Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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726 FXUS62 KCHS 101034 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 634 AM EDT Fri May 10 2024 .SYNOPSIS... A cold front will push offshore today. High pressure will prevail for the weekend into early next week. A storm system could affect the area by the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... A quick update to add headlines for Severe Thunderstorm Watch #230 across portions of SE GA. The watch will remain in effect until noon. Earlier this morning, a cluster of thunderstorms dissipated upstream of the forecast area over southern GA. This activity created a outflow boundary that surged south, nearing the FL/GA line. Recent SPC mesoanalysis shows that nearly all of central and southern GA has little to no SBCAPE and CIN has increased to 250-400 J/kg. In addition, in the wake of the dissipating convection, the mid- levels have warmed and lapse rates have decreased to around 6.5 C/km. HRRR forecast soundings indicate that some elevated instability will remain across the region this morning, with a gradient of around 500 J/kg over central GA to 1500 over extreme southern GA. The gradient of elevated CAPE is depicted well with the SPC mesoanalysis of NCAPE, with a belt of 0.2-.025 from southern LA east to the FL/GA line. The upstream MCS over the Deep South will remain in a corridor of effective bulk shear of 45-60 kts this morning. Recent runs of the HRRR suggests that the convection will track a bit south of due east, tapping into the greater instability closer to the Gulf Coast. Based on the HRRR, a bowing line of thunderstorms is timed to reach the GA coast south of St. Catherines Island by 14Z. The organized line of thunderstorms will likely produce strong to damaging wind gusts. This area has been highlighted with Severe Thunderstorm Watch #230, in effect until noon. To the north, the environment should support a broad band of showers and thunderstorms across SE GA and the SC Lowcountry this morning. The potential for severe thunderstorms will remain limited north of the main squall line. The forecast area should remain under a deck of anvil clouds this morning, gradually decreasing this afternoon. Winds should remain from the west-southwest through this afternoon ahead of an approaching cold front. High temperatures are forecast to peak in the low to mid 80s. As the cold front reaches the Fall Line around sunset, a belt of 1000-1500 J/kg of CAPE should pool just ahead of the cold front. High resolution guidance indicates that scattered thunderstorms will develop along and ahead of the cold front, tracking over the inland counties. However, the window for convection will shorten after sunset and conditions become increasingly stable. The cold front is timed to push off the coast by midnight. In the wake of the front, winds should shift from the north with steady CAA. Given ongoing CAA through daybreak Saturday, low temperatures are forecast to generally range from the mid 50s inland to around 60 along the coast. && .SHORT TERM /SATURDAY THROUGH MONDAY/... Saturday and Sunday: Broad troughing will prevail aloft through the weekend, with high pressure building in at the surface. With high pressure dominating at the surface, the weekend will feature a rather benign weather pattern. Temperatures on Saturday will actually be much cooler than the previous week, owing to FROPA on Friday night. Highs on Saturday are forecast to peak in the mid to upper 70s. Sunday will be slightly warmer, with highs in the low 80s. Sunshine will be plentiful, accompanied by a rain-free forecast. Monday: The upper level pattern shifts a tad on Monday, with models indicating a few shortwave troughs could ripple across the forecast area. This could provide enough forcing for isolated to scattered showers and thunderstorms. Temperatures are forecast to reach into the upper 70s to low 80s. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... Beginning Monday night the forecast turns more active as a warm front approaches the forecast area from the south. Aloft, a mid- level trough is forecast to swing through the southeastern states through Thursday. MOisture is expected to build into the region after the warm front lifts northward, with PWATs approaching 2". Several rounds of showers and thunderstorms are expected as the region remains well within the warm sector with plentiful moisture, aided from the approaching mid-level trough. Temperatures are expected to gradually warm through the period, with upper 70s to low 80s on Tuesday warming to the mid to upper 80s by Thursday. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... Prior to the 6Z TAFs, IR satellite indicated widespread debris clouds across the terminals. Regional radar indicated a cluster of thunderstorms over south central GA, tracking to the southeast. This activity is expected to dissipate before reaching KSAV. However, a period of MVFR ceilings may develop over KSAV from 9-13Z. The main challenge will be the timing and intensity of MCS, located over southern AL and MS before 6Z TAFs. Based on the majority of the CAMs, the core of the MCS track along the FL/GA this morning. A band of showers and thunderstorms on the north side of the MCS is timed to pass over KSAV, expected between 13-16Z. The KSAV TAF will feature a mention of SHRA with VCTS between 13-16Z. KCHS and KJZI, the coverage TSRA will remain limited, the TAFs will indicate SHRA between 14-19Z. Late in the afternoon, a narrow band of showers and thunderstorms will develop along a cold front west of the terminals. After sunset, the coverage of showers and thunderstorms will decrease as the front approaches the terminals. The cold front is time to pass over the terminals between 3-4Z, turning winds from the NW at 10kts. Extended Aviation Outlook: VFR conditions will prevail through the weekend. Showers and thunderstorms could bring flight restrictions to the terminals Monday afternoon into the middle of next week. && .MARINE... A line of thunderstorm could push across the GA waters this mornings. These storms may yield wind gusts in excess of 35 kts, Special Marine Warnings may be issued. Otherwise, winds should remain from west-southwest between 15-20 kts. Wave heights are forecast to range between 3-4 ft. This evening, a cold front will approach from the northwest, timed to reach the coast around midnight. The front should rapidly sweep across the marine zones, turning winds from the north. Speeds will favor values between 15 to 20 kts, gusts could reach 25 kts at times. Seas will change very little overnight, remaining between 2-4 ft. Saturday through Wednesday: Generally tranquil marine conditions are forecast through the weekend as high pressure extends over the local forecast area. Winds will generally be around 10 knots, with seas averaging 1 to 2 feet. Monday night S to SE winds will surge slightly as a warm front lifts northward through the region, generally around 15 knots with some gusts around 20 knots. Seas will also increase, averaging 3 to 4 feet. These conditions will persist into the middle of the week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...CPM LONG TERM...CPM AVIATION...CPM/NED MARINE...CPM/NED