NWS Wilmington, OH wrote its last area forecast discussion before the first event at Feb 2, 12:55 PM EST, 5 minutes earlier.
Area forecast discussion, Feb 2, 12:55 PM EST, 5 minutes before
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
1255 PM EST Wed Feb 2 2022
.SYNOPSIS...
A potent winter storm will move into the region today through
Thursday, bringing a mix of rain, freezing rain, sleet, and
snow to the region. Drier weather is expected by later Friday,
but with very cold air moving in for the weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Primary update for this morning is the upgrade from a Watch to a
Winter Storm Warning for our remaining southeastern counties.
This now puts the entire ILN CWA in a Winter Storm Warning for
the upcoming storm. More details can be found in the short term
discussion regarding information/impacts from this winter storm.
In the near term, expect rain to overspread our remaining
eastern counties through the morning, with periods of rain
persisting for most of the daytime hours. Temperatures have
trended a smidge warmer this morning, so did some minor tweaks
to the grids for temps/dewpoints. A transition to a brief
wintry-mix followed by snow will occur in our northwestern
counties first later this afternoon, with accumulating snowfall
occurring this evening into the overnight for those
northwestern counties.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
A significant winter weather event is expected over the next few
days. There remains high confidence in hazardous conditions
across the ILN forecast area, but unfortunately, confidence
remains somewhat mixed with regards to specific precipitation
timing and placement.
A frigid (though shallow) near-surface air mass will be moving
south into the area later today, gradually making more southward
progress over the course of Thursday. Atop this boundary,
southwesterly flow (under the right entrance region of a jet
streak) will bring moisture and lift into the area. This will
spark the first main wave of precipitation, which is expected
from Wednesday morning (moving into the area as rain right now)
through early Thursday morning. Overall confidence in the timing
and placement of this precipitation, including precipitation
type, is actually fairly good for this first wave. As time goes
on, particularly tonight, this activity will start to see more
of a mixed precipitation profile -- as the cold surface air
undercuts some warmer air aloft. It still looks like the far
northern ILN CWA will be mainly snow, with a transition zone
(including freezing rain and sleet) across east-central Indiana,
the Miami Valley, and central Ohio.
Although there may be no clean break between the two waves of
precipitation, there will definitely be an uptick in intensity
with the second wave, as it begins early Thursday afternoon.
This is where the forecast gets much more complicated, as
confidence in the location of the transition zone is fairly low.
As an illustration, at 18Z Thursday, it is virtually guaranteed
that there will be snow in Mercer County OH and rain in Lewis
County KY. What happens in between is the crux of the forecast,
particularly as this is the beginning of the time period in
which accumulations will be at their most robust. There has
definitely been an overall trend in the models that suggests the
potential for a few things. First, slightly lower snow
accumulations near the southern edge of the heavy snow, due to
potential sleet contamination. Second, a slight southward shift
with the ice accumulations. It is still possible that there will
be a band of more significant ice numbers, somewhere south of
the Interstate 71 corridor, but unfortunately confidence has not
yet increased in where exactly this may occur. There have also
been a few models suggesting a brief period of heavy snow making
it as far south as the Interstate 71 corridor on Thursday
evening, just behind the mixed precipitation, but for now this
is just a possible solution to note -- and the expectation for
more of a mix will remain in this forecast update.
Overall, this forecast did not make significant changes to the
previous snow and ice numbers. There was a slight reduction in
snow amounts through the middle part of the CWA, particularly
from east-central Indiana through the Columbus OH area. The ice
forecast is very similar to before, perhaps slightly further
southeast, but with similar value. Would prefer not to indicate
anything higher than about 0.2" to 0.4" of ice unless higher
confidence in a particular focused band develops.
This was not an easy forecast for deciding on Watches and
Warnings, with forecast uncertainties and different timing
concerns all factoring into the collaboration with surrounding
NWS offices. To be specific, there are some portions of the ILN
forecast area that might not reach the hard warning criteria
for either ice /or/ snow amounts. With that said, there is
little doubt that the overall combined impacts will be warning
level in practice, if not in the numbers. Thus, the vast
majority of the ILN CWA has been upgraded to a Winter Storm
Warning. It is definitely not an ideal scenario to have to make
a decision to issue a warning for some counties in which
hazardous wintry weather is still 36 hours from beginning,
particularly when precipitation type forecasts for that second
wave remain so uncertain. The absolute greatest uncertainty
remains in the far southeastern CWA, where snow will be limited
to the back side of the system, and ice may not even begin until
late Thursday afternoon. So, although it was just two counties,
it seemed very prudent to leave Scioto OH and Lewis KY in the
watch phase.
Some consideration was also given to the idea of an Ice Storm
Warning, given that there will be some parts of the ILN CWA
where FZRA is the primary hazard. Given the aforementioned
uncertainties regarding where the worst of the FZRA will set up
(and the potential for an oops all sleet scenario) it was
decided that a more general Winter Storm Warning was the smarter
call for now. This can always be adjusted if confidence
increases.
A few other items to note...
* It is possible that a brief period of freezing rain or
freezing drizzle could occur early Thursday morning in the far
northern ILN CWA, when forcing is lighter in between the two
main waves of precipitation.
* Blowing Snow is likely once the transition to snow has
occurred, particularly north of the Interstate 71 corridor on
Thursday afternoon and evening. Winds will gust up to 25-35
MPH.
