Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 160549
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1249 AM EST Mon Jan 16 2017

.UPDATE...
Issued at 1249 AM EST MON JAN 16 2017

Surface analysis shows high pressure to our NE along the
Mid Atlantic coast and we are seeing NE to E winds in the wake.
While there may be a weak gradient, most will be under a
subsidence inversion. Model soundings continue to indicate a
stratus build down and we are certainly seeing low clouds and some
sites are seeing fog. The real question is will this become more
widespread in the valleys. Right now think the SPS will work, but
will monitor through the night to see if more will be needed.
Grids are in good shape and therefore will only update for obs and
near term trends.

UPDATE Issued at 1040 PM EST SUN JAN 15 2017

Widespread showers have moved out of the area, as a mid-level
short wave exits off to the east. Only a few light showers remain,
and these should continue to dwindle across the area over the next
1 to 2 hours. Subsidence will be moving in aloft overnight, which
should gradually build the low stratus/fog down into the lower
elevations through dawn. Temperatures look to remain near steady
if not slowly rise through dawn, as winds veer around to the
southeast. Updates have been sent.

UPDATE Issued at 651 PM EST SUN JAN 15 2017

Showers/light rain has become more widespread along and north of
the Mountain Parkway over the last hour. As such, will be raising
POPs to categorical, as most locations will measure. As forcing
exits later on this evening, mid-level ridging will move in aloft,
helping to promote stratiform build-down fog, as abundant low
level moisture remains in place. As such, have issued a Special
Weather Statement highlighting this concern.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 345 PM EST SUN JAN 15 2017

As of mid afternoon, an upper level ridge was centered near
Florida with the ridge axis extending into the Southeastern states
to Mid South Region. Meanwhile, a weak shortwave was moving
through the OH Valley region while a broad trough encompasses much
of the Western and especially Southwestern Conus. Within this
trough, an upper level low was located over the Southern NM and
far West TX area while a shortwave trough was digging south off
the California coast. At the surface, an area of low pressure was
moving from the Southern Rockies into the Southern Plains region
with a warm front that extended east and became stationary across
the Gulf Coast states and into the Carolinas. North of the
boundary across the Lower OH Valley region, moisture remains in
place within the rather broad frontal zone in place. Meanwhile,
sfc high pressure was in place across the Eastern Great Lakes
region with weak east to north flow across the area. Stratus build
down across the area is leading to low clouds across all but the
far south with visibilities already reduced on the ridges.

Through this evening, the shortwave trough will move across the
area this evening with another round of scattered to numerous
showers and some drizzle or sprinkles across the far south.
Behind this shortwave, the upper level ridge axis will move into
the Lower OH Valley and Eastern KY while the upper level now
nearing TX moves into the Southern Plains. Meanwhile the surface
low will track into the KS and OK area. The stationary front
meanwhile will begin to return north as a warm front into the TN
Valley tonight. After the round of showers through this evening,
moisture will become more shallow so the chances for getting
measurable precipitation will likely end. However, the low levels
will remain moist and this combined with subsidence associated
with the ridge should lead to further stratus build down tonight
and some sprinkles or patchy drizzle will be possible. Patchy
coverage to areas of fog coverage is expected, especially on the
ridgetops.

The upper level ridge axis will move east of the area
on Monday while the upper level low moves into NW MO and SW IA.
The sfc low should move to northern MO by Monday evening. The
upper level through will move into the western Great Lakes region
with the sfc low also reaching southern Lake MI or MI by the end
of the period. The warm front should lift north of the area by
Monday evening into Monday night. Elevated instability will also
be on the increase late especially in the southwest and west.
Thus, much of Monday morning into mid afternoon should feature
precipitation free weather and skies possibly brightening up a
bit. However, as the warm front nears and the upper level system
approaches, isentropic lift should bring another good chance for
showers. A rumble or two of thunder cannot be ruled out late in
the south and west.

.LONG TERM...(Tuesday through Sunday)
Issued at 230 PM EST SUN JAN 15 2017

Convoluted weather pattern throughout the long term period with
split jet streams. Multiple closed lows will meander about the
central part of the CONUS keeping southwest flow in place over our
area and this will provide the one constant for the period: above
normal temperatures. Relied heavily on the blended model guidance
in this complex pattern.

A cold front will be stretched out across the area Tuesday into
Tuesday evening as a shortwave scoots across the Ohio Valley. This
should provide for numerous showers during the day and cannot rule
out a few thunderstorms with models showing some instability along
with a fairly healthy 850 mb jet aloft. The chance for showers
will linger into Wednesday morning as the front slowly works to
our southeast. Timing is very suspect beyond Wednesday, but it
appears now that we can expect a brief break Wednesday afternoon
through Thursday morning. A southern stream disturbance then rides
north-northeast out of Texas and this will bring renewed rain
chances Thursday night into Friday. Saturday looks dry right now
but another system ejecting out of the southwest appears to spread
more rain across the area by Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1220 AM EST MON JAN 16 2017

The period has begun with IFR or worse conditions for VIS, CIG or
both. This will likely be the story overnight, as soundings show a
more stratus build down scenario. Lowest values will be from now
until dawn before improvements are expected. That said, we will
see improving CIGS and VIS to MVFR by the early afternoon, as warm
front advances north. Winds will continue to remain light with
winds out of the east before coming around to the SE and south to
end the period.

&&

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

$$

UPDATE...DJ
SHORT TERM...JP
LONG TERM...ABE
AVIATION...DJ



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