Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 210603 AAD AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 203 AM EDT Wed Jun 21 2017 .UPDATE...
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Issued at 155 AM EDT WED JUN 21 2017 Thicker cirrus is streaming from West Tn east northeast to the KY/V border region into the Central Appalachians. A surface ridge of high pressure remains in control across the Appalachians with the region in a seasonably moist airmass between weak cold front or outflow boundary north of the Ohio River and nearly stationary boundary from east TX east northeast to the Delmarva which is the leading edge of the much deeper tropical moisture to the south. This moisture is being transported into the Gulf states around Tropical Storm Cindy. Sky cover has been increased a bit across the south to account for the greater abundance of cirrus initially although guidance suggests that this should decrease toward dawn. Additional debris mid level clouds could cross the OH River and move into the northern part of the area as well. Temperatures in some valley locations were not dropping as quickly as the inherited forecast and have been increased a couple of degrees for the next few hours. However, min T in these valley areas was only raised a degree or two as a thinning in clouds is expected prior to dawn more to the upper 50s versus some mid 50s. Overall, this update led to no substantial changes. UPDATE Issued at 1047 PM EDT TUE JUN 20 2017 WSR-88D still picking up on a few isolated rain showers and/or sprinkles. These will remain light and most spots will remain dry tonight. Updated to allow a bit more time on the sprinkles and also updated clouds with latest obs and satellite trends. Also, the clouds are playing a role in keeping temperatures a bit warmer than the current temperature curve. Therefore, adjusted the curve some to better match trends. UPDATE Issued at 857 PM EDT TUE JUN 20 2017 Despite surface high pressure, a 500MB wave and 300mb divergence is just enough to POP off a rain shower or sprinkle this evening based on WSR-88D radar this hour. The HRRR seems to be handling this fairly well and will somewhat lean toward it with edits. For now will update to add in sprinkles at most for a couple of hour. These will be showers will be light and are expected to dissipate over the next couple of hours. UPDATE Issued at 625 PM EDT TUE JUN 20 2017 Surface high pressure continues to build into the region and matter of fact the highest pressure reading nearby is at CSV in the TN Valley region. Overall this and mixing will lead to a drier night and based on crossover temps not as much fog. However, while the CU will dissipate and we will be left with mostly high clouds streaming in from the SW. No major changes needed for this update but did load in the latest obs and trends.
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&& .SHORT TERM...(This evening through Wednesday night) Issued at 359 PM EDT TUE JUN 20 2017 The latest surface map features broad high pressure across the mid-Mississippi Valley, with Tropical Storm Cindy located across the central Gulf of Mexico. Aloft, a strong ridge remains poised across the Desert Southwest, with troughing in the northeastern quadrant of the CONUS. Eastern Kentucky has been enjoying dry weather, with temperatures in the low to mid 80s and dew points down as low as the lower 50s in places at times. Dry weather will continue through the rest of the short term, as high pressure remains nosed in from the east southeast through the column. Tonight will feature a mostly clear night, with lows ranging from the mid 50s in some of the cooler valleys, and lower 60s on the ridges. Wednesday will feature a warmer day, with highs in the mid 80s, and dew points also a bit higher. The moisture will make a bigger increase through Wednesday night, as thicker high clouds stream in from the approach of Cindy. Lows will be in the mid to upper 60s. .LONG TERM...(Thursday through Tuesday) Issued at 359 PM EDT TUE JUN 20 2017 The extended portion of the forecast begins on Thursday with the upper level pattern favoring a more northern track with the jet leaving the central and southern CONUS under weak flow to begin the extended. Focus of the extended will be on the approach of the remnants of or rather a still organized Tropical Depression possible moving into Kentucky. Models have wavered a bit on the track and QPF amounts but overall have kept a consistent time period of rainfall. As the surface tropical low track north and northeast around the mid level ridge parked over the southeastern CONUS it will track east into KY and the TN Valley. At this point the system interacts with a cold front dropping from the western Great Lakes southeast into the Ohio Valley. Models have indicated, though slightly inconsistent on the placement of the heaviest band of precip, that this interaction with the front and the deep rich tropical moisture will produce the heaviest rainfall during the Sat 00Z to 12Z period. Model soundings during this time indicate a 2 inch plus PWAT over eastern Kentucky. However, the inconsistency of models and the lessened QPF of WPC 12Z solution has made the case to reduce QPF a bit so added a 50% blend to the super blend from the WPC run. Thus have gotten a more reasonable QPF amount and in agreement with the neighboring offices. So will continue to mention the heavy rainfall threat in the HWO for Friday through Saturday night with the best chance being Friday night into Saturday. By Sunday, expect a brief period of dry weather before the next disturbance tracks east across the mid MS Valley into eastern Kentucky by Sunday afternoon. The front will hang up along the middle Appalachians keeping the chance of precip lasting from Sunday afternoon into Monday afternoon. Confidence at this point is not very high given the uncertainty of the track of the remnants of Tropical system Cindy. Thus pop chances will be slight for Sunday night through Monday night. && .AVIATION...
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(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 202 AM EDT WED JUN 21 2017 Surface high pressure centered to the east and southeast will keep VFR in place through the period. We will remain VFR for the period as surface high pressure remains in control. Any valley fog should not affect the TAF sites as Tuesday afternoon crossover temps are not likely to be met. Some generally high thin cu is possible on Wed afternoon and will re evaluate this potential for 12Z issuance, but kept TAFs simple VFR one line for now. Winds will remain light at 10KT or less through the period.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...JP

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