Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 220300 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 1100 PM EDT SAT MAY 21 2016 .UPDATE...
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Issued at 1100 PM EDT SAT MAY 21 2016 Showers continue to dissipate. Seeing some fairly rapid clearing upstream as well. Thoughts are we could see some fog development depending on how quickly skies clear versus how soon drier air manages to work its way into the area. Guidance has backed off on the fog. Will keep an eye on this and adjust the forecast as necessary. Otherwise updated the forecast package to remove thunder and to freshen up the zones. Made some minor adjustments to overnight lows based on latest hourly trends in sfc obs. UPDATE Issued at 817 PM EDT SAT MAY 21 2016 Update this evening was mainly to adjust pops towards latest radar trends. A fairly solid band of light rain is currently swinging through the area, with some isold embedded thunderstorms within the band for good measure. It appears our radar is overshooting some of the activity based on sfc obs. The threat for thunder should be waning through the remainder of the evening. While some clearing is expected through the overnight it will only be gradual. Did tweak temps towards hourly obs, which mainly resulted in lower temps corresponding to rain cooled air. Will leave the threat of thunder in until next update.
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&& .SHORT TERM...(This evening through Sunday night) Issued at 400 PM EDT SAT MAY 21 2016 19z SFC shows low pressure east of Kentucky but still swinging showers and stray thunderstorms through the CWA. The latest visible satellite loop shows mostly cloudy skies with only a few breaks across the area. The clouds and isolated to scattered showers also affected temperatures today with readings generally kept in the mid to upper 60s this afternoon. Meanwhile, dewpoints are holding in the mid to upper 50s most places. Winds through East Kentucky are generally from the west at 5 to 10 mph with some gusts to 15 mph or so in western areas. The models are in good agreement aloft through the short term portion of the forecast. They all depict the eastern trough deepening and settling southeast of the area by Monday morning. A key part of this development will be a mid level wave dropping just west of the CWA tonight sending energy south through East Kentucky. This will help to sharpen up the low and drag it a tad southwest on Sunday. This upper low will further deepen and close off Sunday night into early Monday as it shifts east. This represents a return to an idea from a couple of days ago but with more credence now given the good model clustering and zero hour being only 36 to 48 hours out. Accordingly, have followed a general model blend with a strong lean toward the HRRR and NAM12 for weather details through Monday morning. Sensible weather will feature an unsettled evening with showers and a couple of thunderstorms around. This will be followed by low clouds and some patchy fog through the night. While Sunday will be drier for most, as the upper low shifts southwest, there is a decent shot at more convection in the east and even a few thunderstorms. Sunday night will see the clouds start to break up in the east and again some fog, especially for the valleys and places that clear earlier in the night. Do expect temperatures to be fairly uniform tonight and Sunday night owing to the clouds and some slight CAA to neutral advection during the nights. Started with the ShortBlend for most elements of the forecast with only limited terrain adjustments to temperatures through the period. During the latter part of the forecast the SuperBlend was used to initialize the forecast with some tweaks made mainly to increase the PoPs in the east Sunday afternoon. .LONG TERM...(Monday through Saturday) Issued at 350 PM EDT SAT MAY 21 2016 Patchy valley fog will kick off the week with surface ridging extending from the Great Lakes into the Ohio Valley. Shortwave, but amplified, upper riding will build across the Great Lakes through the Mississippi Valley in wake of this weekend`s disturbance digging across the Mid-Atlantic coast. Rising heights and deep layer subsidence will bring clearing skies from west to east throughout the day as temperatures warm back to near normal, topping out generally in the mid 70s. Surface ridging will then be in control once again Monday night into Tuesday, leading to another ridge/valley temperature split ranging from the mid-upper 40s in valleys and low 50s on ridgetops. Continued increasing heights and plenty of solar insolation will propel highs into the upper 70s to lower 80s Tuesday afternoon. An unsettled pattern will then return for midweek through the end of the week and likely into the upcoming weekend. Flow aloft will back southwesterly in response to cyclonic flow developing from central Canada through the Intermountain West. Subsequent increasing warmth and moisture will lead to a more favorable thermodynamic environment supportive of convective development. While the thermodynamics should be conducive for showers and thunderstorms, dynamical prospects may be lacking as the core of any upper forcing may lift north well west of the Commonwealth. This will in turn keep a nearly stationary frontal boundary west of the region through much if not all of the upcoming week, furthermore decreasing the chances for seeing any appreciable forcing locally. Nonetheless, scattered thunderstorms certainly look possible in the warm sector whenever forcing becomes realized, rather from passing upper perturbations or at least along the higher terrain. High temperatures in the lower 80s and lows in the lower 60s look likely by midweek into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 817 PM EDT SAT MAY 21 2016 A fairly solid band of light rain is currently swinging through the area, with some isold embedded thunderstorms within the band for good measure. It appears our radar is overshooting some of the activity based on sfc obs. The threat for thunder should wane through the remainder of the evening. Cigs have varied between IFR and MVFR within the band of showers and isold thunderstorms, to VFR outside of the main band. While some partial clearing is expected through the overnight it will only be gradual as llvl moisture lingers. However based on upstream obs expect CIGs should lift steadily into VFR range once the current band of rain showers has exited to the east. Right now thoughts are that gradient flow behind tonights departing system will be strong enough to keep the boundary layer mixed. This combined with drier air filtering into the area should result in a less likelihood of fog developing. However, model guidance was quite pessimistic on the topic so will maintain a close watch. Skies should clear out more completely Sunday morning. But steep boundary layer lapse rates will result in the redevelopment of a substantial CU field, with actual CIGs more likely in the east, along with the threat of some instability showers. Winds will be generally be out of the west-northwest through the forecast period, somewhere between 5 and 10 kts. && .JKL Watches/Warnings/Advisories...None. && $$ UPDATE...RAY SHORT TERM...GREIF LONG TERM...GUSEMAN AVIATION...RAY

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