Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 190001 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 701 PM EST Wed Jan 18 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 THURSDAY MORNING/... 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 THURSDAY 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 /00Z THURSDAY THROUGH MONDAY/...
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Overcast cloud deck on the cusp of IFR/MVFR range will lift slightly to be above 1kft over the next 2-3 hours. Patchy drizzle will impact central Ohio through about 2z and could reduce vsbys to 5sm briefly. Warm advection kicks in overnight and spreads from southwest to northeast, reaching central Ohio TAFs after daybreak. This will also be the noted feature that will push a definitive back edge to the low stratus out of the region. Cloud cover will still be topped by bkn if not ovc ci in advance of the next system coming in from the southwest. KCVG will be raining by the end of the valid 30 hour TAF period, while KLUK may see a small possibility of rain at the end of their 24 hour TAF. Ceilings will drop the MVFR range in rain as a strong surface low in the midwest helps push a warm front to the northeast through the TAF sites. Rain will overspread the region in the 0-6z time frame tomorrow night, possibly later than this at KCMH/KLCK. 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...Hickman SHORT TERM...Hickman LONG TERM...Hatzos AVIATION...Franks/Sites is the U.S. government's official web portal to all federal, state and local government web resources and services.