Area Forecast Discussion
Issued by NWS Jackson, KY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KJKL 220133 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 933 PM EDT Mon Aug 21 2017 .UPDATE...
-- Changed Discussion --
Issued at 933 PM EDT MON AUG 21 2017 No substantive changes are needed this evening as forecast is tracking obs nicely. Forecast may be a tad too fast ramping up PoPs tomorrow based on some of the 18z guidance but decided in the end to leave it alone and let midnight shift digest the 00z data before making any changes. The timing for the greatest severe threat tomorrow remains as early as mid afternoon in our northwest counties through the evening for the remainder of the area. Have a great night...
-- End Changed Discussion --
&& .SHORT TERM...(This evening through Tuesday night) Issued at 324 PM EDT MON AUG 21 2017 With the partial eclipse reaching a maximum of about 95 percent here at the NWS office in Jackson we observed a temperature drop of 6 degrees with the fall beginning around 1750Z. The temperature fell from 87 to 81. The temperature had risen back to 84 by 1912Z. The few cumulus clouds we had also diminished during the partial eclipse. Pretty interesting! Anyway, the focus now turns from the weather for the eclipse to the threat for severe thunderstorms on Tuesday into Tuesday evening. As a strong short wave moves along the U.S Canadian border on Tuesday surface low pressure will deepen as it moves from the upper Great Lakes into Ontario and eventually Quebec. A cold front trailing from the low will move into KY Tuesday night and will pass southeast of our area Wednesday morning. Models have been suggesting some scattered storm development well ahead of the front with some outflow boundaries from upstream convection, so we could see storms as early as early Tuesday afternoon. Storms should become more numerous as the afternoon progresses and the front nears and low level wind fields increase. Instability will increase Tuesday afternoon as well with MLCAPE in excess of 2500 J/kg expected. Shear values in the 0-6km range will also be better than in recent events. The freezing level and wet bulb zero height will still be elevated so the main severe threat looks to wind and not hail. SPC has most of the area in a slight risk for Tuesday and since this is the best chance for severe storms we`ve had in a while we`ll be highlighting the threat in our messaging. Also with PW in excess of 2 inches, locally heavy rains will also be a threat, and WPC has placed the area in a marginal risk for excessive rains for Tuesday. We will also be highlighting this threat in our messaging. .LONG TERM...(Wednesday through Monday) Issued at 324 PM EDT MON AUG 21 2017 With the passage of the cold front Wednesday morning, much cooler and drier air will invade the area, with an extended period of below normal temperatures which will last into early next week. A couple of short waves will move across the Great Lakes/Ohio Valley from Thursday into Friday and again Sunday or Monday, helping to keep a mean trough over the eastern United States. The drier and cooler air mass will be noticeable with highs will mostly in the upper 70s from Wednesday through Monday, with lows mostly in the mid and upper 50s. Dewpoints will mostly be in the 50s through the long term portion of the forecast but will begin to increase again early next week. Confidence remains low on details and timing for any shower or storm chances, but blended model load keeps a small chance very close to the VA border on Saturday afternoon, a better chance across the south on Sunday, and then a chance area wide on Monday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 750 PM EDT MON AUG 21 2017 VFR conditions and light winds will prevail at the TAF sites through early Tuesday afternoon. Valley fog is expected to develop tonight with some local IFR conditions, however fog is not expected to affect the TAF sites. Clouds will be on the increase by around dawn but bases should remain VFR. An approaching cold front will then bring scattered thunderstorms Tuesday afternoon, with the storms becoming more numerous by Tuesday evening. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ABE SHORT TERM...SBH LONG TERM...SBH AVIATION...ABE

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.