Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 301215 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
815 AM EDT Tue May 30 2017

.UPDATE...
Issued at 755 AM EDT TUE MAY 30 2017

Hourly grids were freshened up based on recent observations and
trends. Some of the 6Z guidance and some of the convective
allowing models suggest greater coverage late this afternoon and
evening in the Cumberland Valley and less coverage of convection
in the southeast. With that in min, opted to increase pops to 30
in the Cumberland Valley, but did not decrease pops in the
southeast just yet.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 358 AM EDT TUE MAY 30 2017

Early this morning the region was under the influence of trough
extending south into the MS valley region from a closed low over
Ontario. Several weak shortwaves were rotating around this low and
through the trough. One is currently moving into the Eastern
Great Lakes and middle and upper Oh Valley regions. Another is
upstream over IA south into MO with one or more additional
shortwaves upstream entering the Dakotas and MN area. In advance
of the first upstream shortwave was an associated surface cold
front with yet another upstream of that associated with the
shortwave entering the northern Plains.

The center of the upper low should meander north through the
period with the shortwaves and cold fronts working across the OH
Valley and Great Lakes region. The first will move through the
area today with the second one approaching the area on Wednesday.
With the trough in place, a considerable amount of cloud cover is
expected through the period along with chances for showers and
perhaps a few mainly diurnally driven thunderstorms. Moisture and
instability will be higher across the south and southeastern
counties this afternoon and evening and thus slight chance to
chance pops were carried across these locations. The model
consensus keeps locations in the far north, especially form I 64
north dry today.

Models generally bring another shortwave into the MS Valley and
Lower OH Valley and TN Valley tonight. The NAM guidance is likely
overdone with moisture and lift with this feature, but at least
some convection will be possible mainly late tonight across the
southwest part of the area near Lake Cumberland. This shortwave
should move through early with another rotating into the Great
lakes sending the cold front into East KY in the afternoon.
Moisture and instability will be somewhat limited, but isolated
to scattered convection is anticipated. With more convection
expected earlier in the day than 24 hours ago the risk of any
strong to severe thunderstorms is diminished. However, one or two
stronger storms with gusty winds cannot be completely ruled out
nearer to the TN and VA borders in the afternoon.

.LONG TERM...(Wednesday night through Monday)
Issued at 245 AM EDT TUE MAY 30 2017

High pressure will progress southward across the area Wednesday
night through Thursday evening, providing a dry period of weather.
As the high shifts south and east, return flow will start to bring
better moisture into the area by Friday. We could see a few pop up
showers or storms on Friday, but the lack of any forcing will keep
things fairly isolated. A nice connection to the gulf develops
Friday night and Saturday with ample moisture streaming north into
the region. This occurs as a back door cold front pushes in from
the north and east. Some weak ascent will spread over the area on
Saturday with a vort max passing across the area. This should
allow for better coverage of showers and storms. PW`s will
increase to near 1.70 from Saturday through Sunday. With the front
stalling to our north and the flow lining up nearly parallel to
the front, the threat for training storms and more flash flooding
will return. Overall details remain uncertain, but will continue
to highlight the potential for flash flooding in the HWO. 00z GFS
has trended slower with moving things out Sunday night/Monday, so
have kept pops going into Monday, before drying things out Monday
night. The added length of the moisture air over the region, will
likely aid in the threat for flash flooding.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 805 AM EDT TUE MAY 30 2017

VFR conditions will generally be the rule throughout the period.
One exception will be initial fog, especially in the valleys.
This will affect LOZ and SME Winchell with MVFR reductions.
However, the fog should dissipate areawide by 13Z. The other would
be any direct hits from isolated to scattered showers or
thunderstorms will accompany the passage of a weak front/surface
trough mainly between 18Z and 00Z. For now have used VCTS at LOZ,
SME, JKL, and LOZ. The activity should remain south of the
northern counties and SYM is not expected to be affected. Winds
should remain 10KT or less through the period outside of any
thunderstorm gusts.

&&

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

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...KAS
AVIATION...JP


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