Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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632 FXUS62 KCHS 012340 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 740 PM EDT Sat Jun 1 2024 .SYNOPSIS... High pressure will extend across the area through early this upcoming week. A cold front could approach late in the week. && .NEAR TERM /THROUGH SUNDAY/... Early this evening, KCLX detected isolated light showers over the coastal SC waters, moving towards the coast. Latest runs of the HRRR and HREF have indicated that showers may develop as the mid-level ridge shifts to the east. Given the radar trends and recent guidance, the updated forecast will feature the addition of SCHC PoPs for light showers and very light QPF. It is not out of the question that a couple of coastal locations could receive measurable rainfall tonight. Given increasing cloud cover and dewpoints, overnight lows will not be as cool as the last few nights with lows spanning the 60s...possibly some upper 50s in the normally cold spots. Upper 60s to low 70s along the coast. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Sunday: Even though we`re under the influence of high pressure, there is a short wave that moves through aloft. That along with increasing moisture courtesy of a southerly low level flow, e might actually get rain in some places. However, since MLCAPE isn`t overly impressive, there isn`t much deep layer shear, and condensation pressure deficits are around 100 mb, we aren`t inclined to show anything more than slight chance/chance PoPs. Max temperatures were derived from the MOS, NBM and NBM50Pct, equating to highs mainly in the middle 80s away from the coast. Sunday night: Withe the passage of the short wave, NVA develops, and with nocturnal influences any early convection far inland on the sea breeze will come to an end. Some of the guidance suggests that marine activity could attempt to make a run for some coastal sections of South carolina where the low level convergence is the best. However, other guidance keeps any convection offshore, which is where we leaned toward at this point. Within a southerly synoptic flow our low temperatures won`t be as cool as recent nights. Monday: Surface high pressure is still in control, with maybe some weak lee side troughing forming. Another short wave might approach late, and that along with additional moisture will promote at least some convection. But once again, the MLCAPE and deep layered shear are rather weak, and condensation pressure deficits are once again close to 100 mb, so nothing more than slight chance/chance PoPs. Something to watch for would be the DCAPE values, which are potentially near 1000 J/kg due to dry air above 700 mb. This could lead to some strong wind risk in the taller t-storms, and where boundary interactions occur. Low level thickness and model consensus supports highs in the upper 80s to perhaps 90F inland from the beaches. Tuesday: Ridging develops aloft, so the associated subsidence will prevent much convection from developing. There is more MLCAPE available, and with the sea breeze and the lee trough nearby, we still show isolated PoPs, mainly inland. Utilizing a mixture of the MOS and NBM guidance with 850 mb temperatures and the low level thickness, we arrive at highs a bit warmer than on Monday, and many places will reach 90F or greater. And with that comes some higher dew points over the coastal corridor. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Flat riding or quasi-zonal flow will prevail aloft through Thursday, before a deep upper low develops near the Great Lakes late in the week. We`ll still be south of the associated trough, but this pattern will force a cold front to likely approach late in the week. For now we don`t have anything more than 20/30 PoPs, especially since it`s difficult to get cold fronts into our neighborhood this time of year. We feel more confidence on hotter conditions as 850 mb temperatures that reach 17-18C Wednesday, are as high as 19-20C by Friday. Max temperatures are look to be in the 90-95F range through the period, provided the cold front doesn`t get this far southeast. Associated heat indices Thursday and Friday could be near 100F in many areas. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... VFR conditions will prevail at KCHS, KJZI, and KSAV through 0z Monday. Extended Aviation Outlook: Conditions will generally be VFR through the period. && .MARINE... Tonight: Surface high pressure over the mid Atlantic will slip into the Atlantic tonight with northeasterly/easterly flow currently across the coastal waters veering southeasterly tonight. A touch of gustiness (gusts up to 20 knots) out there this afternoon will diminish tonight with speeds largely 10 to 15 knots. Seas will run 2 to 4 feet, highest in the Georgia outer waters. Sunday through Thursday night: No real marine concerns outside of any convection, with high pressure generally in control. Even with afternoon/evening sea breeze influences, and nocturnal low level jetting, winds will mainly be 15 kt or less, with seas no more than 3 or 4 feet. Rip Currents: There were numerous reports of rip currents at Tybee Beach earlier today, mainly due to the strong long shore current reported by the lifeguards. Sunday could be similar, but given the lack of swells, and both the in-house Rip Current Calculator and Rip Current MOS showing low risk for all beaches, that`s what we have at this time. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...Adam/NED SHORT TERM... LONG TERM... AVIATION...NED MARINE...Adam/BSH