1/11 - 1/12 Southern Midwest Snowstorm

[Grizzcoat]

06Z NAM fwiw-

[Grizzcoat]

Fwiw- I believe Instant Weather Maps (IWXM) snow maps are far more accurate than those on TT or PW. IWXM redid their snow algorithms this past DEC and even beforehand, they have seemed over the years to be more accurate even though IWXM claims they used to use the Kuchera. - hence- the differences you see. You can read about the changes here ---  

 

https://twitter.com/IWXM

[Grizzcoat]

DMX with one of their better AFD's this morning. Imagine that. Will not post the entire AFD, but they mention better phasing and NW trend.

 

By Friday morning a 500 mb trough will be moving slowly eastward
off the Rockies, and subsequently this trough will progress across
the central U.S. with its axis crossing Iowa around Saturday. It
appears several shortwave impulses will initially move through and
into the larger trough, slowly phasing into a more consolidated
system just after it passes our area, in the latter half of the
weekend. However, these solutions have changed since last night
and the phasing is a bit better/faster than it had been.

 

With the somewhat
better phasing of the 500 mb trough in recent model solutions, it
appears more likely that we will see fairly significant moisture
advection into this region, and that it will curl a bit further
northwestward compared to previous solutions.

[Grizzcoat]

From DVN AFD-

 

Friday night and Saturday: Models similar in depicting low pressure
developing in eastern TX and then tracking to northern MS, with an
inverted trof extending northward to eastern IA. Isentropic
lift/upglide in this cold air on se winds into the cold air should
allow snow to develop over much of the cwa Friday evening,
continuing overnight and into Saturday. Latest model runs are coming
in wetter and also offering more dynamics as a h5 low deepens. Gulf
moisture will also continue to be pushed northward and forecast
soundings indicate moisture/forcing in the dendritic growth zone.
The wet bulb zero height is also below 0c so much of this event will
be in the form of snow, at times moderate to possibly locally heavy.
This is now looking to be at least a solid advisory criteria
snowfall in the 1-4 inch range, possibly higher in our far southern
counties. With the inverted trof in our area at least the winds will
be rather light. While it is too soon for any headlines,
weekend travelers should continue to monitor the latest forecasts.

[Grizzcoat]

LOT with a great write up. one of the best I've read in a long time--

 

Fairly complex set-up looks to bring accumulating snow to most, if
not all, of the CWA. Longwave trough currently digging south into
the Great Lakes and new England region will begin to lift out
Friday into Saturday. Meanwhile, a not terribly strong, but full
latitude trough extending from northern Mexico north into Canada
with both northern and southern stream shortwave components is
progged to move bodily eastward into the Great Plains Friday. To
varying degrees, guidance is decent agreement in consolidating
this wave into a more coherent system across the central and/or
southern Plains into the lower and middle Mississippi Valley
region Friday night into Saturday.

The forecast track of the surface low and 500mb vort max would
generally result in minimal threat of accumulating snow as far
north as northern IL, with even our southern CWA being out of
range of accumulating snow with a typical system depending on the
model forecast track you look at. The latest ECMWF and NAM are
farther north with the 500mb vort max, while the GFS and GEM are
farther south. All the models maintain weak troughiness and some
degree of interaction between this system and the departing
northern stream long wave trough that will be exiting the region.

What appears to be driving the precipitation over northern IL that
the majority of models are producing looks to be driven more by
jet dynamics. Models depict building heights with some downstream
ridging in advance of the trough moving out of the Plains. These
building heights result in a tightening of the geopotential height
gradient on the southern flank of the departing long wave trough,
resulting in a strengthening upper level jet (130kt+ at 250mb)
over the Great Lakes Friday night into Saturday. Strengthening
upper level divergence in the entrance region of this jet appears
to be one of the driving factors in the QPF the models produce in
our area.

While the exact evolution of the developing trough is low
confidence, the idea of downstream ridging aiding in the
development of a jet streak over the region seems pretty likely.
The categorical PoP from the blended model solution look right on
target. Overall the large scale forcing over the area doesn't look
terribly impressive and precipitation will initially be battling
dry low levels that will require top-down saturation. On the
synoptic scale, really would appear that we are in for a about a
12 hour period of modest forcing, likely sufficient to support
mostly light snow over the area. Currently looks like around an
inch over snow (+/- 0.5") is likely north of I-80.

Farther south across the southern CWA the forecast confidence is
lower. The potential closer proximity to a farther north tracking
system does raise the specter of potentially more meaningful
snowfall totals (like depicted in the 00Z NAM and EC). For now,
at this distance with models still struggling to resolve the
complex interaction of features, so no reason to deviate from the
blended model solution which would favor 1-3" of snow south.
However, it is strongly advisable that everyone in area keep an
eye on later forecasts as non-trivial changes in model forecasts
could still occur and result in changes (up or down) in these very
preliminary forecast snowfall amounts.

[Grizzcoat]

06Z GFS = weak sauce and S. Not even worth a map upload. Hoping that it's bad like the article I posted yday says it is.

[Tom]

Last night's Euro certainly spreads the wealth farther west and north this run and would even make NE peeps happy.  The 00z EPS snow mean has also shifted NW and N quite a bit over the last 3 runs. This is getting pretty interesting for many folks on here and hope trends continue.

 

SREF's through Noon on Saturday....FWIW, the snow shield looks very similar to the 00z Euro from last night and spread the wealth farther west and north.

 

http://mag.ncep.noaa.gov/data/sref/03/sref_namer_087_snow_total_sprd.gif

[Clinton]

Hope the trend continues, I'm starting to feel confident about a 5 in or more snow and in my area thats a very good storm.

