textproduct: Charleston

SYNOPSIS

A strong cold front will push away from the region this evening. High pressure will then prevail for the remainder of the week. Another cold front could affect the area this weekend.

NEAR TERM /UNTIL 6 AM TUESDAY MORNING/

Early this evening: The cold front has shifted offshore and the rush of colder and drier air has been ongoing for the last few hours. The front produced a period of strong wind gusts this afternoon, with a few observation sites measuring gusts in excess of 40 mph. Through the early evening, gusts should mostly top out in the 25-30 mph range, then diminish more significantly through the late evening hours. Northwest winds will then remain elevated through the overnight, but come down more into the 5-10 mph range.

Temperatures are forecast to drop into the upper 20s across the inland tier, ranging to the low to mid 30s as you get closer to the coast. These temperatures combined with persistent northwest winds will yield wind chill values down into the mid to upper 20s for the entire area. The inland tier of counties where the lowest temperatures are expected will see wind chills into the low 20s. The main forecast challenge is whether or not we see Cold Weather Advisory criteria, which is wind chill of 20 degrees or less. There is potential for isolated locations seeing a wind chill of 20, primarily across an area that includes Jenkins, Screven, Bulloch, Candler, Evans, and Tattnall counties. Current thinking is wind chill will mostly be in the 22-25 degree range and there are no plans for a Cold Weather Advisory right now.

SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/

Quiet and notably cooler temperatures return Tuesday in the wake of FROPA, as CAA limits highs to the upper 40s to lower 50s. With the aid of clear skies and efficient radiational cooling, will see most locations inland drop into the mid to upper 20s Tuesday night, with areas along the coast hovering near freezing. As noted in the previous discussion, winds look to remain fairly light during this time, which should negate the need for any cold weather headlines.

Northwesterly flow, albeit weak, will persist on Wednesday. This coupled with ample sunshine should allow highs to moderate back into the mid 50s. Warming trend continues into Thursday as a weak front shifts winds a bit more westerly. Thus, look for highs in the upper 50s to lower 60s to become common.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Should see largely dry conditions prevail Friday ahead of an advancing cold front. Rain chances then gradually return heading into Saturday as the aforementioned front encroaches upon the region. 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, the GEFS ensemble only showcases a 25-45% chance of seeing accumulations greater than or equal to 0.25 in. Whereas the ENS/GEPS ensemble both suggest around a 50-75% chance. All guidance then shows a less than 45% chance of seeing greater than or equal to 0.50 inch. So, all this to say - will likely only see a few tenths of rain with system, which should keep any flooding concerns low. Outside of a few lingering showers along the coast Sunday morning, expect dry conditions to return to the region.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

The 00z TAF period begins with VFR conditions and gusty northwest winds at KCHS, KJZI, and KSAV. Gusts up to around 25 knots will still be possible through about 02-03z before diminishing. We will hang on to some mid and high level clouds through much of the night and we don't expect skies to clear completely until around midday onward Tuesday.

Extended Aviation Outlook: VFR.

MARINE

Tonight: The combination of a steep pressure gradient and CAA will support gusty conditions across all marine zones through late tonight. Wind gusts are forecast to peak between 25-30 kts, with some higher gusts possible with the pre-frontal showers. Seas are forecast to peak between 4 to 8 ft around midnight, then gradually subside. Small Craft Advisories will remain in effect until 1 AM, then will gradually taper down through Tuesday.

Blow Out Tides: Strong offshore winds could result in tides dropping to -0.6 to -0.8 ft MLLW at Fort Pulaski and Charleston Harbor at low tide this evening. Levels should remain above critical low water thresholds of -1.5 ft MLLW in the Charleston Harbor and -2.0 ft MLLW at Fort Pulaski. Mariners should still exercise caution as some structures that are typically underwater could become exposed and pose a risk to navigation.

Tuesday through Friday: Conditions continue to improve throughout the day as northwesterly winds weaken and seas calm, allowing for the small craft advisories to expire. Winds remain out of the northwest overnight and 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 as winds gusts near 25 knots for a few hours Thursday morning. Westerly winds remain gusty throughout the day, weakening overnight into Friday.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Lake Wind Advisory until 1 AM EST Tuesday for SCZ045. MARINE...Small Craft Advisory until 1 AM EST Tuesday for AMZ330. Small Craft Advisory until 5 AM EST Tuesday for AMZ350-352-354. Small Craft Advisory until 1 PM EST Tuesday for AMZ374.