Cincinnati, Ohio 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

825
FXUS61 KILN 181053
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
553 AM EST Sat Jan 18 2025

.SYNOPSIS...
Rain, possibly mixed with snow at times, will taper off through
the afternoon with colder air filtering back into the area by
tonight. Some light snow and snow showers are expected Sunday as
the leading edge of an arctic airmass begins to move in. A
bitterly cold stretch is on tap for the Ohio Valley Sunday
night through the first part of next week before a warming trend
evolves by the end of the workweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Rain is beginning to overspread the area from the SW, slowly
eroding the abundance of deep dry air entrenched locally.
Dewpoint depressions on the order of ~15 degrees will promote
some wet bulbing upon pcpn onset, allowing air temps to
decrease despite the overall WAA regime in place. Most of the
pcpn is expected to be rain through about 12z, but certainly
there could be brief RASN mix occurring near/N of I-70 before
daybreak where the BL is the most supportive. Around 12z or so,
there likely will be a bit more SN mixing in from EC IN through
WC OH, which may transition briefly over to all snow for several
hours within a corridor from about Fayette/Union Cos IN to
Delaware Co OH and points N. This may promote some
light/grassy/elevated accumulations, particularly in/near the
Wayne Co IN to Hardin Co OH corridor. The confidence on this
occurring is still rather low, but do think that these areas
will have a chance at seeing light grassy/elevated accums of up
to half of an inch before the RASN or SN tapers off by the
afternoon.

Further to the S, near/S of I-71, the pcpn is expected to remain
primarily rain, with liquid-equivalent totals on the order of
one quarter to one third of an inch area-wide. Pcpn will
decrease in intensity and coverage between 15z-18z, with
lingering pcpn becoming ISO/light in nature past 18z. Could see
a few flurries or patchy light SHSN late afternoon in the post-
frontal environment, with CAA underway region-wide by sunset.

Temps will be largely steady until the FROPA, generally in the
mid to upper 30s. Expect that the front will move NW to SE
through the ILN FA through the afternoon hours, with temps
settling back below the freezing mark by this evening area-wide.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Although a few flurries cannot be ruled out this evening through
most of the night, dry conditions are expected until the predawn
hours when some wintry weather will make a reappearance.

The setup for Sunday has become a bit more concerning for us,
but the threat for impactful wintry weather will come in two
forms.

1) A S/W rounding the base of the expanding/digging longwave
trof will pivot E into the srn OH Vly by early Sunday morning,
spreading deep-layer ascent into a still amply-saturated LL
profile. This will promote the development of a large band of
SN, which should pivot to the NE through KY into far srn OH by
daybreak Sunday, bringing light accumulating snow to the SE
third or so of the ILN FA. There is still quite a bit of
uncertainty regarding latitudinal placement of this band, with
the synoptic and ensemble guidance supportive of one to perhaps
two tenths of an inch of liquid-equivalent pcpn stretching from
Robertson Co KY through Hocking Co OH and points to the S.
Given above- climo SLRs on the order of ~15:1, this would
translate into a broad axis of 1-3" within this corridor from
about 09z through 18z Sunday. This being said, there is still
some disagreement regarding just how far N this band will
extend, lending itself to uncertainty in how expansive this band
of 1-3" of snow will be locally.

2) Sunday is shaping up to be a fairly cold and blustery day
area-wide, with steep low-level lapse rates coinciding with
increasing forcing as a midlevel S/W swings through the area.
Good saturation within the DGZ and sufficient lift within the
DGZ suggest that SHSN activity should be fairly widespread by
Sunday afternoon into the evening. Of particular concern is
several focused bands of SHSN activity along the leading edge of
the incredibly deep/sharp PV anomaly, which will move E through
the area late Sunday afternoon into the evening. This signal is
so strong that it is actually appearing within several coarse
synoptic QPF plots, suggesting that the SHSN could be locally
intense. Bottom line is that we very well could be dealing with
some snow squalls Sunday afternoon into the evening, with LL
temp profiles more-than-supportive for efficient accumulation on
roads and the overall setup being favorable for impactful
SHSN/squall activity. As with these setups, it is not about the
amounts, but rather the rapid change in conditions that come
with the passage.

So regardless of whether the light snow early Sunday
materializes locally, there is likely to be impacts from
SHSN/squalls on Sunday afternoon/evening across a much broader
portion of the local area. At this time, Winter Weather
Advisories have been considered, but the question remains for
which parts of the area and whether to include the SHSN/squall
portion of impacts Sunday afternoon/evening, despite the
expectation for not meeting/exceeding advisory-level snow criteria
except perhaps within the aforementioned SE third of the ILN FA
due to light banded snow Sunday morning. Will highlight this
potential in the HWO and other messaging platforms as the snow
squall potential will likely be the greatest concern through
the short term period.

