781 FXUS62 KCHS 041937 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 337 PM EDT Wed Aug 4 2021 .SYNOPSIS... A stalled front will linger over or near the area through the week. More typical summertime weather should then return early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... At the surface the forecast area remains weakly wedged in a shallow cold-air-damming set up. A stationary front is located offshore, accompanied by a surface low pressure in the vicinity of the Outer Banks, along with a ridge along the eastern facing slopes of the Appalachian Mountains. Aloft, a mid-level trough is positioned over the Ohio River Valley. Circulation between the low and surface ridge will support northerly to northeasterly winds which are reinforcing the very persistent low stratus deck present over the forecast area. These winds are also advecting upper 60 degree dew points into the region. The stratus deck should slowly erode as the evening approaches, however models are in good agreement that the stratus deck will remain positioned over the SC Lowcountry. Temperatures today have been nearly 10 to 15 degrees below normal and should remain nearly steady in the mid 70s and may only increase another degree or two in the rest of the afternoon. Instability is extremely limited due to the thick, low stratus layer. Therefore, showers will struggle to develop. The HRRR has been consistent in showing showers developing along the coastal counties as well as the Charleston Tri-County. Increased POPs a smudge, however showers will most likely be very light. Thunder probabilities are near or at zero across the entire forecast area, so showers will be maintained as the convective mode. The stratus deck is forecast to erode this evening, becoming almost clear by daybreak. In addition, winds will subside to near calm across most of the region, creating good conditions for radiational cooling. Low temperatures tonight are forecast to dip down into the mid to upper 60s across the forecast area, with low 70s at the beaches. These temperatures are about 5 degrees below normal for early August. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... Forecast confidence: Moderate. Thursday: Surface high pressure wedging into the area from the north to start the day will weaken and allow the low pressure near the FL panhandle along the stalled front and some deeper moisture to shift a bit northward into GA. More of an onshore flow/weak sea breeze along with deeper moisture should allow for some showers/isolated storms, mainly later in the day near the GA coast, then shifting more north into SC Thursday night. Locally heavy rainfall/flooding will be possible. Friday: Strengthening low-level flow should allow for the surface front to shift inland and with deeper moisture in place we should see higher rain chances/amounts, especially inland. Some more showers/storms are possible Friday night as the upper trough shifts closer and deep moisture remains in place. Localized heavy rain/flooding will be possible through the period. Saturday: The upper trough should linger over the Deep South with continued favorable conditions for showers and storms. Some of the rain could be heavy so localized flooding will still be possible. Temperatures should be a bit warmer than previous days but still likely below normal. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Forecast confidence: Moderate. Upper troughing to start the period will give way to more ridging with a return to more typical summertime conditions expected. Highs generally in the lower to mid 90s away from the coast with lows in the lower to mid 70s inland. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... MVFR ceilings will persist into the afternoon at KCHS, KJZI, and KSAV. Ceilings should lift to VFR around 00Z this evening before returning to MVFR for a brief period around 12z Thursday at KCHS and KJZI. VFR thereafter. Extended Aviation Outlook: High confidence in mostly VFR conditions at KCHS/KJZI/KSAV through the period, with the best chance of restrictions from showers/storms and some low clouds/fog Friday through Saturday night. && .MARINE... Through Tonight: A stationary front will remain positioned offshore with winds northerly to northeasterly generally 10 to 15 knots. Seas will average 2 to 4 feet. Thursday through Monday: Moderate confidence this period. Atlantic high pressure along with an inland stalled front/trough will prevail through the period. Mainly south to southwest winds could briefly get near Small Craft Advisory levels at times across a portion of the southern SC/northern GA coastal waters but confidence is low in the need/timing for any headlines at this time. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...CPM SHORT TERM...RJB LONG TERM...RJB AVIATION...CPM/RJB MARINE...CPM/RJB