Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251106 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 706 AM EDT Wed Apr 25 2018 .UPDATE...
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Issued at 658 AM EDT WED APR 25 2018 Forecast is still in good shape based on the latest observations for temps, dew points, and winds. However still receiving reports of light drizzle, with little in the way of showers showing up on the radar. Drizzle wording will change over to shower wording at 12Z, but if current conditions persist, may need to extend drizzle wording a bit longer and reduce scattered shower mention. All grids have been published and sent to NDFD/web.
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&& .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...
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(For the 12Z TAFS through 12Z Thursday morning) ISSUED AT 706 AM EDT WED APR 25 2018 A large upper level low pressure system is continuing to exit east of the state. In its wake, deep NW flow is in place, pulling moisture southward from the Great Lakes region. This will continue the IFR CIGs at most TAF sites through the morning, with slow improvement back to MVFR expected through the afternoon as a drier airmass begins to take hold and we lose the deep NW flow. Some sites may reach VFR conditions by this evening, however it will be short lived. Guidance continues to point at a lowering of CIGS during the overnight, especially for the second half of the night, as well as the increased risk of fog development. This could easily bring TAF sites back down to IFR or lower to round out the TAF period. Exactly impacts and timing are still in low confidence at this time. Winds will be predominately out of the NW around 5 kts throughout the day, becoming light and variable overnight.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...JMW LONG TERM...HAL AVIATION...JMW

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