Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 281223 AAA
AFDJKL

Area Forecast Discussion...UPDATED
National Weather Service Jackson KY
823 AM EDT THU JUL 28 2016

.UPDATE...
Issued at 759 AM EDT THU JUL 28 2016

Hourly grids have been updated based on recent observations.
Recent HRRR runs generally support the ongoing forecast so no pop
adjustments have been made so far, though they could be a touch
fast over the next hour or two.

&&

.SHORT TERM...(Today through Friday)
Issued at 355 AM EDT THU JUL 28 2016

A warm front continues to lift north and generally resides near
the OH then southeast into WV. A warm and moist airmass is in
place across the region with sfc dewpoints in the upper 60s to
lower 70s. PW is analyzed around 2 inches across the northern
half of the area with 1.75 to 2 inches across the southwest part
of the area. A mid and upper level low is meandering up the MS
Valley into the Lower OH Valley. Isentropic lift in advance of
this system is producing areas of convection across the
Appalachians and OH Valley at this time. At present, nearly all of
Eastern KY is rain free. However, patchy fog has developed in the
wake of afternoon and evening convection. Mid and high level
clouds however have kept the fog in check so far. To the east of
the mid and upper low is a ridge of high pressure centered north
of the Bahamas with another ridge centered over Western Conus. A
closed low is over northern Quebec with disturbances rotating down
into the northern Plains and Great Lakes as they move around the
Western Conus ridge.

The mid and upper low/trough nearing the Lower OH Valley will move
into the Central Appalachian region this evening with this system
interacting with another weak shortwave that is currently nearing
the Kansas City, MO area. This system will have a moist airmass in
place to work with and with nearly stalled a frontal zone in
place just north of the region, heavy rain remains a concern from
the convection. PW is expected to climb over 2 inches today
across most of this morning, with the possible exception of the VA
border counties where it might not reach those levels until late
this afternoon or this evening. PW is expected to remain at 2
inches or greater along and north of the Mountain parkway the
longest, peaking near or a bit above 2.25 inches near the I 64
corridor today. PW though should begin to decrease this evening
into the overnight as the mid level wave departs. With a slightly
drier airmass and the potential for more solar insolation this
morning into early afternoon, locations south of the Mountain
Parkway corridor and east of Interstate 75 will have the highest
chances of stronger to possibly marginally severe thunderstorms
with wind gusts being the greatest threat. However, any of the
strongest storms will be able to produce wind gusts of 30 to 40
mph due to precipitation loading.

The Flash Flood Watch remains in effect through 12Z (8 AM on
Friday) although the threat should diminish by late Thursday evening
across much of the area. Convection may linger longer in the
higher terrain near the VA border. The sfc frontal zone should
move little through the period, perhaps moving a bit further
southeast. A broad trough/weakness is expected to extend from the
Great Lakes down into the MS Valley region to end the period in
between the two ridge centers. This favors unsettled weather for
Friday with a diurnal peak in convection with weak disturbances
interacting with a lingering moist, but not quite as moist
airmass, with PW generally averaging in the 1.5 to 1.75 inch
range.

Considerable cloud cover and cooler 850 mb temps compared to
earlier in the week should lead to highs closer to climatological
normals for late July during the short term period. Overnight lows
will be mild with the airmass remaining moist, however.

.LONG TERM...(Friday night through Wednesday)
Issued at 315 AM EDT THU JUL 28 2016

Based on the latest model data, the weather will remain unsettled
through out the extended period, with almost daily chances of
showers and storms across the area. A stalled out frontal boundary,
along with a series of disturbances aloft moving along it, will be
the weather makers for days 3 through 7. The best chance for rain in
the extended looks to be on Saturday as a front moves across the
area. This boundary then looks like it will get hung up in the
Tennessee Valley, but will be close enough to our area to spark
additional showers and storms for several days across eastern
Kentucky. Temperatures are expected to top out in the mid to upper
80s each day, and bottom out in the upper 60s to around 70 each
night.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 810 AM EDT THU JUL 28 2016

A weak disturbance is nearing the lower OH Valley and another
upstream over MO should combine to bring convection across the
area through about 6Z or so. The atmosphere is moist as well so MVFR
vis and or CIGS have been kept through at least the 20Z to 0Z
period, with further reductions possible thereafter at all sites.
If partial clearing occurs late, fog could become an issue by the
6Z to 12Z period. There will likely be varying conditions and
some at least brief VFR in between showers and storms cannot be
ruled out between 12Z and 18Z at most sites, with IFR or even
below airport mins for a time in the stronger showers and storms.

&&

.JKL Watches/Warnings/Advisories...
Flash Flood Watch through Friday morning for KYZ044-050>052-
058>060-068-069-079-080-083>088-104-106>120.

&&

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...AR
AVIATION...JP



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