Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 301347 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 947 AM EDT TUE AUG 30 2016 .UPDATE...
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Issued at 947 AM EDT TUE AUG 30 2016 The majority of the morning fog has now lifted and have therefore removed mention of it in the HWO. Also freshened up the hourly sky cover and temperature grids to reflect most recent obs. UPDATE Issued at 630 AM EDT TUE AUG 30 2016 Clear and calm so far this morning across eastern KY, with varying degrees of fog reported at the observation sites. Freshened up the near term forecast with the latest observations to make sure they matched up well with current conditions. Otherwise forecast seems to be well on track. All changes have been published and sent to NDFD/web. No new forecast package is needed at this time.
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&& .SHORT TERM...(Today through Wednesday) Issued at 356 AM EDT TUE AUG 30 2016 An upper level ridge will be in place across the region today and tonight, keeping subsidence and calm weather across the region during this time. Meanwhile, a closed upper level low will push southeast along the shores of the Hudson Bay today. This will result in upper level troughing as the low continues on into James Bay overnight, and lowering heights across the eastern US during the day Wednesday. As for sensible weather... High pressure across the region has led to clear skies and light winds early this morning. Locations that received rain yesterday have been prone to patchy dense fog overnight, as have many of the deeper river valleys. This fog will slowly dissipate through the morning hours as temperatures begin to warm. Generally clear conditions are expected through the day today under continued light NE to N flow. That being said, afternoon heating could lead to a few diurnal cumulus, and possibly an isolated shower or thunderstorm. All hi-res CAM models are pointing at the best potential for this occurring along the highest terrain in the far southeast portion of the state, so did include some isolated pops here. Under strong subsidence, temperatures will be similar to that of yesterday, nearing 90 degrees by the afternoon. Thankfully with the NE to N flow in place, this will keep some of the humidity levels down, and apparent temps will remain close to the actual temp values. Any diurnal clouds will clear out once again tonight, with valley fog formation being the only weather concern. Temperatures will fall into the upper 60s to near 70, similar to that of this morning. The big change will come during the day Wednesday. A surface low pressure system associated with the above mentioned upper level closed low will track southeast across Canada, pulling with it a cold front. This cold front is expected to push eastward and towards KY, reaching just north of the Ohio River by Wednesday afternoon. An interesting thing to note, however, is that the winds never turn southerly ahead of this front, instead they will shift from NE to NW along and behind the frontal passage. That being said, a lot of the convection along the frontal boundary will actually be diurnally driven, with the aid of afternoon heat/instability. Clouds really won`t start building in until just ahead of the frontal zone, along with the best convection, given the lack of moisture. Did keep some isl to sct pops in during the afternoon, though coverage may be limited to the far northern portion of the CWA (closer to the actual frontal zone), as well as in the high terrain as a result of upslope NW flow across the CWA. Overall, much of the CWA should see minimal impacts during the day Wednesday, and much of the convection should cease by Wednesday night with the loss of diurnally induced lift. Temperatures Wednesday will still manage to boost back into the upper 80s, though if cloud cover winds up being more extensive than originally thought, this may keep temps a degree or two cooler. .LONG TERM...(Wednesday night through Monday) Issued at 450 AM EDT TUE AUG 30 2016 The models are in pretty good agreement aloft through the long term portion of the forecast. They all depict a northeast trough diving through the Ohio Valley and Central Appalachians from Wednesday through Friday. This trough will be accompanied by plenty of energy, but the best of it will stay to the north and east of Kentucky. Some lingering patches will be scooped up out ahead of the trough into Thursday morning - pushed into Kentucky in conjunction with the best height falls. Later as the trough moves out, another batch of energy will settle into the area Friday afternoon into the night but heights will be rebuilding at that time and should dampen the effects of this on sensible weather. Strong ridging then will move over the region and dominate the weather into next week. Given the model similarities have accepted a general blend as a good starting point through the extended portion of the forecast. Sensible weather will feature a chance for showers and storms from Wednesday night into Thursday morning as a cold front settles through eastern Kentucky, pushed by a fairly strong area of high pressure. This high will settle into the Ohio Valley by the end of the week with a nice taste of the cooler and drier weather that will soon be upon us as summer`s grip relaxes. However, a resurgence over the weekend and into next week will bring very warm temperatures and a slow build up of humidity back to our forecast. The retreating high should keep any renewed threat of convection out of the picture until beyond Monday, though. Mainly made temperature adjustments to the extended grids - capturing the ridge and valley distinctions, especially from Friday night on through Monday morning. Also, tweaked the hourly PoPs Wednesday night and Thursday tracking the front into our area and its departure to the southeast by midday Thursday. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 637 AM EDT TUE AUG 30 2016 Clear and calm conditions were in place this morning under a strong ridge of high pressure. Varying degrees of fog were also being reported across eastern KY, though the only TAF sites affected so far are JKL and SJS. Fog should slowly burn off over the next few hours, leaving clear skies and light winds. Few/sct diurnal CU may develop during the late morning/afternoon time frame, with some isolated convection possible near the VA border, but this should pose little threat to any of the TAF sites. Winds will remain light, generally from the N to NE and less than 5 mph. && .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...JVM SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW

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