Absolute Vorticity

1004 MB low cross the MS river along the MS / TN border a little further south then I thought but not a bad thing for Cincinnati to keep us in snow as long as possible.

dce wrote: ↑Sun Jan 05, 2025 3:17 pm Not snowing here yet. There are good returns overhead but I'm still waiting for the column to saturate. I'm encouraged though by the nice returns to my west about a county row to my north. Once the column is saturated I will see decent banding.

Update to that. As soon as I posted that, I'm now starting to see the first flakes so the column has begun to saturate.

Yawn, so far nothing visibly falling here in G'ville, bro. Radar returns are showing blue over my city but so far eerily quiet in the lower levels of the atmosphere. Column is slow to saturate. Still forecast for 3 to 5" with possible isolated areas of up to 6", so we'll see.

.NEAR TERM /UNTIL 9 AM MONDAY MORNING/...
Key Messages:
- Precipitation will start off as snow everywhere, with heavy
snow expected to evolve for locales near/S of I-70 through the
evening. Travel conditions will become very difficult, if not
impossible, across much of the region through tonight.

- A transition from snow to a mix of snow, freezing
rain/drizzle, and/or sleet is expected for most spots S of
I-70 after midnight through daybreak.

- The wintry mix will transition back to snow progressively from
mid morning through early afternoon, with greatest
coverage/intensity of snow Monday morning through late
afternoon expected from the Tri- State eastward through the
lower Scioto Valley.

- Snow totals of 6-10 inches are expected for a large swath of
the ILN FA, particularly between I-70 through N KY. Freezing
rain/ice accretions will be greatest near/S of the Ohio River,
with 0.1" to 0.3" ice possible from Carroll/Owen Co KY to
Lewis Co KY and Scioto Co OH.

- Gusty NNE winds around 30-35 MPH early Monday will create some
instances of blowing snow and low visibilities, even in
lighter snow rates.

The details: WAA-induced banded snow continues to expand from our
SW, with strong H8 frontogenesis developing across the mid MS Rvr
Vly and SW OH Vly. While pcpn tries to expand to the NE into the
local area, LL sfc flow is quite dry (dewpoints in the lower teens)
and with winds out of the NE, the dry air will be somewhat difficult
to rapidly erode on the leading edge through mid afternoon into WC
through central OH. In fact, it is this dry air in the lowest
several thousand feet which may delay onset of steadier snow N of I-
70 into early evening. Through mid afternoon, the steadiest/heaviest
snow will align from SE IN through far srn OH through most of n-
cntrl into NE KY, where accumulations through 22z will be on the
order of 3-5" within this corridor. Further to the N, from Franklin
Co IN through Ross Co OH, amounts through 22z will generally be on
the order of 2-3," with closer 1-2" near I-70.

For this evening, 22z-06z, the heaviest snow is expected to evolve
for most of the area. We are already seeing the early stages of
development of this surge of moisture on composite radar coming NE
through S IL and SW IN, which will expand to the NE into our area
during this time frame. There is quite a bit of concern,
particularly in N KY, EC/SE IN, and the Tri-State area extending
into SW OH and the Miami Valley, for a period of very heavy snow
(hourly rates >=1") within the 22z-06z time frame. This potential is
shown well via the HREF snow band prob tracker data set,
suggesting a pivoting band of 1"-1.5" hourly snow rates from SE
IN through south- central OH between 22z-06z. During this time
(especially from 00z through 04z), there should still be
tremendous overlap of deep-layer moisture and strong lift within
the DGZ, supporting a thumper of a snow band in the 2/3 of the
area prior to 06z. This will likely create very difficult, if
not impossible, travel conditions for this evening near/S of
I-70, with lighter rates/amounts favored N of I-70 through 06z.
It is within this window that locales in the Tri-State into N KY
and SC OH will receive the /bulk/ of their snow for this event,
with many locales receiving in excess of 6" by 06z.

