Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 170217 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1017 PM EDT Mon Apr 16 2018 .SYNOPSIS... Northwest flow will continue tonight. High pressure will briefly build across the area Tuesday and Tuesday night. Low pressure will pass across the lower Great Lakes Wednesday into Wednesday night. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Latest radar imagery shows what will likely be the last hurrah for snow showers moving through north-central portions of the ILN FA as of this writing. This area of light snow/showers will track east-southeast through portions of central Ohio through midnight before slowly coming to an end thereafter. Cannot completely rule out an isolated light snow shower through the remainder of the overnight period, particularly in central Ohio and far northeastern portions of the ILN CWA. Even with all of this said, accumulation, if any, will be confined to elevated and grassy surfaces and will generally be less than a tenth or two. With lingering extensive cloud cover and a fairly steady surface flow expected through the entirety of the overnight period, temperatures are not expected to fall too far from current values (lower 30s). Certainly think that outlying areas will dip into the upper 20s, especially towards sunrise, but there won`t be too much temperature fluctuations through the near term period. Have maintained the freeze warning as is, although confidence in parts of northern Kentucky experiencing subfreezing temps is a bit lower than would usually be expected this far out. Clouds will be on the decrease in the far southwest part of the area toward the very end of the near term period, but expect that most of the clearing will occur from southwest to northeast during the day on Tuesday. Westerly winds of 10 to 15 MPH will persist overnight with some gustiness to 20 MPH possible towards the very end of the near term period and the start of the short term period.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... High pressure will build into the area through the day. However, clouds may be stubborn to clear until warm air advection increases during the afternoon into the evening. Clearing will be brief as additional clouds will occur later Tuesday night as a warm front develops southwest of the region. Forecast temperatures are on the cooler side of guidance for both Tuesday and Tuesday night. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The long term will be characterized by below normal temperatures slowly transitioning to near normal and slightly above normal temperatures by the beginning of next week. Most of the extended forecast looks relatively dry also with only one system moving across the area Wednesday night. During the day Wednesday high pressure will be exiting the area to the east with an upper level disturbance pushing east across Michigan/ Ohio. Rain chances with this system still look marginal as surface convergence is forecast to be weak with a prefrontal trough expected out ahead of the main front. Also, dry air in both the NAM and GFS forecast soundings (between 700 and 500 MB) will limit development along the front. Wednesday evening into Thursday the flow does amplify though with an upper level low diving southeast out of Ontario/ Quebec. As the low amplifies and pulls northeast a potent piece of WAA and a reinforcing cold front will dive south. Forecast soundings on the GFS and NAM do saturate as this happens. Due to this have kept holding onto the PoPs through Thursday morning (maybe even slightly better precipitation chances here than with the front Wednesday evening). Thursday afternoon the upper level low will slowly exit the area to the east with surface high pressure building in from the west. Temperatures behind the front will be again 10 to 15 degrees below normal with highs Thursday ranging from the upper 40s north to the mid 50s south. For the remainder of the extended (Friday through Monday) the warm up will commence. Each day will likely be a little warmer than the last with temperatures approaching 70 degrees by Monday. Confidence with this is below average though as a strong upper level low will be pushing east out of the Rockies. Overall models have slowed the progression of this low down and pushed it further south of the area. This means drier and warmer conditions. Have gone ahead and trended the forecast this way. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... The numerous snow showers that impacted the terminals earlier this afternoon are becoming a bit more scattered to isolated in nature as the upper level disturbance begins to pull away from the area and daytime heating wanes. With this, the intensity of the shower activity has also decreased, leading to less VSBY restrictions than were seen earlier in the day. Expect that the snow shower activity will continue to decrease in coverage and intensity through the first part of the TAF period before dissipating altogether past 06z. The greatest potential for brief MVFR reductions in VSBYs will exist for the eastern sites of KILN, KCMH, and KLCK. This being said, low level moisture will continue to linger through the overnight period, especially for northern terminals, so kept MVFR CIGs through a good chunk of the TAF period. After 12z Tuesday, the back edge of MVFR CIGs will likely be approaching KCVG and KLUK through the morning hours, although there remains some model disagreement in just how fast this clearing lines works to the north and east. With this being said, MVFR CIGs will likely remain in place through most of the period for the northern terminals of KCMH and KLCK, although KDAY and KILN may see a transition to VFR conditions between 18-00z. The other item of interest for the TAF period will be the continued persistence of steady westerly surface flow. Although the winds will subside somewhat for the overnight period (with less gustiness), expect an uptick in the winds again towards sunrise and beyond, with gusts to 25kts likely for most of the area after 15z. Winds will remain generally out of the west, with a slight shift to more west-northwest towards the very end of the period. VFR clouds should be on the increase from the south again towards the end of KCVG 30-hr period, but decided to hold off inclusion in the TAF for now. OUTLOOK...MVFR ceilings and visibilities possible Wednesday and then again Thursday. Wind gusts 25 kt or higher possible Thursday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Freeze Warning until 10 AM EDT Tuesday for OHZ060>065-070>074- 077>082-088. KY...Freeze Warning until 10 AM EDT Tuesday for KYZ089>100. IN...Freeze Warning until 10 AM EDT Tuesday for INZ058-059-066- 073>075-080. && $$ SYNOPSIS... NEAR TERM...KC SHORT TERM... LONG TERM...Haines AVIATION...KC

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