Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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494 FXUS62 KCHS 081754 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1254 PM EST Fri Nov 8 2024 .SYNOPSIS... A weak front will slowly move south across our region through tonight, becoming located south of our area by late Saturday. High pressure will then prevail until a cold front moves through Monday night into Tuesday. && .NEAR TERM /THROUGH TONIGHT/... Radar from early this afternoon showed scattered showers developing, mainly over southeast Georgia. This should largely continue through the afternoon with a weak boundary lingering in the vicinity and Pwats still well above climo. Temperatures will peak in the upper 70s to lower 80s. Tonight: Any shower activity will fade by evening leaving quiet conditions for the night. Again, light/calm winds...wet grounds and high dewpoints will lead to some fog development and another Dense Fog Advisory could be needed. && .SHORT TERM /SATURDAY THROUGH MONDAY/... Saturday: The mid-levels in the morning will consist of a broad ~590 dam High centered over FL, with a ridge axis stretching north into the Great Lakes Region. As time progresses, the High will slowly shift eastward, along with the ridge axis, which should be located over the East Coast late at night. At the surface, a weak cold front should be near our SC/GA border in the morning. It`s forecasted to move south during the day, becoming located south of our area during the evening and overnight hours, while troughing develops just offshore. Additionally, High pressure will pass to our north and northeast. The highest moisture values (PWATs >1.5") should stay just south of the front. All of the synoptic models generally have isolated to maybe scattered showers forming south of the Savannah River by the afternoon and persisting into the evening and overnight. The long-range CAMs point towards minimal coverage. We leaned more towards the synoptic models. QPF should be minimal. Across our SC counties, it should remain dry. High temperatures should be in the 70s. But it`s possible a sharp gradient could setup between our northern and southern zones due to northeast surface winds and clouds across a good portion of our area. Lows will range from the lower to middle 50s far inland, to the lower 60s at the beaches and near the Altamaha River. Additionally, winds will be gusty at the beaches. Sunday: A mid-level High will be located off the East Coast of FL in the morning, with a ridge axis stretching north over the rest of the East Coast in the morning. Both will shift offshore as time progresses. A stationary front will be located just south of our area in the morning, while troughing is just offshore. Additionally, High pressure will be centered off the Northeast U.S. The High will quickly shift further offshore. This will cause the front to quickly lift north during the afternoon, becoming located north of our area in the evening. Also, another front will be approaching from the west and northwest, becoming located generally over the spine of the Appalachians late at night. As the front lifts north it`ll bring a plume of moisture with it (PWATs ~1.75"). Likewise, models are in fairly good agreement indicating isolated to scattered showers initially south of the Savannah River, shifting north across our entire area during the evening and persisting into the overnight. We`ll note that some of the models do hint at decent coverage and with a bit more QPF. We went with slight chance POPs to try to match with our neighbors, but wouldn`t be surprised if both POPs and QPF have to be raised quite a bit with future forecasts. Highs will generally be in the 70s. Lows will range from around 60 degrees far inland to the upper 60s near the beaches. Monday: The mid-levels will consist of zonal flow over our region. At the surface, weak troughing should be located to our north, while a cold front is over the spine of the Appalachians in the morning. The cold front will quickly approach our area, possibly reaching our inland zones by late in the day. A decent amount of moisture will be across the region, ahead of the front. But models don`t point to much shower activity. If anything, they indicate isolated showers late in the afternoon with minimal QPF. Hence, the forecast has POPs ranging from 10-20%. Temperatures warm up just ahead of the front due to southwest surface winds and more sun than clouds. Highs should reach around 80 degrees. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... A cold front will move through our area Monday night, perhaps bringing a brief period of isolated showers. High pressure should then prevail Tuesday through Thursday, bringing dry weather. High temperatures are expected to be near normal. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Main concern for the TAF period is the potential for IFR or lower conditions in fog and stratus tonight. It appears all terminals will see restrictions. KCHS/KJZI will likely improve faster, maybe even right around daybreak, as a cold front pushes south through the area and winds increase. Restrictions could persist through the valid TAF period at KSAV, but will generally be improving. Extended Aviation Outlook: Brief flight restrictions are possible due to showers Saturday into Sunday night. && .MARINE... Light winds and diminishing seas prevail today and much of tonight. Northeasterly flow will begin to increase very late tonight, although impacts will not occur until Saturday. Meanwhile, satellite imagery and webcams are showing some fog, mainly Beaufort county nearshore waters and south across the Georgia waters. Guidance does indicate fog could linger and possibly expand later today and into tonight. Saturday: A weak cold front should be near our SC/GA border in the morning. It`s forecasted to move south during the day, becoming located south of our area during the evening and overnight hours, while troughing develops just offshore. Additionally, High pressure will pass to our north and northeast. This synoptic pattern will cause the pressure gradient to steepen, leading to strong and gusty NE winds and steep seas. Small Craft Advisories will be needed for all of the ocean zones, and possibly the Charleston Harbor. Sunday: A stationary front will be located just south of our area in the morning, while troughing is just offshore. Additionally, High pressure will be centered off the Northeast U.S. The High will quickly shift further offshore. This will cause the front to quickly lift north during the afternoon, becoming located north of our area in the evening. NE to E winds in the morning are expected to ease into the afternoon, while also clocking around to the S overnight. The Small Craft Advisories within 20 nm should come to an end during the afternoon. But the Small Craft Advisory for the GA waters beyond 20 nm should persist into the overnight because seas will take longer to subside. Monday and Beyond: A cold front will quickly approach our area from the west and northwest during the day, moving through our area overnight. It doesn`t appear that winds and/or seas will be high enough to prompt Small Craft Advisories. High pressure should then prevail Tuesday and Beyond. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...ETM SHORT TERM... LONG TERM... AVIATION...ETM MARINE...Adam