Area Forecast Discussion
Issued by NWS Jackson, KY

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670 FXUS63 KJKL 172121 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 521 PM EDT Sat Mar 17 2018 .SHORT TERM...
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(This evening through Sunday night) Issued at 520 PM EDT SAT MAR 17 2018 A cold front was bisecting the forecast area from east to west late this afternoon, with a low pressure system tracking along the front from central into eastern KY. Showers and thunderstorms have quickly developed along the front. The regime will shift southward this evening. There is good speed shear in place, and dry mid levels with steep lapse rates. The severe weather parameter which is looking puny is the moisture. Strong heating has mixed drier air to the surface with dew points only in the 30s and 40s over most of the southern portion of the area late this afternoon. Can not rule out severe weather in places where higher dew points linger or redevelop, but for much of the area late afternoon conditions don`t look all that favorable. Freezing level and wet bulb zero height are quite low, which favors large amounts of small hail. Any large hail would probably need to come from storms with significant rotation. Storms should taper off from northwest to southeast this evening after cold fropa. Surface high pressure passing to our north will provide fair weather Sunday into Sunday night. Another low pressure system heading east from the southern plains will pull the front back north toward KY as a warm Sunday night. Showers could make a return to our southwest counties by dawn, but will more likely hold off until the daytime on Monday. .LONG TERM...(Monday through Saturday) Issued at 520 PM EDT SAT MAR 17 2018 Model solutions are in decent agreement, sufficient enough to pick out the main features of concern through the extended. Flow aloft amplifies with time but remains fairly progressive, with implications that our generally unsettled pattern will continue with only one relatively short period of fair weather from Thursday through at least part of Friday. Consequently our weather is active straight out of the gate as a mid level low, upper level wave moves into the region Monday. Additional shortwave disturbances follow Tuesday into Wednesday before exiting to our east by Thursday. Solutions differ on timing another shortwave disturbance into the region by the end of the period, with the 12Z GFS bringing our next weather maker into the area by late Friday into Saturday. The 0Z ECMWF and 12Z Canadian hold off on this system until beyond the end of the period, and seem to suggest a deeper, more organized storm system. Closer to the surface, a low pressure system will pass through the Tennessee Valley Region Monday/Monday night. Instability is marginal but may be enough to kick of a thunderstorm or two late Monday into Monday night. Shortwave disturbances following in the wake of the initial low will be responsible for the redevelopment of another surface low or two over the southern Appalachians through Tuesday and Wednesday. If enough cold air manages to be drawn southward into the region from the north, sensible weather may feature a wintry mix of rain and snow showers for a period of time late Tuesday night into Wednesday morning, particularly across the higher terrain. However, details remain a bit too sketchy to provide any specifics for now. Drier conditions will work into the area by Wednesday night and Thursday as ridging moves in from the west. Fair weather should continue through much of Friday before the next potential weather maker moves in from the west by late week or early into the weekend. Comparing models favored a slower arrival of the precipitation for the end of the extended and would not be surprised if Friday winds up dry in the end. But should not discount the GFS solution totally based on its recent very good performance with the last few systems to affect our area. Otherwise, near normal temperatures initially will cool to well below normal for the mid week time frame. Temps then rebound for the end of the week and following weekend. |
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(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 300 PM EDT SAT MAR 17 2018 A slow moving cold front was located near the Mountain Parkway and was dropping south through the forecast area at the start of the period. Most places were VFR with scattered to broken cu. The northern edge of the forecast area was likely IFR due to ceilings in portions of Fleming, Rowan, and Elliott counties. The front will continue to sink southward today. Showers and thunderstorms are expected to develop near and ahead of the front late this afternoon and early this evening, but will taper off after frontal passage tonight. IFR and MVFR ceilings are forecast to develop southward over the region behind the front late today and tonight, affecting the entire region by about 02z. Ceilings are forecast to break up and give way to VFR conditions from north
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HAL LONG TERM...RAY AVIATION...HAL is the U.S. government's official web portal to all federal, state and local government web resources and services.