Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 060031 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 731 PM EST Mon Dec 5 2016 .UPDATE... Issued at 731 PM EST MON DEC 5 2016 Broken band of rain extending from the lower Mississippi Valley into the Tennessee Valley continues to look rather disorganized as it journeys northeastward. With the upper low just now pushing into east Texas, lift ahead of the warm/moist conveyor belt will steadily make headway toward the Tennessee and eventually Cumberland Valleys. Increasing lift associated with this feature, along with isentropic upglide, will not take place until after midnight. Thus, have slowed timing of the best rain chances down to account for this, along with backed easterly/downslope winds remaining in place on the eastern side of the approaching surface low. These will not veer south/southwesterly until Tuesday morning, keeping the best rain chances and highest rainfall amounts in check until then. Have also updated temperatures as slower progression of low clouds from the southwest will likely allow valleys in the Big Sandy region to cool off early this evening prior to the onset of warm air advection. && .SHORT TERM...(This evening through Tuesday night) Issued at 300 PM EST MON DEC 5 2016 An area of low pressure aloft is forecast to move out of the southern Plains/western Gulf coast region this evening, and will be our primary weather maker through tomorrow night. Most of the latest model data is suggesting that precipitation onset will still be a couple of hours later than the night shift forecast was indicating. The new forecast will reflect a blend of the latest model data with precipitation onset anticipated around 1Z this evening in our far southern counties, or roughly two hours later than previously forecast. Based on the expected temperature profiles, precipitation will be in the form of all rain across eastern Kentucky. The best chance for rain will occur from late tonight through Tuesday afternoon. The rain should begin to taper off Tuesday afternoon and evening, with the last rain showers exiting the area between 9 and 10Z Wednesday. Area wide we can expect around an inch of rain from this event. Temperatures are expected to run at or slightly below normal through tonight, with a non diurnal temperature progression tonight. There will likely be a period of time tonight during which temperatures actually begin to increase, as winds also increase and shift more to the south and widespread precipitation sets in. Highs on Tuesday are expected to top out in the 50s, with lows in the 40s tonight and the 30s Tuesday night. .LONG TERM...(Wednesday through Monday) Issued at 328 PM EST MON DEC 5 2016 We transition to a much colder weather pattern to end the work week as a deep, but transient, trough digs into the Ohio Valley. Models usher in this colder airmass without much precipitation. However, we come under the influence of the right entrance region of a stout 150kt upper level jet as the cold front works through Thursday morning and models hint that this could force some light snow and/or rain Wednesday night into Thursday morning. Will keep PoPs rather low as moisture is limited. Isolated snow showers and flurries will remain possible Thursday night into Friday with strong cold advection wringing out any lingering moisture. Temperatures will likely not rise out of the 20s on Friday. Cold high pressure settles into the region Friday night and this will likely be our coldest night. However, models show the potential for some high clouds to interfere with our radiational cooling. Nonetheless, temps in the teens are a good bet for just about everyone. Models show a fast transition to southwest flow aloft by Saturday night in advance of a shortwave digging into the northern Plains. This will result in increasing clouds and precipitation chances late in the weekend. Timing remains questionable with this system with large differences in the modeling so stayed close to the blended model guidance. However, 60-70 PoPs on Sunday seemed a bit high with the uncertainty involved, so dropped them down into the chance range. Current forecast timing would introduce the threat for a mix of rain and snow at onset late Saturday night/early Sunday morning, but the bulk of the precipitation Sunday into Monday should be rain. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 731 PM EST MON DEC 5 2016 VFR conditions will deteriorate, beginning near midnight at SME. All other sites will see this take place overnight from southwest to northeast as lowering ceilings and light to moderate rain move into eastern Kentucky. MVFR ceilings later tonight will likely lower to IFR and possibly LIFR Tuesday morning as rainfall becomes more widespread. Visibilities will also decrease to MVFR and potentially IFR as rain falls. Should see the bulk of the rain taper off by late afternoon, allowing visibilities to increase to VFR criteria. However, IFR ceilings look to be a good bet through 00Z. Winds will increase to 5-10 knots overnight, while veering southeasterly. Will see these veer further to the west/southwest Tuesday afternoon, with speeds increasing to near 10 knots with higher gusts during the latter portion of the afternoon as a cold front gets set to move through the Ohio Valley and Commonwealth. Additionally, southeasterly low level wind shear near 35-40 knots may become an issue tonight across far southeast Kentucky. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GUSEMAN SHORT TERM...AR LONG TERM...ABE AVIATION...GUSEMAN is the U.S. government's official web portal to all federal, state and local government web resources and services.