Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 211807 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
207 PM EDT Wed Jun 21 2017

.UPDATE...
Issued at 207 PM EDT WED JUN 21 2017

The forecast remains on track. Once again, just freshened up the
hourly temperatures and dew points through the rest of the
afternoon. Updates have been sent.

UPDATE Issued at 1132 AM EDT WED JUN 21 2017

Mainly just freshened up the hourly temperatures and dew points
through this afternoon. Forecast highs mainly in the mid 80s, with
a few upper 80s, look on target. Updates have been sent.

UPDATE Issued at 805 AM EDT WED JUN 21 2017

Hourly grids were freshened up based on recent observations and
trends. This led to no substantial changes at this time.

&&

.SHORT TERM...(Today through Thursday)
Issued at 425 AM EDT WED JUN 21 2017

Early this morning, surface high pressure was located over the
Appalachians. Thicker cirrus is streaming from West Tn east northeast
to the KY/VA border region into the Central Appalachians. The
region is in a seasonably moist airmass between weak cold front or
outflow boundary north of the Ohio River and nearly stationary
boundary from east TX east northeast to the Delmarva which is the
leading edge of the much deeper tropical moisture to the south.
This moisture is being transported into the Gulf states around
Tropical Storm Cindy. Aloft, an upper level trough extended south
from Ontario and Quebec and Ontario into the Great Lakes and
parts of the OH Valley with a ridge centered southwest of Bermuda
and another ridge centered over the Desert Southwest. In between
was weakness with the center of Tropical Storm Cindy over the Gulf
of Mexico. Observations indicate generally less in the way of
valley fog compared to recent mornings.

Through this morning, a general decrease in the thickness of the
cirrus is expected for most locations through some debris mid and
high clouds could affect northern portions of the area. The axis
of the trough to the north and northeast of the area will shift to
the north and east today with an increase in mid level heights.
Some diurnally driven cu may form but should be rather shallow or
capped by some subsidence. Temperatures should moderate further
from readings over the past couple of days with surface and upper
level high pressure dominating. Highs should average above normal,
generally in the mid 80s with a few upper 80s across the area
with slightly warmer readings in the north with a bit less in the
way of clouds.

Through today and into tonight, the center of tropical storm Cindy
should continue moving across the northern Gulf of Mexico and
associated upper low should move toward the upper TX coast with
the southwest US ridge and ridge near Bermuda remaining in
generally the same location and strength. Disturbances will pass
by to the north in rather quick westerly flow. East KY will
dominated by surface and upper level ridge through the night, but
moisture will begin to increase especially in the southwest. PW
will also begin to increase today and especially tonight form
values currently near 1 inch to an inch to an inch and a third by
sunset. The more dramatic increase will occur tonight and into
Thursday with values reaching in excess of 1.5 inches toward
sunrise on Thursday.

As the center of Cindy moves into the upper TX coast or western LA
as well as an upper low moisture will continue increasing form the
southwest with some isentropic lift across the area. PW should
climb above 1.5 inches in the far north and east by the end of the
period with PW nearing or exceeding 2 inches in the far southwest
at that time. A shortwave should also approach in the westerlies
at the time. This and some solar insolation will lead to
increasing chances for showers and a few thunderstorms through the
day though the west moisture and lift will be in the southwest
where chances and qpf are expected to be the greatest through 0Z
Friday. However, the heaviest rainfall should off until the long
term period.

.LONG TERM...(Thursday night through Tuesday)
Issued at 319 AM EDT WED JUN 21 2017

The primary concern in the extended will be the potential for heavy
rainfall associated with the remnants of tropical storm Cindy Friday
night and Saturday. At this time the latest model data has several
rounds of moderate to heavy rainfall occurring across the Ohio and
Tennessee valleys at the end of the week and into the upcoming
weekend. Whatever is left of Cindy will likely interact and merge
with a cold front that is forecast to approach from the north. There
is still a considerable amount of uncertainty as to what the exact
track of the two weather systems will be, and therefore the amount
of rainfall that will fall across the area. The model data has
several rounds of moderate to heavy rain occurring across the
region, with bulls eyes of maximum rainfall amounts randomly
appearing across the area. Because of this, the forecast will need
to be refined a number of times over the next couple of days as the
models hone in on a more common and consolidated solution. In
general, it does appear that 2.5 to 4.25 inches of rainfall will be
possible across the area during the duration of the event, the bulk
of which should fall Friday night and Saturday. After a brief break
in the rain Saturday night through Sunday morning, a fast moving and
weak area of low pressure is forecast to bring isolated to scattered
showers and storms to the area Sunday afternoon through early Monday
afternoon.

Temperatures for most of the period are forecast to be below normal,
due to extensive cloud cover, multiple rounds of rainfall, and the
invasion of cooler air into the region after a couple of weather
systems move east of the area. Friday night and Saturday should have
close to normal temperatures, with lows in the upper 60s and highs
in the lower 80s expected respectively. Once this initial system
moves east of the area, our first round of cooler air will spread
across the area. A second shot of cool air is expected to filter
into the region behind a second weather system after it departs the
area on Monday, thereby reinforcing the cooler air that will already
be in place. This will be the primary reason whey we see below
normal temperatures through the middle of next week. From Sunday
onward, daytime highs are forecast to top out mostly in the mid to
upper 70s across the area. Nightly lows are expected to average in
the mid to upper 50s for most locations.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 207 PM EDT WED JUN 21 2017

High pressure will maintain control through late this evening,
with afternoon cumulus dissipating by dusk. A low level jet will
then increase from the south and southwest towards dawn Thursday,
bringing lowering ceilings and eventually showers and a few
thunderstorms to the area during the day on Thursday. West
southwest winds at 5 to 10 kts, will gradually back to the south
southwest later in the period.

&&

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

$$

UPDATE...GEOGERIAN
SHORT TERM...JP
LONG TERM...AR
AVIATION...GEOGERIAN


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