textproduct: NWS Wilmington

SYNOPSIS

Unsettled weather will continue through early next week as waves of low pressure develop along stalled front offshore. Dry and cold high pressure will build over the area into Tuesday. Temperatures return to normal midweek as high pressure shifts off the coast. Rain chances increase Friday ahead of a cold front.

NEAR TERM /THROUGH TONIGHT/

Very broad, weak 5h trough remains in place over much of the CONUS with deep west-southwest flow over the Southeast. Stalled front lingers offshore today into tonight and over time it will creep farther away from the coast. Weak surface waves moving northeast along the front will briefly push the front closer to shore, before the offshore flow on the back edge of each wave combined with the offshore flow around the eastern edge of surface high over the Lower Mississippi Valley pushes the front farther offshore. Rather than smoothly moving offshore the boundary will walk back and forth, making larger movements away from the coast each time. This process will continue into the tonight.

Each of these waves will have the potential to spread light to moderate rain onshore, the deciding factor in how far the rain moves onshore will be down to moisture in the 900-700 mb layer. This is where the only dry air will be found today and tonight. Dry air in this layer is what brought about the end to rain Fri evening and this dry air lingers into Sat morning. Cannot rule out patchy drizzle from the nearly saturated layer below 900mb for the rest of the night and maybe some light rain along the immediate coast, but meaningful rain will hold off until mid-morning Sat. Precipitable water increases to 150-200% of normal by midday, lingering until late afternoon. Much drier air below 600mb moves in from the northwest, ending rain chances west of I-95 a little before sunset while along the coast rain will linger into the evening.

High cloud lingers past midnight, but skies will attempt to clear out by daybreak Sun. Boundary layer winds may be just strong enough to prevent widespread dense fog, but given the amount of moisture in the boundary layer areas of fog seem likely and dense cannot be ruled out Sunday morning. Temperatures today will run well below normal with lows right around normal. The rainfall gradient will be tight and hard to say just how far rain will push inland. The good news is not expecting a lot of additional rainfall. Areas west of I- 95 could stay dry with potential for around 0.05" in places while along the SE NC coast 0.10-0.20" is possible. Highest rainfall will be along the NE SC coast where 0.10-0.25" is possible.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/

Broad trough aloft will maintain W-SW flow while weakening sfc high to the north will maintain a light N-NE flow at the sfc early Sunday. The best moisture and lift will run from SW to NE along lingering front over GA/SC early Sun with a fairly dry column aloft over most of the inland NC/SC. Some very shallow moisture will remain over the area especially Sun morning but expect to see clouds break up some over the area, especially over NC Sunday aftn. As shortwave rounds the base of the broad trough aloft, should see a slight amplification of the trough as backdoor front drops down from the north and another weak wave of low pressure develops to the south. This should lead to slightly better moisture and lift getting nudged up closer to the coast with a reinforcing shot of northerly flow at the sfc later on Sun. The weak isentropic lift could help to produce some low clouds and/or light rain or drizzle later on Sunday, especially along the SC coast.

High pressure builds down from the NW on Mon as more potent shortwave drives the lingering front farther south and east. As shortwave passes, it should produce the last bit of clouds and pcp over the area before dry high pressure builds in through late Monday. Soundings do show temps below freezing above the sfc but the moisture is shallow, below 5-6k ft with very dry air above so should be cold rain or drizzle to finish before the column dries out.

Temps will be a bit higher than previous days on Sunday with some drying, and readings in the low to mid 50s. Low temps Sun night will be in the mid 30s north to near 40 south. High temps Mon will be within a few degrees of 50 with much cooler air settling over the area for Mon night. Temps should drop below freezing most places for lows with mid 20s most places inland.

LONG TERM /TUESDAY THROUGH FRIDAY/

Dry and cold conditions on Tues will modify as the high moves off the coast and a southerly flow develops through midweek. Should see plenty of sunshine until a front moves into the Carolinas on Fri with increasing clouds and chc of pcp. Temps in the mid to upper 40s on Tues will rebound back to normal or above until front moves through by Fri night.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

IFR continues at all terminals with sub 1k ft ceilings hanging around through daybreak. Periods of drizzle and mist will be possible overnight with somewhat more substantial drizzle and light rain arriving mid to late morning Saturday. Rainfall will be on and off through late afternoon, lightest inland heaviest at the coast. Mix of MVFR/IFR ceilings possible during the day with best chances for IFR along the coast during the periods of increased rainfall. Confidence in timing of IFR/MVFR switch is on the low side, but do think all sites will see some MVFR this afternoon. Rainfall comes to an end by evening as the stalled front moves farther offshore and drier air starts moving in from the northwest. Combination of recent rains and lingering boundary layer moisture suggest potential for MVFR/IFR fog right around 06Z. Just beyond the end of the valid TAF period IFR visibility becomes much more likely as skies start to clear out and winds go calm.

Extended Outlook...IFR likely Sunday morning with mix of MVFR/VFR Sunday afternoon. Nightly MVFR/IFR ceilings and visibility possible Sunday through Wednesday with daytime VFR.

MARINE

Through Tonight...Light offshore flow today will become more northeasterly tonight as high pressure to the west gradually moves east. No real cold surge associated with the arriving high and gradient remains weak, speeds will be around 10 kt today and tonight. Seas around 2 ft with occasional 3 ft well away from shore. Both an east and a southeast swell will be present with the easterly swell stronger. A southerly wind wave will also be present today with a northeast wind wave developing late tonight.

Sunday through Wednesday...High pressure nearly overhead on Sun will weaken as wave of low pressure moves by to the south and east. Another high will build in from the north Sun night into Mon tightening the gradient with northerly winds increasing from 5 to 10 kts up to 15 to 20 kts by Mon and possibly up to 20 to 25 kts Mon night. Seas 3 ft or less Sun into sun night will build to 4 to 6 ft late Mon into Tues. Small Craft Advisory conditions should develop Mon aftn into Mon eve and last into Tues. Winds and seas subside Tues into midweek as high pressure weakens and shifts off the coast with SW winds developing Wed.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory from 6 AM to 10 AM EST this morning for NCZ106-108-110. Coastal Flood Advisory from 9 AM this morning to noon EST today for NCZ107. SC...Coastal Flood Advisory from 7 AM to 10 AM EST this morning for SCZ054-056. MARINE...None.