textproduct: NWS Wilmington

WHAT HAS CHANGED

Rain chances have been reduced substantially for today and Sunday. Monday's cold front is now anticipated to reach the area slightly later in the day, but still should be accompanied by numerous showers and thunderstorms.

Updated aviation discussion for the 12Z TAF issuance.

KEY MESSAGES

1) Good chances of showers and thunderstorms will accompany the next cold frontal passage on Monday.

DISCUSSION

KEY MESSAGE 1...Good chances of showers and thunderstorms will accompany the next cold frontal passage on Monday.

After models have trended faster and farther offshore with a shortwave on Sunday and rain chances have fallen to only 10-20 percent, the next good chance of rain now appears to develop Monday ahead of a cold front. There's still a fair amount of spread in just how much 850-700 mb moisture arrives on Monday bracketed by the wet GFS and the somewhat drier ECMWF and Canadian models, but increasing upper level divergence and the front itself swinging in during the afternoon should lead to scattered to numerous showers with embedded thunderstorms developing across the area.

0-6 km bulk shear should increase to near 30 knots ahead of the front Monday, coincident with the time where GFS/NAM forecast soundings suggest 1000-1500 J/kg of uncapped CAPE could be present. This amount of shear and instability could support organized multicells with some threat for strong wind gusts. SLU's CIPS Severe Analog's website shows no significant severe weather threat based on yesterday's 00z GFS, but this still may be our one potential for impactful weather over the next five or six days.

Behind the front, cooler air will build in north to northeasterly winds Monday night. The upper trough should take its time coming through, allowing a thick zone of humid southwest winds above the slowly deepening frontal inversion to keep rain going through at least the first half of Monday night. Storm-total rainfall forecasts over the coming three days are over one inch for most locations east of I-95, very welcome news given the ongoing D2/D3 drought and daily record low river levels we're been experiencing.

AVIATION /09Z SATURDAY THROUGH WEDNESDAY/

Predominant VFR. Some spotty showers this morning but not seeing any impacts. Towards this afternoon CIGs will get to near or just below MVFR thresholds but little impact to VSBYs expected due to light rainfall. The exception would be any isolated thunderstorms with higher rain rates where VSBYs could drop to MVFR. Rain chances will clear out around 00Z but there may be fog/CIG issues after 06Z. MVFR possible at this time.

Extended Forecast... Restrictions likely due to unsettled weather through Monday night with VFR returning Tuesday and likely prevailing through Wednesday. Restrictions are possible Thursday with another frontal system.

MARINE

Through Saturday... SW winds 10-15 knots with gusts 15-20 kts. Seas generally around 2 feet within 20 NM from shore and near 3 feet out to 60 NM.

Sunday through Wednesday...Generally light southwesterly winds are expected Sunday and Monday in advance of a cold front that should reach the waters Monday afternoon. Model consensus is now slightly faster with the timing of the frontal passage than was anticipated this time yesterday. Trends are also toward considerably less coverage of rain for Sunday into Sunday night with little more than isolated showers now expected.

As the front arrives Monday afternoon, chances of showers and thunderstorms should increase substantially and winds will shift to the north and then northeast, increasing to 20 to 25 knots Monday night as a surge of cooler air builds in. A Small Craft Advisory may be needed inside 20 miles of shore. Winds should gradually diminish Tuesday into Tuesday night as a narrow ridge of high pressure moves overhead and then offshore Wednesday.

CLIMATE

The rain gauge at the Florence, SC ASOS (KFLO) clogged during Thursday's rainfall event, only measuring approximately one- quarter of the actual rain that fell. Surrounding mesonet and NWS coop stations recorded accurate totals and the geographically nearest one, 0.98 inches, was selected to use for the Florence climate record for Thursday May 7.

Technicians have not been able to visit the site to unclog the gauge, so it's possible rain that falls this weekend into Monday may not be measured properly.

ILM WATCHES/WARNINGS/ADVISORIES

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