Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 290540
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
140 AM EDT Sat Apr 29 2017

.UPDATE...
Issued at 140 AM EDT SAT APR 29 2017

Storms continue to track from west to east along the Ohio River
just north of our forecast area. A few storms could manage to drop
southward into out extreme northern zones. But models suggest the
general trend will be for activity to lift northward during the
day. Will keep minimal pops in place for our far north. Otherwise
tweaked the grids towards current hourly trends. No update to the
zone package at this time.


UPDATE Issued at 1105 PM EDT FRI APR 28 2017

The focus for shower and thunderstorm activity continues to be
near the Ohio River near a warm front. Steering flow should keep
the activity generally in this corridor. A few showers or a stray
thunderstorm is possible in the far north overnight, but most
locations should remain dry. Valley minimum temperatures were
lowered a bit to account for nocturnal inversion that has set up
in the deeper valleys.

UPDATE Issued at 835 PM EDT FRI APR 28 2017

The mid level cap has generally held across southeast KY this
evening. With mid level height rises, loss of daytime heating, and
lower dewpoints in far southeast KY from deeper mixing and
downslope flow off of the Cumberland Mountains and threat of
strong to severe thunderstorms across East KY is diminishing.
Recent radar, satellite and short term convective allowing models
indicate that the primary risk for severe weather for the
remainder of the evening and into the overnight will probably be
near the OH River and north near the current position of the warm
front. Scattered showers and an isolated strong to possibly
severe thunderstorm still cannot be ruled out this evening
generally along or north of I 64. Across the remainder of the
region, the overnight should be mainly dry.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 400 PM EDT FRI APR 28 2017

Quite a bit of uncertainty still exists in the model data
regarding convective initiation and evolution this afternoon
through late this evening across eastern Kentucky. The best guess
for now is that storms that will be forming to our west and
southwest will eventually move into our northwestern counties late
this afternoon, and will move across the area generally north of
the Hal Rogers Parkway and Highway 80 corridor through early
tomorrow morning. Any storm that does make into the area will have
the potential of producing large hail, damaging wind gusts, and
perhaps an isolated tornado. A severe weather watch may be
necessary to begin the evening shift. The first showers and
storms should move into our northwestern counties around 22Z, and
will move east across the northern half of the forecast area
overnight.

Temperatures should continue to run well above normal, with
nightly lows only bottoming out in the 60s tonight and tomorrow
night, and highs maxing out in the upper 80s and lower 90s on
Saturday. Winds should be primarily out of the south at 7 to
12 mph through the period.

.LONG TERM...(Sunday through Friday)
Issued at 400 PM EDT FRI APR 28 2017

The models are still in good agreement aloft for the bulk of the
extended period. They all depict a strong ridge through the
southeast portion of the nation with broad southwest flow ahead of a
deep closed low moving into the Texas Panhandle early Sunday. This
low will further deepen and lift into the mid Mississippi Valley by
Monday morning with the GFS a bit quicker and more northerly than
the ECMWF. Both are quite deep, though, with height falls spreading
through Kentucky. This bowling ball of a low then barrels into the
western Great Lakes by Tuesday morning similar, but still with the
GFS leading the ECMWF. The Canadian solution is similar to the
others lending confidence to the consensus solution at least through
mid week. As this low transitions past to the north the core of its
energy will swing through eastern Kentucky Monday morning with
another significant node passing early Tuesday. The pattern will
then slowly deamplify through Wednesday with more zonal type of flow
through the region before the next trough starts to take shape over
the southern High Plains. This trough quickly sinks to the south and
reaches the Gulf Coast by Thursday afternoon before wrapping up more
and closing off over the Deep South by 12z Friday - quickest and
furthest east in the ECMWF than the others. This low will then
slowly traverse the Deep South off to the east - maintaining the low
heights and cyclonic mid level flow over eastern Kentucky. Given the
decent agreement for the extended have greater than normal
confidence in the extended forecast from the blend.

Sensible weather will feature a warm and humid end to the weekend
ahead of a drying out cold front. After highs in the upper 80s most
places on Sunday afternoon the front will move through by Monday
morning with a threat for storms as well as ushering in a cooler and
drier air mass. This air quickly gets replaced by another surge of
moisture from the south starting on Wednesday as a warm front stalls
nearby with a concern for storms and heavy rains that afternoon
through Thursday. The developing sfc low to our south for the latter
part of the week will keep the threat of showers and a stray storm
in the forecast through Thursday followed by mainly just showers and
seasonably cool temperatures - a far cry from those that we will see
this weekend.

Raised temps a tad on Sunday with more sunshine expected and being
rain free. Did make some minor adjustments to temperatures each
night - particularly for ridge to valley differences early Sunday
night and again Tuesday night. Also, fine tuned the PoPs to tighten
them up with the fropa on Monday morning and heading into the
Wednesday system.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 140 AM EDT SAT APR 29 2017

Expecting VFR flight conditions through the forecast period.
There is considerable mid and high level cloudiness over the area
courtesy of ongoing shower and thunderstorm activity along the
Ohio River. Storms in general have been moving to the east and
have been as close as about 30 miles north of SYM. High resolution
models suggests some of those storms could drop a bit further
south through the early morning time frame. Consequently, left
mention of some VCTS in place for SYM. There is a considerable
LLJ, about 30-50 kts just above the boundary layer. Our local VAD
wind profile confirms these higher winds speeds. This combined
with the occasional mixing of gusts down to the surface in an
otherwise light and variable wind field strongly suggests the
presence of some non-convective LLWS. Included a mention of LLWS
at all area terminals. Shower and thunderstorms activity to our
north is expected to lift further northward through the day. Winds
will increase from the south-southwest through the day to around
10kts with some higher gusts.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

UPDATE...RAY
SHORT TERM...AR
LONG TERM...GREIF
AVIATION...RAY



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