Area Forecast Discussion
Issued by NWS Jackson, KY

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471 FXUS63 KJKL 242320 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 720 PM EDT WED AUG 24 2016 .UPDATE... Issued at 652 PM EDT WED AUG 24 2016 Surface high pressure has now moved off the Mid Atlantic coast and KY resides in the return flow side of this surface high. This is introducing the warmer and more humid airmass into the Commonwealth with dewpoints reaching back into the 70s. Upper level wise strong upper level ridge is parked across the SE US and will be the main influence on our sensible weather through the rest of the week. We are watching areas of storms developing across portions of the Ohio Valley (north and west of the CWA) this evening. These are influenced by stronger upper level dynamics/short wave and weak surface trough in that region, but some of the CAMs do want to bring some of this convection south and east tonight mainly across central KY. Right now not buying into this and think influence from upper level ridging aka little upper level support combined with loss of daytime heating will lead to minimal chances. However will keep a isolated threat focused along and north of the I-64 corridor. This is backed up well by the SSEO probabilities for this evening. In term of grids overall grid set is in good shape with the above thoughts. Only minor tweaks needed at this point given latest trends. && .SHORT TERM...(This evening through Thursday night) Issued at 324 PM EDT WED AUG 24 2016 A strong upper level ridge is in place across the southeast conus, encompassing much of the Ohio River Valley. Meanwhile a closed low is moving eastward across the central Canada/US border, with several shortwaves located along the resulting troughing pattern across the central conus. At the surface, KY finds itself in a return flow pattern, with a high pressure feature located to the east of the region, and a surface low pressure system located in conjunction with the upper level low along the US/Canada border. A cold front is trailing from this low, southeast across the upper midwest and into the central plains. With the broad upper level ridge in place across the southeast conus, this will prevent best forward propagation of the upper level low through the short term, which will eventually lead to its weakening into the day Thursday, then phasing out by Friday. In lieu of the weakening upper level low, the surface features will also wane, and the cold front will begin sheering out as it slowly pushes toward the region through the day tomorrow. It should eventually pass across the state during the day Friday. As for sensible weather...Low and mid level southwest flow can currently be found between the cold front to our west and the high pressure system to our east. This is working to increase moisture in the form of clouds and humidity across JKL this afternoon, as well as boosting temps into the mid and upper 80s. Hi res/CAM models are still pointing at isolated to scattered showers and thunderstorms developing mainly across the central portion of the state this afternoon under peak heating. A line of convection may form in this location, however with little upper level dynamics to work with, this will likely cause few problems. Furthermore, there is still quite a bit of disagreement in the hi-res CAM models about whether or not this precip will even make it to eastern KY this afternoon/evening, before it falls apart with loss of daytime heating this evening. As such, kept conditions dry across eastern KY through the afternoon, with only isolated chances in the north during the first part of the overnight, transitioning to the east late tonight into tomorrow assuming the line can stay together to some degree. The NMM and ARW both show an uptick in isolated convection throughout the day tomorrow under peak heating, likely due to diurnal influences in a humid regime. However confidence is low on this, with the larger scale models keeping any convection confined to the far southeast in the upslope regions of the state. Kept isolated pops across the far eastern portion of the CWA into the afternoon, before drying out completely. Soundings support this as well, with very little moisture to work with in the low levels, and continued strong drying aloft. Temperatures should be similar to today, if not a degree or two higher, rounding out near 90 degrees. Despite the cold front reaching the Ohio River by Thursday evening/Thursday night, it will be so weak by this point that little influence is expected without the aid of diurnal heating. Some llvl moisture may lead to isolated to sct cloud coverage, but otherwise conditions should be clear with dry air entraining into the area aloft. Low temperatures will be around 70 degrees both tonight and tomorrow night. .LONG TERM...(Friday through Wednesday) Issued at 308 PM EDT WED AUG 24 2016 A stout upper level ridge will dominate our weather into early next week. This will keep temperatures much warmer than normal and muggy dewpoints in the upper 60s to mid 70s. Isolated showers/storms will be possible each day over the weekend into early next week in the warm and humid airmass. It appears the ridge will weaken slightly by the end of the period, possibly allowing a cold front to sag into the region. The front appears very weak in the models so will keep PoPs low and diurnally influenced even during these periods. Models keep any influences from a potential tropical system developing in the Caribbean to our south and east through Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 720 PM EDT WED AUG 24 2016 Another period of VFR expected at this point. While showers and thunderstorms are affecting areas NW of eastern KY, we are expected little if any influence at this point. While a stray storm may be able to make it in the far north, the chances were low enough to keep out of TAF sites. The HRRR model does show convection in the far east by Thursday morning think this may be more in the way of a CU field, and would think best chances of isolated storms would be in the higher terrain nearer the VA border Thursday afternoon. Increasing moisture will continue to be the story therefore valley fog chances will be on the increase, however right now think this will stay out of the TAF sites. Given the lack of jet energy winds will remain weak through the taf period. && .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...DJ SHORT TERM...JMW LONG TERM...ABE AVIATION...DJ

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