Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 240554 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1254 AM EST Fri Feb 24 2017 .SYNOPSIS... A warm front will lift north into the Great Lakes tonight as low pressure tracks toward the middle Mississippi River Valley. Low pressure and a strong cold front will bring showers and thunderstorms late Friday, with severe weather possible. Colder air and brisk winds will follow the front on Saturday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Showers have lifted northeast and out of the CWA this evening and are expected to remain out of the forecast for the remainder of the night. Cloud cover will linger over the northern half of the CWA while breaks are expected in the southern half, and some clear skies may be found towards daybreak in the southeast and over portions of northern Kentucky. Overnight lows will be very warm for late February, only dropping into the mid and upper 50s. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... the main focus in the short term continues to be the threat for severe weather late Friday afternoon into Friday night. The necessary ingredients for different modes of convection will come together late Friday afternoon into Friday night as low pressure tracks northeast toward Lake Huron and its attendant cold front sweeps east across our region. First off, unseasonably warm air will be place across the warm sector for the first part of Friday. It looks like we will see some sunshine, especially east. On breezy southerly flow, high temperatures are forecast to in the lower to mid 70s. These will either threaten or break records. Please see the climate section below for records at the big three climate sites. Winds will gust from 25 mph over the southeast to near 35 mph across northwest. The ingredients are coming together for severe storms across our area late Friday afternoon into Friday night. As the low tracks to our northwest and deepens, bulk shear, either 0-3 km or 0-6 km, will be sufficiently strong for organized updrafts/convection. The key will be how much instability and increasing large scale ascent will be realized late in the day to break through a weak capping inversion. CAMs suggest that the first threat for severe weather will be within a prefrontal trough region where convergent flow, shear, and MLCAPEs near 1000 J/kg will develop thunderstorms across the eastern half of Indiana between 4 pm and 7 pm EST. CAMs also suggest that these storms will likely contain rotating updrafts and may be supercellular in nature. Given steep mid level lapse rates between 7.5 C/km and 8.5 C/km, along with the instability and vertical pressure gradient from rotation, large hail and damaging winds will be possible from these storms. Tornado potential will depend on how shallow CIN remains into the early evening from max heating of the day and whether parcels remain rooted in the boundary layer. As the evening wears on, it appears that the convection, either supercellular or multi cluster/broken lines will try to congeal more into a QLCS as the cold front/convection along this boundary tries to catch up to the prefrontal trough convection. If this occurs, the severe threat will then transition more to damaging winds for our far eastern zones. However, vigilance still must be kept on the QLCS for any potential spin up tornadoes along the shear axis. It appears the convection will be exiting our eastern zones between 1 am EST and 4 am EST. CAA and a dry slot will ensue in the wake of the cold front with lows bottoming out toward sunrise Saturday, which should range from the mid 30s west to the upper 40s. east. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Region will begin Saturday post frontal. The convection should have moved into ern Ohio, leaving the fa dry slotted. Windy conditions are likely in the CAA pattern. Forecast soundings across west central Ohio indicate wind gusts up to 40 mph will be possible into Saturday afternoon. As H5 trof axis swings through the Ohio Valley Saturday, a few rain/snow showers will be possible. The best chance will be north and west of I-71. Highs for the day should be at 12Z with temperatures falling. Surface high pressure builds in Sunday providing dry weather and more seasonable Temperatures. Model solutions then diverge on the timing and placement of systems in quick zonal flow. GFS is spreading pcpn quickly nw into the region, while the ECMWF is holds pcpn off until late Monday night. Ran a blend of the two solutions and brought in only chance pops because of the uncertainty. If the pcpn makes it in it should be a rain/snow mix. Ran chance PoPs Monday night into Tuesday because of the varying solutions. Best chance of pcpn appears to be Wednesday when a front is forecast to push through. Northwest flow develops for the end of the week, which should bring more seasonable temperatures. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... The warm front has pushed north of the area and with it, the threat for additional showers through the early morning hours. In a continued WAA pattern, expect to see sct-bkn mid to high level clouds persist through daybreak. Meanwhile, a 35-45 knot 925mb to 850 mb low level jet will rotate up into the area through the morning hours and this will lead to some marginal LLWS, particularly through daybreak or so and at the western TAF sites. A low pressure system currently in the mid Mississippi Valley will lift northeast into lower Michigan through this evening. An associated cold front will push east across Indiana and into Ohio through this evening. It looks like we will remain capped through much of the day, but the cap will weaken late this afternoon and into this evening as the front approaches. This will allow for some sct to bkn thunderstorms to develop and push east across the area through the evening hours tonight. In addition, gusty southerly winds into the 20-30 knot range will develop later today ahead of the approaching front. OUTLOOK...MVFR ceilings and visibilities possible Saturday and Monday. && .CLIMATE... Record High Temperatures Date CVG CMH DAY Fri 2/24 72(1930) 72(1961) 67(1930/1961) February Record Highs CVG 76 set 2/10/1932 CMH 75 set 2/26/2000 DAY 73 set 2/11/1999 and 2/25/2000 && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Franks SHORT TERM...Hickman LONG TERM...Sites AVIATION...JGL CLIMATE...

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