Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 260803 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 403 AM EDT TUE JUL 26 2016 .SHORT TERM...
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(Today through Wednesday) Issued at 403 AM EDT TUE JUL 26 2016 Abundant moisture with a general subsidence in the low levels and light winds, have come together to create decent fog development across much of eastern Ky early this morning. Fog should slowly lift through about 12z, as daytime heating ensues. A stationary boundary elongated from east to west across much of the state will remain in place through the period. This will continue to be the epicenter for convective development, especially during peak heating in the afternoon/early evening. Since the boundary will remain across the northern portions of our CWA, expect best coverage of storms to be located in this area, especially at initiation. Much like yesterday, storms will then propagate southward, with outflow boundaries helping to initiate convection further downstream across the CWA. That being said, the warm, moist, and unstable atmosphere will create an environment in which initiation of convection may occur anywhere, and possibly not even within the confines of afternoon peak heating. Hence, went ahead and kept scattered pops in across the CWA through the short term period, tapering to isolated in many locations during the overnight hours tonight. Winds in the mid and upper levels today will be similar to yesterday, if not just slightly higher in magnitude. This will continue to promote generally slow moving storms, though any development along outflow boundaries may speed up storm motion. The main concern with any of these storms will be gusty winds, in addition to torrential rainfall and some isolated instances of flash flooding. Flash flooding or urban flooding will especially be of concern for any locations that see training storms, or received heavy rains yesterday as well. Temperatures will continue to be warm despite ongoing cloud dover, with abundant moisture lending itself to high humidity values as well. While highs will be in the upper 80s both today and tomorrow, heat index values will feel closer to the mid and upper 90s, nearing 100 degrees in a few locations. .LONG TERM...(Wednesday night through Monday) Issued at 400 AM EDT TUE JUL 26 2016 Cyclonic flow will remain in place through the end of the week and potentially into the first half of the weekend, as troughing from the northern Plains into the Appalachians resides in between the Bermuda high and Great Basin to Four Corners ridging centered west of the Continental Divide. The subsequent lack of any substantial meridional component to the upper flow will thus keep a frontal boundary anchored near the Ohio Valley, keeping eastern Kentucky firmly in the warm sector. Phasing of a northward propagating Mississippi Valley wave with approaching energy out of the upper Midwest and Great Lakes will take place early Thursday. This will back the upper flow pattern southwesterly and bring an even greater surge of moisture northeastward toward the region. Precipitable water values will approach 2.25 inches or greater as warm cloud processes ensue, making for very efficient rain producing showers and thunderstorms conducive of generating significant rainfall amounts. Omega profiles suggest robust deep layer lift, further aided by the development of a surface low/wave. Uncertainty at this time is mainly confined to the exact timing and placement of the aforementioned features. Overall consensus at this juncture would be for heavier rainfall to begin Thursday morning and last into mid-late afternoon, with the most favored locations locally being along and north of the Hal Rogers Parkway. Will likely need to hoist a flash flood watch at some point once timing and placement become better defined. Storm motions look reasonable ahead of the approaching synoptic features, but training could certainly be an issue further exacerbating flooding concerns as storm motions parallel the surface and upper waves. Scattered storms continue to look like a good bet for the end of the week into early this weekend as renewed troughing develops in the wake of Thursday`s system complete with the presence of a continued warm and moist airmass. Southwestern U.S. ridging looks to then start building northeast into the Great Plains Sunday into next week, perhaps bringing a spell of drier weather to eastern Kentucky. Will keep isolated storm chances in the forecast through early next week at this time given uncertainty in eastward expansion of deep layer subsidence. Following seasonable high temperatures generally in the mid 80s (although lower 80s may be more realistic Thursday pending timing/location of the heavier rainfall) with lows in the upper 60s through much of the week, this may spell a possible return to above average temperatures headed into the start of August.
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&& .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) ISSUED AT 143 AM EDT TUE JUL 26 2016 With loss of best diurnal heating/lift, all precip has ceased across eastern KY. Only some sct to bkn high level clouds remain as of 5Z. Unfortunately, given the heavy rainfall at most of the TAF sites yesterday, lingering moisture has remained intact. Still expecting the combination of light winds, mostly clear skies, and this low level moisture and produce fog in many locations. Kept with alternate minimums late tonight for visibility with the anticipated fog development, though this may need to be adjusted as we actually see the fog form. Kept SJS within the MVFR category, however, since they saw the least amount of rain. A frontal boundary will stall out north of the state through the period, leading to additional sct convection for Tuesday afternoon. Kept with mention of VCTS at all sites during this time, since confidence is still low on the exact timing and placement of any of developing storms. Winds should remain generally light and variable at all sites during the TAF period, but those sites that happen to see a storm Tuesday afternoon could experience some brief gusty winds. && .JKL Watches/Warnings/Advisories... None. && $$ SHORT TERM...JMW LONG TERM...GUSEMAN AVIATION...JMW

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