Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 280624 AAD

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

Issued at 210 AM EDT THU JUL 28 2016

Hourly grids have been updated based on trends in convection and
observations. Convective allowing models were also factored in for
pops. However, most recent trends seem to favor the past couple of
HRRR runs over some of the other convective allowing models. This
would leave the best chance for measurable rain overnight across
the northern and far southeastern counties. Radar trends will be
monitored for possible lower pops for much of the overnight in the
southern counties. Fog could also form in some locations and
might become dense. This will also be monitored. Otherwise, the
region remains in a warm and moist airmass with PW analyzed in
the 1.9 to 2.1 inch range across the CWA. The highest PW is
generally across the middle of the CWA then extending into Central
and Western KY and then south along the MS Valley. Several
locations across the CWA received locally heavy rain and will be
primed for high water issues if heavy rain falls in these same
locations on Thursday.

UPDATE Issued at 1156 PM EDT WED JUL 27 2016

The main activity at this late hour is across our southern
counties. There appears to be a good lightning show and some heavy
rain, but there have not been reports of impressive winds out of
the current storms. Other storms more scattered in nature existed
elsewhere. Models are suggesting the main show late tonight will
come from the area of showers and thunderstorms over western KY as
they develop toward the east and northeast. Because of heavy rain
which has already occurred, the Flash Flood Watch was updated to
start immediately instead of waiting until 2 am.

UPDATE Issued at 630 PM EDT WED JUL 27 2016

Have updated to blend obs into the evening forecast. Clusters of
thunderstorms are ongoing, but coverage has likely peaked for the
time being.


.SHORT TERM...(This evening through Thursday night)
Issued at 305 PM EDT WED JUL 27 2016

...Torrential rainfall on Thursday may lead to Localized Flash

Expect scattered showers and thunderstorms to continue into the
evening with the primary focus turning to the heavy rain potential

A stalled frontal boundary has lifted north of the area and is
expected to stay just north of the state through the day tomorrow.
This has allowed winds to turn more southerly this afternoon. As a
southern stream wave strengthens and lifts out of the Mississippi
Valley overnight tonight, winds will turn a bit more southwesterly
and increase in strength, allowing for an even deeper pull of
moist air. This upper wave will interact with the stationary
frontal boundary, as well as the potential phasing of the
northern and southern stream jets, to create a large surge of warm
deep moisture and lift for which storms to develop across our
area. PWAT values for tonight will be well over 2 inches and will
continue to increase up to 2.4 inches in some places by tomorrow

While CAPE and LI values remain decent per model soundings, the
profiles are long, skinny, and moist with little wind shear. This
type of profile indicates heavy rain and flash flooding concerns,
moreso than severe weather. Mostly unidirectional flow in the mid
and upper levels may lead to training of storms, which would
likely lead to localized flash flooding. Depending on the model,
anywhere from 1.5 to 3 inches of total rainfall is possible
Thursday through Friday morning. Considering the extreme PWATS,
any storm that does form would be a very proficient rain producer.
All this considered, have decided to issue a flash flood watch
for the entire area from late tonight through Friday morning.

The bulk of the rain is expected to exit the area by dawn on
Friday but we can expect unsettled weather to continue into the

Temperatures will take a downward turn tomorrow with the onset of
thick cloud cover and heavy rains, with highs in the low 80s.

.LONG TERM...(Friday through Wednesday)
Issued at 300 PM EDT WED JUL 27 2016

No real break in sight from the unsettled weather as models
project our area remaining in northwest flow aloft with a quasi-
stationary frontal boundary positioned over us over very close by
throughout the period. This will bring us daily chances for
showers and thunderstorms, especially during the afternoon and
evening hours. These should be scattered in nature most days,
although a decent shortwave shown passing through the Ohio Valley
may spawn a little more widespread coverage of showers/storms on
Saturday and indicated higher PoPs there. The ground should be
fairly wet after the short term rainfall so at least isolated
flash flooding will remain a concern, at least through the
weekend. Otherwise, it will remain warm and humid throughout the
period with daytime highs well into the 80s and dewpoints in the
upper 60s to lower 70s.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)

Some convection remains possible overnight, though higher chances
are not anticipated at the TAF sites until the 12Z to 18Z period.
Showers and a stray thunderstorm are possible, generally early in
the period at JKL, SJS, and SYM as an initial disturbance lifts
north. SME and LOZ could experience a stray shower and with some
MVFR fog during the 7Z to 12Z period. MVFR fog is anticipated
elsewhere, though the extent of fog development remains uncertain
with mid and high clouds lingering. A weak disturbance is nearing
the lower OH Valley and should bring convection in from the west
by the 11Z to 16Z period. Convection associated with this
disturbance may linger as late as 0Z, if not after. MVFR vis and
or CIGS have been kept through the 20Z to 0Z period, with further
reductions possible thereafter. 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.


.JKL Watches/Warnings/Advisories...
Flash Flood Watch through Friday morning for KYZ044-050>052-



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