Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 170806
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
406 AM EDT Tue Jul 17 2018

.SHORT TERM...(Today through Wednesday)
Issued at 357 AM EDT TUE JUL 17 2018

The morning surface analysis suggests the cold front is creeping
in and near the Ohio River region this morning. Overall the
morning convection is driven more by some weaker upper level waves
passing through the region. These showers have been fairly shallow
this morning and this is leading to greater precipitation rates
in the stronger showers. Therefore you could pick up a quick inch
out of some of these showers, but they have fortunately been
hitting areas that were not hit as hard yesterday so far. This
front will be the primary player through the day into the later
afternoon hours, but the overall better chances of POPs will be in
the far east and southeast areas today. Areas nearer the
Bluegrass may become dry through the late morning and afternoon as
the better lift progresses south and east. The short term models
have struggled with the placement of this mornings convection but
was able to lean some what toward the HIRES-ARW with
modifications.

This front will progress south of the region through the evening
and tonight. This will usher in a drier airmass as high pressure
builds across the Upper Midwest and Great lakes regions. Given
this do begin clearing skies and introduce at least some patchy
fog into the grids. The coverage will probably depend on mixing
through the night. Then we see a dry day on Wednesday as the
surface high continues to build across the Ohio Valley and Great
Lakes regions. However, we could see a few flat cumulus clouds in
a shallow layer of moisture seen in the soundings by Wednesday
afternoon.

.LONG TERM...(Wednesday night through Monday)
Issued at 406 AM EDT TUE JUL 17 2018

Wednesday night into Thursday will bring a continued period of drier
weather to eastern Kentucky courtesy of shortwave ridging aloft and
downslope flow on the backside of a departing surface ridge.
Afternoon highs will heat up into the upper 80s Thursday as H85
temperatures creep toward the 18-20C mark and dewpoints largely
remain in the low-mid 60s.

Increasing moisture and dewpoints will surge back into eastern
Kentucky Thursday night into Friday as a warm front lifts through in
response to an upper low migrating from Minnesota/Wisconsin into the
Great Lakes. This system will be rather dynamic for mid-summer,
exhibiting a 40-45 knot H85 jet attendant to a surface low across
the lower Ohio Valley. Speed divergence near the left exit region of
an upper jet streak will aid in large scale forcing for ascent
Friday evening into Saturday, bringing the greatest chances of
showers and thunderstorms across eastern Kentucky. Rain chances will
continue through the weekend, with thunder becoming less likely
Sunday as the axis of cyclonic flow pivots overhead and instability
becomes tough to come by in the low-mid levels. Not overly concerned
with the potential for widespread flooding at this time given the
closed low diving south into the Ohio and possibly Tennessee
Valleys, negating deeper/richer southwestern originating moisture
advecting into the Commonwealth. With the bonafide rain chances
through the weekend, temperatures will be cooler with highs in the
upper 70s to lower 80s both Saturday and Sunday.

Backing flow looks to take shape for next week in wake of the
departing upper low and downstream of ridging centered near the
Desert Southwest to the Four Corners region. A system skirting
through southern Canada may attempt to play into the local synoptic
picture through early-mid week, potentially producing an uptick in
shower/storm chances. Nonetheless, a warmup back to the mid 80s
looks likely at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 123 AM EDT TUE JUL 17 2018

Overall we are seeing the TAF sites begin the period with VFR and
hints of lower scattered CIGs. There is the potential for stratus
building down later tonight and tried to include this idea in the
TAFs. Given the convection has been mostly showers started the
TAFs VCSH before transitioning back to VCTS toward dawn. The
short term models indicated the better time for more scattered
showers and thunderstorms would be around 9 to 11Z time frame and
this seems reasonable at this point. A cold front will drop south
across the region in the latter portion of the TAF period and we
will see improving CIGs through the afternoon into the evening.
The winds will remain light through the period, but will shift
from the southwest to the northwest by this afternoon and evening
with the passage of the cold front.

&&

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

$$

SHORT TERM...DJ
LONG TERM...GUSEMAN
AVIATION...DJ


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