textproduct: NWS Wilmington

WHAT HAS CHANGED

Discussions updated. Chances for precip on Thursday are now mainly focused in the late day and overnight period due to a later cold front arrival.

KEY MESSAGES

1) Temperatures remain well above normal through Thursday, particularly for areas west of I-95.

2) Rain chances should increase, especially inland, beginning Thursday as a front temporarily stalls in the Carolinas.

DISCUSSION

KEY MESSAGE 1...Temperatures remain well above normal through Thursday, particularly for areas west of I-95.

An upper high centered near Bermuda and another over the southern Gulf are connected by a ridge axis across the interior Southeast US, and this is responsible for the sustained period of hot inland temperatures which should last through Thursday. Sinking air below the upper ridge will create a deep warm, dry layer in the middle troposphere, supporting abnormally warm surface temperatures. Models continue their 850 mb temp forecasts of +16C to 18C (at or above the 90th percentile climatological values for this time of year), which maintains high confidence in our forecast of 90+ degree heat continuing through Thursday for locations away from the daily cooling influences of the sea breeze.

Our forecast is for 90+ degree heat inland through Thursday. Since Florence and Lumberton highs reached 90 degrees starting on Sunday, a five day streak would eclipse this year's earlier streak of four days of 90 degree temps recorded from April 15-18 in both Florence and Lumberton. Coastal portions of the Carolinas should remain significantly cooler than inland due to sustained south winds dragging air across nearshore water temps in the middle 70s.

Guidance tools remain in line with the front settling through on Thursday night, even making it offshore by Friday morning. However, they are quick to lift the front back northward during the day on Friday, with it likely ending up north of US-76 and near or west of I-95 by early afternoon. Where this front ends up will influence the coverage of showers and thunderstorms over the weekend, and subsequently, the max temperatures each day. Current forecast max temps may be a few degrees too cool if the coverage of precip ends up more isolated.

KEY MESSAGE 2...Rain chances should increase, especially inland, beginning Thursday as a front temporarily stalls in the Carolinas.

Dry weather will come to an end as a front shifts in from the north on Thursday and subsidence aloft weakens enough to permit at least isolated pop-up convection on Thursday, with perhaps some focused development along the front itself overnight Thursday night. However, the front is expected to lift back northward on Friday before stalling across northwestern portions of the area or just north of there. Overall, the best chances exist across northwestern portions of the forecast area each afternoon at least through Monday, particularly between the stalled front and the inland- pushing sea breeze each day.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

High confidence in mainly VFR conditions thru the 18Z TAF period, especially near the coast at KCRE/KMYR/KILM. The best chance of fog/low clouds overnight looks to be inland at KLBT/KFLO but model guidance isn't very agreeable, likely due to the shallow nature of the moisture.

Extended Forecast...Moderate confidence in MVFR/IFR vsbys/ceilings each morning, generally in the 08z-12z timeframe. Restrictions are possible due to showers/storms starting Thu. Potential for daytime restrictions Friday and Saturday due to convection.

MARINE

Through Wednesday...High confidence in mainly benign, summer-like conditions due to prevailing Bermuda high pressure resulting in southerly winds mainly 10 kt or less across the local area. However, winds will be slightly enhanced Wednesday afternoon near the coast due to the sea breeze with gusts up to 20 kt. 2-3 foot, 8-9 second southeast swells will continue to dominate the wave spectrum.

Wednesday night through Sunday... Offshore high pressure will maintain control through the week. A backdoor front is expected to settle towards the waters on Thursday night and may briefly move offshore early Friday morning before lifting back northward on Friday. Generally south to southeast winds can be expected until the front draws near, with a period of east or even northeast winds possible near the coast if the front can push offshore. Sustained winds are expected to stay between 5-15 kts, with enhanced nearshore gustiness due to the sea breeze likely each day. Seas are expected to hold in the 2-3 ft range in the 0-20nmi zone and 3-4 ft range in the 20-60nmi zone through the period, mainly driven by persistent southeasterly swells with a period of 8-9 sec.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.