Temps will range from the lower 20s (NW) to the upper 20s (SE on
Sunday, with a negligible diurnal rise for most spots.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
On Sunday evening, the axis of a mid-level shortwave will be in the
process of clearing through the ILN forecast area. Though the region
will already be quite cold, a secondary cold front will also be
moving eastward through the area on Sunday evening. This front will
come with an increase in WNW winds, and represents the leading edge
of the very cold air mass that is moving into the area through the
first half of the week. Until this front has cleared through the
area, some additional snow showers will remain possible. After 00Z,
this may be confined to just the eastern half of the forecast area,
but any snow that falls will be capable of some additional light
accumulations -- largely a result of the 18-20 to 1 snow-to-liquid
ratios. Once these snow showers move off to the east on Sunday
night, the rest of the extended forecast period appears dry.

The focus for the extended period remains on the period of cold
weather from Monday through Wednesday. A very cold arctic air mass
will remain in place over the region for this time period. Getting
into the details, one area of surface high pressure will be in place
on Monday, before moving eastward. A weak boundary will then move
through the area Tuesday morning, with a second surface high
establishing itself across the Ohio Valley later Tuesday into early
Wednesday morning. The coldest of conditions are likely to be found
associated with the centers of these areas of high pressure,
particularly on Monday morning and Wednesday morning. A very brief
and very weak period of warm advection will result in Tuesday
morning coming in slightly warmer than Monday or Wednesday, though
not enough warmer to really change the narrative regarding this
three-day stretch of dangerously cold conditions. The Extreme Cold
Watch will remain in effect.

Based on the latest guidance, the coldest wind chills may occur on
Monday morning, with values ranging from -10F to -20F across the
forecast area. This is driven by temperatures near or just below
zero, but also by winds that will be around 10 mph at 12Z Monday. To
contrast, the coldest raw temperatures are likely to occur Wednesday
morning, with lighter winds and mostly clear skies leading to ideal
radiational cooling conditions. Temperatures on Wednesday morning
look to be below zero for the vast majority of the forecast area,
with some values approaching -10F in central Ohio. Despite the
lighter winds, wind chills may again approach -20F in the northern
CWA.

Confidence is high that this period will feature large impacts due
to the cold conditions, though confidence is only medium in specific
values -- particularly when dealing with wind chills (apparent
temperatures) due to those values being dependent on two other
elements (temperatures and wind speeds). The other source of
uncertainty is the state of the snow pack, which will definitely be
modified by above-freezing temperatures and rain today (Saturday),
and may be modified by additional snow (Sunday). Wherever the snow
pack remains most robust and most fresh, especially if new snow is
added, that could determine where temperatures end up being the
coldest during the coming week.

As of now, it appears that a very slight warm up could occur for the
second half of the week, so the coldest conditions will likely be
focused on the mornings of Monday, Tuesday, and Wednesday. By later
Wednesday, as the high moves to the east, flow should switch to the
south -- bringing what can technically be described as warm
advection to an air mass that is anything but warm. A stronger
signal for warm advection is showing up for Thursday, when
temperatures should be able to get back into the 20s and 30s.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A mix of MVFR/IFR CIGs will go more solidly IFR early in the TAF
period area-wide, with even some brief LIFR CIGs possible
through 18z. Thereafter, CIGs will go back to MVFR once again
toward 00z and beyond. MVFR/IFR VSBYs are expected with the
rapid column saturation and steady light pcpn through 16z
before VSBYs gradually improve by early afternoon. A RASN mix is
possible at nrn sites through about 16z time frame, but is most
likely at KDAY for perhaps a few hours. Did not have enough
confidence at this juncture to include all SN in the fcst for
KDAY, but certainly a several hour period will be possible mid
morning.

Pcpn will decrease in coverage/intensity progressively from SW
to NE between 15z-18z, becoming more ISO after 18z. Still could
see a few patches of flurries or light SHRASN by late afternoon
along the SE-advancing front itself, which of course could lead
to more brief reductions in VSBYs. But decided to maintain a
mainly dry fcst for most spots past 18z.

Steady S flow at 10-12kts will go more out of the SSW before
abruptly changing to out of the NNW with the FROPA between
18z-22z. Some NNW gusts to around 20kts are expected for several
hours after the FROPA before northerly winds subside to 10kts
or less by 06z Sunday.

Toward 12z Sunday and beyond, the primary item of interest is
going to be the development of some light SN (particularly near
KCVG/KLUK), as well as numerous SHSN throughout the day
(especially during the afternoon/evening).

OUTLOOK...MVFR CIGs and MVFR/IFR VSBYs are possible on Sunday.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Extreme Cold Watch from late Sunday night through Wednesday
     morning for OHZ026-034-035-042>046-051>056-060>065-
     070>074-077>082-088.
KY...Extreme Cold Watch from late Sunday night through Wednesday
     morning for KYZ089>100.
IN...Extreme Cold Watch from late Sunday night through Wednesday
     morning for INZ050-058-059-066-073>075-080.

&&

$$

SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...Hatzos
AVIATION...KC