textproduct: NWS Wilmington

WHAT HAS CHANGED

A Wind Advisory has been issued for coastal areas for today. A Freeze Watch has been issued for the entire forecast area for Tuesday night and Wednesday morning. 06z aviation discussion was updated.

KEY MESSAGES

1) A strong storm system will bring a Moderate Risk (Level 4 out of 5) for severe weather today through early this evening.

2) Subfreezing temperatures are expected Tuesday night.

DISCUSSION

KEY MESSAGE 1...A strong storm system will bring a Moderate Risk (Level 4 out of 5) for severe weather today through early this evening. The primary threats include scattered to widespread damaging wind gusts and tornadoes.

Isolated showers and storms will expand in coverage this morning. Increasing shear and strong low levels winds will produce an immediate concern for severe weather in any showers or storms that develop. Instability will gradually build through the late morning, peaking during the early afternoon. HREF probabilities for severe weather increase rapidly after 15Z which coincides with an increase in instability. Some uncertainty remains regrading the coverage of severe weather due to a cool marine layer advecting onshore by strong southerly flow. Confidence in severe weather is lower at the coast.

Damaging wind gusts will be the primary concern in pre-frontal convection today. Instability will be weak, but strong shear could allow for a few storms to develop a brief supercellular structure. Damaging wind gusts and tornadoes are possible in these regimes. HREF probabilities favor severe weather east of US-701 through much of the day. Inland areas will have the best chance of severe weather after 3 PM and just ahead of the cold front this evening.

Timing of the main squall line has slowed slightly in the latest suite of model guidance. Impacts associated with the squall are most likely to occur between 6 PM and 7 PM inland. Between 7 PM and 8 PM at the coast. Winds associated with the line will be tightly forced at the cold frontal boundary. Damaging wind continue to be the primary concern. An isolated tornado embedded within this convection is also possible.

In addition to severe weather, clear-air wind gusts up to 40 mph are possible at times for much of the area. Stronger winds are expected at the coast due to the unobstructed southerly fetch. A Wind Advisory has been issued for coastal areas where wind gusts up to 50 mph are possible. The Grand Strand and coastal Brunswick County have the best chance of seeing these advisory-level wind gusts prior to the front's arrival this evening.

KEY MESSAGE 2...Subfreezing temperatures are expected Tuesday night.

Freezing temperatures are likely Tuesday night into Wednesday and a Freeze Watch has been issued. Light to calm winds, an unseasonably cold airmass and deep dry air will lead to good radiational cooling conditions. There will be a gradual increase in high cloud after midnight, which could hamper radiational cooling in the pre-dawn hours. Still confidence is high in much if not all of the area reaching freezing, but how far below freezing lows drop is a bit of a question. Another freeze is possible Wednesday night but confidence is lower and it may be confined to typical colder spots.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Messy TAF period upcoming today. MVFR likely for most of the area this morning as southerly flow brings lifting marine stratus onshore. Showers and thunderstorms develop this morning and increase in strength and coverage by late morning and early afternoon. VFR will dominate outside of showers and storms. Any showers and storms that impact local terminals will have the chance to produce wind gusts in excess of 50 knots. A few gusts could peak near 60 knots. Tornadoes will also be possible in the vicinity of our terminals. A strong cold front moves through the area this evening. Winds shift to the west and northwest behind the front this evening and maintain some gustiness overnight. Strong wind shear associated with a low level jet is likely until the front moves through the region this evening.

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

MARINE

Through Tonight... Strong winds and rough seas sum up the next 24 hours quite nicely. Conditions will continue to deteriorate today with enhancement likely in the vicinity of developing showers and storms; storms develop as early as this morning. Strong wind gusts and waterspouts are possible over the waters through this evening. Winds shift to the west and northwest behind the front tonight. Gales develop this morning and continue through around midnight tonight. A Small Craft Advisory will be needed following the Gale Warning to address gustiness in cold air advection. Seas will gradually recover late tonight into daybreak Tuesday.

Tuesday through Friday... Weakening offshore flow Tue as high pressure builds in from the west. May see some winds pushing 20 kt the first part of Tue morning, but by midday speeds will be 15 kt or less. Brief northerly surge Tue night may keep speeds around 15 kt into Wed before gradient collapses and speeds drop to 10 kt or less through Fri. Seas 3-5 ft Tue morning fall to 2-4 ft for Tue afternoon and remain in that range through Fri.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Freeze Watch from late Tuesday night through Wednesday morning for NCZ087-096-099-105>110. Wind Advisory from 8 AM this morning to 7 PM EDT this evening for NCZ106-108-110. SC...Freeze Watch from late Tuesday night through Wednesday morning for SCZ017-023-024-032-033-039-054>056-058-059. Wind Advisory from 8 AM this morning to 7 PM EDT this evening for SCZ054-056. MARINE...Small Craft Advisory until 10 AM EDT this morning for AMZ250- 252-254-256. Gale Warning from 10 AM this morning to midnight EDT tonight for AMZ250-252-254-256.