ILN issues Area Forecast Discussion (AFD) at Jan 21, 12:46 PM EST744
FXUS61 KILN 211746
AFDILN
Area Forecast Discussion
National Weather Service Wilmington OH
1246 PM EST Tue Jan 21 2025
.SYNOPSIS...
Bitterly cold conditions will persist through Wednesday,
with mainly dry conditions expected through midweek. There will
be a few chances for patchy light snow showers Tuesday and again
Thursday into Friday, but precipitation should be isolated and
very light in nature. A slight warming trend is expected by the
end of the workweek, with more seasonable air filtering back
into the Ohio Valley as we head into the weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Only minor changes made with the morning update. Scattered snow
showers will decrease late in the period from west to east as
high pressure begins to build into the Ohio Valley. Winds will
briefly gust just behind the arctic boundary this afternoon
before beginning to subside this evening.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Sfc high pressure will build into the srn OH Vly this evening
through early tonight, creating ideal radiational cooling
conditions locally through at least the first half of tonight.
There is a strong signal that the coldest temps of the entire
stretch are expected tonight given the favorable setup, but this
may not necessarily translate into colder wind chills than what
we have already experienced given the light/calm winds.
With the ~1038mb sfc high traversing srn parts of the region,
do think that most, if not all, areas will experience below zero
air temps tonight. In fact, sheltered/low-lying areas will
likely see air temps around/below -5F, with -10F air temps very
possible in rural/sheltered spots in parts of central/south-
central OH. The fly-in-the-ointment, however, is going to be
that as the sfc high pulls E of the region very late tonight
through early Wednesday morning, return flow on the backside
will allow for winds to begin to increase to around 5-10kts
across parts of EC IN and WC OH during the predawn hours. This
may not seem like much, but with air temps between -5 and -10
degrees, any light wind will have a significant impact on the
wind chill. But it may also help nudge the air temp up a few
degrees around daybreak, too. Either way, minimum wind chill
values are going to get very close to warning-level criteria
(-20F N and -15F S) for a large portion of the area late
tonight into Wednesday morning, but there is not /quite/ enough
confidence at this time to support an upgrade to a warning given
the uncertainties in the ever-delicate temp/wind dance that
will unfold late tonight. It is going to be very cold no matter
the circumstances, even if wind chill values stay in advisory
criteria due to lighter wind.
Breezy conditions are expected on Wednesday amidst a tightening
pressure gradient, with temps rebounding rather abruptly past
sunrise from the -5 to -10 range into the upper teens to mid
20s by the afternoon. The stiff SW breeze will be in response to
the approach of the next weak system, which may bring additional
low-end light snow chances to the area by Thursday.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
On Wednesday evening, surface high pressure will be moving off the
east coast, as a surface low moves east through the Great Lakes.
Boundary layer flow will be generally southerly, as the period of
very cold temperatures will have come to an end. Attention will then
turn to two shortwaves moving eastward through the generally
westerly flow aloft. Although moisture will be limited, these waves
will be capable of producing flurries or perhaps some very light
accumulations of snow. Confidence, however, is rather low in exact
placement and timing. This forecast will simply carry a slight
chance of snow for sections of the forecast area on Thursday (with
the first wave) and Friday morning (with the second wave). In
between the two, a weak surface boundary will re-establish some
slightly cooler air over the area Thursday night into Friday.
Conditions will change a bit over the weekend, as high pressure sets
up over the southeastern states, leading to deeper and stronger
southwesterly flow into the Ohio Valley. This will bring
temperatures above freezing (lower 30s to lower 40s) for the ILN CWA
on both Saturday and Sunday. At some point over the weekend,
probably heading into Sunday, there has been a fairly consistent
model signal for precipitation. As the surface high drifts a little
further to the southeast, theta-e advection on its western periphery
will develop from the Gulf of Mexico through the middle Mississippi
Valley region, with eventually some theta-e advection aloft reaching
the Ohio Valley as well. While sometimes these types of setups could
produce a risk of freezing rain, the warmer conditions on Saturday
and lack of significant overrunning may help to mitigate this, and
model ensemble probabilities suggest only very low probabilities for
anything other than a mix of rain and snow as of now.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Initially, snow showers along and just behind an arctic cold
front will bring occasional dips in cigs below 3,000 feet, with
visibility dropping below 3 miles at times. However, as high
pressure begins to build into the region this evening,
expecting shower activity to decrease and VFR conditions
prevail.
Winds will lighten significantly overnight as the center of
surface high pressure moves across the middle Ohio River Valley.
A light southerly flow will develop on Wednesday as the high
shifts to the east.
OUTLOOK...MVFR CIGs are possible Thursday into Friday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Cold Weather Advisory until 10 AM EST Wednesday for OHZ026-034-
035-042>046-051>056-060>065-070>074-077>082-088.
KY...Cold Weather Advisory until 10 AM EST Wednesday for KYZ089>100.
IN...Cold Weather Advisory until 10 AM EST Wednesday for INZ050-058-
059-066-073>075-080.
&&
$$
SYNOPSIS...KC
NEAR TERM...
SHORT TERM...KC
LONG TERM...Hatzos
AVIATION...
Source:
ILN issues Area Forecast Discussion (AFD) at Jan 21, 12:46 PM EST---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
