Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 271910
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
310 PM EDT Mon Mar 27 2017

.UPDATE...
Issued at 1235 PM EDT MON MAR 27 2017

Pops have been updated to account for convection trends near the
northward lifting warm front and also trends in temperatures and
more clearing in the south to the south of the warm front. This
led to higher pops early this afternoon across the northern part
of the area. This activity should lift to near the OH River and on
into OH through mid afternoon. Additional convection should
develop during peak heating during the late afternoon to early
evening as an upper level trough and surface low pressure system
nears. CAPE and shear will be conducive for a few strong storms.
An isolated severe thunderstorm is possible mainly 5 PM EDT and
after. More vigorous convection is expected to develop from
western and middle TN into western and central KY and could
congeal into lines or lines of convection during the evening and
move into East KY.

UPDATE Issued at 659 AM EDT MON MAR 27 2017

Biggest issue this morning has been breaks in the clouds leading
to areas of dense fog. Did opt to beef up the wording in the
products and we did send out of graphical now to deal with the
issue. Otherwise forecast updated with latest obs and trends.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 407 AM EDT MON MAR 27 2017

This morning the surface analysis shows a weakening frontal
boundary to our west and another surface low across western OK.
This weakening surface boundary to the west is having little
influences on surface winds or temperatures. The bigger influence
on temperatures this morning has been with the breaks in the
clouds which is leading to some temperature splits. Also the fog
is locally dense which could also be holding back temperatures to
an extent. This surface boundary will likely lift north through
the day, as more of a warm front if anything. Therefore we remain
in the warm airmass across eastern KY today. The locally dense fog
is expected to lift through the early morning hours.

All eyes turn to the aforementioned surface low in western OK and
upper level short wave expected to lift into the midwest through
the day. This will induce height falls through the day from west
to east across the Ohio and Tennessee Valleys. Also this will
induce a LLJ that will creep north today and lead to further lift
and moisture. It does look like we will see breaks in the clouds
early in the day and this could lead to modestly unstable
environment. Cloud cover will also be the caveat as it could rob
the potential destabilization. Given the previously mentioned LLJ
and increasing winds with height we will have sufficient shear in
place across the region for strong storms. The shear is more
unidirectional and therefore think storm mode will be more
multicell or perhaps line segments. Model soundings do show a EML
in the mid levels with better reflection in the 00Z NAM. Given
this and dependent on low level lapse rates nearing the 8 C/km
through the day will be enough to support marginally severe wind
risk. Also the EML, reasonable shear, and low freezing levels at
or below 10 KFT will support marginal hail risk as well. Given
some of the caveats and climatology think the marginal risk from
SPC is reasonable. The best chances of seeing stronger storms
right now would be along and west of the I-75 corridor. However,
many of the CAMs suggest a line segment could in fact move
northeast along and near the I-64 corridor this afternoon.
Therefore did increase POPs across that area this afternoon, but
This will have to be monitored in subsequent updates.

This Surface low is expected to move into the Ohio Valley tonight
and overall best lift will come tonight where height falls will
be maximized. Therefore did opt to bring the CAT POPs through
tonight into the overnight from west to east. POPs will wane
through the day on Tuesday, as the upper level wave moves east and
front pushes across the region. This wave will dampen out and
front will weaken therefore not expecting a big airmass change.

.LONG TERM...(Wednesday through Monday)
Issued at 310 PM EDT MON MAR 27 2017

The extended period should once again feature good chances for
showers and thunderstorms from late Thursday morning through early
Friday evening. The trigger for this activity will likely be a
slow moving area of low pressure that is progged to move across
the Tennessee and lower Ohio Valley regions. The slow forward
motion of the system should keep rain in eastern Kentucky through
Saturday morning. Thunderstorm chances should come to an end
around 0Z Saturday, as the best upper level support and overall
lift should be east of the area as the low pressure system moves
off to our east. The rain should begin quickly tapering off
around dawn Saturday morning, with the rain being completely out
of the area before noon on Saturday. The weather should remain dry
from Saturday afternoon through late Sunday night, as an area of
high pressure settles over the region. Our next round of rain
could move into eastern Kentucky very early Monday morning, but
due a lot of uncertainty still exists that far out in the period.

Temperatures will continue to run well above normal, with daily
highs ranging from the mid to around 70 on most days. Thursday
looks to be by far the warmest day, with forecast highs on that
day in the 70s. Nightly lows should generally be in the 40s and
50s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 647 AM EDT MON MAR 27 2017

TAFs have been slightly tricky overnight, as some sites cleared
and subsequently saw MVFR/IFR VIS at times. Otherwise the lower
VIS has been confined to the usual trouble spots. The fog is
expected to clear through the morning and lead to VFR conditions
through the day. The only issue is showers and thunderstorms will
be on the increase through the day and this could lead to isolated
lower CIGS/VIS issues. Overall better chances of showers and
thunderstorms will be late this afternoon and evening. There is
also a isolated chance a few of the stronger storms could contain
small hail and gusty winds. Late tonight thunderstorms will give
way to lingering showers, but the the lower cloud deck is expected
to lower leading MVFR CIGs for most toward dawn Tuesday. Overall
winds will be light out of the south to southwest, but again any
stronger thunderstorms could contain strong gusty winds.

&&

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

$$

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


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