As we progress into the 06z-14z time frame, the thumper of a snow
band should continue to pivot to the NE, aligning closer to/N of I-
70 and becoming more elongated from W-E, with the heaviest snow from
WC through central OH getting going near/after around midnight. The
time period for heaviest snow rates from WC through central OH is
likely to be within the early part of the 06z-14z time frame Monday
before lighter rates evolve after 09z as the band stretches out from
W-E. Further to the SW, for the Tri-State area and N KY to just S of
I-70, there is a /strong/ signal for an abrupt loss of moisture
within the DGZ near/after 06z, suggesting that we will lose ice
nucleation and the ptype will transition to mainly freezing drizzle
and/or light FZRA/IP near/after midnight. This is an aside from
whether the profile (H7-H8 layer) actually goes above freezing,
which still seems probable for locales S of the OH Rvr. But... even
N of the OH Rvr from EC/SE IN through SW/SC OH, the loss of moisture
in the DGZ will be the primary contributing factor for a decrease in
SN coverage/intensity by/past 06z, with latest data suggesting that
there may not be much snow (if any at all) S of I-70 beginning
around 06z through at least 14z Monday, even in a completely
freezing/subfreezing profile. A prolonged period of freezing drizzle
or patchy light FZRA/IP is likely in these areas between 06z-14z,
likely persisting through 15z for locales E of I-75 before better
moisture attempts to filter back in from the W within the
deformation axis past 15z. Quite frankly, the prospect of having
light freezing rain/drizzle with sfc air temps ranging from 20-26F
is concerning, with light rates supporting efficient accretion
through a solid 6-10 hour time frame. There is the possibility that
the near-sfc (i.e. sfc to about 775mb) profile is cold enough/deep
enough that IP may end up being the predominant mixed ptype, which
would be the better scenario from an impacts perspective. This being
said, as of right now, we are expecting the highest ice
accumulations to generally still be S of the OH Rvr, particularly
from Carroll to Lewis Co KY (and points further S) where several
tenths of an inch of ice are possible. This, with a tightening
pressure gradient and increasing winds to 30-35 MPH toward daybreak
and beyond, lends itself to a situation that will become
increasingly favorable for some isolated to scattered tree damage
and power outages near/S of the OH Rvr.

&&

.SHORT TERM /9 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
After about 14z Monday, as the sfc low pulls E of the region, a
deformation axis of snow should pivot back in from the W into the
local area. This should yield some additional (lighter) snow
accumulations from mid morning through mid afternoon before the snow
tapers off from W to E past 21z. Snow amounts after 14z Monday
should generally range from 1-3" area-wide (highest amounts of 2-3"
favored S of I-70), on top of what fell prior to daybreak Monday,
which will likely be 6+" for many spots S of I-70. Regardless of
whether it will be lightly snowing (N of I-70) or lightly
FZRA/freezing drizzle or IP (near/S of I-70) at 12z Monday, the
morning commute will be significantly impacted for the entirety of
the region.

The latest data suggests a corridor between I-70 and N KY where snow
amounts on the order of 5-10+ inches is expected. A foot of snow is
not out of the realm of possibilities for a few spots within this
corridor. There is high confidence in a /very/ sharp gradient
on the nrn fringe N of I-70, with snow accumulations likely to
vary by several inches across only a 20-30 mile N-S distance on
the nrn edge. This should set up in the vicinity of an axis from
Darke Co OH to Licking Co OH, where 3-6" is expected (higher
amounts favored in southern parts of respective counties).
Further to the N in WC OH, even lighter amounts of generally
1-3" are favored from Mercer Co OH to Hardin Co OH.

NE winds will gradually increase tonight to 15-20kts, with gusts
close to 25kts, evolving during the day Monday as the low pressure
begins to pull to the E. Should significant ice amounts on the order
of one quarter of an inch or greater accumulate in N KY or far SC
OH, the gustiness during the day Monday will only exacerbate
potential power outage concerns. So this portion of the forecast
will be monitored closely.

Drier/cold conditions are expected Monday night, with temperatures
dipping into the upper single digits to mid teens, depending on
exactly how much (or little) we are able to clear out. However,
mostly cloudy conditions are expected for the overnight, so it won`t
be ideal radiational cooling conditions, despite the fresh/deep
snowpack.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As low pressure pulls well off to the east, we will continue to see
a cold northwesterly flow through the middle of the week. Initially,
some weak surface ridging across the Ohio River will allow westerly
flow and some breaks in the clouds to start the period on Tuesday.
However, another disturbance rotates through the Great Lakes on
Wednesday. This will bring cloud cover and a chance of light snow,
especially across the north (downwind of Lake Michigan).

After a 30-45 minute lull in the action larger flakes are starting to mix back in here in the Eastgate area.

BTW where is Woolyworm? I haven't seen an update from the woodpile.

