Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 221845 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 245 PM EDT Thu Jun 22 2017 .UPDATE... Issued at 149 PM EDT THU JUN 22 2017 Freshened up the hourly POPs through the rest of the day. Widespread showers will continue to gradually overtake the area. Increased confidence in the heavy rainfall potential for Friday afternoon through early Saturday morning based on some of the 12z data has also prompted the issuances of a flash flood watch. Updates have been sent. UPDATE Issued at 1130 AM EDT THU JUN 22 2017 Mainly light rain showers continue to advance northeast into eastern Kentucky. There has been no lightning activity upstream in Tennessee, and given the weak low and mid level lapse rates, will only allow for a slight chance of thunder for the rest of the day. Have also lowered the highs somewhat, with thicker cloud cover advancing in quickly. Highs look to range from the mid 70s across the southwest, to around 80 to the northeast. Updates have been sent. UPDATE Issued at 755 AM EDT THU JUN 22 2017 Showers on the leading edge of significant moisture increase from the Gulf into the southeast and TN Valley has reached as far north as middle and eastern TN. High clouds have also been increasing as have mid level clouds in the south. The current forecast pops still look on target compared to recent hi res guidance and 6Z models runs. The only changes at this time were minor adjustments to hourly temperatures and sky conditions based on recent observations and satellite trends. && .SHORT TERM...
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(Today through Friday) Issued at 445 AM EDT THU JUN 22 2017 Early this morning, a rather zonal pattern in nature is in place across the northern Conus with a ridge centered over the Desert Southwest and another ridge centered between the Bahamas and Bermuda. Surface high pressure in place from the Appalachians to the Carolinas. Meanwhile, Tropical Storm Cindy is gradually nearing the Gulf Coast near the TX and LA border. Tropical moisture is already moving north across the Southeast and string to surge north toward the TN and OH Valley regions. Despite an increase in mainly cirrus with a few mid clouds, a moderate nocturnal inversion has developed with ridgetops around 70 or the lower 70s and valleys in the 60s. Valley fog was present in a few valley locations. At the same time that Tropical Storm Cindy and eventually its remnants track toward the Arklatex region through this evening, return flow between it and departing high pressure will bring a plume of Gulf moisture north into the East KY. In addition, a shortwave trough will move into the Northern Plains and approach the Great Lakes tonight. A preceding cold front should move into the Central Great Lakes by dawn on Friday and approach the Lower OH Valley. Meanwhile the center of the remnants of Cindy should reach southeastern AR by dawn on Friday. The shortwave trough should move into the Great Lakes on Friday with the trough axis nearing the Lower OH Valley. Also, the cold front should approach the area from the north at that point. A round of showers and a few thunderstorms is expected across the region, arriving around midday into the afternoon in the south and then spreading northeast through evening. The deeper moisture should arrive first in the southwest and this combined with less influence of a downslope southerly flow in the low levels will lead to heavier rainfall there today. The chances for locally heavier rain from thunderstorms will also be greatest across the southwest or west this afternoon and evening. This rain will occur with some isentropic lift on the leading edge of moisture gradient as PW climbs rather dramatically to the 1.95 to about 2.1 inch range by sunset. Some solar insolation may also aid in some shower and thunderstorm development. Scatter to possibly numerous shower chances will continue into the overnight tonight and into Friday morning as the front and shortwave trough approaches and interacts with moisture from the remnants of Tropical Storm Cindy. The threat of heavy rain should return again on Friday afternoon as the center of the remnants of Cindy nears and interacts with some daytime heating. A period of some dry slotting or drier air moving at mid and upper level should work across the area in between the rounds of rain and allow for heating on Friday to warm temperatures to around 80 or the lower 80s. At the same time, moisture will again increase from the south and west and band of showers and some thunderstorms are possible as the approaching front, trough, and circulation form the remnants of Cindy near. This circulation should locally enhance low level shear and this combined with daytime heating in potential bands of convection will bring a chance for a few strong to possibly severe thunderstorms along with heavy rain. Damaging winds would be the main threat although with the increased shear in the afternoon to early evening, a stray weak tornado cannot be ruled out. The heavy rain threat will continue to be highlighted in the HWO as well as an ESF. The threat for a couple of strong to severe storms is also highlighted in the HWO. If current trends continue, a Flood Watch will likely be needed for Friday into Friday night. Uncertainty remains in exact placement of the axis of axises of heaviest rainfall, but one could develop by the long term period over east KY with another closer to the approaching front. .LONG TERM...(Saturday through Thursday) Issued at 244 PM EDT THU JUN 22 2017 The extended portion of the forecast begins on Saturday with the upper level pattern featuring a stout ridge over the western CONUS transitioning into a trough over the Great Lakes. The first wave associated with the combination of tropical moisture and a cold front will finally exit the area at the start of the forecast period. So will see a chance of showers over eastern Kentucky through the day on Saturday as the last of the showers exit the area by the evening. This will usher in a dry period as models have trended drier and drier. The mentioned stout ridge in the west will build as it shifts east nudging the axis over the Midwest by Wednesday. In addition, a bubble of surface high pressure will carve out an area of subsidence over eastern Kentucky and much of the central Appalachians. In fact, the airmass intrusion behind Cindy will bring some welcomed cooler temps to start next week with highs in the 70s expected through Wednesday. One difference in the forecast might be on Monday afternoon as the most recent 12Z Euro and GFS has brought a weak wave dropping far enough south to bring a small chance of showers and a thunderstorm. This is a change to the model trends so am more inclined to keep the dry forecast inherited from the super blend. Otherwise, the extended features dry weather and slightly cooler high temperatures.
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&& .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 149 PM EDT THU JUN 22 2017 Showers and MVFR ceilings at the leading edge of the moisture advection associated with Tropical Storm Cindy will continue to advance northeast across the region. Ceilings then look to raise up this evening, before potentially lowering again towards dawn. Shower chances will be diminishing from southwest to northeast this evening, as the first surge of moisture exits off to the northeast. Low level wind shear will threaten later tonight, as 850 mb winds remain around 40 to 50 kts, while south to southeast winds at the surface remain at around 5 kts or less. There will at least be a threat of scattered showers and a few thunderstorms into Friday, as the cold front begins to move in from the west and northwest. && .JKL WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Friday afternoon through Saturday morning for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...GEOGERIAN SHORT TERM...JP LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN is the U.S. government's official web portal to all federal, state and local government web resources and services.