Chris's Corner - Could This Be the First 1"+ Snow of Season?

3-6" an hour rates in that death band over and east of Boston..been there for a few hours now. Nuts.

yeah doesnt look like much change from last night...good stuff...how much qpf?

Looks like a small uptick compared to last nights run 

I don’t know about you guys, but reading through American wx just makes me want this storm to play out even worse.

Wow that’s heavier than I thought the NBM would have at this point in the forecast. I like that we’re in the middle of most models. This will allow for any changes that may occur. The last few storms, we were on such a razor thin line of change over or snow that didn’t work out that well.

GEM ensemble mean is 2”+ area wide QPF.

2011 and 1982 are in the CIPS analog list. In fact for HR108 they are #1 and #2.

.LONG TERM... (Monday through Next Saturday)
Issued at 159 PM CST Sat Jan 29 2022

Key Messages:

1. An impactful winter storm is forecast to move through the mid-
Mississippi Valley Tuesday-Thursday, producing snow and wintry
mix across the forecast area.

2. Uncertainty remains in where the transition zone between snow,
wintry mix, and rain will occur, resulting in uncertainty in storm
total amounts of snow and ice.

On Monday a shortwave trough will begin to pass through the
northwesterly mid-level flow currently over the central CONUS,
flattening the ridge over the western CONUS and shifting the region
into a more zonal flow. Southerly low-level flow and subsequently
WAA ahead of an approaching low will push Monday`s high temperatures
above normal for late January. It will surely be the nicest day of
the week. The axis of the mid-level shortwave will move across the
US-Canada border during the day Tuesday, while at the surface a low
will track across the same region, dragging a cold front through the
mid-Mississippi Valley during the day Tuesday. Precipitation is
expected ahead of and along the front as it drops into the region,
initially falling as rain as the front pushes into seasonally warm
low-level air. Cold air will move into the region behind the front
and begin to cool area near to below freezing. The cold front is
expected to stall just south of our CWA Tuesday night, draped across
central Arkansas, the Missouri Bootheel, into the Ohio River Valley.

A mid-level trough will come onshore Tuesday and as it swings
through the western CONUS, will throw the mid-Mississippi Valley
into robust southwesterly flow. Warm air advection and isentropic
ascent will overrun the stalled front Tuesday night renewing
precipitation across the region. Uncertainty remains in what type of
precipitation will make it to the ground Tuesday night through
Wednesday, and it depends largely on the depth and robustness of
the cold air behind the front. While areas near the Missouri-Iowa
border are most likely to see snow begin to fall overnight
Tuesday, a period of mixed wintry precipitation is expected
overnight Tuesday into Wednesday as the 850mb temperature cools
below freezing slower than the surface temperature across the
bottom 2/3rds of the forecast area. Surfaces temperatures are
still uncertain at this moment as well. A 10 degree temperature
spread between the 25/75th percentiles still evident, though more
members are showing temperatures closer to freezing and trends
have been cooling over the past couple of cycles. As temperatures
in the lowest levels of the atmosphere come into greater focus in
the next couple of days, so too will precipitation types and
totals.

The mid-level trough will swing through the region Thursday,
mirrored by a surface low moving through the lower to mid
Mississippi Valley. The movement of the low will add another
complication into the mix for this mid-week event. Guidance is
indicating the low will track northeastward along the stalled front,
bringing a more robust surge of sub-freezing air and the potential
for enhanced lift for snow to the forecast area. The exact track,
strength, and speed of the low will impact how much snow falls and
where on Thursday. Confidence is high that once the low moves into
the region and low level temperatures drop below freezing, that all
precipitation that falls in our CWA will fall as snow. Guidance
remains in agreement that the low will push out of the region
Thursday in concert with the northeastward lifting mid-level trough,
but the timing of the system and precipitation exit is still
uncertain and has shifted in recent model runs. Cold temperatures
will linger through the end of the work week behind this system,
aided by high pressure and northwesterly flow at the surface.

Bottom line: An impactful winter storm is expected across CWA
between Tuesday and Thursday. Uncertainty remains in how quickly sub-
freezing air will push into the entire CWA, and the track and speed
of the low. All of this will influence precipitation type and
amounts, which currently continue to vary.

Nam finally getting into range with the 18z run.

It is clearly in the cold/south camp at hour 84.

Extrapolation from there suggests a monster snow for the metro.