Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 071207 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 707 AM EST Thu Dec 7 2017 .UPDATE...
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Issued at 659 AM EST THU DEC 7 2017 High cloud are currently moving southeast out of the state early this morning. Meanwhile a deck of mid level clouds is moving in across the Bluegrass, edging eastward towards our CWA. There has been some reports of flurries along the northern fringes. While flurries our in our forecast for the morning in our far north, this may need to be extended southward slightly based on current trends. Either way this should not result in any impacts. These mid-level clouds are expected to continue pushing eastward and expand across much of the CWA through the morning and into the afternoon. Loaded in the latest observations for temps, dew points, and winds to make sure they were on track with the ongoing near-term forecast. Decent ridge valley splits are present in the far eastern CWA and along the KY river valley. All updates have been published and sent to NDFD/web.
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&& .SHORT TERM...(Today through Friday) Issued at 420 AM EST THU DEC 7 2017 Heights are expected to continue lowering across the Ohio Valley today as a shortwave works southward through the Great Lakes region in the overall broad longwave pattern across the eastern conus. At the surface high pressure will be in place this morning, but will be replaced by a weakening surface trough/cold front which is expected to move through during the afternoon. This front/trough is quite weak and will be dry, posing little concern other than some added mid level clouds. What it will promote, however, is another surge of colder air into the region, aided by strong wind flows from Canada in the mid and upper levels as the longwave pattern continues to deepen. Can`t rule out a few flurries in the north given the lowering temperatures and OVC mid level clouds which will be well below freezing, so added in a small section during the afternoon for our far northern CWA, matching up with ILN and LMK. Highs today will be in the upper 30s and low 40s, falling behind the frontal passage, with overnight temps quickly dropping into the upper teens and low 20s in most locations. With a respectable mean westerly gradient wind the boundary layer remains fairly mixed through the period so do not see much in the way of ridge valley split potential tonight. In addition, CAA patterns typically keep our ridges (thermal belt) cooler than our valleys anyway, and there will still be lingering clouds across the SE CWA throughout the night. However, did wind up adjusting a couple of the usual suspect river valleys down just by a degree or two as winds may be more sheltered. Temperatures on Friday will struggle to warm into the mid 30s in the afternoon, with some higher elevations near the VA border likely not rising above freezing. .LONG TERM...(Friday night through Wednesday) Issued at 449 AM EST THU DEC 7 2017 An upper trough will be the dominant feature over the eastern CONUS during the period. Multiple impulses will rotate through the trough, presenting a possibility of precipitation. The first of these will affect our local area on Saturday. Its main impact will be to our north, and a POP gradient lies across the JKL forecast area. Low level lapse rate are expected to be steep, and the cold temperatures aloft will favor snow as the precip type. However, surface temperatures may push the limit of rain/snow. Precip amounts should be negligible. The main impact of the system will be another shot of cold air which will hold through Sunday. By Monday our low level flow should swing to the southwest ahead of another weather system. A brief warm-up will occur before the passing system sends in another blast from the north. By this time models are showing more variation in the details, but still agree on the general scenario. A bit of snow is possible with the transition back to colder air Monday night into Tuesday. Models show another impulse bringing a clipper type system southeast toward us at midweek, with yet another surge of cold air and potential for snow. && .AVIATION...
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(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 703 AM EST THU DEC 7 2017 VFR conditions will prevail through the period. High clouds are continuing to exit SE of the state this morning. A surface trough will move through from NW to SE during the day today. This should lead to little impact other than a deck of clouds between 4 and 6k feet. These clouds will continue to expand across eastern KY throughout the day as the trough moves through. Light and variable winds will veer to west during the day and increase to 5 to 10 knots with strong mixing in place. Winds will then lesson once again as we lose daytime heating in the evening while shifting to a more NW direction behind the departing system. Clouds should also begin dissipating as we head into the evening, clearing overnight.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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