Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 171050 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 650 AM EDT Sat Mar 17 2018 .SYNOPSIS... An area of low pressure near Missouri will push east across Kentucky and Tennessee today bringing a mix of rain, freezing rain, sleet, and snow to the Ohio Valley. High pressure will move back into the area on Sunday and Monday, before another area of low pressure brings precipitation to the region on Monday night and Tuesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Surface low pressure is currently located in Missouri this morning with widespread WAA commencing out ahead of the system. The first band in association with the upglide is already moving across the area with temperatures below freezing mainly across the central and northeastern zones. Dewpoint depressions across the area are in the 10 to 20 degree range, but with rainfall rates being on the lighter side evaporative cooling has made a smaller impact than initially expected out in Indiana. Road temperatures across the southwest are also mainly around 40 degrees F. Where surface temperatures are below freezing freezing rain can be expected due to a potent low level warm nose. The exception to this will be on the northern fringe of the system where a transition over to pellets and snow will take place (thanks to shortwave cooling). Have gone ahead and left the advisory unchanged for now, but think the chance for freezing rain across the southern edge of the advisory looks pretty slim. As the morning progresses the WAA wing will push east and pivot. At the same time the mid level low will start to shear out and get absorbed into the upper level trough axis that is located over New England. As the mid level low shears out the surface low will weaken and pass south, meaning the ILN forecast area will remain in the cold sector. Also, with the widespread cloud cover, highs will struggle to make it much above 40. As the low passes to the south of us a weak deformation band will setup across the central zones. There has been some minor model disagreement on the exact area of placement, with the NSSL WRF showing the band setting up just north of the Ohio river and the ARW and NMM showing the band moving across the Wilmington area. The latest HRRR is even slightly further north. Given where the low level low is forecast to move across think the Wilmington solution is the most likely. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Tonight, much drier air will begin to work into the area with PWATs forecast to fall to around a tenth of an inch (or below the tenth percentile for this time of year). During the day Sunday beautiful weather is in the forecast with clear skies and near calm winds as surface high pressure settles overhead. 850 MB temperatures are forecast to be around or slightly above zero degrees C. This will equate to high temperatures in the mid 50s, on average, across the forecast area. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A weakening mid level short wave will move out of the Plains Sunday night and across the Tennessee/Ohio Valleys Monday into Tuesday. This will allow for an associated surface low to push east across the Tennessee Valley and gradually weaken through Tuesday. Initially the models are in decent agreement with the evolution of this system although the 00Z ECMWF remains somewhat farther south with the track of the low and thus the northern extent of the pcpn shield Monday into Tuesday compared to the GFS/NAM/CMC. This is the second run in a row that the ECMWF has been farther south so have allowed for a slight southward adjustment in the pops. Thermal fields suggest mainly rain with this initial wave. However, it does look like we will cool off enough across about the northern third of our area to allow for a transition to a wintery mix later Monday night into Tuesday morning, depending on how far north the precipitation makes it. Highs on Monday will range from the upper 40s north to the mid 50s across the south. Some cooler air will begin to be pulled in on the backside of the low later Monday night and Tuesday, leading to highs on Tuesday in the upper 30s to mid 40s. The surface low will will eventually evolve into more of an inverted trough nosing up into our area through Wednesday as the mid and upper level energy shifts off to the East Coast. However, there remains quite a bit of difference between the 00Z ECMWF with this and the remaining suite of models. The ECMWF remains much weaker and farther southeast although it appears the CMC and to a lesser extent, the GFS have also trended somewhat weaker and more southeast. As a result, will trim back pops a bit for Tuesday night into Wednesday night and allow for more of a southeast shift. Ptype will remain an issue depending on how much cooler air gets pulled down into the area. For now, will allow for a rain/snow mix in the south to mainly snow in the north. Highs on Wednesday will be in the mid 30s to lower 40s. High pressure and a drier airmass will build into the area for Thursday with highs mainly in the 40 to 45 degree range. As the high moves east, high temperatures by Friday will moderate into the mid to upper 40s. A warm front lifting up from the southwest could lead to a chance of rain late in the day on Friday. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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The main band of precipitation in association with the isentropic upglide is currently pushing through the TAF sites with RA being reported to the south and FZRA and UP being reported towards the north. The back edge of this band of precipitation has already moved past KCVG/ KLUK with KILN and KDAY almost done for now. An area of surface low pressure will move east across Kentucky today with weak returns on the radar possible this afternoon. Forecast soundings on the HRRR shows dry air moving into the region though so thinking is impacts will be minimal to the terminals. Later this evening the deformation axis will be moving southeast or away from the region allowing for skies to quickly clear. OUTLOOK...MVFR ceilings and visibilities are possible from Monday night through Wednesday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...Winter Weather Advisory until noon EDT today for OHZ026-034- 035-042>046-051>056-060>065-070>074-077>082-088. KY...None. IN...Winter Weather Advisory until noon EDT today for INZ050-058- 059-066. && $$ SYNOPSIS...Haines NEAR TERM...Haines SHORT TERM...Haines LONG TERM...JGL AVIATION...Haines is the U.S. government's official web portal to all federal, state and local government web resources and services.