Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 151735 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 135 PM EDT Thu Mar 15 2018 .UPDATE... Issued at 1154 AM EDT THU MAR 15 2018 Some mid level clouds across the middle of the forecast area are associated with a jet streak. These will likely persist into the early afternoon before diminishing by evening. Outside of this area clear skies will prevail this afternoon. Have updated NDFD based on latest observational trends and model data. Dewpoints are still forecast to increase this afternoon which will be important in preventing relative humidity from bottoming out too much. Relative humidity is already down to 30 percent at the McCreary County KY Mesonet site. UPDATE Issued at 700 AM EDT THU MAR 15 2018 Did a quick update to the grids mainly to add in the latest obs and trends. Winds have picked up from the southwest and helped to mix out many of the colder spots, while some mid level clouds still hold on in the east. These updated grids have been sent to the NDFD and web servers. && .SHORT TERM...(Today through Friday) Issued at 315 AM EDT THU MAR 15 2018 Current conditions across the area features some mid level cloud cover passing through the area, mainly in the northeast and eastern Kentucky. This is associated with the last of the upper low exiting to the northeast as it brings some moisture south on the back end of the low. This will clear out heading into the coming day as westerly winds and clear skies will allow afternoon temps to warm into the 50s and even around 60 in the south. Increasing gradient from the ridge over the southeastern CONUS shifting east and the exiting trough over the northeast will allow strong westerly winds to engage through the day this afternoon. In fact, may see some 25 to 30 MPH winds at times. Heading into tonight, will expect clear skies to start off the evening before some mid and lower level cloud cover to push in from the east. This allow for a ridge to valley temperature difference to begin the night but will slowly disappear as cloud cover increases through the night and winds switching around to the north. A warm front developing and extending east will allow precip to develop into the area by mid morning. One change in the model trends, shows a later arrival of precip, thus the cold air should be scoured out of the valleys by this time. Will not expect any freezing precip with this event as it unfolds into the late morning hours of Friday. With the slow development, will expect showers to develop into southern Kentucky. Many locations to the north will not see any showers develop into the north until Friday evening. This will also slow the northerly lift of the front keeping temps fro Friday afternoon in the upper 40s and low 50s for highs. .LONG TERM...(Friday night through Wednesday) Issued at 505 AM EDT THU MAR 15 2018 The models remain in only fair agreement aloft through the long term portion of the forecast during this busy and progressive, transition season, pattern. Some agreement at the largest scale breaks down and become more disjointed at smaller scales through the forecast period. This results in lower confidence in any specific model solution and favors an ensemble and blended solution as a starting point. The models depict 3 separate and significant impulses to move through the region over the next week. The first of these comes out of the Central Plains as a closed low but dampens quickly as it slides east Friday night into Saturday. The GFS is quicker and weaker than the ECMWF and CMC with this feature. Fairly flat ridging follows for the area into Sunday with still plenty of energy packets moving through the swift mid level flow. For Monday, the next impulse will be inbound with the GFS again fastest, but with similar strength. The core of this dampening, but still distinct and healthy, wave rides over eastern Kentucky early Tuesday morning. The pattern then becomes more convoluted by mid week as more energy passes through the Midwest and into the Ohio Valley with heights falling and a full latitude trough taking shape over the region into Wednesday - quicker, further south, and not quite as strong in the GFS than the ECMWF - but similar enough to make for a clear trend toward continued active and changeable weather. Despite the larger than desired spread to the models it is clear that near normal to mild regional temperatures early on will turn colder toward the end of the period while damp conditions look to remain in place or worsen with time. Sensible weather will be quite active through the period with several sfc lows passing through the Ohio Valley from Friday night through Wednesday. The first of these will lift a warm front through eastern Kentucky Friday night into Saturday morning. The leading edge of this will push into cold and dry air in place over the northeast parts of the JKL CWA and the pcpn may catch up to this air to result in a brief period of mixed weather towards dawn, though the amount of warming aloft should mitigate this threat. In fact, the sfc low may also take advantage of its warm surge on Saturday to kick off a few thunderstorms, but model uncertainty precludes adding any TRW to the grids, at this time. Cooler and mainly dry weather follows into Sunday before the next warm front lifts into Kentucky early Monday with this later sfc low passing right through the state with showers and potential thunderstorms that afternoon followed by colder temperatures into Tuesday. Some snow may start to mix in later Tuesday and into Wednesday as the larger trough aloft takes shape and lowers sfc pressure throughout the region - though significant uncertainty remains at these later time steps. Made only minor adjustment to most of the temperature grids through the period, but did nudge them strongly toward the CONSRaw blend Friday night into Saturday (along with dewpoints). As for PoPs, again tried to limit them bulk of them to the sfc features - focused on each successive wave passage. && .AVIATION...
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(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 135 PM EDT THU MAR 15 2018 Mixing has allowed some stronger winds aloft to make their way down to the surface. As a result west winds will gust to between 20 and 30 knots this afternoon. The winds will diminish quickly this evening and become variable and light in most areas by Friday morning. VFR conditions will prevail through the TAF forecast period, with mid level clouds gradually increasing over southern and central parts of the forecast area tonight.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...SHALLENBERGER LONG TERM...GREIF AVIATION...SBH is the U.S. government's official web portal to all federal, state and local government web resources and services.