Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 290832 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 432 AM EDT Mon May 29 2017 .SHORT TERM...(Today through Tuesday) Issued at 420 AM EDT MON MAY 29 2017 The period begins with a closed low over the Northern Great Lakes and Ontario with an associated trough south into the MS Valley region. Upper level ridges were in place across the Western Conus and Gulf of Mexico and Caribbean. At the surface, low pressure was over Ontario with an occluded front to a triple point low over the eastern Great Lakes with a cold front trailing south and then southwest into the OH Valley to the Southern Plains. A secondary front extended from the low into the WI and then west across parts of the MO Valley. Today and tonight, the first cold front will depart into VA and TN early and begin to stall south of the area with high pressure nosing northeast into the region from the Southern Plains. Mid level heights should rise some and then remain steady this afternoon capping off any cu development. Mid level clouds should depart early with areas of stratocu or stratus mixing into rather shallow cu through the morning and into the afternoon. There should be a period with mostly clear skies from near sunset into very early on Tuesday morning and this may allow for a small ridge/valley temperature split to develop with a nocturnal inversion setting up in the valleys. The secondary cold front should increase late with an associated increase in low and mid level clouds. Highs today should be near to slightly above normal for the end of May with lows tonight near to slightly above normals as well. On Tuesday, the secondary cold front will cross the region with limited moisture. Moisture should be a bit more substantial across the southern and southeastern counties closer to the stalled frontal zone and somewhat higher dewpoints. The bulk of the model guidance suggests isolated to scattered coverage of showers and perhaps a few thunderstorms near the VA border. The past two NAM runs appear overdone with moisture and instability and thus coverage of convection and were weighted very little for this forecast. GFS forecast soundings across the north indicate less instability and perhaps a bit of capping so thus thunder chances were confined to one to two counties nearer to the VA and TN border where CAPE could reach near 500 J/kg and LI on the order of -2C. With more cloud cover, highs on Tuesday should be slightly lower as compared to today. .LONG TERM...(Tuesday night through Sunday) Issued at 345 AM EDT MON MAY 29 2017 A weak cold front will slip south across the area late Tuesday night and Wednesday. Forcing with the front will be quite weak, but instability may build south of the front on Wednesday and spark a few showers and thunderstorms, especially across the southern half of our forecast area. Looking at 00z model forecast soundings, there would be some potential for a few strong or damaging wind gusts as we have modest speed shear from the surface to 500mb. We also have a pocket of mid level dry air that may aid in the potential for some downburst winds. The best threat for the stronger storms would be in southeast Kentucky at this time. Front will push south Wednesday evening, with showers and storms exiting south. As high pressure builds south across the region, this will provide dry weather Wednesday night through Thursday night. As the high shifts east Friday, moisture will start to stream back to the north from the Gulf region. A mid level trough will push north and could spark some showers and storms during the day Friday. In the wake of this system, looks like plenty of moisture will reside over the region through the weekend. It looks like a zone of active convection will develop and align east to west again through the weekend. PW values will climb back to around 1.50 to 1.60 inches over the weekend. With the mean steering flow aligned with the east to west front to our north, we could be looking at more potential for flash flooding. Models are in good enough agreement to at least mention the potential in the HWO. Looks like front will finally push south Monday night, ending the threat of heavy rain. With the active weather over the weekend, will maintain the likely rain chances from Saturday through Sunday. Taking a very early look at severe potential, it appears shear will be too weak to support much of a severe risk. Thus, this time around, we could be more focused on hydro concerns. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 235 AM EDT MON MAY 29 2017 VFR is observed at this time and VFR should continue for at least the first 2 or 3 hours of the period even with an isolated to shra or tsra possibly impacting one of the TAF sites. As the cold front moves through overnight, some stratocu or stratus may develop along with some fog, and a period of MVFR is possible generally between 7Z and 13Z. This should mix out shortly after sunrise with VFR developing areawide and prevailing through the end of the period. VFR conditions will then be expected into the day tomorrow. Winds should generally remain at 10KT or less through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...KAS AVIATION...JP

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