Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 130613 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 213 AM EDT Tue Mar 13 2018 .UPDATE... Issued at 213 AM EDT TUE MAR 13 2018 Issued an update to input the latest observations into the forecast and trend them into the predawn hours. The snow showers across the area will be coming to an end with the next few hours this morning and have adjusted the pops to reflect that. A new zfp will not be needed for this update. UPDATE Issued at 1100 PM EDT MON MAR 12 2018 Some embedded heavier snow showers are currently moving across the area. These may put down a quick dusting to a tenth or two of an inch where they track. The forecast generally remains on track, with these snow showers gradually diminishing from northwest to southeast, as the short wave trough pulls further away to our east. Forecast lows in the mid to upper 20s still look good, as some partial clearing works in from the northwest overnight. Mainly freshened up the hourly temperatures and dew points through the rest of the night. Updates have been sent. UPDATE Issued at 836 PM EDT MON MAR 12 2018 A short wave trough is currently moving southeast across the Ohio Valley. Some scattered snow showers are moving into eastern Kentucky, although given the higher cloud bases, these have not been producing much in the way of accumulating snowfall, mainly just some reduced visibilities on local observations. Will continue to mention these through around midnight, before they likely become more confined to our southeast terrain. Forecast lows look on track for now, and have only adjusted the temperature curve a bit based on the latest trends in observations. Updates will be out shortly. && .SHORT TERM...(This evening through Tuesday night) Issued at 420 PM EDT MON MAR 12 2018 An upper level ridge extended from Mexico into the Intermountain West this afternoon with a trough extending across much of the eastern Conus. The upper level low that affected the region with snow last night into early this morning is currently working across South Carolina. Meanwhile, an upper level trough was moving through the Great Lakes with an upper level low dropping into the Northern Great Lakes. A shortwave trough was rotating through this trough and approaching the OH Valley. Temperatures late this afternoon were mainly in the mid 30s to lower 40s across the area with the coldest readings where snow cover was deeper and over the southeast. Colder air continues to move into the region in the northwest flow. The upper level low will move off the Carolina coast this evening while a shortwave trough rotates through the OH Valley and into the Appalachians. Northwest flow aloft will lead to continued cooling aloft which should steepen lapse rates this evening into the early part of the overnight hours. This combination will lead to the threat of snow showers and flurries from before sunset into the overnight hours and especially over the southeast counties with northwest upslope flow, not only at the mid and upper levels with the trough, and between high pressure over the Plains and MS Valley and low pressure developing along the eastern seaboard. The bulk of any activity should peak between about 8 PM and midnight though flurries may linger later. Accumulations should be minimal at most a dusting in most cases so some fluffy higher accumulations above 1500 or 2000 feet are possible. Lows will be below normal in the mid to upper 20s. Two additional shortwave troughs in northwest flow will approach the region early on Tuesday with the first working through the area on Tuesday afternoon to early evening and the second moving through overnight. This and continued upslope flow will lead to the threat of isolated to scattered snow showers again. Some light accumulations with these are possible late Tuesday afternoon and evening over the eastern part of the area and over the terrain near the VA border before the focus shifts into the far southeastern counties where some light accumulations will be possible on Tuesday night. Again elevations of 1500 feet and above and especially above 2000 feet will be favored for some light accumulations with not much more than a dusting in nearby valleys. With the cold airmass in place temperatures will average 15 to 20 degrees below normal for highs on Tuesday and about 5 to 10 degrees below normal for lows on Tuesday night. .LONG TERM...(Wednesday through Monday) Issued at 345 PM EDT MON MAR 12 2018 The long term period will begin as a system moves east of the Commonwealth, bringing slight chances of lingering snow showers to the far eastern counties. These chances linger into Thursday as well, represented by both the GFS and ECMWF. However, the main system of focus comes during the weekend where a frontal boundary stalls over the Ohio Valley. With south/southwesterly flow, this will usher in ample moisture as well as warm temperatures from the Gulf for the weekend. The models are not in particularly good agreement for this weekend. The GFS shows two rounds of precip. The first, looking to arrive Friday morning, has the higher QPF of the two rounds with QPF ranging from 0.50 to 1 inch in the southwestern counties of the CWA. The second round looks to develop Sunday morning through the afternoon in the southernmost counties and linger through Monday. However, this QPF will be a bit lighter, ranging from 0.25 to 0.50 inches. In comparison, the ECMWF shows one round of precip for the weekend developing Saturday morning through the afternoon and lingering through Sunday morning. This rain is more widespread and the QPF is lighter than the QPF shown by the GFS. The ECMWF does not show another round of precip until Monday night into Tuesday morning. Therefore, there is not good agreement on timing and intensity of this weekend system as of yet. Will continue to monitor future model runs to see if the models come into better agreement with the development of this system. Lastly, models have shown less impressive amounts of instability for the late weekend. Therefore, thunder has been reduced on this update. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 107 AM EDT TUE MAR 13 2018 Expect northwest flow to persist tonight as a few snow showers will continue to push through the area in the next few hours. A few IFR cigs but mostly MVFR cigs will continue for the next few hours. With this, will see clearing skies before another wave will pass through the area tomorrow afternoon. This will bring another round of rain and snow showers lasting through the end of the TAF period. Will expect another round of MVFR cigs and near field mins for visibility with these snow showers. Winds will be on the increase as well with some 20 knot wind gusts out of the northwest by the afternoon and lasting into Tuesday night. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...JP LONG TERM...CGAL AVIATION...SHALLENBERGER is the U.S. government's official web portal to all federal, state and local government web resources and services.