Area Forecast Discussion
Issued by NWS Jackson, KY

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635 FXUS63 KJKL 201819 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 219 PM EDT Tue Jun 20 2017 .UPDATE...
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Issued at 219 PM EDT TUE JUN 20 2017 Freshened up the hourly temperatures and dew points through the rest of this afternoon, otherwise, no changes are planned. UPDATE Issued at 1108 AM EDT TUE JUN 20 2017 Temperatures are running a little ahead of the forecast in places. Still think most locations will top out in the lower 80s, but did allow for a few mid 80s based on the warmup thus far. Updates have been sent. UPDATE Issued at 700 AM EDT TUE JUN 20 2017 The forecast remains on track so far this morning. Areas of valley fog will dissipate across the area through 12Z or so and should be gone by 13Z. Aside from that partly cloudy to mostly clear skies, light and variables winds, and warm temperatures will be on tap. Ingested the latest obs data into the hourly forecast to establish new trend. No other changes to the forecast were required at this time.
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&& .SHORT TERM...(Today through Wednesday) Issued at 300 AM EDT TUE JUN 20 2017 A ridge of high pressure will be the dominate weather feature across the region over the next few days. As a result, dry weather, warming temperatures, and partly cloudy to mostly clear skies will be on tap. Winds should be light and variable during the period. Areas of valley fog will form and persist through early this morning before dissipating. The fog may even be dense in locations that received rainfall Sunday and Sunday night. After a full day and night of dry weather, the fog threat Tuesday night will not be as high, therefore only patchy fog is expected early Wednesday morning in valleys, especially near bodies of water. Temperatures should be at or just above normal, with highs in the low to mid 80s expected today and tomorrow. .LONG TERM...(Wednesday night through Monday) Issued at 425 AM EDT TUE JUN 20 2017 The period is expected to begin with ridging centered near the Four Corners region and another ridge centered south of Bermuda. A shortwave trough is expected to be moving across the Northeast US with a shortwave ridge over the western Great Lakes and a broad trough extending into parts of the Northern Rockies and Northern Plains. At the same time, a tropical system is expected to be nearing the Gulf Coast with sfc high pressure centered in the vicinity of Bermuda. The return flow between the ridge and the tropical system will have begun to bring in increase in deep tropical moisture north into the Gulf states. Futher north and west, an area of sfc low pressure ahead of the broad trough is expected to be moving across southern Canada with a warm front lifting north toward the Great Lakes and a cold front trailing south into the Plains and portions of the Rockies. From Wed night through Friday, the upper ridges are generally expected to remain in place near Bermuda and the desert southwest with a weakness in between. Models vary with the strength of these from run to run. This leads to uncertainty on the timing of the tropical system remnants as they move toward the Arkalatex region and eventually portions of the TN and lower OH Valley as insentropic lift spreads north and east. At the same time, low pressure should move rather quickly east across southern Canada and the Northern Conus with the center of the low reaching Quebec on Friday while the trailing cold front becomes sheared from northeast to southwest north of the region. This front to some extent will interact with the increasing tropical moisture and probably some solar insolation on Friday to bring a round of showers and thunderstorms to the region. Some locally heavy rain will be a possibility. From Friday night into Saturday, some jet entrance region dynamics may come into play and lead to deeper enhanced lift across the area. However, models vary on this from run to run and model to model. The threat for locally heavy rain will continue into the day on Saturday across East KY. The deeper moisture with the tropical remnant and associated weakening shortwave should depart to the east by Saturday evening. To end the weekend through early next week, a trough the axis of which should move from the central to eastern Conus should be the dominant features. Disturbances moving through the trough may combine with lingering moisture for chances of convection, especially during the afternoon and evening on Sunday and Monday. What is certain as there will be an increase of deep tropical moisture into the region by Thursday night and into Friday. However, uncertainty remains in rainfall amounts and areal extent of higher amounts. Some solutions have quite widespread high amounts but may be suffering from convective feedback issues. The model consensus blend of 48 hour totals of 2.25 to about 3.5 inches is a reasonable compromise of all solutions at this time. Locally higher amounts than that are possible. As the strength of the ridges and the tropical system become more clear, the timing and strength of the remnants will be more certain as should rainfall amounts. At this time, we have opted to include the threat of heavy rain in the HWO, but highlight the uncertainty. The expected presence of deeper moisture and rather extensive cloud cover will bring rather limited diurnal ranges from Thursday night through the end of the period. After near to slightly above normal highs on Thursday below normal highs are expected with mild overnight lows Wed night through Friday night. The period should end with temperatures averaging below normal with the trough in place. && .AVIATION...
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(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 219 PM EDT TUE JUN 20 2017 High pressure will keep VFR conditions in place, besides some patchy IFR or worse fog between 06 and 13z. This should be confined to the deeper river valleys. Scattered cumulus at 6-7k feet agl will gradually dissipate through this evening, with some increase in mid level clouds possible towards dawn Wednesday morning. West winds at 5 to 10 kts will become light and variable by this evening.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...AR LONG TERM...JP AVIATION...GEOGERIAN is the U.S. government's official web portal to all federal, state and local government web resources and services.