* There remains a very low potential for some hydrologic issues,
as the air mass in the rainy part of the event will be quite
moist, but as of now the expected precipitation amounts do not
raise too much cause for concern.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
The long term period will be relatively quiet for the ILN FA,
especially in comparison to the near/short term periods, as
discussed above. This being said, the most active, and perhaps
concerning, part of the fcst lies within the first 24 hours of
the long term period as snow may be a tad slower to actually
exit the ILN FA Friday morning as some of the more recent trends
have suggested a ribbon of lighter snow associated with a
trailing convergent/frontogenetic axis positioned at about the
H7 level. The lift generated within this layer is rather weak,
but there is enough moisture lingering in the DGZ with an arctic
airmass in place -- a setup that has proven to overproduce
guidance on more than one occasion. Have kept high chance PoPs
across the southern third or so of the ILN FA from about 09z-15z
Friday before the convergence decreases and the lift becomes
much more negligible. This being said, would not be surprised at
all to see another half to one inch of snow within this
trailing band across parts of the Tri-State into NE KY and SC OH
with the higher SLRs we will have to work with.
After the light snow tapers off by the afternoon, attention
will quickly turn to the /very/ cold temps expected for Friday
night into Saturday morning. This setup is particularly
concerning in the wake of the major winter storm will be
contending with in the near/short term periods, especially with
the prospect of some parts of the area having power outages due
to freezing rain/ice accretion. The fresh/deep snowpack will
offer its own source for very cold temp potential, but there is
still a lack of agreement in the guidance in just where the sfc
high will be positioned by 12z Saturday. This has obvious
implications on not only wind chill, but actual air temps as
well. Either way, feel confident that wind chills will go below
zero just about everywhere early Saturday morning, with the
greatest potential for advisory-level thresholds (<= -10F)
residing near/north of I-70. If the sfc high ends up more
centered over the OH Vly by 12z, the sfc winds would be lighter
to nearly calm, allowing for nearly ideal radiational cooling
conditions, but thus not providing the wind needed for advisory
criteria. So while confidence is not all that high on what
exactly the actual air temps will be (i.e. near zero or closer
to -10F), the apparent temps should be approximately the same
either way it shakes out. And therefore, feel that an advisory
will eventually be warranted for at least parts of the ILN FA.
Another weak system will pivot SE through the region Sunday
night into Monday, but most of the area should remain dry except
perhaps for a few flurries. Temps will warm briefly on Sunday
ahead of the system Sunday night, but colder air will quickly
return Monday before temps once again moderate toward the middle
of next week, with /generally/ tranquil weather conditions
expected during this time.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
MVFR/IFR conditions overspreading the region this afternoon
associated with the rainfall. Pockets of IFR vsbys exist in some
of the heavier rainfall, but generally expect MVFR vsbys to be
the prevailing category with the rain. As for CIGs, MVFR
reductions will be followed by IFR reductions later this
afternoon/evening, with IFR CIGs persisting for much of
Wednesday night into Thursday.
Wind speeds of 10-15 kts out of the SSE will continue through
the day, with isolated gusts of 20-25 kts possible. Overnight, a
cold frontal boundary will slowly move in from the northwest and
shift the wind direction from the north. While a brief period of
weaker winds are possible as the front moves through, there will
be a notable increase in wind speeds behind the front.
Sustained winds of 15-20 kts with gusts up to 30-35 kts out of
the NNE are possible Thursday morning through afternoon.
The other important item to note here is the transition from
RA to a mix of FZRA, PL and SN that will eventually work their
way across all taf sites. The transition to these different
precipitation types seems very probable due to the movement of
colder air underneath warmer air aloft. However, the length of
time in which the specific mixed precipitation types are
observed is still uncertain. Tried to incorporate the most
likely transition times for each of these different pcpn types,
but future updates will help narrow a window for transition
times. Regardless, expect a messy mix of various pcpn types
across all taf sites early Thursday morning through afternoon. A
transition to snow will eventually occur later on Thursday into
Thursday night.
OUTLOOK...IFR to LIFR ceilings and visibilities will occur
through Thursday night. Precipitation will transition to
freezing rain, then sleet, then snow before ending late
Thursday night. In addition, wind gusts up to 35 kt will be
possible Thursday afternoon and evening. MVFR/IFR ceilings will
likely persist into Friday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...Winter Storm Warning from 5 PM this afternoon to 7 AM EST
Friday for OHZ046-051>056-060>062.
Winter Storm Warning until 7 AM EST Friday for OHZ026-034-035-
042>045.
Winter Storm Warning from midnight tonight to 7 AM EST Friday
for OHZ063>065-070>072-077.
Winter Storm Warning from 6 AM Thursday to 7 AM EST Friday for
OHZ073-074-078>082-088.
KY...Winter Storm Warning from 6 AM Thursday to 7 AM EST Friday for
KYZ089>100.
IN...Winter Storm Warning from 5 PM this afternoon to 7 AM EST
Friday for INZ050-058-059-066.
Winter Storm Warning from midnight tonight to 7 AM EST Friday
for INZ073-074.
Winter Storm Warning from 6 AM Thursday to 7 AM EST Friday for
INZ075-080.
&&
SYNOPSIS...Hatzos
NEAR TERM...Clark
SHORT TERM...Hatzos
LONG TERM...KC
AVIATION...Clark