textproduct: Wilmington

SYNOPSIS

High pressure will slowly build into the middle Ohio Valley today. The high will exit to the east Thursday as an upper level disturbance brings widespread rain Thursday night into Friday. Above normal temperatures will persist through the first half of the weekend. More seasonable conditions will return early next week.

NEAR TERM /THROUGH TODAY/

Weak cold air advection will enter our area from the west early this morning, providing light westerly winds and overcast skies. Surface high pressure is likely to eventually scatter these clouds late in the day. High temperatures will reach the upper 40s to lower 50s despite the cloud cover.

SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/

Mostly clear skies and light winds are expected tonight under high pressure. A mid-level shortwave digging across the Intermountain West will cause ridging to develop over our area on Thursday. This, along with increasing southerly flow will bring temperatures reaching the upper 50s to lower 60s by Thursday afternoon. Mid and high clouds will increase through the day.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Moist ascent will increase into Thursday evening/night with the approach of a S/W into the region. The combination of increased forcing and moisture advection will allow for showers (with a few isolated thunderstorms possible) to overspread the ILN FA toward midnight and beyond as the sfc low tracks through the nrn OH Vly and Great Lakes region. Enhanced SW LL flow will become established locally during this time, with most of the rain locally focusing just ahead of the trailing cold front, which will drift into the area into Friday morning.

Within the WAA regime and expansive cloud cover and pcpn, lows on Thursday night will bottom out in the mid to upper 50s, about 30 degrees above seasonal norms. Additionally, a tightening pressure gradient Thursday night will yield increasing SSW sfc flow, with sustained winds of around 20-25 MPH with sporadic gusts near 35 MPH likely into early Friday morning as the sub-1000mb low darts NE into the Great Lakes region. The gradient will relax into the afternoon Friday with the slowing/stalling of the front into ern parts of the OH Vly by late in the day.

Into the day Friday, the approaching trof becomes stretched out/elongated as a midlevel high is established near FL. This will promote the development of an expansive corridor of enhanced mid/upper level flow from TX into the OH Vly, with a second impulse within this flow providing enough lift and forcing for another round of rain by Friday night, especially near/SE of I-71. This impulse (and the associated cyclogenesis) will induce a northward nudge/pivot of the LL baroclinic zone, with some pcpn development expected on the nrn/wrn side of the front as the boundary is overrun with increased moisture once again.

While there are still some details to be worked out regarding the evolution of the overall system, the progressive nature of the parent trof, which will dig into the OH Vly by Saturday, should keep the overall potential for heavy rain lower than would otherwise be the case, despite /very/ high PW anomalies persisting in the region for an extended period of time Thursday into early Saturday. In fact, PW anomalies may exceed 300% of seasonal norms both Thursday night and Friday night, suggesting that rainfall rates should be fairly efficient where there is sufficient lift. Essentially, this paints the picture of a favorable pattern for a rainy stretch Thursday night into early Saturday with some soaking rain, but not one that would be highly-favorable for excessive rainfall or flooding concerns locally. Certainly, as mentioned, some details are still not yet in focus and the current signal for the heaviest rain in parts of KY/TN and nrn MS/AL may shift subtly in the coming days. But the greatest potential for over an inch of rain is confined to far srn parts of the ILN FA in nrn KY into far srn OH, with the bullseye heavier ensemble QPF footprint (>1.5") more across SE KY into NE TN. So the evolution will be watched to determine whether a brief heavy rain/flooding setup could unfold Friday night from N KY into far srn OH or whether the greatest potential will stay to the S of the ILN FA as is currently expected.

Although the latest guidance has trended a bit slower with the progression of the front back through the ILN FA (late Saturday afternoon into Saturday evening), CAA will still develop into the region Saturday night into early Sunday, with breezy conditions (gusts of 30-35 MPH) expected on the backside of the departing system. Some snow showers are likely Saturday night into Sunday afternoon as forcing coincident with the main trof axis pivots through the region. With sufficient moisture and a cooling profile, some light snow showers are expected, particularly near/N of I-70, with minor accumulations possible.

Highs on Sunday will only reach into the upper 20s to lower 30s, with some flurries/snow showers likely across parts of the region. Lows Saturday night and Sunday night will bottom out in the 20s, with moderating temperatures into early next week once again. Return flow will become established fairly quickly by Monday into Tuesday, with warmer temperatures (highs in upper 30s to lower 40s) building back into the OH Vly once again.

AVIATION /05Z WEDNESDAY THROUGH SUNDAY/

Stratus deck will develop and thicken across the TAF sites overnight and persist into the midday hours as weak high pressure builds into the region. For this afternoon, guidance suggests these clouds will erode from southwest to northeast, eventually bringing VFR conditions for the Columbus terminals by evening.

Main uncertainty is whether IFR cloud bases occur this morning. Ceilings will likely be on the low side of MVFR. Therefore, have include a tempo group for the sites north of Cincinnati between around 11 and 15Z.

VFR conditions are expected tonight.

OUTLOOK...MVFR to IFR conditions possible Thursday through Friday night.

ILN WATCHES/WARNINGS/ADVISORIES

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