FXUS61 KILN 281805 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 205 PM EDT Thu Mar 28 2024 .SYNOPSIS... Surface high pressure will lead to dry conditions and slightly below normal temperatures today. A few sprinkles will be possible tonight as a weak warm front moves into the region. Dry and warmer conditions are expected on Friday. && .NEAR TERM /UNTIL 7 PM THIS EVENING/... Mostly clear skies will continue through the morning hours as surface high pressure shifts off to our southeast. A developing weak warm front will nose into our area from the west later this afternoon, leading to an increase in mainly some mid level cloudiness. Temperatures will be slightly below normal with afternoon highs ranging from the lower 50s north to the mid 50s in the south. && .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM FRIDAY/... The weak warm front will remain across northern portions of our area through tonight. Moisture will be somewhat limited, but with some weak isentropic lift associated with the boundary, suppose it will be tough to rule out some sprinkles or spotty light rain showers tonight, mainly to the north of the Ohio River. Any pcpn should taper off late tonight into early Friday morning as we begin to dry out and the better lift shifts off to our east. Lows tonight will be in the 35 to 40 degree range. In developing WAA on Friday, temperatures will climb into the 60s through the afternoon across much of the area. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... On Friday evening, surface high pressure will be centered over the southeastern states, as heights continue to rise over the Ohio Valley. This period of quiet weather will be short-lived, as the broad ridging through the region flattens into more of a zonal flow pattern. As early as Saturday morning, a more active weather pattern will be setting up across the Ohio Valley, and this will continue through the remainder of the extended forecast period. The first chance for precipitation will occur early Saturday morning, as a shortwave and weak surface low move through the Great Lakes. This will be accompanied by an increase in WSW flow in the 925mb-850mb layer. This activity will primarily impact the northern half of the ILN CWA. As a surface front trails this feature and settles into the ILN CWA, some additional development will likely occur further south on Saturday afternoon and evening. A frontal zone will likely remain in place across the region for the following day or two, and as renewed warm advection aloft overspreads the boundary, additional precipitation will likely develop by Sunday morning and even into Monday. Confidence in this scenario is fairly high for Saturday, then only medium for Sunday and Monday. What does look certain is that there will be continued chances for showers and perhaps some thunderstorms through this entire period. In terms of hazardous weather, repeated rounds of rain could lead to some concern for flooding, especially with an environment that will be anomalously moist for late March into early April. Both instability and wind shear appear marginal, though a few strong storms could also occur, particularly Monday. Timing for any threat for stronger convection is very uncertain, with multiple potential rounds of activity from Saturday through Monday. By Monday, the surface frontal boundary will likely be making some northward progress, and Monday appears to be the warmest day of the period -- with highs ranging from the lower 60s in the northern ILN CWA to mid 70s in the southern ILN CWA. Still some model differences on just how far the surface boundary will move northward, so this temperature forecast is only medium confidence at best. Tuesday will be an even more active day, as a deeper trough ejects out of the central CONUS and into the Great Lakes. A surface low will also track through the area, bringing a renewed focus for activity -- with stronger forcing through the depth of the troposphere. The common elements across the model suite include cold frontal passage some time late Tuesday into Tuesday night, the potential for some better-defined convection near or ahead of this front, and the eventual development of a closed low over the Great Lakes on Wednesday. However, there are still significant differences in the strength of the trough and the depth of the surface low. Both of these factors will impact the eventual forecast for the strength of convection. At this point, while confidence is low, this does look like a setup that could produce some severe weather somewhere in the Ohio Valley region on Tuesday -- in addition to Monday, as mentioned earlier in this discussion. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... A surface high pressure ridge will continue to pivot southeast through early evening. Westerly winds between 8 and 12 knots with local gusts around 20 knots can be expected. There will be a mix of cumulus and altocumulus clouds, all VFR. Winds will temper down after 00Z Friday. For tonight, a weak warm frontal boundary will develop across central Indiana and central Ohio. A low level jet impinging on this boundary, combined with some moisture, will bring a chance of showers near the KDAY/KCMH/KLCK terminals between 03Z and 09Z. Conditions should remain VFR despite some possible measurable precipitation. Borderline non convective LLWS conditions could occur near KCVG/KLUK, but confidence is not there yet to include in the terminals yet. By Friday morning, the low level jet will have shifted off to the east/southeast, ending the shower threat. The weak boundary will remain across the north with some surface ridging located along and south of the Ohio River. Conditions will be dry with VFR conditions. Winds will increase from the west again, with some local gusts up to 20 knots possible after 18Z. OUTLOOK...MVFR conditions possible Friday night into Saturday. MVFR/IFR conditions along with a chance of thunderstorms possible Sunday through Tuesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...Hickman/JGL SHORT TERM...JGL LONG TERM...Hatzos AVIATION...Hickman