Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231727

Area Forecast Discussion
National Weather Service Jackson KY
127 PM EDT SAT JUL 23 2016

Issued at 1031 AM EDT SAT JUL 23 2016

Best chance for scattered showers and thunderstorms this afternoon
still appears to be near the remnants of an outflow boundary near
the TN border. This idea is supported by the latest HRRR runs.
Have updated the NDFD based on the latest observational trends.

UPDATE Issued at 733 AM EDT SAT JUL 23 2016

Areas of dense fog continue in a few of the deeper river valleys,
as well as across portions of northeastern Kentucky where better
clearing occurred overnight on top of greater rainfall amounts
Friday. Will see this mix out in the next hour or two. Could see
a few showers start up at anytime near the Lake Cumberland region
in vicinity of a remnant outflow boundary.


.SHORT TERM...(Today through Sunday)
Issued at 359 AM EDT SAT JUL 23 2016

Lingering light shower activity has just about wrapped up early
this morning across the Lake Cumberland region. Should continue to
see this trend as peak diurnal cooling approaches and only sign of
any lift sits across southern Kentucky into the Tennessee Valley
in the form of a convective outflow boundary. Areas of dense fog
will continue in the deeper valleys this morning and in locations
that received appreciable rainfall amounts Friday, especially
across northeast Kentucky into the Big Sandy region in the
presence of better clearing. Will see this mix out come mid
morning as turbulent mixing ensues.

Main focus for isolated to scattered thunderstorms today will come
by way of the aforementioned outflow boundary. This should spell
the best precipitation chances beginning along the Tennessee
border as diurnal heating takes place in a sultry airmass. Locales
along the Virginia border will see a slightly better potential for
storms as well due to the aid of orographic forcing. Not much if
anything to work with in terms of forcing aloft as the eastern
extent of central through southern U.S. ridging remains overhead.
Given Friday`s rainfall, high temperatures should remain capped in
the lower 90s, still leading to heat indices near the century

Upper forcing for ascent will be lacking once again for Sunday as
upper ridging strengthens across the region, leading to greater
thicknesses and subsequently hotter temperatures given a likely
lower coverage in rainfall. Heat indices could very well approach
heat advisory criteria (105F) Sunday afternoon, but this will be
dependent on the presence of any rainfall, which will be dependent
on any remnant outflow boundaries near eastern Kentucky. Terrain
induced storms may once again develop, but likely not covering
enough real estate to alleviate the significant heat likely to

.LONG TERM...(Sunday night through Friday)
Issued at 359 AM EDT SAT JUL 23 2016

Broad elongated high pressure will remain across the southern half
of the conus throughout much of the extended...keeping deamplified
troughing and shortwaves passing across the northern half. The Ohio
River Valley will find itself oscillating between the two main
features, being affected by multiple shortwaves, before a slightly
deeper trough moves into the upper midwest during the midweek. This
will result in height falls across KY which will persist into next
weekend as an even larger/deeper trough moves into the region,
rounding out the period.

Scattered showers and thunderstorms will start off the period Monday
as a cold frontal boundary drops southward to the Ohio River by late
in the day. This boundary stalls out and will tend to keep any
convection focused across the region through mid week. What`s left
of the boundary lifts northward late Wednesday, just as another
slightly more amplified trough begins to drop into the region from
the northwest by late Thursday or Friday, pushing the frontal zone
back closer to the Ohio River while remaining focused north of the
CWA, as well as enhancing precip chances, especially during the
afternoon/evening hours.

From here, more drastic height falls will take hold as the deepest
of the troughs moves through the region through the weekend. Despite
no frontal boundaries passing through the region, overall
instability and upper level forcing will continue to drive scattered
to numerous convection across eastern KY through the weekend.

The loss of mid and upper level ridging combined with daily
convection will help keep our high temperatures close to normal for
this time of the year, or possibly slightly cooler as we head into
the weekend. But overall our weather will remain quite muggy.
Overnight lows will be warm, running a little above normals, in
the upper 60s and low 70s.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)

Fields of cumulus clouds in the northern part of the forecast area
as well as parts of the southeast have resulted in some local
MVFR ceilings just below 3k feet early this afternoon. The only
TAF site affected has been SYM, though some other airport sites
such as PBX also seeing MVFR ceilings. The cloud bases should
lift to above 3k by mid afternoon and will go with VFR for the
remainder of the afternoon in the TAFS.

Isolated to scattered thunderstorms still appear most likely near
the TN and VA borders from mid afternoon to early evening. Have
carried VCTS at SME to account for this possibility but have left
out of other TAFs sites.

Outside of typical river valleys the fog last night was pretty
well correlated to where rain occurred yesterday afternoon and
evening. Have low confidence on exactly which TAF sites may be
affected by fog tonight into early Sunday. Have based the fog
forecast partly on persistence but if more rain occurs later
today than expected there will be more fog than currently


.JKL Watches/Warnings/Advisories...


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