274 FXUS62 KCHS 211359 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 959 AM EDT Sun Apr 21 2019 .SYNOPSIS... High pressure will build across the region today, then dominate the weather through Thursday. A cold front is expected to cross through the region on Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Mid/upper level low pressure and its attendant trough will gradually lessen their influence on the region today as elongated high pressure centered across the north-central Gulf of Mexico propagates to the east. A weak surface trough across the South Carolina Pee Dee and Midlands will shift southeast and exit off the coast by late in the afternoon. Scattered to broken stratocumulus associated with the low aloft will develop and move through parts of the region through mid afternoon. Cloud cover will be a little more prevalent across the Charleston quad-county district, where skies for a couple of hours could become partly sunny. Otherwise, mostly sunny to sunny skies will dominate. We're already starting to see winds increase due to deepening mixing of the modest winds within the boundary layer. This will equate to westerly wind gusts as high as 15 or 20 kt at times. Of course this is nothing compared to the past two days. Temps are somewhat of a challenge, already running behind the hourly LAV values. Plus the SREF, HRRR and RAP all hold temps several degrees cooler than the MOS consensus and the ongoing forecast. However, given downsloping trajectories, the strong spring sunshine and H85 temps warming to 3C to 6C north to south, we have left max temps as before, mainly 70-75F. Instead we slowed the hourly climb, and will adjust later if necessary. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... Tonight: A strong radiational night is expected as high pressure dominates and skies clear as any linger stratocumulus dissipates with the loss of insolation. The boundary layer looks to decouple by mid-evening with calm to light/variable winds prevailing. Sided with the cooler side of guidance once again with lows ranging from the upper 40s inland to the upper 50s/near 60 at the beaches with mid 40s in some of the normally colder locations. Monday: The mid-levels will consist of a trough to our northeast in the morning. This trough is forecasted to move away with time, allowing ridging to build over the Southeast. At the surface, high pressure will prevail over the Southeast. Expect dry weather and sunny skies. The rising heights will allow temperatures to rise a few degrees above normal. Though, they will be cooler at the beaches with the afternoon sea breeze. Tuesday: The mid-levels will consist of riding over the Southeast. It may dampen and move a bit offshore overnight. At the surface, the center of broad high pressure initially over the Southeast in the morning will start to trend offshore in the evening and overnight. Dry weather and mostly sunny skies are forecasted. Though, a warming airmass will allow temperatures to rise into the mid 80s, cooler at the beaches with the afternoon sea breeze. Lows will be mild, generally around 60 degrees. Wednesday: Mid-level ridging may dampen a bit with time, leading to semi-zonal flow over our area. At the surface, high pressure will be moving offshore. A cold front will approach from the distant north while a storm system develops over the Southern Plains. Neither feature will reach our area, meaning another dry day. Though, high clouds should increase with time. We may see our highest temperatures in a so far this year. Highs may make a run for the 90 degree mark in some locations, assuming the clouds don't get to thick too quick. Once again, relief in the form of cooler temperatures will be at the beaches. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... High pressure will shift further offshore Wednesday night into Thursday as a cold front approaches from the north and a storm system approaches from the west. The storm system with its associated cold front is expected to move through the region on Friday, bringing showers and cooler temperatures. Saturday, the models differ on whether it will be dry or remnant showers will persist. Since most of the models lean towards it being dry, we trended our forecast in that direction. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR. Extended Aviation Outlook: VFR. && .MARINE... Through Tonight: West winds will veer to the northwest this afternoon in the wake of a surface trough then becoming north overnight. Speeds will remain 15 kt or less through the period with seas seas 2-4 ft this morning subsiding to 1-3 ft by daybreak Monday. Monday through Thursday: High pressure will prevail over the Southeast Monday. The center of the high will trend offshore Tuesday night, continuing further offshore through Thursday. A weak pressure gradient will bring fairly good marine conditions through midweek along with a sea breeze each afternoon. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...