Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 291843 AAC AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 243 PM EDT Wed Mar 29 2017 .UPDATE... Issued at 230 PM EDT WED MAR 29 2017 Hourly temperatures and sky cover have been updated based on recent satellite and observation trends. This led to no significant changes at this time. UPDATE Issued at 1155 AM EDT WED MAR 29 2017 Surface high pressure extends from the Hudson Bay region south across the Great Lakes and into the OH Valley. Meanwhile, a mid level ridge extends from the Caribbean and Florid north into the OH Valley and southern Great Lakes. Low level moisture trapped below a subsidence inversion remains across the region behind the low pressure system that moved across the area Monday night and early Tuesday morning. The stratus and stratocu are gradually thinning and eroding from the TN Cumberland Plateau and high terrain of SW VA north and northwest. Some CU has developed in its wake however in portions of the Cumberland Plateau. This clearing or scattering of the low clouds should continue to gradually move from south to north with high pressure in control. This pattern should lead to the highest max T near the TN border where low to mid 70s are anticipated with near 60 in the north. Hourly grids have been updated for temperature and sky trends. UPDATE Issued at 755 AM EDT WED MAR 29 2017 Updated the grids to take out the morning patchy valley fog and also to fine tune the cloud cover through midday. Also tweaked the near term T and Td grids per the latest obs and trends. These have been sent to the NDFD and web servers - along with a freshened set of zones. && .SHORT TERM...(Today through Thursday) Issued at 455 AM EDT WED MAR 29 2017 08z sfc analysis shows high pressure building south into Kentucky. This has brought just slightly drier and cooler air to the region with plenty of low level moisture remaining. As a result, low clouds still plague our night sky with some earlier clearing in the Cumberland Valley and north of Interstate 64 now filling back in. Temperatures are running just a tad cooler than last night with most places in the upper 40s to lower 50s while dewpoints are holding within a couple of degrees of the dry bulb values. The amount of clouds and light north to northeast winds have prevented the fog from getting much of a foothold so far across eastern Kentucky - but do expected a few patches in the valleys toward dawn particularly in places that manage to get some clearing. The models are in much better agreement aloft through the short term portion of the forecast when compares to yesterday at this time. They all depict a decent mid level ridge through Kentucky and the Ohio Valley today as a deep southern stream low rolls into the Southern Plains. This trough then will progress northeast to the Central Plains tonight further bolstering the ridge over our area. Energy from the trough will approach Kentucky Thursday morning as the main portion lifts further into the middle of the country. This continues to be the case through Thursday with the trough holding strong while crossing Missouri with the GFS and ECMWF nearly identical at mid levels - heightening confidence in the blended solution. This will also place eastern Kentucky in southwest flow for that afternoon and evening as heights start to fall. Given the strong model agreement have favored a blended solution with a lean toward the higher resolution ones for wx details, especially on Thursday. Sensible weather will feature a return of sunshine later today with temperatures climbing into the mid to upper 60s most places. However, there will be a significant difference in warmth north to south across the area with low 70s found near the Tennessee border and cooler lower 60s to the far north closer to the center of the departing high pressure. A large ridge to valley temperature difference is anticipated tonight in the course of WAA and southerly sfc winds kicking in through the night keeping the ridges better mixed while radiational cooling chills the sheltered valleys. Patchy valley fog can be expected, as well, into Thursday morning. For Thursday proper, warm temperatures will be the rule with southerly winds and some sunshine helping readings soar into the mid and upper 70s. This will also raise instability throughout the area later in the day and should triggers arrive showers and storms will be possible - along with a potential for severe weather late depending on upstream development and evolution. The better chances for severe activity for eastern Kentucky will occur later in the night and not match up all that well with the best diurnally driven instability. Again used the ShortBlend and CONSShort as a starting point for the grids with some rather large, terrain based adjustments made to temperatures tonight. As for PoPs, made some minor adjustments to better target the still generally low chance PoPs later in the day Thursday. .LONG TERM...(Thursday night through Tuesday) Issued at 308 AM EDT WED MAR 29 2017 A shortwave trough will advance east across the region Thursday night into early Friday morning sending widespread showers and a few thunderstorms across the region. Given good moisture and lift, will maintain the categorical pops through this period. The mid level low will cross northern Kentucky Friday afternoon with numerous showers likely well into the afternoon, making for another cloudy, cool, and damp day. Rain showers will wind down into Friday night, but may transition to some patchy drizzle as some low level moisture will remain left behind. Any drizzle will come to an end by midday Saturday with the rest of the weekend featuring a return to dry weather as a surface ridge spreads eastward across the region. Our next storm system looks to arrive on Monday and Monday night sending another round of rain showers into eastern Kentucky. Looks like pretty strong southeast winds with this system through Monday, so we`ll have to see how much that eats away at potential rainfall given the downsloping conditions. In fact, some areas may struggle to measure with the kind of solution models are currently centering around. Eventually forcing will win out and we should see some showers or storms over most of the area, certainly by Monday night. Wrap around moisture may keep a chance of showers going into mid week with another system following on the heels of this system yet again. The active and wet weather looks to continue. Models also support a continuation of the mild weather outside of a cooler day on Saturday with the clouds. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 215 PM EDT WED MAR 29 2017 Low level moisture continues to mix out with high pressure in place. This is leading to improvement from MVFR to VFR from south to north. SME and LOZ are already VFR and JKL, SJS, and SYM should improve to VFR during the first 2 to 3 hours of the period. VFR should then persist through the end of the period. An increase in high and then mid level clouds should occur 0Z to 12Z, with some low clouds and cumulus development possible late in the period. A stray shower or even a thunderstorm cannot be completely ruled out late, but better chances will come after the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...KAS AVIATION...JP is the U.S. government's official web portal to all federal, state and local government web resources and services.