3/13 - 3/14 Midwest/Lakes Snow System

[jaster220]

SWMI - the lameness of all things synoptic continues. Some models hardly show anything while a couple are decent. I highly doubt GRR gives any headlines due to long duration

[Tom]

So is it 3 to 6 inch event from Sunday night to Monday evening, and then the lake kicks in for the Chicago area?

Yup, I could see additional 3-6" from the lake. Let's see if the signal stays put.

[Madtown]

Hope it happens for you guys by the lake....so hard for events like that to play out on this side of the lake. I remember 1 in the 25 years I lived over there. It was during a packer 49 wild card game around 95 I believe. A one degree change in wind direction and it's game over.

[Niko]

00z NAM came west. Amounts are being adjusted with the EC storm. More of an inland hit now instead of the coast.

[gosaints]

00z NAM came west. Amounts are being adjusted with the EC storm. More of an inland hit now instead of the coast.

The nam at 60 hours on a coastal... Good luck

[Tom]

Wow, RPM paints 6-9" for N IL...8.5" for ORD thru 7pm Tuesday. Widespread 6-8" across all of N IL. It pivots just right and it looks like it doesn't weaken as much as it heads east.

[Tom]

Most of N & E IA do very well also. Couldn't tell what Wisco and MN looked like. NW IN had 6"+ as well.

[Tom]

00z GFS...

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031200/078/snku_acc.us_mw.png

[Tom]

The last time I saw model runs on the GFS showing the lake plume reaching down towards Kankakee, IL it turned out to be a fun band...

 

http://www.tropicaltidbits.com/analysis/models/gfs/2017031200/gfs_mslp_pcpn_frzn_ncus_10.png

 

 

http://www.tropicaltidbits.com/analysis/models/gfs/2017031200/gfs_mslp_pcpn_frzn_ncus_11.png

 

 

Surface temps just outside of the convergence band in the single digits will fuel this thing if it goes to its full potential...

 

http://www.tropicaltidbits.com/analysis/models/gfs/2017031200/gfs_T2m_ncus_11.png

[Tom]

Total qpf...0.7 right near Mt. Geo's place...that could easily fluff up to 10"+

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031200/078/qpf_acc.us_mw.png

[Tom]

00z GGEM...little more generous with 0.5" qpf...

 

http://www.tropicaltidbits.com/analysis/models/gem/2017031200/gem_apcpn_ncus_14.png

[Niko]

SEMI right now looking good for 4-7" snowfall.

[Niko]

The nam at 60 hours on a coastal... Good luck

There is a sharp line between nothing to 12"+, to no snow, rain and or a blizzard. