Area Forecast Discussion
Issued by NWS Wilmington, OH

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KILN 191407 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1007 AM EDT Thu Oct 19 2017 .SYNOPSIS... High pressure will remain from the mid Atlantic to the Tennessee Valley today while a weak, dry cold front pushes southeast into the Great Lakes. The front will wash out tonight, while high pressure strengthens over the Ohio Valley into Friday. High pressure will then extend across the region into Saturday. The next weather system to affect the area will arrive late Sunday into Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Very few changes to forecast this morning as surface cold front approaches from the northwest. The front will then stall out north of the area. High temperatures will likely be in the lower 70s this afternoon as 850 mb temperatures tick upwards. Only minor adjustment to forecast was to lower dewpoints this afternoon a bit thanks to mixing. Didn`t bring down dewpoints more than a degree or two though thanks to low level dry air eroding ahead of surface cold front (seen on RH field). New zones already out. Prev Discussion-> High pressure will remain from the mid Atlantic to the Tennessee Valley today while a weak, dry cold front pushes southeast into the Great Lakes. FEW-SCT cirrus is expected with southwest winds and sunshine boosting temperatures into the lower 70s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... The weak, dry front will wash out over northern Ohio this evening, allowing high pressure to begin reestablishing itself over the Ohio Valley. Under mostly clear skies and decreasing wind, lows tonight will range from the lower 40s in the east/southeast to the upper 40s northwest. Conditions look favorable for river fog formation across our southern/eastern river valleys, so have included this in the forecast. Mid level ridging will build northward into the Ohio Valley on Friday while high pressure also remains at the surface. Under mostly sunny skies, temperatures will warm slightly from Thursdays readings, ranging from the lower to mid 70s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Under an amplified mid-level ridge over the eastern half of the CONUS, a sprawling area of very dry surface high pressure will be centered somewhere in the mid-Atlantic region, slowly moving east as the weekend begins. This scenario will still maintain control of the weather situation over the Ohio Valley for at least another day or so, as deep-layer southerly flow sets up over the region on both Saturday and Sunday. There is high confidence in a dry day Saturday, which means that confidence remains high in this being a notably warm day -- with max temps in the middle to upper 70s, it will be about 10 degrees above normal. As the progression of the next weather system appears to be slower than previously expected -- to be discussed further below -- the change is that Sunday may well set up to be dry for the majority of the day, which forces an increase in the max temp forecast for the second day of the weekend as well. Though there could be more of a gradient in temperatures, as clouds increase from the W and NW, values in the upper 70s will again be possible in the southeastern ILN CWA. On Sunday, a sharp mid-level trough will begin its progression eastward across the Mississippi Valley, eventually reaching the Ohio Valley at some point between then and Monday. With the southerly flow helping to provide a northward flow of moisture from the gulf, there is high confidence that this trough (and its associated cold front) will result in precipitation developing across the region. However, with regards to timing and specifics, model agreement remains sub-par with this system, and the differences are primarily focused around the interaction between the southern end of the trough (which is likely to form a cut-off low) and the strong jet stream pushing east across the northern tier of states. Unfortunately, this time frame remains in an unstable part of the forecast cycle, with GFS/ECMWF run-to-run consistency performing poorly. Depending on how the cut-off low develops, there is the potential for the surface front to stall or develop waves somewhere in the vicinity of the Ohio Valley, which could significantly affect the timing of the most likely chances for precipitation. With the above in mind, PoPs will yet again be limited to the chance range until this really gets locked in a little better. Seeing an overall trend toward a slightly slower progression, as of now, the greatest precipitation chances appear to be during the Sunday night into Monday time frame. Secondary wave development could keep precipitation possible through Monday night. Once this moves out of the area, there appears to be potential for a larger upper trough to move into the Great Lakes on Tuesday into Wednesday, which should provide two things -- much cooler temperatures and continued chances for rain. Not seeing enough potential for instability to include chances for thunder at this point in the forecast cycle. After warm temperatures on Sunday, a relatively sharp cooling trend will commence, as the front moves into the area and precipitation becomes more likely. Though Tuesday may be close to normal, under the deeper trough going into the middle of the week, temperatures will likely fall to values below normal. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... River valley fog will burn off between 13Z and 14Z. Otherwise, for today, surface high pressure will extend from off the mid Atlantic coast southwest to the Tennessee Valley. Meanwhile, a weak, dry cold front will push east/southeast into the western Great Lakes. Only FEW to perhaps SCT cirrus is expected with southwest winds around 10 knots, local gusts around 16 knots. For tonight, the western end of the weak, dry front will sag into northern Ohio will it will wash out by Friday morning. Winds will decrease overnight with some areas seeing calm conditions. Skies will be mostly clear. OUTLOOK...MVFR ceilings and visibilities possible Sunday night into Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines/Hickman NEAR TERM...Haines/Hickman SHORT TERM...Hickman LONG TERM...Hatzos AVIATION...Hickman

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.