ILN issues Area Forecast Discussion (AFD) at Nov 19, 9:45 PM EST008
FXUS61 KILN 200245
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
945 PM EST Tue Nov 19 2024
.SYNOPSIS...
A disturbance impacts the area Wednesday and Thursday, bringing
much cooler temperatures, gusty winds, rain, and even some
slushy snow. Temperatures moderate back to near seasonal
normals through the weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
The fog and low stratus continues to expand rather aggressively
locally, with a Dense Fog Advisory now covering the SE 3/4 of
the ILN FA. In the lower Scioto Valley, there is admittedly
still some uncertainty regarding whether the LL moisture will
manifest itself in a low stratus (but not at the sfc) or whether
it will be more dense fog. But given recent obs trends, it
seems like the latter may be more and more likely. The
widespread dense fog will be with us through the overnight, with
difficult travel conditions expected through daybreak and
beyond. Overnight low temperatures fall to the low 40s in the
west, low 50s in the east.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Any fog development should dissipate after sunrise as winds
begin to shift to out of the west and increase on Wednesday.
Complicated forecast in store for the upcoming days with much to
talk about. Synoptically, the low pressure system that has been
influencing our sensible weather continues to occlude and decay
to our northwest. However, the parent system aloft (a closed low
around 500H located near the Dakotas) will start the process of
wrapping a speed max around its base. This will be the catalyst
for cyclogenesis of a secondary surface low across the Great
Lakes and into Appalachia. This low will rapidly strengthen and
deepen through Wednesday and into Thursday. Isallobaric response
prompts (event stronger) thermal advection and,
consequentially, we'll notice our wind speeds increasing
throughout the day as the system deepens and temperatures
respond.
Westerly winds ramp up during Wednesday afternoon, sustained
around 15-20 MPH with gusts up to 30 MPH possible. There is a
weak signal for precip Wednesday morning and afternoon given
ascent moving through the region, so some light showers are
possible.
High temperatures on Wednesday were tricky, given that diurnal
heating would normally bump temperatures a bit higher, but cold
air advection processes will counteract this... for now, have
highs in the upper 40s/low 50s in our west, low 60s in our
southeast, where CAA won't have penetrated as far. However, by Wednesday
evening and into the overnight, CAA will be occurring in
earnest and we'll plunge into the 30s are wide.
Again, weak signal for precipitation remains
in place and any precip that falls will likely start out as a
very cold rain before slowly transitioning to a wintry mix and
even some snow in the far northwest by Thursday early morning
hours. Winds remain elevated overnight, out of the west, around
10-15 MPH with gusts to 20 MPH possible.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Initial impulse will be swinging through the area at the beginning
of the period. This will result in scattered to numerous showers
during the morning. There will be a lull in precipitation before a
vertically stacked low drops south out of the Great Lakes Thursday
afternoon into Thursday evening and then turns southeast during the
overnight hours. This will bring an extensive shield of
precipitation across the area late Thursday and through Thursday
night. Much of this precipitation will be snow. And with QPF
trending upwards, snowfall amounts have trended similarly. The
ground is starting out warm, so there will be melting and compaction
after initial accumulation, and on pavement there will be even less,
with perhaps only wet roadways.
Another weak impulse rotating around the upper system will drop
across the area on Friday with additional scattered showers. But air
temperatures will be warming sufficiently for much of that to end up
as rain showers.
Upper low pulls away allowing mid level flow to become zonal through
the weekend with surface high pressure passing south of the region.
Temperatures will get back closer to normal by Sunday.
Temperatures will become even milder heading into early next week as
a warm front develops into the region. However, a chance of rain
will return as weak disturbances move through broad west southwest
flow aloft.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Bottom line up front: Quite a busy TAF period ahead with
multiple periods of low CIGs and VSBYs, with breezy conditions
as well.
Precip: A narrow band of SCT/numerous SHRA will pivot E quickly
from 15z-19z across the local area and may lead to brief
reductions in VSBYs in the heavier activity. Have included only
a VCSH for now, but a TEMPO for MVFR VSBYs may eventually be
warranted.
Wind: Calm/light winds through daybreak will increase through
the late morning into the afternoon hours. Sustained W winds
will be between 15-20 kts, with gusts to 25-30 kts possible,
especially in the several hour period around 18z.
CIGs and VSBYs: With calm/light winds and clearing skies, BR/FG
is expected to develop in a fairly widespread fashion through
the first part of the TAF period, leading to LIFR or VLIFR
conditions for several hours, especially for
KCVG/KLUK/KILN/KCMH/KLCK between 08z-13z. However, there are
some indications for BR already developing, so some locales,
such as KILN/KLUK, may have significantly reduced VSBYs for an
even longer stretch. Either way, the BR/FG is going to be very
slow to lift/improve through the morning hours until about
14z-16z with the arrival of slightly stronger sfc winds. The FG
is expected to lift into an LIFR/IFR stratus deck before the
arrival of the aforementioned SHRA. Following the SHRA, skies
should trend clearer, with conditions returning to VFR area-
wide past 18z-19z.
OUTLOOK...Multiple rounds of rain, snow, breezy winds, and
MVFR/IFR conditions are possible through Friday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Dense Fog Advisory until 9 AM EST Wednesday for OHZ044>046-
051>056-061>065-070>074-077>082-088.
KY...Dense Fog Advisory until 9 AM EST Wednesday for KYZ091>100.
IN...None.
&&
$$
SYNOPSIS...CA
NEAR TERM...CA/KC
SHORT TERM...CA
LONG TERM...
AVIATION...KC
Source:
ILN issues Area Forecast Discussion (AFD) at Nov 19, 9:45 PM EST---------------
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