Area Forecast Discussion
Issued by NWS Jackson, KY

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348 FXUS63 KJKL 122052 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 352 PM EST Tue Dec 12 2017 .SHORT TERM...
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(This evening through Wednesday night) Issued at 352 PM EST TUE DEC 12 2017 Scattered snow showers were ongoing over the eastern portion of the forecast area late this afternoon in upslope cold air advection, but the back edge of the activity was shifting eastward as drier air advected into the area and the low level moisture mixed away. The last of the snow should end from west to east this evening, and no appreciable accumulation should occur. Clouds were already diminishing from west to east as well late this afternoon, and this trend will continue through most of the night as surface ridging builds in from the west and low level cold air advection eases, and warm air advection begins. Warm air advection will continue on Wednesday as a potent clipper type system moves southeast toward Ohio. Mid level clouds will likely show up at times over the northeast part of the forecast area, but dry low levels should prevent any precip. The low will pass to our north on Wednesday night, and all significant precip associated with the system will be to our north. However, the trailing cold front will bring another quick burst of colder air to the region beginning late Wednesday night. Once again, low level lapse rates will steepen, and forecast soundings suggest that the top of the shallow, moist convective layer may reach temperatures cold enough for ice production overnight over the northeast part of the forecast area. A low POP for snow showers will be included there. .LONG TERM...(Thursday through Tuesday) Issued at 352 PM EST TUE DEC 12 2017 The extended portion of the forecast begins on Thursday with an amplified meridional pattern in place. The period begins with the OH Valley in northwest flow as a weak wave is in the process of swinging through the area. The next wave passes through the area by Friday afternoon but stays a tad further north than the previous. By the weekend timeframe, the pattern seems to become more progressive and less amplified as the closed low over the southwest CONUS ejects east into the lower MS Valley, this shifts east as another stronger wave moves through the Central Plains and into the Midwest. These features seem to combine over the OH Valley with the next shot of precip arriving for Sunday and Monday. Concerning the lower levels, the waves expected to impact eastern Kentucky on Thursday and again on Friday, while in upslope flow, still appear to be starved for moisture. A slight chance of snow showers will still be on tap for Thursday despite the lack of moisture but the Friday wave appears to be a tad too far north with a small chance over the far northern counties. Also expected, the daytime high temperatures will be a bit too warm for snow all day so will expect a mix and or change over to rain. A surge of moisture ahead of the stronger system Sunday evening into Monday will provide the next best chance for rainfall. As temperatures cool Sunday night into Monday, a few spots, especially the higher terrain may change over to snow before changing back to liquid by the daytime on Monday. At this point, there is little consistency to pin point any accumulation. Even so, it will be little to none at this point.
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&& .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 152 PM EST TUE DEC 12 2017 Scattered snow showers were ongoing at the start of the period, and were most concentrated over the eastern part of the area. Showers will show an overall decline as time goes by. Aside from the more significant snow showers, conditions were mainly VFR. Localized IFR was likely present in the heavier showers. Once the last snow showers dissipate over the eastern part of the area this evening, VFR conditions are expected through the remainder of the period. Gusty west to northwest winds of this afternoon will gradually diminish through the evening. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HAL LONG TERM...SHALLENBERGER AVIATION...HAL is the U.S. government's official web portal to all federal, state and local government web resources and services.