Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 190628 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 128 AM EST Thu Jan 19 2017 .SYNOPSIS... High pressure will move east across the Ohio Valley tonight. As the high moves toward the Atlantic seaboard on Thursday, low pressure will travel from the lower Mississippi valley to the lower Ohio Valley. The low will then move north through the region Thursday night into Friday. Warmer temperatures will follow for the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Have slowed any improving cloud cover tonight in favor of overcast skies. Even if the lower levels clear out from southwest to northeast, they will be quickly covered over by a significant cirrus deck. Overnight temperatures were raised in the southeast where slower than expected falls were seen this evening. Previous discussion still valid -> Surface high pressure will traverse east across the Ohio Valley overnight while a mid level ridge lags behind aloft. Satellite and surface observations still show considerable low level clouds from our region westward across most of Indiana. The scouring and/or moving out of low clouds this time of year is always tough to forecast, especially when the moisture becomes trapped underneath an inversion. Will allow a slow process for this to occur from west to east overnight. Even so, high level clouds begin to push northeast aloft, so any period of partly cloudy late tonight into the first part of Thursday will likely be short lived. Lows will range from the lower to mid 30s. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... Surface and mid level ridge will move off to the east on Thursday. This will allow the next weather system to eject northeast into the southern Plains/lower Mississippi River Valley. Clouds will be on the increase through the day. Mid level circulation over the southern Plains will open up as its mid level trof axis pivots northeast through the Ohio Valley and the Great Lakes Thursday night into Friday. At the lower levels, warm, moist ascent associated with a broad/modest low level jet, along with convergent directional flow, will bring widespread showers to the region late Thursday into Thursday night. Precipitation will taper off from the southwest to the northeast during Friday morning as the deeper moisture and low level forcing shift to the north. For Friday night, broad warm air advection will remain across the region. Clouds will linger. There is an isolated threat for a shower, but most locations will remain dry. Have used a non-diurnal trend for temperatures Thursday night into Friday night. Readings continue to be warm considering the time of the year. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A warm and moist southwesterly flow pattern will be in place across the Ohio Valley on Saturday, which is expected to be the warmest day of the forecast period. Low pressure moving into the upper midwest will be too far from the region to provide strong forcing, but continued moist flow will support the development of some precipitation by evening and going into early Sunday morning. With as warm as it may get, some very limited instability could develop, but thunder will be kept out of the forecast until (and if) confidence increases in this scenario. However, confidence continues to increase in warm conditions for Saturday, and this forecast will increase values by another degree or so. Record highs are in the 70s for all three climate sites, and these records appear safe. A fast-moving upper level low pressure system is expected to move across the southern tier of states on Sunday, with widespread precipitation (and some heavy rainfall) expected to develop in the Tennessee Valley region. On the northern periphery of this low, precipitation is eventually expected to spread northward into the Ohio Valley on Sunday, with another wave arriving on Monday as precipitable water values continue remain high for January (near or just under an inch). Overall, model differences are not large, though the ECMWF is slightly faster with the progression of this stacked low pressure system. Once the low has moved from south of the region to southeast of the region, a switch to northerly flow will allow for a gradual drop in temperatures through Monday and Tuesday. Timing out the end of precipitation is uncertain, however, as there is significant model spread (within GEFS members) regarding how the mid-level low / trough progress northeastward on Monday night into Tuesday. Beyond the passage of the low and the arrival of a narrow ridge, model solutions diverge significantly with regards to the next system moving through the quick westerly flow. Thus, confidence in specific temperature and precipitation details beyond Tuesday is fairly low. However, a general warmer-than-normal trend is almost certain to continue going into the rest of the week. && .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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Low clouds with CIGS below 1000 feet will slowly erode from the southwest overnight as WAA develops. High level clouds CIGS this morning will thicken into the mid levels this afternoon in advanceof the next system. Mid level flow backs tot he southwest durg the aftn with embedded shortwave and sfc low tracking northeast into the Ohio Valley by Friday morning. As favorable isentropic lift develops, expect rain to overspread the TAF sites around 00Z at KCVG/KLUK to 05Z at KCMH/KLCK. Expect CIGS and VSBYS to drop into MVFR category with the rain. OUTLOOK...MVFR/IFR ceilings possible through Friday, and then late Sunday into Monday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Franks/Hickman SHORT TERM...Hickman LONG TERM...Hatzos AVIATION...AR

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