Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 241900 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 300 PM EDT Fri Mar 24 2017 .UPDATE... Issued at 1139 AM EDT FRI MAR 24 2017 Satellite and surface observations show quite variable sky conditions across the area late this morning with some spots broken to overcast and others clear. The overall trend though has been for a little less cloud than earlier forecast, though clouds are expected to increase later this afternoon. With more sunshine temperatures have surged upward in some areas with it already 71 at 1135 EDT here at the NWS office in Jackson. With all this in mind have made forecast updates based on latest observational trends, with the main changes to decrease clouds and increase afternoon maximum temperatures. Pushed maximums into the mid 70s in the areas experiencing more sun, but if the clouds do not become more widespread this afternoon, this may not even be high enough. UPDATE Issued at 645 AM EDT FRI MAR 24 2017 IR SAT this morning showing an area of lower clouds likely due to isentropic lift continuing to expend north out of Middle Tennessee. While initial expansion into the greater Tennessee Valley was blocked by the Cumberland Plateau the next surge will not be blocked as much. Therefore, did opt to increase cloud cover particularly across the western portion of the CWA. Temperatures have been a bit of a challenge, and continue to be with cooler spots being the deeper valleys that have been able to decouple. Updates sent to NDFD and Web. && .SHORT TERM...
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(Today through Saturday) Issued at 357 AM EDT FRI MAR 24 2017 Morning surface analysis indicates surface high pressure centered off the coast of VA/NC. A weak warm front is progressing NE and while there is a slight kink in isobars the front is tough to define. Winds have already switched to a more southeast to south direction around the surface high this morning. Therefore temperatures are mild at the more mixed sites. The exception to the rule are the deeper valley locales where decoupling is leading to lower 40s. First forecast challenge of the day will be cloud cover. We have seen clouds streaming out of the TN Valley and southward likely associated with isentropic ascent ahead of the approaching system in the Front Range. Most of the model soundings indicate some lower clouds are not out of the question as we move through the day. Right now keeping the better coverage across the western and northern portions of the CWA and seems reasonable right now based on the SAT trends. The next challenge will be how much moisture recovery do we get particularly in the far east toward the Big Sandy. There will be decent afternoon mixing and given the strengthening LLJ would lead to 15 to 20 mph gusts particularly in the Lake Cumberland and Bluegrass. Overall think recovery should be enough to lead to higher RH than yesterday, but even so far east could be looking at lower 30 RH values. All of this will play a crucial role in temperatures and did lean up a bit given SUPERBLEND was higher than previous forecast. Tonight the cloud challenge will continue as the lower deck is expected to dissipate. However, we will keep a higher deck at minimum, but the deeper valleys could see a decent split once again. Think this will be more confined to the far eastern valleys given the better LLJ to the west. Moving into Saturday the clouds will continue to be on the increase through the day and more a top down saturation seen in the model sounding data. The one caveat to the increased cloud cover will be the backed flow by Saturday afternoon which could promote downslope flow in the far east. That said, did opt to keep lesser coverage as you move east. Also think most will remain dry on Saturday given upper level trough will negatively tilt across the Midwest and slow surface features down. However, did opt to bring slight POPs in the Lake Cumberland region by late Saturday given some CAMs support the possibility. .LONG TERM...(Sunday through Friday) Issued at 300 PM EDT FRI MAR 24 2017 The extended period looks to be quite active, with several periods of showers and thunderstorms expected. The first wave of rain is expected Saturday night through Sunday night as a low pressure system moves northeastward out of the south central Plains and into the Great Lakes region. This system will drag a cold front across the Tennessee and Ohio Valleys, which will spark numerous showers and scattered thunderstorms in the warm and fairly muggy air mass ahead of the boundary. Once the low passes by to our north, the rain will taper off steadily Sunday night into early Monday morning. The model data has the front stalling just to the south of the area on Monday. A wave of low pressure is then forecast to form along the western end of the boundary. This area of low pressure is then expected to move northward across our area Monday and Monday night, bringing more rounds of showers and a few thunderstorms to eastern Kentucky. This round of rain will likely linger across the area through the day on Wednesday, depending on how quickly the parent low pulls eastward out of the region. A ridge of high pressure should then settle over the region Wednesday night, bringing a temporary break from the precipitation. However, the break may be short lived, as the models have another weather system coming out of the Plains and across our neck of the woods again Thursday and Thursday night. At this time, due to model uncertainty late in the period, decided to leave out thunder for now to end the extended. Temperatures through out the period should be well above normal, with daily highs in the 60s and 70s, and nightly lows in the 40s and 50s.
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&& .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) ISSUED AT 154 PM EDT FRI MAR 24 2017 Clouds increased across the area early this afternoon, and expect ceilings of 4K to 6K feet to prevail for the remainder of the day. Southwest winds will be gusty across the Cumberland Valley and Bluegrass regions with gusts to near 20 knots at times this afternoon. Winds will diminish early this evening and become more southerly. VFR conditions will prevail through the night and into the day Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...DJ LONG TERM...AR AVIATION...SBH is the U.S. government's official web portal to all federal, state and local government web resources and services.