[Tom]

Took a glance at the EPS members and many of them were decent hits for members in the KC area, SE NE, IA, IL, IN and even into S MI.  Even the last couple runs off the FV3 have trended farther NW and N with the snow shield.

 

00z FV3...

 

[Tom]

Hope the trend continues, I'm starting to feel confident about a 5 in or more snow and in my area thats a very good storm.

IMHO, I think your in a good spot to see a Winter Storm Warning and your 2nd 5"+ storm of the season.  There are some big hits for MO off the EPS members and GEFS ensembles.  The trend this season has been for juicier systems and we know how this system has trended over the past few days from "zilch" to now possibly a widespread snow system.  I might have to change the Title and include the Plains peeps!

[Clinton]

Took a glance at the EPS members and many of them were decent hits for members in the KC area, SE NE, IA, IL, IN and even into S MI.  Even the last couple runs off the FV3 have trended farther NW and N with the snow shield.

 

00z FV3...

 

That would be fantastic, temps will be critical as pertains to ratios.  I am hoping for 8:1 or better.

[Tom]

That would be fantastic, temps will be critical as pertains to ratios.  I am hoping for 8:1 or better.

I'll be honest, I think if this system lays down a wetter snow for your area it bodes well for the snow to survive some of the warmer days ahead next week before the cold really locks in.  

[Clinton]

That's true and I have a few mid 40s in the forecast for next week.

[Grizzcoat]

12Z NAM (the 3KM NAM apppears S of the 12KMNAM at HR 60.

 

[Minny_Weather]

I'm punting. Any appreciable amounts look like they will be below the state line. I'm not counting on a drastic change. Congrats KC.

[Grizzcoat]

GFS appears to be  S and weak and IS a dud for many. 

[bud2380]

GFS is very weak, NAM shifted south on the northern edge from the 6z run.  Looking at the black and white maps on the canadian, it also looks pretty weak in Iowa.  

[Grizzcoat]

Yep CMC definetly cut back totals in IA (actually nearly everywhere) and further S and more progressive. Overall trends this morning are not like they were 12 hours ago. 

[GDR]

Yeah another bla on to the next

[Grizzcoat]

Ukie maybe a tad N from 00Z-- but it's hard to tell without any posting precip maps past 72 hours from last night. But it definetly better than the GFS and CMC at HR 72 for S.IA. Don't ever under estimate Uncle Ukie at this range-- it's 2nd only to the EURO at this time range. 

 

[Tom]

On my phone and the 12z Euro looks amazing for a lot of posters.

[Tom]

IA into N IL certainly still in the game with a plowable system...looks like 2-6” across S and SE IA into N IL.

[Grizzcoat]

On my phone and the 12z Euro looks amazing for a lot of posters.

Yep. Still tough for me tell- but it looks like even CHI town gets into the mix.  Way different than GFS and CMC - that is for sure. Will post a map ASAP

[Tom]

Yep. Still tough for me tell- but it looks like even CHI town gets into the mix. Way different than GFS and CMC - that is for sure. Will post a map ASAP

This run is even stronger/juicier and more widespread than previous 00z run.

[Grizzcoat]

12Z even further N than 00Z-- and that is saying something. 

[Hawkeye]

So, the euro is going north while the others are going south.  

[Grizzcoat]

Euro- 

[hlcater]

ecmwfued_rapid-null--usnc_ll-96-C-kucheratot_whitecounty.pngEuro- 

Oh I like that run.

[hlcater]

This run is even stronger/juicier and more widespread than previous 00z run.

Looks more phased to me??

[Grizzcoat]

Looks more phased to me??

Like what many AFD's said this AM. Perosnally I think the GFS is out to lunch and this without bias. The UKIE somewhat with EURO- both drastically different than GFS / CMC .  

[Hawkeye]

I won't get more excited until the models agree.  If the euro shifts back south a couple counties, Cedar Rapids drops off quite a bit.

[Tom]

Even S WI scores a couple inches off the Euro and our S MI peeps. STL crush job....

[bud2380]

That was an awesome run on the Euro.  It's been wrong everytime this year for my area, so we're bound to finally get one right!

[Clinton]

Even S WI scores a couple inches off the Euro and our S MI peeps. STL crush job....

6-7in for me I'll take it.

[Grizzcoat]

If this storm comes to fruition- and that seems likely. I must give some credenace to the LRC posted on here by Tom and others. This seems to be very similar to the snow event in late NOV. Regardless of track- I'am impressed. Been in the weather field professionally for 20 years and I recently thought the LRC by Lexak was a joke. Maybe not so. The weather is nearly infintie in it's possibilites. I will look into the LRC more deeply- esp if this transpires.

[Clinton]

If this storm comes to fruition- and that seems likely. I must give some credenace to the LRC posted on here by Tom and others. This seems to be very similar to the snow event in late NOV. Regardless of track- I'am impressed. Been in the weather field professionally for 20 years and I recently thought the LRC by Lexak was a joke. Maybe not so. The weather is nearly infintie in it's possibilites. I will look into the LRC more deeply- esp if this transpires.

Living in the KC area I have learned to lean on it.  I have seen many of its successes and even a few failures.  It is not easy to grasp fully, but it is by far the best long range forecasting tool I have seen.

[FV-Mike]

Nice Euro run

[Tom]

I like the shift N on the 12z EPS 2” snow mean across N IL and SW MI. Def nice trends on the Euro. IA peeps look good into the KC/MO region. SE NE may even get something out of this.

[james1976]

Man that is a widespread 6+.

I'd lean toward the Euro. Not cuz it's the best looking run but cuz it's been the most consistent. I bet the offices will lean toward the Euro. Should be some good AFD's.

[Hawkeye]

FV3-GFS drifting south like the regular GFS, CR gets little.