textproduct: Charleston

WHAT HAS CHANGED

The aviation section has been updated for the 00Z TAF issuance.

KEY MESSAGES

- 1) A period of unsettled and warm conditions for the end of the week into the weekend.

DISCUSSION

KEY MESSAGE 1: A period of unsettled and warm conditions expected for the end of the week and into the weekend.

A significant warm up is expected to take place starting Wednesday. A west-east oriented ridge that extends from the eastern Pacific and into the southwest Atlantic will drive deep layered southwesterly flow across the Southeast late this week and into the weekend. At the surface, high pressure will set up over the Atlantic and help to provide warm and moist southerly and southwesterly flow across the region as well. Ensemble support for very warm temperatures is strong, with temperatures through the column on the order of 2-3 standard deviations above normal and above the 90th percentile. The result is Wednesday highs in the low to mid 70s (8-10 degrees above normal), Thursday highs into the mid to upper 70s (10-15 degrees above normal), and Friday highs into the upper 70s to low 80s (15+ degrees above normal). In fact, Friday's high temperatures could be within shouting distance of daily records (see Climate section below). Saturday should be another day with well above normal temperatures prior to a cold front sweeping through Saturday night and ushering in cooler air Sunday and into early next week.

With the warm up will come some increase in rain potential primarily in the form of diurnal convection as the area remains largely devoid of any notable large scale forcing. Diurnal coverage will perhaps be highest as we head into Friday and Saturday as the upstream cold front draws closer to the area. An isolated thunderstorm could be possible as well, though model soundings suggest weak instability at best.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions are expected at CHS/JZI/SAV terminals through 00Z Thursday. There remains a low risk for patchy fog near the terminals overnight, but increasing high clouds likely limit this concern. Otherwise, south-southwest winds should become breezy Wednesday, gusting to around 20 kt at all terminals for a bulk of afternoon hours.

Extended Aviation Outlook: Mostly VFR though the potential for overnight fog and stratus across the region will increase through the late week time period.

MARINE

Wednesday through Sunday: The pattern will support south to southwesterly flow across the local waters beginning Wednesday and continuing into the weekend. This should result in moderate wind speeds, perhaps getting into the 15-20 knot range at time, especially by Friday as the gradient tightens a bit more. The gust potential is likely limited due to SST's across the nearshore waters in the low to mid 50s which will produce shallow mixing profiles within the warm advection regime. Expect increased potential of stronger winds and Small Craft Advisory conditions Saturday night and Sunday behind a passing cold front.

Another forecast consideration with the anticipated modest south to southwest flow across the local waters is the potential for sea fog development. The nearshore waters are quite cool as noted above, and the expected south to southwest surface flow will usher in upper 50s to low 60s dewpoints in the mid to late week time period. Confidence in the conducive setup is moderate across the general mid to late week time period, but specific timing highlighting the greatest threat is low. Probabilistic guidance isn't very aggressive at this point either. For now we will continue to highlight patchy fog for later Thursday and Thursday night.

CLIMATE

Record High Temperatures:

February 20: KCHS: 82/2018 KCXM: 78/1918 KSAV: 84/1991

CHS WATCHES/WARNINGS/ADVISORIES

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