Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 290016

Area Forecast Discussion
National Weather Service Jackson KY
816 PM EDT TUE JUN 28 2016

Issued at 816 PM EDT TUE JUN 28 2016

Models all showing drier air advecting into the area overnight.
This drier air will be responsible for a pleasantly warm start to
the evening and possibly a cooler overnight than originally
expected, especially across our north. However, weak upper/mid
level wave will also pass through the region overnight, producing
some extra clouds across our area through the predawn time frame.
Ultimately this makes the overnight forecast a bit more
challenging with respect to lows and the development of patchy
fog. Updated grids for latest hourly trends. Will continue to
evaluate and decide whether or not to drop temps a couple degrees
by our next update.


.SHORT TERM...(This evening through Wednesday night)
Issued at 332 PM EDT TUE JUN 28 2016

Based on obs this hour the fairly weak front has progressed south
of the region as winds at most sites are out of the NW. Behind
this front surface high pressure is progged to build SE into the
region. We will also remain in cyclonic flow aloft and this should
help to reinforce the drier and cooler air. Overall the surface
high will progress through the Ohio Valley and become more broad.
Issues weather wise will be some of the forecast soundings do
suggest some potential for fog or perhaps low stratus, however
confidence is low given the increasingly drier air that progresses
into the region. Did however keep with some clouds that the blends
were giving but kept them mostly in the east and also added a bit
of fog in mainly valley locales that do not mix out left over

Models are in good agreement with a shortwave moving across
eastern KY Wednesday afternoon and this will be enough to bring
few to sct CU across the region, however given the dry air these
CU will be fair weather. Otherwise below normal temps will be the
story given high temps could run as much as 8 degrees below
normal. That said also nice to see CIPS analog showing low signal
for dewpoints above 65 degrees given recent stretch of 75 degree
plus dewpoints seen in some spots. The morning lows Thursday will
also be running nearly 10 degrees below normal with lows in the
mid to upper 50s.

.LONG TERM...(Thursday through Tuesday)
Issued at 400 PM EDT TUE JUN 28 2016

The models are in relatively good agreement with the large scale
pattern aloft through the extended portion of the forecast. They
all agree that the eastern trough will tighten up through the end
of the work week as a sharp shortwave pivots through the northern
Great Lakes. While this wave passes by to the north of Kentucky,
the bulk of the energy will stay closer to the center of the mid
level low until Friday afternoon when some of it slips east near
the Ohio/Kentucky border. As the upper trough pulls away from the
area, and the pattern flattens out, over the weekend additional
energy will slide along the northern boundary of a sub tropical
ridge parked above the deep south. This stream will affect
Kentucky through the weekend and into the start of the next work
week. One or two of these smaller waves will strengthen as they
pass, particularly from Sunday through Monday night - driving the
Wx over our state. Given the general model agreement have favored
a blended solution, with some emphasis on recent trends to the
more prominent SFC features.

Sensible weather will feature a quiet and comfortably dry start to
the latter portion of the forecast as a cold front will remain
south of the area with high pressure in charge. This regime breaks
down on Friday, though, as the next, mainly dry, cold front
approaches the area from the northwest. It appears that this
boundary will wash out over the southern Ohio Valley by evening
and provide a glide path for potential MCS activity through the
weekend and beyond. The tracks and subsequent, somewhat chaotic,
effects of each storm cluster will make timing and placement of
the best chances for showers and storms through the rest of the
forecast problematic at best. The 12z ECMWF seems to have shifted
a tad toward the more northern solution from the GFS but is still
different enough to keep confidence in either solution low.
Nevertheless, fairly high, mainly diurnal driven PoPs will be the
rule for this time owing to the quality of air mass in place,
nearby boundaries, and some upper level support. There may be
movement on Monday as a SFC wave looks to ride through the Ohio
Valley and points east. This could shift the front and soupier air
mass further south by mid week, but that remains to be seen. For
now we can expect near normal temperatures for the period, with
highs capped through at least the weekend by the anticipated
fairly widespread convection.

Made only minor, cosmetic adjustments to the CR extended init
scheme, mainly to push the PoPs and QPF towards a point between
the ECMWF and GFS on a 6 hourly basis, but not necessary a
straight blend. Also incorporated a diurnal influence into the PoP
and Sky grids, but left most terrain influences out of the MinT
grids given the return of clouds and higher humidity.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)

Models all showing drier air advecting into the area overnight.
Expectations are that the drier air should restrict the
development of widespread fog through the overnight. Guidance is
hitting our lower valley locations pretty hard through the
predawn time frame, generating LIFR/IFR vsbys in fog. However,
guidance has been trending more optimistic as well and does not
appear to be handling the advection of drier air into the area
very well. Therefore went more optimistic with the terminal
forecast overall. There is a weak upper/mid level disturbance
moving through the region overnight. This will be responsible for
some clouds between 015 and 040 AGL. However, boundary layer
appears to remain dry enough that MVFR CIGS are not expected to
develop except possibly in the higher terrain of our extreme
eastern most areas. Winds are expected to be light through the
forecast period, and generally northerly.


.JKL Watches/Warnings/Advisories...None.



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