Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 221150 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 750 AM EDT Sat Apr 22 2017 .UPDATE... Issued at 740 AM EDT SAT APR 22 2017 Did a quick bit of touch up on the grids, primarily to move in the heavier pcpn a bit quicker with this first wave. This should set the stage for decent flooding potential across the south with subsequent waves likely to pose the greatest threat for flash flooding - though would not be surprised if a few urban and small stream advisories could be needed for local minor issues with this wave. Also, fine tuned the T and Td grids per the latest obs and trends. These grids have been sent to the NDFD and web servers. && .SHORT TERM...(Today through Sunday) Issued at 325 AM EDT SAT APR 22 2017 07z sfc analysis shows a developing area of low pressure over the central Gulf Coast to the southwest. A warm front/inverted trough extends northeast from this stretching across southern parts of eastern Kentucky. This boundary and points south will likely be the location of the heaviest rains with this system through the next 36 or so hours. Currently, showers, mainly light, continue to propagate over the northern portions of the CWA as they stream off to the east northeast. Skies are overcast across the area with just warm clouds noted on satellite. Temperatures vary from near 50 degrees over the extreme northwest portion of the CWA to Low 60s southeast on the other side of that boundary. Dewpoints vary in a similar manner with some mid 40s seen up north and low 60s found in the south. The winds overnight show evidence of the front with north to northeast ones for much of the CWA north of the Hal Rogers Parkway while to the south and east they are still southerly. The models are actually now in excellent agreement aloft through the short term portion of the forecast. They all depict a slow moving and evolving upper low closing off and dropping into the Tennessee Valley. The clustering of the models are impressive and lends confidence to the overall forecast through 00z Monday. As such have favored a blended solution with emphasis on the high resolution models for specific details on PoPs and QPF through the first 24 hours. Sensible weather will feature a renewed development of showers, and even some thunderstorms across the south, this morning as the next surge of pcpn pushes into the area. This is well depicted in the HRRR and its timing was generally followed in the grids through 15z. The initial batch of rain after sunup will target our central and northern counties moreso than the south, but that changes by afternoon as the next surge will be focused more over the Cumberland Valley. Overall, the broad sfc low passing just south of the CWA during the short term portion of the forecast will be a source for showers and heavier bouts of rain through tonight before easing off to the southeast on Sunday. While the best chances for thunder will be in the south today and this evening heavy rain will remain a threat in the far southeast through Sunday afternoon. For this reason, a flash flood watch will be issued shortly for our southern tier of counties starting at noon today and running through 4 pm Sunday. Sustained rains during this event over the headwaters of the Cumberland and Kentucky Rivers will also raise the specter of river flooding later in the weekend and into the start of next week. Temperatures will be on the chilly side through this period with only the far south seeing readings remotely near normal today. After highs in the low to mid 50s today, the north could rebound into the lower 60s on Sunday thanks to the main focus of the rain being in the south and perhaps some sun filtering through the clouds in the afternoon. Temperatures tonight will be fairly uniform in the upper 40s most places - coldest north and milder south. Started the grids from the CONSShort and ShortBlend through the short term portion of the forecast. Did not make much adjustment to temperatures or dewpoints given the limited diurnal range. However, did beef up PoPs and QPF from the blend across the south given the certainty for rain and many surges of shower activity during this time (thunderstorms early in the event). .LONG TERM...(Sunday night through Friday) Issued at 330 AM EDT SAT APR 22 2017 The upper level low will meander up the east coast Sunday night through Tuesday with mid level heights slowly recovering through the period as the eastern system slowly pushes farther off shore into the Atlantic. Some lingering rain chances will hold on Sunday night, especially in southeast Kentucky before we dry out early Monday. This will provide a much needed dry period Monday through Wednesday morning. Temperatures will stay cool into Monday with highs in the 60s. As return flow kicks in Tuesday highs should climb back into the 70s. The next chance of rain will come late Wednesday/Wednesday night as a shortwave trough drives another cold front across the Ohio river valley. The front may be shearing out as it crosses the area, so opted to stay with the lower blended pops as it may not be a widespread rain event for the area. Regardless, a few thunderstorms would be possible, especially up in the bluegrass region. Whats left of the washed out front will lift back to the north as a warm front by weeks end, with much warmer weather surging north across the region. This is also about the time our next system may be taking aim on the area by Friday afternoon, but some model inconsistencies will keep the uncertainty high with the late week system. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 750 AM EDT SAT APR 22 2017 The first wave of pcpn will push across eastern Kentucky over the next few hours. Look for ceilings to continue to gradually lower into and through IFR. These will likely stay low for much of the day, as a low pressure area tracks along a stalled frontal boundary near the Tennessee and Kentucky border. Periods of showers - at times heavy - along with a few thunderstorms, generally along and south of a line from KSME to KPBX, will affect the forecast area into Saturday evening. The worst conditions will primarily be found through the southern part of eastern Kentucky during this event. Winds will be north to northeast at 5 to 10 kts today and continue as such through the rest of the period. && .JKL WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from noon EDT today through Sunday afternoon for KYZ079-080-083>088-110-113-115>118-120. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF

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