Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 302346
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
746 PM EDT Thu Mar 30 2017

.UPDATE...
Issued at 730 PM EDT THU MAR 30 2017

Current conditions across the area feature some thunderstorms well
east of the main line of activity in western Kentucky that have
developed along the I-75 corridor. Likely tapping into the bit of
instability ahead of the system as much of eastern Kentucky has
had a good portion of the day to destabilize. Thus have updated
the forecast to bring in the pops a bit earlier. A new zfp has
been sent out for this update.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 442 PM EDT THU MAR 30 2017

Surface low pressure was centered over central IL this afternoon,
with the associated mid/upper level low lagging just to the west.
Warm, moist, unstable air was streaming north from the Gulf of
Mexico in the system`s circulation. Locally, deep mixing and
downslope flow across the Smokies was limiting our surface
moisture this afternoon. The better supply of low level moisture
is to our west. The storm system will move east tonight, bringing
its cold front through the area. Showers and thunderstorms are
expected with the system, and with ample shear, a severe threat
can not be ruled out (especially wind). However, due to the
aforementioned moisture situation and the unfavorable diurnal
timing of the storms, the greater threat will be to our west.

Behind the front, the mid/upper low will be moving eastward over
the area on Friday, bringing scattered showers. The clouds,
showers, and cold air advection will result in a cool day with
little rise in temperatures.

Most of the precip will pull out by Saturday morning. However,
clouds will linger in the upslope flow and cold air advection on
Friday night.

.LONG TERM...(Saturday through Thursday)
Issued at 410 PM EDT THU MAR 30 2017

The period will begin with upper level low progressing into New
England states and upper level ridging building in the wake. We
may have some lingering rain showers in the far east Saturday
morning, However, these will wane and we will see some clearing
from SW to NE by the late afternoon. Surface high pressure will
build over top and track across portions of the Ohio Valley and
Great Lakes. Now the active pattern continues, with another upper
level low progressing out of the Four Corners to begin next week.
There remains some timing issues and which stream will dominate.
Right now the southern stream will dominate, but the track of the
surface low is some what north in the ECMWF versus the GFS. Even
so, will keep the CAT POPs provided by the blend given it looks
like it will measure regardless. The question becomes more of how
much precipitation particularly given we can become more cutoff
from the better moisture, as storms near the Gulf coast rob the
better flow. After this we see another break and some ridging on
the backside Tuesday night into early Wednesday. The models become
even more divergent moving into the later half of the period as
the 12Z GFS/00Z ECMWF were running about 24 hour difference with
respect to the front by Wednesday/Thursday respectively. Given
this will cap POPs at chance for now both Wednesday/Thursday and
see how this shakes out as we move closer to the period. However,
the latest 12Z ECMWF was closer to the GFS for what it is worth at
this point. Most of the period will be met with above normal
temperatures, before we go back to near normal to round out the
period given the northern stream wave.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 746 PM EDT THU MAR 30 2017

Expect VFR conditions for the first several hours of the TAF
period. However, IFR and below conditions will begin to develop by
04Z as the line of showers and thunderstorm in central Kentucky
move into the area. A few scattered storms developing ahead of the
line will impact some of the western TAF sites through the
evening. Expect below mins cigs and possibly vis as well by dawn
as still a few showers will be passing through. A post frontal
trough will swing in behind the front tomorrow keeping MVFR and
possibly IFR cigs over the area. Winds will be gusting up to 20
knots ahead of the front tonight and will then swing to the
northwest tomorrow with still some 15 knots gusts expected.

&&

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

$$

UPDATE...SHALLENBERGER
SHORT TERM...HAL
LONG TERM...DJ
AVIATION...SHALLENBERGER


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