Area Forecast Discussion
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FXUS61 KILN 211053
Area Forecast Discussion
National Weather Service Wilmington OH
653 AM EDT Fri Oct 21 2016
Low pressure will continue to move northeast today slowing pulling
the backedge of the rain eastward with it. A much colder airmass
will filter into the region today and Saturday, before warmer air
works back into the region for Sunday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The center of low pressure and a cdfnt are located over West
Virginia early this morning. This has allowed winds to turn to the
north and temperatures to fall into upper 40s and 50s. However,
sharp H5 trof will swing thru the fa this morning. This is
combining with a deformation axis to produce a secondary band of
rain across IN into wrn OH.
It will take a good part of the morning for deformation zone to
work thru the fa, and to bring an end to the chance of rain. Some
rain could linger in the extreme eastern counties into early
Strong pressure gradient on the backside of the low will keep
winds gusty, especially this morning. Gusts 20-30 mph will be
possible. CAA will persist through the day with 850 mb
temperatures dropping down below 0C by late afternoon. This will
counteract the drier air trying to build in this afternoon, to
linger the clouds today. With the cloud cover, temperatures
will be limited to the lower to mid 50s, with a few spots in the
Cincy Tri-State making the upper 50s.
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
By 00Z the H5 trof axis will be into the Appalachians, leaving
the fa in nw flow both at the sfc and aloft. Feel that there will
be enuf cold air aloft to linger the clouds overnight. The clouds
will help keep temperatures up a little, but they still be a
little below normal falling in the upper 30s and lower 40s.
Surface high pressure will begin to build up into the Tennessee
Valley. While this keep dry conditions on Saturday, lingering cold
air aloft will allow for clouds to redevelop especially during the
afternoon. This will keep temperatures in the 50s, ranging from
the lower 50s in the east to the mid 50s in the west.
Saturday night will see H8 temperatures warming, but think that
the atmosphere will decouple enough for a small diurnal drop in
temperatures. Lows Saturday night will drop back into the lower to
On Sunday, southwest winds at the sfc will bring warm air back
into the region. A few high clouds could affect the region in fast
flow aloft, but there will be plenty of sunshine and temperatures
should make the mid to upper 60s for highs.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Sunday night into Monday morning a shortwave will push southeast
down mid-level ridging and around the upper level low. The GFS is
slightly more progressive and weaker with the shortwave compared
to the ECMWF. Both 20.12z model runs bring the shortwave slightly
further west than yesterday and therefore try to bring the heart
of the colder air slightly further west as well. The ECMWF and the
GFS push the front through the area by Monday evening. The frontal
passage also appears to be a dry frontal passage as PWATs remain
around 0.60". Behind the front highs will cool down back to normal
as the heart of the cold air still misses the area (850 mb
temperatures around 4 degrees C).
Tuesday the upper level trough will finally head east of the area
taking the cooler air with it. Wednesday into Thursday a shortwave
will eject out of the midwest and approach the area. This means
clouds will begin to increase on Wednesday and into Thursday. Have
also introduced a chance of rain into the forecast Thursday as the
low approaches. PWATs on the GFS rise to above 1.00" with limited
instability. Upper level forcing looks good though as the ILN
forecast area is in the diffluent side of the trough axis and
widespread PV moves over the area. For now have just edged the
chance of precipitation up as model consistency remains low at this
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A weak low pressure east of the terminals will continue to lift
northeast away from the area. Pcpn associated with the deformation
axis is now beginning to pivot east across the region. This area
has filled in quite nicely over the past several hours with
-SHRA/-DZ with pockets of heavier pcpn. Still do think that back
edge of pcpn will work east of KDAY/KCVG/KLUK around/shortly after
14z. Anticipate drying trend towards latter part of the afternoon
for eastern sites of KCMH and KLCK.
In the meantime, CIGS will continue to hover around 1k ft and
periodically bounce between low MVFR and IFR. IFR CIGs have been
more prevalent in pockets of heavier pcpn, so have accounted for
this in the TEMPO groups. Do anticipate that as axis of -SHRA
works east, that CIGs will go strictly MVFR, with the potential
for VFR late afternoon for western sites of KCVG, KDAY, and KLUK.
In the wake of the low, a fairly pronounced pressure gradient has
settled over the area which will lead to northwesterly winds of 12
to 15 kts with gusts up to 25 kts through the afternoon. The
gradient will relax from west to east late this afternoon,
allowing for a weakening trend by evening. Winds will be 5 to 10
Main concern tonight will be potential for a stream of low level
moisture off Lake Michigan to filter into western parts of the area.
Models have been fairly consistent showing this axis developing,
which may lead to MVFR CIGs once again for western sites past 06z
Saturday. Although there remains some uncertainty on the exact
extent and location of the stream of low level moisture, the eastern
sites will likely remain VFR through the overnight period.
OUTLOOK...No significant weather expected.