textproduct: NWS Wilmington

WHAT HAS CHANGED

The Freeze Watch for Coastal Georgetown County has been upgraded to a Freeze Warning.

KEY MESSAGES

1) Subfreezing temperatures are expected tonight, and possible again Wednesday night.

DISCUSSION

KEY MESSAGE 1...Subfreezing temperatures are expected tonight, and possible again Wednesday night.

Freezing temperatures are likely tonight. Therefore the existing Freeze Warning remains in effect. Coastal Georgetown County was the only forecast zone awaiting a potential upgrade. Various probability sources have nudged probs for freezing temperatures upward due to advection behind a reinforcing surface trough. With these considerations, the Freeze Warning has been expanded to all areas of our CWA.

Tonight's temperature forecast is not certain. Aforementioned surface trough will produce a light boundary layer wind which would keep temperatures closer to freezing. This surface trough will bring some weak cold air advection with it. In addition to the potential for light winds, thin cirrus could limit variability due to radiational cooling. Lows should bottom-out around 30 degrees for most of the area; around freezing near the coast.

For Wednesday night, the surface ridge axis elongates, setting up north and west of the area. Not a pattern that would lead to calm winds. Additionally it appears there will be at least some cloud cover, which could be substantial for the first half of the night. This suggests the potential for temperatures near freezing is very low. However, patchy frost is expected over much of SE North Carolina and NE South Carolina.

AVIATION /04Z TUESDAY THROUGH SATURDAY/

VFR. Lingering gustiness will continue through 12Z. There could be a brief period where the boundary layer decouples prior to post- sunrise mixing. Deep mixing in dry air this afternoon could mix down some periodic gusts up to 20 knots. Winds become light this evening and any existing gusts will subside.

Extended Forecast... Breezy tonight and early Tuesday. VFR through Friday.

MARINE

Through Tuesday... The Gale Warning has been replaced with a Small Craft Advisory which is in effect through this morning. The advisory end times are staggered between SC and NC nearshore waters. This attempts to reflect the gradual cessation of 6 foot seas from west to east. Seas linger a few hours longer for the NC nearshore waters. Winds maintain a west to northwest direction today. Cold advection over the relatively warmer waters should maintain some gustiness up to 20 knots. Winds turn northerly tonight as high pressure traverses the area.

Wednesday through Saturday... Sprawling high pressure over the east coast Wed through Fri will be suppressed south by low pressure passing well north of the area and its weak surface trough Fri night into Sat. Weakening northerly surge Wed morning will lead to winds around 15 kt, but by afternoon winds will be around 10 kt. Ill-defined gradient keeps northerly flow weak through Fri. Return flow develops after the ridge axis is pushed south early Sat, but speeds will remain 10-15 kt. Seas on the high end of the 2-4 ft range Wed morning settle closer to 3 ft by midday Wed and generally stay on the low end of the 2-4 ft range through the end of the week.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Freeze Warning from 2 AM to 10 AM EDT Wednesday for NCZ087-096- 099-105>110. SC...Freeze Warning from 2 AM to 10 AM EDT Wednesday for SCZ017-023- 024-032-033-039-054>056-058-059. MARINE...Small Craft Advisory until 10 AM EDT this morning for AMZ250- 252. Small Craft Advisory until 7 AM EDT this morning for AMZ254- 256.