showers will likely move close to the southern Savannah River Valley, then gradually dissipating. PoPs will remain limited to SCHC and the mention of thunderstorms will be removed from all zones. High temperatures are forecast to range from the low 80s across inland GA to the low to mid 70s across the beaches. Tonight, the axis of a weak sfc ridge will pivot west over the GA/SC coast. The sfc pattern will support light SE onshore flow across the forecast area through the night. At the mid levels, heights should slowly increase in the wake of the shallow S/W. I will keep PoPs limited to the single digits. Low temperatures are forecast to range in the upper 50s to around 60. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... Atlantic high pressure will weaken through the period, especially by Wednesday when a weak cold front is expected to push offshore around the Mid-Atlantic but struggle to move all the way through southeast GA. Expect a decent chance of showers and thunderstorms Monday and Tuesday when instability will be greatest and the sea breeze and upper shortwave energy will be present. However, no appreciable rainfall and/or severe weather is anticipated at this time. Temperatures should push into the lower to mid 80s inland each afternoon, likely warmest across interior southeast GA. Wouldn`t be surprised if upper 80s occurred Wednesday, mainly interior GA, due to compressional heating with the front and offshore winds. Onshore winds will keep beach areas much cooler, mainly in the 60s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... The stalled front should shift north as a warm front Friday followed by a cold frontal passage Saturday or Saturday night. Drier high pressure should then return later in the weekend. Showers and thunderstorms will be possible, mainly Thursday through Friday night, with temperatures running above normal through at least Saturday. && .AVIATION /11Z SUNDAY THROUGH THURSDAY/... Flight conditions are forecast to remain VFR through 12Z TAF period. As of 1120Z, IR satellite showed an expanding area of the cooling cloud tops across the coastal plain. I will indicate at least scattered mid level clouds over KCHS and KSAV through early this morning. Onshore flow will likely result in increasing moisture on top of the mixed later during the daylight hours, I will mention SCT050-070 from late morning through most of the afternoon. Winds should remain between 130-160 degrees through the TAF period, peaking between 10-15 kts during the afternoon. Extended Aviation Outlook: Mainly VFR. Brief restrictions possible in any showers/thunderstorms, mainly Mon/Tue/Thu/Fri. Low probability of restrictions due to early morning low clouds and/or fog. && .MARINE... A sfc ridge will remain off the GA/SC coast through today and tonight. Steady SE winds should remain over the marine zones through the near term. Wave heights are forecast to persist between 2 to 3 feet within 20 NM, 3 to 4 feet across AMZ374. Monday through Friday: No significant concerns with Atlantic high pressure generally in control until a weakening cold front moves into the area Wednesday. The front will transition into a warm front as it moves back north Friday. Seas could reach 6 feet near the Gulf Stream through Tuesday due to swells from low pressure well offshore. Advisories will be possible across the outer GA waters through Tuesday and then for more of the area Thursday night/Friday as strengthening southerly winds build seas to 6 feet again. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...RJB LONG TERM...RJB AVIATION...NED/RJB MARINE...NED/RJB

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