FXUS61 KILN 121749 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1249 PM EST Mon Nov 12 2018 .SYNOPSIS... Low pressure will move from the Gulf Coast into the Central Appalachians today as a cold front moves in from the west. These systems will bring initially rain this afternoon, mixing with and changing to snow tonight. Some light snow accumulation will be possible through early Tuesday. High pressure will build into the area Tuesday into Wednesday, offering dry weather conditions. The next chance of precipitation arrives Wednesday night into Thursday with the arrival of a low pressure system. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Rain with embedded sleet is moving out of the southeast counties. Cannot rule out some additional patchy light rain across this same area, but for the most part it appears that conditions will be dry through the remainder of the daylight hours. Bumped highs down just a bit in the southeast. Otherwise only very minor adjustments to temperatures based on latest trends. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Favorable isentropic lift associated with srn stream system to result in an increase in pcpn coverage this evening as northern stream trof digs southeast into the Great Lakes and sfc cold front pushes into ILN/s Fa. As a result pcpn to overspread the entire area early. As the boundary layer cools, pcpn will change from rain to snow from northwest to southeast. Thermal profile will likely remain warm enough in the far southeast to keep most of the pcpn rain until very late tonight when pcpn is diminishing. Forecast soundings show a period later this evening into the overnight hours where the moist lower layer is warmer than -10 deg C...suggesting all liquid supercooled water. To complicate the matter - there is a layer aloft which may enable a seeder feeder scenario resulting in snow. Eventually, the separation between these layers increases to more than 1500M, pointing to the potential for drizzle/freezing drizzle. As better lift exits have a period of this freezing drizzle/drizzle but do not expect much in the way of ice accumulation. Regarding snow accumulation - have up to an inch in the far northwest to very little in the far southeast. Pavement temperatures look to start out warm but some slick spots will remain possible for the Tuesday morning commute. Lows tonight to range from the upper 20s northwest to the lower 30s southeast. Region of 5H confluent flow to work into the Ohio Valley with surface high pressure nosing in Tuesday. Any lingering pcpn will come to an end early. High temperatures to range from the lower 30s northwest to the upper 30s southeast. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Complex low pressure arriving from the southwest will be the main weather maker for the long term. Surface high pressure developing under a westerly flow aloft will provide dry weather Tuesday night and Wednesday. A closed upper low will track across Arkansas Wednesday night, before reaching Western Kentucky by Thursday evening. The strengthening upper low will trigger a surface trough that will lift through Kentucky to Ohio by Thursday night. Though deeper moisture and more potent forcing will be near a stronger surface low along the East Coast, there will be enough lift generated in a zone of divergence aloft ahead of the upper low to develop widespread precip over the ILN FA. Current model temperature profiles indicate snow to start on Wednesday night into Thursday morning, with precip changing to rain by Thursday afternoon as the boundary layer warms above freezing. Light snow accumulations will be possible before the transition to rain. As the upper low tracks across Kentucky Thursday night, and the majority of precip moves east, precip may change back to snow as colder air filters in behind the system. While the upper flow flattens to zonal, surface high pressure is forecast to bring dry weather on Friday. For Saturday, a disturbance traveling across the Great Lakes may bring a few rain and snow showers. High pressure and dry conditions are expected Sunday following the disturbance. Temperatures staying below normal through the period will vary slightly with respect to weather systems. Wednesday may be the coldest day of the period, when highs are forecast to reach the 30s. Highs for the remainder of the long term will be in the mid 30s to low 40s. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Expect rain to develop into the TAF sites towards 00Z with the exception of KDAY. VFR will continue to prevail even after precipitation begins. But eventually lower levels moisten which will bring a period of MVFR ceilings. In addition, precipitation may mix with or even change over to some light snow which will also reduce visibilities. Expect precipitation to move past the terminals by 09Z although cannot completely rule out a few flurries or some drizzle through 12Z. While ceilings may rise back to VFR once precipitation stops, this will be temporary as ceilings below 2000 ft are forecast to move back into the area. MVFR will then prevail through the rest of the TAF period although clouds will lift above 2000 ft towards 18Z. Winds will back around to around the time precipitation begins. Further backing to northwest will occur with an increase to 10 to 15 kt on Tuesday. OUTLOOK...MVFR ceilings will linger into Tuesday afternoon. MVFR ceilings and visibilities possible late Wednesday night into Thursday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR NEAR TERM... SHORT TERM...AR LONG TERM...Coniglio AVIATION...
