textproduct: Wilmington

SYNOPSIS

Strong low pressure brings the chance of severe storms and heavy rain this evening into tonight. Additional waves of low pressure will cause more rounds of storms with heavy rain Thursday night through Sunday morning.

NEAR TERM /UNTIL 6 AM THIS MORNING/

Axis of thunderstorms moving in the area has a mixture of bowing segments and supercells. This will continue to track across the forecast area through the night with some decrease in intensity expected as it gets further east. Strong shear with highly curved hodographs support the potential for tornadoes in addition to strong to damaging straight-line winds. Isolated large hail cannot be ruled out but will not be the primary hazard with this event. In addition, there will be some locally heavy rainfall, but that should be fairly transient, so while flooding potential in non-zero, it is on the lower end of threat.

SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/

As the cold front moves through the area Thursday morning, dry air likely keeps most of the day on the drier side, but PoPs continue to be mentioned for southern Ohio, northern Kentucky, and southeast Indiana. With the remnant cold pool boundary likely south of the area, destabilization and severe weather appears considerably lower than previously anticipated. This is shows well through the Day 2 SPC Severe Weather Outlook update earlier this afternoon which limits any severe threat to the far south (northern Kentucky and southern Ohio). Depending on the advancement of the convective outflow overnight, these may be lowered even more.

In response to a shortwave moving northward through the Mississippi Valley, deep moisture advection occurs Thursday afternoon into the evening hours. PoPs return and expand across the whole area during the evening and into the overnight. An additional 1-2 inches is forecast with this period, with locally higher amounts possible in convective downpours. Isolated flash flooding is possible, but the main concern will be the increasing coverage of areal flooding and rising creeks and rivers due to saturated ground. Most area rivers will begin to respond to this period of rain as a result.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

The active pattern with widespread showers and thunderstorms will continue through the weekend as moist southwest flow aloft continues and several waves of low pressure move east along a quasi-stationary boundary draped across the Ohio Valley region.

By Friday morning, the boundary should be right along the Ohio River, but it is forecast to lift north as a warm front Friday afternoon into Friday night as a somewhat stronger surface wave develops back to our west. Depending on how far north the front makes it, we may get into somewhat of a lull in pcpn heading into Friday night. However, the boundary and pcpn will sag back down into our area from the northwest through the day on Saturday with another wave then riding east along the boundary Saturday night into Sunday, bringing the last round of significant pcpn.

There will be at least a low end severe threat for Friday into Friday evening, but this will be dependent on how far the front makes it and the amount of surface based instability that is able to develop. There could also be a lower end severe threat across our southeast Saturday afternoon/evening, again dependent on the exact placement of the boundary and the amount of instability present. But all in all, the main threat through the weekend remains the potential for flooding, given the multiple rounds of showers/storms and periods of heavy rain.

The main axis of heaviest QPF totals still looks to nose up into the Tri-State area, but our entire area will see more than enough rainfall through the weekend to result in significant rises on area creeks and streams, as well as river flooding.

A significant pattern change will develop through the later portions of the long term period as a deep upper level trough settles in across the Great Lakes region. This will lead to unseasonably cool temperatures and some lower end chances for showers Monday through Wednesday.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Widespread showers and thunderstorms will quickly advance east through the remainder of the night. Some IFR conditions can be expected in heavier showers and storms. LLWS will continue until morning as a strong LLJ moves away to the east.

A cold front will move across the TAF sites from 12Z to 15Z. Winds will be decreasing as the front moves through. In addition, the MVFR ceilings are forecast to improve shortly after frontal passage. This will leave VFR conditions with westerly winds around 10 kt.

OUTLOOK...Periods of showers and thunderstorms will occur Thursday night into Sunday. This will result in MVFR/IFR conditions from time to time.

ILN WATCHES/WARNINGS/ADVISORIES

OH...Flood Watch through Sunday morning for OHZ026-034-035-042>046- 051>056-060>065-070>074-077>082-088. KY...Flood Watch through Sunday morning for KYZ089>100. IN...Flood Watch through Sunday morning for INZ050-058-059-066-073>075- 080.