FXUS61 KILN 211938 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 338 PM EDT Sat Sep 21 2019 .SYNOPSIS... Southerly flow over the Ohio Valley will persist through the weekend, offering increased moisture and continued warm temperatures. A few showers are expected through this afternoon, then the chance for showers and thunderstorms will increase Sunday night ahead of a cold front that will cross the region early Monday. The threat for storms will decrease Monday, as surface high pressure begins to build into the region. && .NEAR TERM /THROUGH TONIGHT/... Initial area of showers that moved across central Ohio earlier today has dissipated, but scattered pop up showers/isolated thunderstorms have developed across the Miami Valley and west- central Ohio. This activity is on the fringe/periphery of a mid- level ridge that is building into the Ohio Valley and within/near a local area of higher instability. A few of these showers may work into portions of central Ohio later this afternoon, but given the influence of the ridge, am not expecting any development much further south into the CWA. Those areas that receive convection will have moderate to briefly heavy downpours and the potential for lightning strikes, but strong/severe storms with wind/hail are not expected. Any convection along with cumulus will dissipate by sunset this evening, leaving mainly mid-high clouds overnight. Lows will be in the lower to mid 60s. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... Mid level ridge starts to move away on Sunday as a trough swings east in the Upper Midwest/Upper Mississippi Valley. Sunday will be another very warm day with temperatures in the mid 80s. Gradient tightens up a bit as well, with midday and afternoon wind gusts possibly 25 to 30 mph. Sunday should be dry, then as a cold front approaches from the northwest Sunday night, clouds will increase during the evening and showers and perhaps a few thunderstorms are expected to move into western portion of the CWA, generally after midnight. Convection will spread through much of the CWA through sunrise Monday. && .LONG TERM /MONDAY THROUGH SATURDAY/... Model consensus remains in good agreement showing a fairly quick progression of the much-anticipated cold front southeast through the ILN FA Monday morning, yielding progressively drier conditions from late morning onward from northwest to southeast. Even with this said, do expect a gradual weakening trend of one or more initially cohesive bands of showers and isolated thunder as the activity pushes further to the south/east -- owing to a gradual loss of focused forcing. This will result in mainly dry and clearing conditions by mid/late afternoon -- even in the east. And with the arrival of the aforementioned drier air will come seasonably cool overnight lows Monday night and Tuesday night with highs generally in the mid to upper 70s both days. The cold front will allow for cooler and drier air to infiltrate the Ohio Valley from Monday afternoon through at least midweek -- with near normal to slightly above normal temperatures during the first part of next week. This will occur coincident with surface high pressure briefly building into the region followed by a secondary weak frontal passage Wednesday night into early Thursday morning. While certainly this FROPA could deliver another round of scattered showers to the area -- as of right now, it does appear that the forcing and moisture availability will be rather meager. This would tend to suggest for the front to progress through the area with just some chance PoPs at best before drier conditions once again return by Thursday afternoon. Beyond Thursday, longer range guidance remains in remarkable agreement showing potent quasi-zonal mid/upper level flow transitioning to anomalously expansive and strong ridging initially across the southeastern U.S. late in the workweek before overspreading pretty much all of the Tennessee/Ohio Valleys by next weekend. While there are some natural discrepancies that exist in longer range solutions -- specifically as they relate to exact positioning and timing of ridge development -- there remains above normal confidence in another period of very warm temperatures setting up by the end of the long term period. The persistence of several deterministic and ensemble solutions showing this highly- amplified pattern lends itself to high confidence in above to even much-above temperatures to close out the month next weekend into the following week. In fact, EPS mean H5 heights approaching 2 standard deviations are being advertised across the Tennessee Valley about 7 days from now, with H8 temps 8C+ above normal. This type of pattern -- should it evolve in such a manner -- would suggest the potential for record or near record temperatures to close out the month. Of course, the specifics of the pattern which will ultimately dictate the sensible weather locally will still be coming into better focus in the coming days. So certainly this pattern and the eventual evolution will be watched closely in the coming week. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... A stray shower could still affect KCMH/KLCK through mid- afternoon, otherwise with a mid level ridge bumping up into the Ohio Valley, expect dry conditions with prevailing VFR conditions. Exception late tonight would be KLUK where MVFR/IFR visibilities may occur for a time in fog. On Sunday, as south-southwest flow tightens a bit, expect midday/afternoon wind gusts to increase to 20-25 knots. OUTLOOK...Thunderstorms possible on Sunday night into Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...BPP NEAR TERM...BPP SHORT TERM...BPP LONG TERM...KC AVIATION...BPP
