Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 210519 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 119 AM EDT Mon May 21 2018 .SYNOPSIS... An east-west front extending across the region will lift north on Monday as low pressure moves across the lower Great Lakes. As the low progresses east, a trailing cold front will cross the area late Monday night into Tuesday. High pressure will build in behind this front. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Scattered showers and thunderstorms are pushing southeast across southeast portions of our area. These have been weakening over the past hour or so and expect this trend to continue through the remainder of the evening as we continue to lose the daytime heating. A weak boundary will lift slowly north overnight with the models indicating some weak low level convergence developing across northern portions of our area. This could lead to a narrow axis of some isolated to scattered shower or thunderstorm development later tonight across our north and will continue with some lower chance pops to account for this. Lows tonight will range from the upper 50s north to the mid 60s across the south. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Boundary will lift north on Monday as low pressure moves towards the lower tip of Lake Michigan. Scattered to numerous showers and thunderstorms will occur with this boundary. Some convection will remain possible in the warm sector with better coverage late in the day into the evening along a pre-frontal trough. There is quite a bit of uncertainty in terms of how much instability will occur in the warm sector as well as the timing of the pre-frontal trough. A later arrival of the trough will mean that instability will be starting to wane as stronger- forced storms move in to the area. Any of the more robust storms could result in a damaging wind threat during the afternoon and evening. Showers and some thunderstorms will remain possible through the remainder of the night. Generally went a bit above guidance for temperatures. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Tuesday again has the potential to be active with drier weather finally moving in Wednesday and Thursday. Tuesday afternoon an upper level disturbance will be heading east across Michigan with a surface cold front slowly progressing southeast. The NAM has the front pushing through slightly quicker Tuesday while the ECMWF and GFS are slightly slower with the front. Given the front is pushing through the area in the afternoon have favored the slower solution here. This means that showers and thunderstorms will be possible southeast of the cold front Tuesday as the warm sector again quickly destabilizes. The GFS has MUCAPE values of 2000 J/kg to 3000 J/kg while the NAM has most of the instability displaced to the south and east. Wednesday morning the cold front will be south of the area with surface high pressure moving in. PWATs will fall to below 0.75" Wednesday and with the drier air mass high temperatures Wednesday have the chance to be warm (esp. with 850 MB temperatures not cooling much). Have gone ahead and pushed high temperatures slightly above guidance here. Thursday the upper level low that was over the Western United States will get picked back up into the main flow with surface high pressure sliding east. This will allow low level thicknesses to moderate along with the corresponding high temperatures. Friday through the weekend models continue to struggle with multiple upper level features and how they progress. The first is an upper level low that was mentioned above. The second is a weak counter propagating upper level low over the Gulf of Mexico. The ECMWF keeps the low over the southeastern United States while the GFS is more progressive with the system. The CMC actually forms a tropical system. These wide range of solutions just propogate downstream towards the Ohio Valley. The overall idea is for showers and thunderstorms to return to the region early Saturday as gulf moisture surges north. A cold front will then approach the area Sunday into Monday. The GFS solution allows for the upper level trough axis to deepen while the ECMWF and CMC are more progressive with the upper level low. Either way the end of the extended looks active. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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Humid airmass continues to affect aviation. Early this morning, BR will reduce visibilities as low as IFR under light winds and high clouds. Once BR burns off after sunrise, showers and thunderstorms are forecast to develop in the vicinity of TAF sites as instability increases along a front extending from low pressure to the west. There is still uncertainty as to timing and effects at airports. Convection will once again diminish after 00z with loss of daytime heating. OUTLOOK...Thunderstorms possible through Tuesday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS... NEAR TERM...JGL SHORT TERM... LONG TERM...Haines AVIATION...Coniglio

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