textproduct: Wilmington

WHAT HAS CHANGED

Higher rainfall amounts expected today into Wednesday, which could pose a minor flooding risk.

KEY MESSAGES

1) Higher rainfall amounts resulting in minor flood potential today into Wednesday morning.

2) Seasonably warm and wet conditions continue through the weekend, leading to the development of thunderstorms and an increased potential for areal and river flooding.

DISCUSSION

KEY MESSAGE 1)

Synoptically, zonal mid level flow has developed across the eastern CONUS, with troughing in the west. Persistent, deep layer southwesterly flow will usher in a tropical air mass, resulting in unseasonably warm and wet air. For perspective, PWATs will increase to about 2-3x the normal values today and persist for the majority of the week.

Warm front will begin to lift north of the Ohio River today before stalling out. This quasi-stationary front will be the primary forcing mechanism that will result in a prolonged period of steady rainfall for nearly 24 hours straight.

Some light rain/sprinkles will continue to move through during the early morning hours, but a more broad complex of moderate rainfall will be ushered in from the west during the mid to late morning hours. This slug of rain will persist through a good portion of the day and into the overnight hours. CAM guidance, ensembles and HREF LPMM all seem to be in agreement that the most prolonged period of moderate rainfall will be somewhere between the Ohio River and the I-70 corridor, resulting in the largest QPF footprint. During this next 24-36hr time period, most of these locations can expect 1-3" of rainfall, with perhaps some isolated amounts just over 3". Seasonably, lower soil permeability will also contribute to the potential flood risk without having a good spring thaw yet, nor a green-up with vegetation. The biggest risk with this period of rainfall will be some localized areal flooding and frequent hydroplaning on roadways with the steady rainfall.

It should be mentioned that some guidance does show a fairly robust swath of this higher QPF aligning itself across the Ohio River. Other rivers and tributaries will have to be monitored closely as these vulnerable locations may see increased hydro issues, especially later this week after multiple days of rainfall.

KEY MESSAGE 2)

Wednesday afternoon appears to offer some breaks in the rain as the warm front tries to shift slightly to the north. This will place the ILN CWA more in the open warm sector and result in some instability building in. Models begin to show the potential for complex of storms moving in from the west late day Wednesday into Wednesday night. While some strong storms may develop, bufkit soundings seem to keep most of the instability elevated with some resemblance of a low level inversion maintaining itself during the evening/overnight period. Combine this with very saturated profiles, it will likely be difficult for hail or wind to reach severe criteria. However, some localized stronger wind gusts and small hail certainly plausible. ML tools also not strongly in favor of severe potential, but will continue to monitor trends with this.

Robust shortwave trough expected to swing through the Midwest region Thursday, offering another good potential for thunderstorm development and heavy rainfall. With every round of rainfall, the flooding risk will only continue to rise. The more convective-type rainfall on Wednesday and Thursday could also result in more flash flooding scenarios as well.

While Friday may not be completely dry, it does appear that we will observe more breaks in the rain, particularly Friday afternoon and Friday night. However, this remains short-lived as another mid level trough and associated upper level energy will usher in a complex of showers and storms on Saturday. Too far out to get into details on timing/intensity, but the primary concern is yet another wave of convective rainfall that will add to the already saturated soils and rising rivers/tributaries.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Light rain/sprinkles will continue to move across the terminals during the early morning hours. Precip will generally be light during this period, so tried to remove SHRA mention in the tafs for a few hours this morning when pcpn should be the lightest or most limited in coverage.

Warm front will lift northward overnight, stalling out across south- central Ohio. This stalled boundary will result in continuous development of rain showers through the day. This steady rainfall is likely to become light tonight across our terminals, so tried to time out a transition from moderate to light SHRA for KCMH/KLCK and KDAY. Elsewhere, confidence is higher for a more prolonged period of moderate SHRA.

CIGs likely to remain at least IFR for the entirety of the taf period. Some pockets of MVFR/VFR certainly possible this morning, but by the afternoon, IFR/LIFR CIGs likely become socked in. As for vsbys, a mix of MVFR/IFR primarily expected with the rain. MVFR becomes more favored later this morning and afternoon, but guidance suggests better chances for IFR tonight.

Winds generally remain below 10 kts through the taf period. Winds will be out of the southeast to start, shifting to the southwest this afternoon but becoming much more variable tonight with the meandering frontal boundary.

OUTLOOK...MVFR/IFR conditions are possible through Friday.

ILN WATCHES/WARNINGS/ADVISORIES

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