textproduct: Wilmington

SYNOPSIS

An upper level disturbance will bring showers to the region tonight into Christmas morning. An active pattern will continue into the weekend with multiple rounds of precipitation. Mild conditions will prevail through the weekend before a much colder airmass moves into the region early next week.

NEAR TERM /THROUGH TONIGHT/

Areas of fog have developed this morning with some of the fog locally dense. So far, the fog has been somewhat transitory and with some high clouds moving in aloft, there is some uncertainty as to how persistent the dense fog will be. Have covered it with an SPS for now but will continue to monitor for a possible Dense Fog Advisory for at least parts of our area over the next few hours.

Surface high pressure overhead this morning will shift off to the east through this afternoon. This will allow for a continued increase in mainly high level clouds with highs today ranging from the mid 40s north the mid 50s in the far south.

SHORT TERM /THURSDAY/

In northwest flow aloft, some weak mid level energy will drop southeast across the Ohio Valley tonight into early Thursday morning, while at the surface, a weak frontal boundary sags slowly south across our area. This will be accompanied by a weak low level jet that will shift eastward overnight and allow for some weak moisture advection up into the region. As a result, expect light showers to develop tonight and continue into Christmas morning. Some weak elevated instabilities will also develop, so suppose it will be tough to rule out a rumble of thunder across mainly our southern areas later tonight.

With the boundary across our area, we will end up with a decent temperature gradient from north to south. Lows tonight will range from the upper 30s northeast to near 50 degrees in the far southwest. Highs on Christmas Day will range from the upper 40s far north to the lower 60s along and south of the Ohio River.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

On Thursday evening, an active, pseudo-zonal flow pattern will remain in place across the Great Lakes and Ohio Valley region. Conditions will remain considerably warmer than normal through the weekend, before a pattern change occurs and brings colder air into the area for the start of next week.

Rain is expected on Friday, beginning early in the morning due to isentropic ascent ahead of a surge of theta-e aloft, then ending late in the day after the shortwave axis and and a weak cold front move through the area. Between waves, a dry period is expected for Saturday, before a stronger wave brings additional rain on Sunday morning. Throughout this period, although the boundary layer theta-e boundary will be shifting a bit north and south, conditions will remain very warm -- particularly for the southern half of the ILN forecast area, where there is higher confidence on remaining south of the theta-e gradient. There are no significant concerns with the rain on Friday.

On Sunday, the upper pattern will amplify significantly, as a surface low and upper low track east through the Great Lakes. Rain will develop ahead of these features early Sunday morning, with additional precipitation in the vicinity of a cold front. This front will mark a significant change in the weather, bringing in a much colder air mass -- with a quick drop in temperatures and windy conditions expected. Although it is out on Day 5/6, and confidence is low at this distance, will have to keep an eye on Sunday and Monday for the potential for winds to approach headline criteria. Beyond any potential hazards, it should be noted that max temps may fall by as much as 30-35 degrees from the days before the cold frontal passage to the days after the colder air mass has arrived.

AVIATION /11Z WEDNESDAY THROUGH SUNDAY/

Areas of fog will result in IFR to locally VLIFR vsbys early in the TAF period before dissipating through mid to late morning. High pressure will move off to the east today with mainly high level clouds streaming overhead.

A frontal boundary will move south into our area tonight and this will lead to a developing chance for showers later this evening through the overnight hours and on into Thursday morning. Some weak instabilities may even support an isolated thunderstorm later tonight.

MVFR clouds will develop this evening and then trend into IFR through the night. IFR to VLIFR cigs will then persist through Thursday morning. MVFR to IFR vsbys will also be possible with the rain showers during the second half of the TAF period.

OUTLOOK...MVFR ceilings possible through Sunday.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Dense Fog Advisory until 9 AM EST this morning for OHZ034-035- 042>044-051>053-060>062-070-071-077-078. KY...Dense Fog Advisory until 9 AM EST this morning for KYZ089>096. IN...Dense Fog Advisory until 9 AM EST this morning for INZ050-058-059- 066-073>075-080.