Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 250829 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 429 AM EDT Wed Apr 25 2018 .SHORT TERM...(Today through Thursday) Issued at 416 AM EDT WED APR 25 2018 The deep 500mb low that has been sitting across Kentucky is finally on its eastward exit this morning. It will shift northeast from the Carolinas to Virginia today, as it becomes absorbed within longwave troughing from another upper level low located over the Great Lakes. Heights will flatten a bit across Kentucky during the day, however this will be short lived as another upper level low deepens across the Central and Southern Plains during the day, shifting southeast into the lower Mississippi Valley tonight and across the Deep South during the day Thursday. At the surface, low pressure associated with the current exiting upper low will also continue to shift east of the region through the day , as it rides up the mid Atlantic coast. This will result in continued NW flow across the state throughout the day, including in the mid and upper levels. Furthermore, a weak cold front is expected to shift eastward across Kentucky during the day, connected to both a surface low pressure system over the Great Lakes region, and another low moving across the mid-Mississippi Valley, associated with the above-mentioned incoming upper level system. While the frontal system itself will have little impact, the deep N to NW flow across the region will be enough to pull moisture from the Great Lakes region southward into Kentucky. This will result in continued clouds across the region, and also promote isolated to scattered rain showers, especially in areas where upslope flow is favored. The front should exit SE of the region overnight, with weaker flow and high pressure taking hold in its wake, effectively cutting off any remaining precip chances for the night. Could see some patchy fog development, though forecast soundings are still supporting low clouds lingering across the region. As we head into Thursday, high pressure will remain in control for much of the CWA throughout the first half of the day. However as the low pressure system to our south traverses eastward across the Tennessee Valley towards the Appalachians, moisture from this system will begin to push northward into Kentucky. As such, expect yet another day of cloudy skies. Scattered rain showers will be possible across the far southern CWA throughout Thursday morning, expanding north and eastward during the second half of the day as the center of the low draws closer to the region. As for temperatures, the ongoing cloud cover expected throughout the short term portion of the forecast will keep temperatures fairly uniform across the CWA, and mild overnight. Deeper NW flow today will keep temperatures around 60 degrees for highs. Overnight lows will fall into the upper 40s across the region. Weaker flow (less northerly wind influence) will be enough to boost temps a few more degrees for Thursday, with highs in the low to mid 60s. .LONG TERM...(Thursday night through Tuesday) Issued at 429 AM EDT WED APR 25 2018 A weak low pressure system will be passing by to our south as the period starts. Models have come into better agreement on this system compared to yesterday. The ECMWF trended toward the American models for a track further to the north, bringing rain to the JKL forecast area Thursday evening. In light of this, a likely POP is being used in southeast Kentucky, with a 20% POP extending all the way to the northwestern edge of the area. This system will depart to the east overnight. No meaningful change in air mass will occur with the system, but following it, there are a couple of cold fronts expected. One should pass on Friday, and the other on Saturday. They will be weak and will have very little moisture present when they pass. Their main effect will be to hold temperatures in check in the face of strong spring sunshine. The cold frontal passages will be enabled by an upper trough over the northeast CONUS. This trough will depart to the east late in the weekend, and an upper level ridge is expected to become established over the southeast CONUS for the early part of the week. Coupled with a return of warm air advection, this will send our temperatures well into the 70s or near 80. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 159 AM EDT WED APR 25 2018 A large and stacked weather system over the TN and OH valleys continues to rotate to the east, at present centered southeast of the state. Showers associated with this system have diminished throughout the evening resulting in the removal of VCSH from overnight portion of the TAF, though did keep VCSH mention for during the day Wednesday at most sites as activity is likely to ramp back up with daytime heating. Despite the current lack of rainfall, flight conditions are still expected to generally deteriorate through the overnight as the upper system slips over the area. The poor aviation categories will be mainly from the CIGS as they drop into IFR/LIFR territory, and even below airport minimums at many of the TAF sites. Expect these conditions to persist through at least the first half of the day Wednesday, with slowly improving conditions expected for the afternoon and evening. Most sites should see the return of MVFR CIGS by evening, continuing into the overnight. Winds will be light and variable throughout the period, with any predominate winds generally out of the NW 5kts or less. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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