Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 180212 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1012 PM EDT Mon Oct 17 2016 .SYNOPSIS... With surface high pressure over the southeastern states, warm conditions will continue over the Ohio Valley tonight and tomorrow. A cold front will move into the region on Tuesday night, stalling over the area through the middle of the week. As low pressure moves along this front, occasional chances for rain will occur. Cooler conditions are expected for the end of the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Another mostly clear and warm night across the region. Expect a few patches of cirrus to work through, but in general skies should be mostly clear. Winds will hold up overnight which will also help keep temperatures well above normal. Lows will only fall into the mid 60s, with some of the extreme eastern counties seeing lows in the lower 60s.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... Warm temperatures will be the main story for Tuesday, but an approaching (and stalling) cold front will complicate the weather through the middle of the week. The warmest 850mb air will be moving over the ILN CWA during the peak of the diurnal cycle on Tuesday -- around 16C at ILN. While continued warm advection through the boundary layer should lead to another well-mixed (and slightly gusty) day, there will also be increasing clouds from the northwest, well in advance of the approaching cold front. Raw model and SREF plume output still appears too low based on observed conditions Monday and the expected continued warming going into Tuesday. However, with clouds moving in and only a slight change in 925mb-850mb temps, it was important to not jump too high for max temps on Tuesday. In particular, ECMWF guidance has been running too warm, and represents the high end of the envelope -- unlikely to verify. Thus, combined with mixing expectations from GFS/NAM soundings, the max temp forecast for Tuesday ranges from around 2F-4F higher than Monday in the southeastern CWA (mid to upper 80s) to values close to Monday in the northwestern CWA (lower 80s). This will again bring Columbus into contention for a record high temperature, with a lesser (but not impossible) chance for Cincinnati or Dayton. The approaching cold front will become more and more detached from its parent low as Tuesday night approaches, eventually pivoting into a WSW-to-ENE orientation, and stalling near the northern border of the ILN forecast area. Initially, convergence along this front will be somewhat limited, with weak forcing on Tuesday night / early Wednesday aided by a more favorable positioning with regards to the 500mb jet. However, the majority of model solutions do not support widespread precipitation development, and PoPs have been limited to 20-30 percent. The front will remain in place on Wednesday, moving very little, but forcing a re-orientation of the temperature fields. Temperatures are likely to remain well above normal, though 80s will be limited to the southeastern CWA, with the front (and its associated clouds and low-end rain chances) limiting temperatures to the middle to upper 70s through the main metro areas of the ILN CWA. It will not be until Wednesday evening that chances for precipitation begin a more significant upward trend, with a 500mb trough finally focusing some stronger forcing in the vicinity of the surface front. As this occurs, NAM/GFS projections both indicate the development of a surface low along the front, which will be moving northeast into the region at around the same time. PoPs increase significantly between 00Z and 12Z on Thursday, especially in the northwestern CWA, along and just behind the surface front. Instability is marginal, but enough to include a slight chance of thunder for a few hours Wednesday evening. && .LONG TERM /THURSDAY THROUGH MONDAY/... An upper level trough will pivot east across the Mid and Upper Ohio Valley Thursday into Thursday night with an associated cold front sagging slowly southeast across our area. Broad southwesterly flow ahead of this feature will allow for good moisture advection up into our region through the day on Thursday. The combination of this, some mid level energy rotating around the base of the trough and low level convergence associated with the front, will lead to widespread precipitation during the day on Thursday, slowly shifting east through Thursday night. There are some timing issues with the trough and front as well as with some possible low pressure waves riding up along the front on Thursday. The 12Z ECMWF is the fastest with the 12Z NAM the slowest and have generally trended toward the 12Z GFS which is somewhat in between. This timing will help determine the amount of instability that is able to be pulled up into our area during the day but it does look like there will be enough to support at least a chance of some embedded thunderstorms through Thursday afternoon. The upper level trough will begin to shift east of the area on Friday but both the ECMWF and CMC are indicating some secondary short wave energy dropping down the back side of the trough heading into Saturday. This would help keep a broader trough back across our region into the weekend. Will therefore hang on to some lower end pops for Saturday, primarily across northeastern portions of our forecast area. Mid and upper level ridging will then try to build in from the southwest through the first part of next week, keeping our region in a general northwest flow pattern. This will allow for some weak energy to drop down across the area Sunday into Monday, but timing and placement is uncertain so will maintain a dry forecast for now. A colder airmass will settle into the region behind the front for late in the week. This will lead to below normal temperatures Friday and Saturday with highs mainly in the 50s. We should then see a gradual moderation to highs back into the 60s through the first part of next week. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... High pressure ridging at the sfc and aloft will provide one more night of mostly clear skies. However, the tight pressure gradient will keep winds up tonight. Gusts around 20kt will be possible. In addition, models swing a H9 jet of 45-50kts from the mid MS valley into the Lower Great Lakes tonight. With this feature moving through, there will be a chance of some LLWS, so kept the previous mention of LLWS at the TAFS from 06Z-14Z. Between 12-18Z the heart of the H9 jet pulls away, but there should still be enough wind aloft that when daytime mixing kicks in that gusts on Tuesday will reach into the lower 20 kts. Also during the morning, models bring a surge of H8 moisture in the region, so brought in VFR broken cigs around 14-15Z. By late afternoon, winds will be tapering down as the h9 and h8 winds continue to decrease. Cigs however will be dropping with the approach of a cdfnt. With convergence and lift ahead of the front, scattered pcpn will begin to develop. so added a VCSH to the DAY TAF aft 21Z. For the extended CVG TAF, MVFR cigs will be possible and the rain will continue to develop. OUTLOOK...MVFR Ceilings and visibilities possible Wednesday into Friday. && .CLIMATE... -------------------------Cincinnati-----Columbus-------Dayton---- 10/17 record highs ----- 86 in 1950 --- 83 in 1968 --- 86 in 1910 10/18 record warm lows - 67 in 1905 --- 65 in 2007 --- 65 in 1947 10/18 record highs ----- 86 in 1938 --- 83 in 1938 --- 86 in 1908 ..........................................................1910 && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Sites SHORT TERM...Hatzos LONG TERM...JGL AVIATION...Sites CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.