textproduct: Charleston

SYNOPSIS

High pressure will prevail for the remainder of the week, followed by a cold front moving through the area this weekend.

NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/

Clear skies, calm winds, and dew points in the 20s have allowed temps to drop quickly into the mid-30s to lower-40 within a few hours after sunset this evening. However, with the expectation that many locations will not consistently decouple through the whole night, the lower temp forecast in the mid-to-upper 20s away from the beaches still looks on track.

Previous Discussion: The base of a H5 longwave trough will remain over the region tonight. Downslope H85 flow should support a sfc lee trough across the Carolinas tonight. Northwest flow should also yield weak CAA through this evening, with some slow recovery late tonight. Near term guidance indicates that sub- zero H85 temperatures will remain over the CHS Tri-county through daybreak Wednesday. The sfc pressure gradient will remain very weak this evening, increasing to around 2 mb by the pre-dawn hours. After light to calm winds this evening, wind speeds over portions of SE GA may increase to around 5 mph late tonight, providing some mixing. It is interesting to note that the HREF indicates a solid band of mountain wave cirrus over the western Carolinas this evening, it is possible that some tufts of cirrus could reach the Midlands before dissipating. Given the clear sky and light winds, low temperatures are forecast to range in the mid to upper 20s along and west of I-95, with values around 30 degrees east. The cold temperatures combined with wind up to 5 mph may yield some low 20s wind chill across inland GA. Similar to this morning, conditions appear just above criteria for a Cold Weather Advisory.

SHORT TERM /7 AM WEDNESDAY MORNING THROUGH FRIDAY/

Northwesterly flow, albeit weak, will persist on Wednesday. This coupled with ample sunshine should allow highs to moderate back into the low to mid 50s. Overnight lows will be a touch warmer than days past, as temperatures range from the mid 30s inland to upper 30s along the coast. A weak front then dives across the region Thursday, bringing a resurgence of westerly winds, which could become marginally breezy through the afternoon. Warming trend continues under sunny skies, allowing highs to rise into the lower 60s. Otherwise, expect largely dry conditions and mild temperatures to persist Friday.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Rain chances return late Friday night into Saturday ahead of an advancing cold front. While a bit of model variability still exist concerning timing, most guidance generally agrees that Saturday morning and afternoon will be the best time frame for seeing showers. In terms of QPF, ensemble guidance continues to showcase a 70-80% chance of seeing accumulations up to a quarter of an inch. Probabilities then decrease to less than 40% when looking at accumulations up to half an inch. While a few light showers may linger overnight Saturday, should see dry conditions return to the region by Sunday. Otherwise, look for quiet conditions to prevail for the remainder of the extended period, with highs in the low to mid 60s.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

00Z TAFs: VFR. Light and variable winds persist overnight. Northwest winds between 5 to 10 kts should redevelop during the early daylight hours Wednesday morning.

Extended Aviation Forecast: VFR conditions expected to prevail through the rest of the week. Chances for rain return on Saturday, along with possible flight category restrictions from both lowered cigs and vsbys.

MARINE

Tonight, the pressure pattern will support northwest winds between 10 to 15 kts, strongest over the GA waters. Wave heights will range between 2-4 ft.

Wednesday through Saturday: Winds remain out of the northwest throughout most of Wednesday as surface high pressure builds across the southeast. Winds pickup overnight into Thursday as a front moves towards and then through the area, bringing the waters from Savannah to Altamaha Sound 20-60nm out to Small Craft Criteria, due to wind gusts near 25 knots for a few hours Thursday morning. Westerly winds remain gusty throughout the day, weakening overnight into Friday. Chances for rain return on Saturday as a cold front begins to move through, with gusty winds near Small Craft Criteria possible, especially in the outer Georgia waters Saturday morning/afternoon.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.