textproduct: Wilmington

WHAT HAS CHANGED

No major changes.

KEY MESSAGES

1) Widespread precipitation is expected Sunday afternoon into Monday, with a chance of heavy rain and a few strong storms.

2) Below normal temperatures are expected next week.

DISCUSSION

KEY MESSAGE 1)

High pressure is beginning to drift east of the region this morning, with very light winds and radiational cooling leading to some fog development across the southern half of the forecast area. This seems to be mostly confined to river valley locations so far, but could expand somewhat before sunrise.

A shortwave in the zonal flow will move quickly east out of the middle Mississippi Valley today. A surface low is also forecast to move east ahead of the wave, with a warm front moving north into the southern sections of the ILN forecast area. Theta-e advection ahead of the wave will lead to a significant increase in deep-layer moisture, with precipitable water values reaching well over an inch and a half, and HREF ensemble guidance suggesting maybe as high as 1.7 to 1.8 inches. Widespread precipitation is expected to develop out ahead of the shortwave and the surface low, and there may be several waves of precipitation through the evening and overnight hours. There is also evidence of an MCV that may develop and move east into the area, perhaps associated with the first wave of precipitation this evening. There is also an increase in 850mb flow associated with a LLJ, primarily nocturnally, which could renew precipitation during the overnight hours. With all of this said, CAMs are still suggesting a lot of uncertainty in the location of the heavier swaths of precipitation. There could be some places where multiple rounds of heavy convection lead to 2-3 inches of rainfall, but confidence is low on where and when that will occur. WPC continues to highlight most of the area with a Slight Risk of excessive rainfall for Sunday and Sunday night, but in collaboration with neighboring offices, there was not enough certainty to issue a flood watch as of now.

Instability remains the primary limiting factor for a severe risk across the area, with soundings looking generally moist adiabatic, with boundary layer thermodynamics that are quite marginal. The HREF mean suggests about 500 J/kg of SBCAPE in the southwestern ILN CWA. The forcing and wind fields would definitely be supportive of a severe risk, with deep-layer westerly bulk shear of around 50 knots, and considerable backed surface flow resulting in curved hodographs and an enhancement to SRH values, particularly in the 00Z-06Z time frame. This is a conditional severe risk based on the amount of instability that ends up being present, but sometimes strong forcing and higher-end shear can compensate for a lack of instability. The 06Z D1 SPC outlook captures this well, with the greatest potential in the southwestern ILN CWA. Several CAMs have depicted the potential for a few organized / bowing cluster of storms, which may be capable of damaging winds (and perhaps a tornado).

With the slow passage of an incoming cold front Monday, additional convective development is likely in the southeastern ILN CWA on Monday afternoon. Couldn't rule out a few strong storms before precipitation exits early Monday evening.

KEY MESSAGE 2)

Behind the system, dry weather will return to the area Monday night through the middle of the week. Temperatures are expected to remain a little below normal through the week, with perhaps a trend toward slightly warmer conditions going into the weekend.

Overall, precipitation chances look fairly low, though a weak shortwave could bring some showers and storms late Wednesday into Thursday.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

While prevailing VFR conditions are expected overnight, some fog is possible at KCVG/KILN, and fog appears likely for KLUK.

Winds will remain light today, before picking up out of the southeast during the late afternoon and evening. Some gusts to around 20 knots are possible. Showers and storms will begin to move into the area after 01Z, with winds shifting to the southwest, and eventually MVFR ceilings moving into the area as well.

OUTLOOK...Thunderstorms are possible Sunday evening through Monday. MVFR conditions are possible on Sunday night and Monday as well. Thunderstorms are possible again on Thursday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...None. KY...None. IN...None.