Area Forecast Discussion
Issued by NWS Wilmington, NC

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681 FXUS62 KILM 170745 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 345 AM EDT Fri May 17 2024 .SYNOPSIS...
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Weak high pressure will exit the coast today. Low pressure moving east across the Carolinas this weekend will bring periods of showers and thunderstorms. A cold front will sweep south on Sunday bringing drier and cooler weather Monday into Tuesday. A warming trend is expected during the middle portion of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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High pressure overhead this morning will be shunted offshore as storm system currently over the Gulf states approaches. Mid clouds will thicken during the day today with as a rather potent shortwave moves across from the southwest. Despite PVA and increasing moisture, rain chances may be limited this afternoon owing to an impressive subsidence inversion developing at 500mb midday across the area likely due to ongoing convection in the Gulf. May see some shallow showers develop beneath the inversion before it lowers, and weakens, through late afternoon. Pops generally less than 30% through sunset. Highs today approach 85F with increasing low level WAA. Rain chances ramp up after midnight as isentropic lift develops from the surface up to ~310K (around 600mb) ahead of a warm front and PWATs increase to 1.75+". Rainy and cloudy night will keep low temps in the upper 60s. Rain coverage will begin to decrease before dawn Saturday.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY/...
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A well-defined shortwave will move eastward across the Southeast states Saturday and Sunday, slowing significantly as it reaches the Carolina coast Sunday night. An upper ridge expanding across PA/NY will likely trap the disturbance just off our coast Monday, potentially allowing it become a closed feature as shown on the 00z GFS. At the surface, a diffuse area of low pressure should exist across the central and eastern Carolinas Saturday morning, likely responsible for sustaining scattered showers and thunderstorms across the area. Although I certainly expect there to be convective activity on radar, I`ve trimmed PoPs back slightly versus previous forecasts as there are hints in most models that a slug of mid level dry/stable air from subsidence downstream of Gulf coast convection will traverse the Carolinas for a portion of the day. The surface low should push offshore by Saturday evening. The low should remain weak, however the building upper ridge to our north will cause rising surface pressures across the Mid Atlantic and a tightening pressure gradient here. This will help push a cold front south across the area Sunday. A second round of shower and thunderstorm chances should accompany this frontal passage, which happens to align with the upper level trough pushing overhead too. Forecast PoPs remain rather high (70 percent) for Sunday. Cool air should deepen with continued northerly winds Sunday night. Some scattered showers could continue especially along the coast.
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&& .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
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The upper ridge to our north will likely continue to trap this weekend`s shortwave and weak surface low between the Carolinas and Bermuda through Wednesday. Shower potential should diminish rapidly in the cool, dry northerly wind across the Carolinas. Eventually by Thursday a significant shortwave pushing across the Great Lakes should erode the ridge to our north, removing the block and allowing our old (and very tired) offshore disturbance to escape off to the east. In terms of sensible weather, below normal temperatures are expected Monday into Tuesday with northerly flow across the area. Later forecasts may need to make further downward adjustments to Monday as some guidance shows the potential for temperatures barely eclipse 70 during the day. A warming trend should begin in earnest by Wednesday and by Thursday summerlike temperatures in the upper 80s are expected.
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&& .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Currently VFR across the area. There remains a chance for fog before morning, mainly MVFR with patches of IFR/LIFR possible, although saturated layer at surface is quite thin. Couple things to keep an eye on: stretch of mid clouds moving down from the south across NC and lingering WSW winds around 5 kts in the area. If clouds and winds linger, chances of fog will decrease quickly and TAF amendments will be necessary. After daybreak, VFR to dominate rest of TAF period. Mid clouds will be thickening during the day, around 10 kft, and lowering this evening into tonight, though expect sub-VFR ceilings to hold off until after 6z Saturday morning. A few storms are possible this afternoon and evening associated with an upper shortwave, but coverage not enough for TAF inclusion. Rain chances increase tonight, with isolated thunder possible. Winds remain relatively light out of the south today into tonight. Extended Outlook...The next storm system and associated periodic flight restrictions will affect the area late Fri night thru the weekend and likely into Mon. && .MARINE...
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Through Tonight...Light southerly winds today will increase a bit tonight as a warm front lifts north across the waters. This will be accompanied by increasing rain chances after midnight tonight, with isolated thunder possible especially for northern coastal waters. Seas linger around 2 ft today and tonight, primarily from a SE 6 sec swell and a weak NE 8-9 sec swell moving in later today. Saturday through Tuesday...Low pressure across interior North Carolina will slide eastward during the day Saturday accompanied by scattered showers and thunderstorms. Light southerly winds should veer southwesterly Saturday night as the low goes by. Once the low gets farther offshore and strengthens Sunday morning, it will drag a cold front southward across the coastal waters. Another period of rain and possible thunderstorms is expected. Northerly winds should increase to near 20 knots by Sunday night into Monday and there is an outside shot we`ll get to Small Craft Advisory conditions across the Cape Fear waters. Breezy northerly winds should continue into Tuesday as the low stalls 300 miles southeast of Cape Fear.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... NC...None. SC...None. MARINE...None. && $$ SYNOPSIS...TRA NEAR TERM...VAO SHORT TERM...TRA LONG TERM...TRA AVIATION...VAO MARINE...TRA/VAO