textproduct: NWS Wilmington

WHAT HAS CHANGED

Aviation discussion updated for 00Z TAFs.

KEY MESSAGES

1) Potential for stronger or possibly severe storms ahead of cold front on Thursday.

2) Potential for Patchy Frost/Light Freeze Thursday night/Friday morning.

3) Low-End Severe Risk Possible Late Sunday/Monday, followed by an extended period of below-normal temperatures and a risk for freeze/frost during the middle to late part of next week.

DISCUSSION

KEY MESSAGE 1...Potential for stronger or possibly severe storms ahead of cold front on Thursday.

Amplified mid to upper trough will push a cold front through the area Thursday. Very warm and moist air ahead of the front will be replaced with much colder air behind it. High temps will come early on Thursday with temps up around 70 early morning and dewpoint temps in the low to mid 60s, along with gusty southerly winds. Isolated thunderstorms are expected, but the earlier timing and limited instability should somewhat limit the strength of any convective development. Overall, seems like the best chc of stronger storms will be mid to late morning inland to mid afternoon as the front moves eastward across the area with best dynamics from front, but the strength of the low level winds alone, above the surface will produce the potential for stronger wind gusts in showers or storms. SPC has outlined our area for marginal risk (level 1 of 5) of severe storms across a portion of the area, mainly north of a line from Kingstree to North Myrtle Beach. Winds will remain strong ahead and behind the front. The QPF should be limited due to the fast movement of the system. Temps will drop through the afternoon as flow transitions to cooler NW winds behind the front, with readings a good 30 degrees lower than today by late aftn on Thurs.

KEY MESSAGE 2...Potential for Patchy Frost/Light Freeze Thursday night/Friday morning.

Post-frontal surface high pressure builds rapidly over the Carolinas, becoming centered over the area by daybreak Friday. Strong CAA through the first half of the night will wane as pressure gradient relaxes. This sets the stage for good radiational cooling during the second half of the night as winds diminish, potentially decouple, particularly inland. Expect mins in the lower to mid 30s, supporting a threat for patchy frost or light freeze, mainly in outlying/rural areas. The Frost/Freeze Program remains inactive; therefore no headlines will be issued.

KEY MESSAGE 3...Low-end severe risk possible late Sunday/Monday, followed by an extended period of below-normal temperatures and a risk for freeze/frost during the middle to late part of next week.

A warm front is progged to lift north across the area Sunday afternoon. Strengthening southwesterly flow ahead of a strong cold front will support periods of showers and storms from Sunday afternoon through Monday evening/night. While instability remains the primary limiting factor, robust low-level shear may support a marginal threat for severe storms, with CSU ML ensemble guidance currently highlighting Monday as the window of greatest concern. best chance. We will continue to evaluate this severe potential as mesoscale details become clearer.

In the wake of the cold front, a deep longwave trough will overspread the Eastern US as a chilly Canadian high builds over the area. This pattern will support an extended period of below normal temperatures and a elevated risk for frost/freeze risk for a few nights.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR to start off the 00Z TAF period. A cold front approaches from the west tonight, with increasing winds aloft leading to low-level wind shear especially near the coast. Expect showers and isolated thunderstorms with the front Thursday from late morning into the afternoon, with high confidence in MVFR cigs and low confidence in IFR/LIFR. Strong winds will accompany the front for much of the day, including in the NW to N flow just behind the front.

Extended Forecast...VFR is expected late this week and for the first half of the weekend. Restrictions are possible due to increasing rain chances on Sunday.

MARINE

Through Thursday...Winds will increase as gradient tightens ahead of an approaching cold front. Gusts could approach 20 knots within the sea breeze this afternoon and sustained winds will continue to increase this evening, leading to sustained winds near 20 knots and gusts near SCA thresholds tonight. The sustained winds will increase above SCA thresholds on Thurs and should see gale gusts to 35 kts Thurs aftn through Thurs night. The Gale Watch is now a Gale Warning for frequent gusts over 35 kts. Winds will remain strong as they shift from SW to W Thurs aftn and then NW to N by Thurs eve. This strong southerly flow will push seas up above as high as 5 to 7 ft.

Thursday night through Monday...Post-frontal offshore flow will allow winds and seas to subside rapidly Thursday night as high pressure builds over the area. There's high confidence in sub-SCA conditions Friday through early Sunday with seas generally 2-3ft.

Winds veer to southerly late Sunday afternoon into Sunday evening as a warm front lifts north, with winds increasing to 20-25kts. Seas respond accordingly, building to 6-7 ft late Sunday afternoon into Sunday night. SCA conditions may persist through Monday, ahead of a strong cold frontal passage Monday evening.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...Gale Warning from 2 PM Thursday to midnight EDT Thursday night for AMZ250-252-254-256.