Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 270813
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
413 AM EDT Sat May 27 2017

.SHORT TERM...(Today through Sunday)
Issued at 413 AM EDT SAT MAY 27 2017

An active weather pattern setting up to kick off this holiday
weekend. The lower levels are moistening up this morning thanks to
some southwest flow in the low levels advecting some moisture into
the region. This has already set off a few isolated showers in the
bluegrass region. This activity will likely expand through the
daybreak hours with cloud heights coming down as moisture streams
into the lower levels. We remain very capped this morning, so not
expecting any storms to develop just yet. This all changes as a
boundary just to our north settles south into northern Kentucky.
Instability will build to the south of this boundary with over
2000J/kg of MLCAPE and LI`s around -8C. This is pretty good
instability for our neck of the woods. Added convergence along the
frontal zone in the north could help to spark some showers/storms
as we head through the afternoon and early evening hours. With the
front stretched out east to west and the mean flow coming from
the west, will have to watch for potential some training storms.
PW values will reach nearly 1.6 inches by this afternoon putting
us very close to the 99th percentile for May. This all points
towards the potential for heavy rainfall and flash flooding.
Freezing level is also quite high supporting more warm rain
processes. Thus, we have issued a flash flood watch for most of
eastern Kentucky. There will also be a severe threat this
afternoon with the good instability mentioned above. Shear is not
the best in the northern portion of our area, but does get a bit
better to the south. Regardless, instability may be enough to make
up for the lack of shear and thus pose a damaging wind threat
with any storms that develop. The weaker shear would probably
limit the overall hail threat, although some small hail would be
possible. Finally with outflow boundaries possible, this could
help to escalate low level SRH and possibly lead to a low tornado
threat. However, this will be highly conditional on storm
evolution today, so will continue to downplay the overall tornado
threat.

Activity will likely diminish by late evening with a shortwave
ridge pushing across the Ohio river valley. This will provide a
lull overnight into early Sunday morning. The lull could be
interrupted by any upstream convection that may try to work into
the region from the west. This will be clearly determined by where
convection forms and the overall steering pattern. At this point,
CAMS all seem to support a more southerly track of any MCS
tonight, likely missing our area, assuming the mid level ridge is
strong enough.

Then the focus shifts to Sunday as instability builds once more.
00z NAM really doesn`t bring the better instability in until late
Sunday evening, suggesting we may see a later onset of stronger
storm potential on Sunday. However, shear is stronger on Sunday,
so whatever forms upstream and tracks into the area could have
some damaging winds with it late Sunday. Hail doesn`t appear to
be a great threat as storm initiation should take place upstream
with the cold front with stuff turning more QLCS in nature by the
time it reaches us. With the potential for additional rounds of
showers, have put the flash flood watch out through Sunday
evening.

.LONG TERM...(Sunday night through Friday)
Issued at 413 AM EDT SAT MAY 27 2017

Long term discussion will follow shortly.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 214 AM EDT SAT MAY 27 2017

VFR conditions will be replaced with a period of MVFR conditions
towards daybreak through the remainder of the Saturday morning
hours as the low levels moisten up overnight. A few showers may
accompany the lower cigs. Cloud heights will return to VFR by
early afternoon. The threat for showers and storms will develop as
we head through the afternoon and evening hours on Saturday, but
still some question on how much coverage we will see with this
activity. Thus, have gone mainly VCTS in the TAFS, but more
prevailing in the south, where there might be a slightly better
chance for thunderstorms. Strong winds will be seen around the
thunderstorms that do develop today. Activity will wind down by
late evening with a lull expected overnight Saturday night.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 2 PM EDT this afternoon through late
Sunday night for KYZ050>052-058>060-068-069-079-080-083>088-104-
106>120.

&&

$$

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



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