Area Forecast Discussion
Issued by NWS Jackson, KY

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 252336 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 736 PM EDT MON JUL 25 2016 .UPDATE... Issued at 603 PM EDT MON JUL 25 2016 WSR-88D radar shows convection continuing mainly south of a line from Pikeville, to Jackson, to McKee this hour. Expanded pops for a short period of time, but much of this will be diurnally driven and should continue a downward trend. Also locations north of this have been scoured out by earlier convection and outflow boundaries. CAMS have about as good of a handle on the convection, as one would expect and therefore no preference on any one model. Temperature curve has been difficult to pin down given the coverage of storms and outflow boundaries. Mostly went toward a blend approach with current obs and trended into the evening. The GLAMP seems to have the overall best curve at the moment in terms of guidance. Otherwise no major changes needed at this point. && .SHORT TERM...(This evening through Tuesday night) Issued at 317 PM EDT MON JUL 25 2016 Showers and thunderstorms continue to erupt this afternoon, with the best concentration occurring over our northern counties closer to a weak frontal boundary paralleling the Ohio River. This boundary will remain fairly stationary just to our north and remain a focusing mechanism for scattered to numerous showers and thunderstorms. While the storms should exhibit a diurnal trend, with coverage peaking in the afternoon hours, cannot rule out a storm at any time over the next 36 hours. The main threat with storms will remain heavy rainfall and lightning in the high CAPE but low shear environment. Storms seem to want to move along fairly well at 10 to 15 mph and that is a good thing considering PWATS are approaching 2 inches. However, there will be a minor threat for flash flooding in areas that see repeating rounds of thunderstorms. We are also seeing storms today gust out pretty easily and an isolated severe storm remains possible this afternoon with DCAPE exceeding 1000 J/kg. With the front remaining to our north through the period, the airmass over our region will remain very muggy with dewpoints staying well into the 70s. Increased clouds and showers during the day tomorrow should keep temperatures below 90 for most areas, and heat indices below 100 for a change. .LONG TERM...(Wednesday through Monday) Issued at 317 PM EDT MON JUL 25 2016 Models are in reasonably good agreement with general mid/upper level flow and larger scale synoptic features through the period. But significant differences are beginning to crop up with respect to details of embedded disturbances within the general flow pattern and corresponding sfc features thereby lowering overall confidence of the extended package, particularly with respect to sensible weather. Somewhat zonal flow quickly amplifies with a mean trough forming over the Great Lakes and Mid-West which remains in place across the region through the period. Rather significant ridging does develop aloft and replaces this eastern CONUS trough as it lifts northeast out of the region just beyond the end of the extended window. At the surface, it appears that a nearly stationary frontal boundary will exist somewhere across the northern portions of the Commonwealth. This feature will provide a focus for the bulk of our sensible weather through the extended in the form of showers and thunderstorms. However, main concern revolves around a sfc wave tracking through the region Thursday into Thursday evening. The last three runs of the GFS have been quite consistent with this wave that develops and moves across the Commonwealth. The GFS advertises PWATs increasing to between 2 and 2.25 inches during this window. In addition, freezing levels increase to between 14 kft and 15 kft AGL with moderately high CAPEs of 1000-1500 K/kg and LCLs between 500 and 1000 ft AGL. Should this scenario pan out there is a potential for some warm water processes. And while storm motions are considerable at 15-25 kts, flow aloft would be favorable for training along the sfc boundary wherever it eventually sets up. Consequently hydro issues may become a concern by Thursday. The 0Z ECMWF suggest a similar potential but carries the surface wave further north and west of our forecast area thereby keeping the heavy rain threat north of the Ohio River. A quick look at the 12Z ECMWF shows that it has trended slightly towards the GFS solution. With a mean trough over the eastern CONUS and expected rounds of mainly diurnal precipitation, daily high temperatures should be cooler than we have been experiencing, much closer to the mid 80 norms for this time of year. However, conditions will also be quite muggy keeping overnight lows in the upper 60s to near 70. Thus diurnal swings will be limited as well. && .AVIATION...
-- Changed Discussion --
(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 736 PM EDT MON JUL 25 2016 WSR-88D radar showing most of the showers and thunderstorms have now moved into the southern most portions of E KY nearer the VA/TN border this evening. Most likely TAF sites to see issues will be SME/LOZ, so will add a TEMPO group to handle this at SME where best chance resides. Otherwise added fog at all the sites with best chances at sites that saw rain today. That said went IFR at all sites, but SJS given the lesser chances of actually seeing rain. Frontal boundary will stall out to the north and this will lead to additional convection for Tuesday afternoon. Therefore opted to go VCTS at all sites, and this can be better narrowed down in future TAF issuances. Most sites will see little if any issues in terms of winds through the period, but those sites that happen to see a storm could see some brief gusty winds.
-- End Changed Discussion --
&& .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...DJ SHORT TERM...ABE LONG TERM...RAY AVIATION...DJ is the U.S. government's official web portal to all federal, state and local government web resources and services.