Heavy snow here - I’d say we are in the 2-3” range so far. Traffic cams in Troy which is just north of Dayton show zero snow thus far. Amazing cutoff in the snowfall so far.

Yes a nice 30 minute break before we get to the main course. The appetizer was nice but been waiting all day for the main course. I hear the dessert on Monday is to die for as well. Time to head upstairs to grab a bite and then head back down to the weather center for a wonderful evening and yes a nice football game tonight. Denver is going to kill the Chiefs and just watching the first few minutes and you can tell the difference between your stars and the secondary players on KC. Les will be rooting for the Lions and hopefully this would help folks get a little healthier

Counties bordering the river will again see the heaviest qpf with this next round

Stopped again in Middletown…

cloudy72 wrote: ↑Sun Jan 05, 2025 4:47 pm Heavy snow here - I’d say we are in the 2-3” range so far. Traffic cams in Troy which is just north of Dayton show zero snow thus far. Amazing cutoff in the snowfall so far.

ILN is still saying 4 to 6" for Darke Co., but I'm starting to wonder if that range is being overdone now. I'm starting to wonder if just 1 to 3" with isolated 4" amounts at most here in my region, just anything more than a mere coating lol.

MVWxObserver wrote: ↑Sun Jan 05, 2025 4:58 pm

cloudy72 wrote: ↑Sun Jan 05, 2025 4:47 pm Heavy snow here - I’d say we are in the 2-3” range so far. Traffic cams in Troy which is just north of Dayton show zero snow thus far. Amazing cutoff in the snowfall so far.

ILN is still saying 4 to 6" for Darke Co., but I'm starting to wonder if that range is being overdone now. I'm starting to wonder if just 1 to 3" with isolated 4" amounts at most here in my region, just anything more than a mere coating lol.

I understand your concern. I will say that from the ILN discussion and the looks of the radar I believe you should fill in quite nicely. It will just take a little patience. Check out the Indy radar. That heavy band developing has eyes for Darke county and I-70.

I’m in the donut hole now! Lol

Les, it stopped almost completely here about 20 min ago. Very quiet. But expecting the main course to arrive in a bit! Fingers crossed!

With that band in Southern Indiana moving into the area travel is going to be very difficult later this evening. If you have plans to be out and about this evening you may want to change them anywhere from northern Kentucky to I-70.

dce wrote: ↑Sun Jan 05, 2025 5:09 pm

MVWxObserver wrote: ↑Sun Jan 05, 2025 4:58 pm

cloudy72 wrote: ↑Sun Jan 05, 2025 4:47 pm Heavy snow here - I’d say we are in the 2-3” range so far. Traffic cams in Troy which is just north of Dayton show zero snow thus far. Amazing cutoff in the snowfall so far.

ILN is still saying 4 to 6" for Darke Co., but I'm starting to wonder if that range is being overdone now. I'm starting to wonder if just 1 to 3" with isolated 4" amounts at most here in my region, just anything more than a mere coating lol.

I understand your concern. I will say that from the ILN discussion and the looks of the radar I believe you should fill in quite nicely. It will just take a little patience. Check out the Indy radar. That heavy band developing has eyes for Darke county and I-70.

I hear ya, bro!

Kennyaker wrote: ↑Sun Jan 05, 2025 5:11 pm I’m in the donut hole now! Lol

I love donuts

Snowing hard here now.

Sleet here in Oakbrook. Noticed the radar looked good over us but no flakes. Can hear the sleet hitting the ground. If this stays sleet our totals bust way low IMO, we need the next 4 hours to be heavy snow.

Sleet mixing in here now

Ouch , when is next storm lol

Right now I think the snow line is somewhere near Middletown. Still scanning traffic cams to see if this is true.

Switched back to snow here, I still hear some sleet but it's mostly snow and pretty heavy. whew. Cancel the cancel until cancelled again.

markalot wrote: ↑Sun Jan 05, 2025 5:58 pm Switched back to snow here, I still hear some sleet but it's mostly snow and pretty heavy. whew. Cancel the cancel until cancelled again.

Nice to hear!!! I’m rooting for you guys!

It looks like snow in Cincy now too! I’m not ever sure it switched from snow to sleet I’m just looking at traffic cams

I'm going by sound, snow is silent, if you can hear it then sleet is mixing in. Some mixing was kind of expected but no model, not a single one, predicts sleet until 9:30-10pm timeframe.

Still snowing in Oxford, no change over