Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 200850
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
450 AM EDT Tue Jun 20 2017

.SHORT TERM...(Today through Wednesday)
Issued at 300 AM EDT TUE JUN 20 2017

A ridge of high pressure will be the dominate weather feature
across the region over the next few days. As a result, dry
weather, warming temperatures, and partly cloudy to mostly clear
skies will be on tap. Winds should be light and variable during
the period. Areas of valley fog will form and persist through
early this morning before dissipating. The fog may even be dense
in locations that received rainfall Sunday and Sunday night. After
a full day and night of dry weather, the fog threat Tuesday night
will not be as high, therefore only patchy fog is expected early
Wednesday morning in valleys, especially near bodies of water.
Temperatures should be at or just above normal, with highs in the
low to mid 80s expected today and tomorrow.

.LONG TERM...(Wednesday night through Monday)
Issued at 425 AM EDT TUE JUN 20 2017

The period is expected to begin with ridging centered near the
Four Corners region and another ridge centered south of Bermuda. A
shortwave trough is expected to be moving across the Northeast US
with a shortwave ridge over the western Great Lakes and a broad
trough extending into parts of the Northern Rockies and Northern
Plains. At the same time, a tropical system is expected to be
nearing the Gulf Coast with sfc high pressure centered in the
vicinity of Bermuda. The return flow between the ridge and the
tropical system will have begun to bring in increase in deep
tropical moisture north into the Gulf states. Futher north and
west, an area of sfc low pressure ahead of the broad trough is
expected to be moving across southern Canada with a warm front
lifting north toward the Great Lakes and a cold front trailing
south into the Plains and portions of the Rockies.

From Wed night through Friday, the upper ridges are generally
expected to remain in place near Bermuda and the desert southwest
with a weakness in between. Models vary with the strength of
these from run to run. This leads to uncertainty on the timing of
the tropical system remnants as they move toward the Arkalatex
region and eventually portions of the TN and lower OH Valley as
insentropic lift spreads north and east. At the same time, low
pressure should move rather quickly east across southern Canada
and the Northern Conus with the center of the low reaching Quebec
on Friday while the trailing cold front becomes sheared from
northeast to southwest north of the region. This front to some
extent will interact with the increasing tropical moisture and
probably some solar insolation on Friday to bring a round of
showers and thunderstorms to the region. Some locally heavy rain
will be a possibility.

From Friday night into Saturday, some jet entrance region dynamics
may come into play and lead to deeper enhanced lift across the
area. However, models vary on this from run to run and model to
model. The threat for locally heavy rain will continue into the
day on Saturday across East KY. The deeper moisture with the
tropical remnant and associated weakening shortwave should depart
to the east by Saturday evening.

To end the weekend through early next week, a trough the axis of
which should move from the central to eastern Conus should be the
dominant features. Disturbances moving through the trough may
combine with lingering moisture for chances of convection,
especially during the afternoon and evening on Sunday and Monday.

What is certain as there will be an increase of deep tropical
moisture into the region by Thursday night and into Friday.
However, uncertainty remains in rainfall amounts and areal extent
of higher amounts. Some solutions have quite widespread high
amounts but may be suffering from convective feedback issues. The
model consensus blend of 48 hour totals of 2.25 to about 3.5
inches is a reasonable compromise of all solutions at this time.
Locally higher amounts than that are possible. As the strength of
the ridges and the tropical system become more clear, the timing
and strength of the remnants will be more certain as should
rainfall amounts. At this time, we have opted to include the
threat of heavy rain in the HWO, but highlight the uncertainty.

The expected presence of deeper moisture and rather extensive
cloud cover will bring rather limited diurnal ranges from
Thursday night through the end of the period. After near to
slightly above normal highs on Thursday below normal highs are
expected with mild overnight lows Wed night through Friday night.
The period should end with temperatures averaging below normal
with the trough in place.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 147 AM EDT TUE JUN 20 2017

VFR conditions are expected through out the period at JKL, SYM,
and SJS. LOZ and SME may experience some MVFR conditions due to
fog between 8 and 12Z this morning. SCT clouds with bases around
6K are expected to form across the area by 15 or 16Z this morning.
These clouds will likely persist through the end of the TAF period
once they form. Winds should be light and variable.

&&

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

$$

SHORT TERM...AR
LONG TERM...JP
AVIATION...AR



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