Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 220755

National Weather Service Jackson KY
355 AM EDT Tue May 22 2018

.SHORT TERM...(Today through Wednesday)
Issued at 348 AM EDT TUE MAY 22 2018

Current conditions across the area feature some mid and upper
level cloud cover moving through the area. In addition, the last
of a few showers will move northeast out of the Bluegrass area.
With the cloud cover moving through, fog development has been
halted. A few spots in the south with some clearing will see some
visibility drop but this is the exception. The overall pattern
indicates a continued return flow with ample moisture continuing
to stream north into the OH Valley. This will be the case heading
into the day today. Model soundings indicate a continued PWAT
values of 1.65. Though as been the case for the pas several days,
the lack of a good impulse tracking by and organizing this
convection, the activity remains largely scattered despite the
amount of moisture being pumped into the region. Thus will go for
a good chance heading into today. A weakened front from the north
will begin push southeast through the day. Convection will
intensify a bit along this washed out boundary as it pushed
southeast. Will keep pop chances going through the day today and
into tonight. Despite the scattered nature of the showers and
storms, this is still a saturated air mass and any storm can put
down enough rain to cause some minor flooding issues. For tonight,
good saturation of the boundary layer will allow for fog
development with ongoing showers through the night slowly pushing
southeast. Behind the boundary, the hint of some clearing as some
dry air attempts to enter area will allow for some more widespread
fog to develop.

Heading into the day on Wednesday, the front will have pushed
southeast and slow along the TN and VA border. Will expect some
shower and a few thunderstorms to develop along the boundary and
especially in the higher terrain. Meanwhile clearing skies to the
northwest will allow temps to rebound into the low 80s. This is
still above normal despite the cooler air moving into the area.

.LONG TERM...(Wednesday night through Monday)
Issued at 355 AM EDT TUE MAY 22 2018

The models are in fair agreement with the longwave pattern and major
features aloft through the extended portion of the forecast. They
all depict a relatively weak full latitude ridge over the region to
start this portion of the forecast. This ridge weakens and fades out
by the end of the work week under twin assault from the northern
stream and a potential tropical system to the south. The northern
stream will return a flow of energy into the Great Lakes region to
start the weekend while to the south heights will be falling due to
the developing upper low along the central Gulf Coast. Some energy
associated with this low will start to ooze into Kentucky late in
the weekend and to start the next week. The main factor in the model
differences late in the period revolve around the depth and
development of this southern low with the ECMWF more aggressive than
the GFS having a mid level low somewhat deeper and more westerly
than the GFS. Will favor a blended solution here with monitoring
needed to see if the deeper scenario of the ECMWF starts to pan out
and work better with the predictions out of the NHC - in time.

Sensible weather will feature a respite from the afternoon/evening
showers and storms - and their periodic deluges - from Wednesday
night through Friday. However, after that, return flow moisture and
potential for tropical interaction will put us right back in an
environment of potential heavy rains from diurnally enhanced showers
and storms for Friday night through Monday. This will be more so the
case should the ECMWF solution pan out when compared to the GFS, but
both suggest a wet and active weekend and beyond. For now we will
need to make the most of the dry patch to close out the work week.

Made mainly terrain based adjustments to the lows each night during
the work week from the SuperBlend starting point with enough dry air
initially suggesting small to moderate ridge and valley temperature
splits. Did not deviate far from the blended PoPs into the weekend,
though did beef them up each afternoon to better match the
anticipated diurnal impact on this upcoming pattern.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)

Expect VFR conditions to persist through much of the night. The
only exception is in the north where some showers and
thunderstorms will be passing through to the north impacting SYM
as well. Later tonight, where clouds are slower to increase,
expect some valley fog to develop. This is especially true at SME
and LOZ. At least MVFR conditions will occur. Heading into the
day, showers and thunderstorms will once again develop, mostly by
15 and 16z. This activity will continue the evening. Coverage is
in question so went VCTS at the TAF sites. Outside of
thunderstorms, winds will be relatively light.




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