Area Forecast Discussion
Issued by NWS Jackson, KY

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860
FXUS63 KJKL 230931
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
531 AM EDT Fri Jun 23 2017

.SHORT TERM...(Today through Saturday)
Issued at 531 AM EDT FRI JUN 23 2017

The remains of Tropical Storm Cindy were very obvious in radar
and satellite imagery over AR early this morning. Meanwhile, a
cold front over northern MO and northern IL was moving southeast.
Models are in general agreement on the evolution of these features
during the period. Interaction with the prevailing westerlies will
continue to carry the tropical remnants east northeast ahead of
the cold front, with a track expected to be through KY. Low to mid
level wind fields will strengthen as the low approaches, and
continue to transport very moist air into the area, with
precipitable water expected to reach 2-2.5". A significant lull in
the precip is expected through much of the day, allowing warming
and destabilization. This would aid convective development as the
system arrives in the afternoon and evening. Both heavy rain and
severe weather are threats.

In term of rainfall, the deep tropical atmosphere will support
very efficient precip production. Models agree on the heaviest
amounts to be in our northwest counties. This is also where the
heaviest rain has already fallen. A flash flood watch was already
issued area wide, but the greatest threat looks like it will be in
our northwest counties. That being the case, confidence is not
all that high that we will see problems in our southeast counties.
However, with the watch already out, the onus is to prove that
hydro problems won`t occur there. Certainly don`t want to have
flips in the watch situation, so will leave it run in the
southeast.

In terms of severe weather, low level shear looks significant,
both in terms of speed and direction. The more questionable factor
seems to be the degree of surface based instability which will be
present. At most, it should be rather weak for this time of year.
However, with the degree of shear, any surface based instability
would be a concern. Dragging down environmental winds and adding
on a bit due to convection could be enough for damage. Also, the
low condensation heights along with the high storm relative
helicity in the soundings are supportive of brief tornadoes. Due
to the warm atmosphere and lack of strong instability, hail is not
a concern.

The tropical remnants pull out to the east this evening, wind
fields weaken, and the severe threat drops off. It will be a
little while longer until the cold front passes, and some
additional showers or thunderstorms could fire until it passes
late tonight and early Saturday. However, mid level drying is
expected when the tropical system departs, which will also allow
the heavy rain threat to diminish during the night. Much drier air
will arrive at the ground behind the front on Saturday.

.LONG TERM...(Saturday night through Thursday)
Issued at 358 AM EDT FRI JUN 23 2017

A period of drying is on the horizon and near record cool
temperatures possible early next week. That said, in the wake of
a cold front we will see falling heights and a building Canadian
surface high pressure. The models are in fair agreement on this
Canadian surface high pressure and matter of fact really strong
agreement in the GFS ensemble members. Also several reinforcing
waves will bring single digit 850MB temperatures into the region
for the first part of next week. These temperatures will be
significantly anomalous, with 500mb to 850mb temperatures expected
to be 3 plus standard deviations below normal for this time of
year.

At the surface, the coolest day may be Wednesday morning depending
on how cloud cover shakes out on Tuesday morning, but temperatures
in the low to mid 50s and some valleys could drop into the upper
40s. These kinds of temperatures will be close to record
temperatures for both days with JKL current record for Tuesday is
54 degrees and 53 degrees on Wednesday. However, our records at
JKL may be a little weaker compared to LOZ, where LOZ records
showing 48 degrees Tuesday and 50 degrees on Wednesday which may
be more difficult outside of valley locations. Temperatures by
Wednesday do warm, as the high pressure moves off toward the VA/NC
coast line and we see increased return flow. By Thursday, the
models show a little less agreement, but a wave could generate
some showers by the afternoon. Past this the CPC would suggest
more chances of precip becomes possible as we begin July.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 302 AM EDT FRI JUN 23 2017

A break in the action was ongoing at the start of the period, with
mostly VFR conditions. As the remnants of Tropical Storm Cindy
approach from the southwest ahead of a cold front, low clouds are
expected to increase overnight, with much of the area expected to
see MVFR ceilings for a time late tonight or Friday morning,
followed by an improvement to largely VFR during the day Friday.
However, there is not a lot of confidence in the specifics of the
TAFS regarding timing of MVFR versus VFR into Friday afternoon.
The prospect of showers and thunderstorms will be rising during
the day Friday, with the most likely time for rain being late in
the day and in the evening. An eventual drop to IFR and low end
MVFR conditions is expected Friday evening, as a cold front
approaches and moves through.

Some of the storms and heavier showers on Friday afternoon and
early evening may bring high winds. Also concerning winds, LLWS
has been included in the TAFS tonight and into the day Friday,
until sufficient mixing occurs to dissipate it.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from noon EDT today through Saturday morning
for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.

&&

$$

SHORT TERM...HAL
LONG TERM...DJ
AVIATION...HAL



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