textproduct: NWS Wilmington

WHAT HAS CHANGED

Patchy fog has been introduced to the public forecast for tomorrow morning, primarily east of I-95 and just inland from the coast. This potential has also been reflected in the latest 00Z TAF forecast. Aviation discussion has also been updated.

As of 3 PM EDT... Confidence in forecast rain chances are not high late this week as a front sinks south and stalls across the Carolinas. In particular, coastal areas may struggle to see significant coverage of showers and thunderstorms as appears in the current forecast.

KEY MESSAGES

1) Inland portions of the eastern Carolinas should see their longest heat wave of the year so far with 90 degree heat expected to continue through Thursday.

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

DISCUSSION

KEY MESSAGE 1...Inland portions of the eastern Carolinas should see their longest heat wave of the year so far with 90 degree heat expected to continue through Thursday.

A 590 dam upper ridge centered near the North Carolina coast is responsible for the sustained period of hot inland temperatures which began today and should last through Thursday. Sinking air below the upper ridge should create a deep warm and dry layer extending down through 700 and 850 mb. Models have maintained their 850 mb temp forecasts of +17C to 18C (at or above the 90th percentile climatological values for this time of year) which increases confidence in our forecast of 90+ degree heat continuing through Thursday for locations more than 25 miles inland.

Our forecast is for an additional four days (Monday through Thursday) of 90+ degree heat inland. Assuming that Florence and Lumberton highs touch 90 degrees this afternoon, this 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 still near 70 degrees.

The upper ridge will become more narrow with time as an upper low strengthens across the northern Bahamas Tuesday into Wednesday. This feature looks a lot like an early season TUTT low, but any enhanced convection or other sensible weather impacts should remain far to our south. The arrival of a surface cold front Thursday afternoon should end this heat wave with temperatures returning toward normal for the coming weekend.

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

A warm and dry subsidence inversion should keep the forecast essentially dry through Thursday morning. Scattered showers and thunderstorms could begin to develop inland as a cold front arrives Thursday afternoon. Relatively cool and stable southerly winds may help keep coastal areas dry.

An interesting dichotomy develops among model guidance late in the week about how widespread convection may become across the area. GFS MOS guidance rain chances have really come down and confine any PoPs better than about 40 percent to the Elizabethtown-Lumberton-Bennettsville corridor close to where the front may stall Thursday night through Friday. South and east of this area PoPs are generally in the 20-40 percent range given lingering ridging and some dry air aloft. However ensemble-based NBM PoPs are much, much higher and would imply high rain chances (60-70 percent) Friday, Saturday, and Sunday even down near the coast.

Model trends have been toward somewhat lower rain chances, especially at the coast, and I ultimately lean toward that idea. This should still be our best rain chance in almost a week, but significant rainfall chances will likely remain inland.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR conditions this evening.

Fog chances increase tonight with more humid low levels observed across the region today. Kept most of the fog east of I-95 and just inland from the coast where boundary layer winds will be higher. This puts southeast NC at a better chance of more significant restrictions overnight. Only exception was to maintain persistence at CRE from last night's tidal creek fog.

Sea breeze should dominate after noon with gusts to 20 knots at the coast, mid-afternoon inland.

Extended Forecast... Predominantly VFR through Wednesday though morning fog potential should increase through Wednesday as low level moisture increases. An approaching front could bring restrictions in scattered showers and storms Thursday and Friday.

MARINE

Through Monday...Within 20 NM, light S TO SE winds are expected through period with seas of 2 to 3 feet.

From 20 to 60 NM out, generally expecting s winds less than 15 KT with seas of 3 feet.

Monday night through Friday...Bermuda high pressure will remain over the western Atlantic through the period with generally light southerly winds expected. Seabreeze enhancement nearshore could locally increase nearshore wind speeds to around 15 knots from mid afternoon through early evening each day. A cold front will approach from the north Thursday night into Friday, but only a subset of the latest models show the boundary actually reaching the coastal waters. What may happen is southerly winds will back more southeasterly on Friday with some increase in the potential for showers and thunderstorms. Forecast confidence for Friday is certainly lower than for Monday night through Thursday.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory until 1 AM EDT Monday for NCZ107. SC...Coastal Flood Advisory until 11 PM EDT this evening for SCZ054- 056. MARINE...None.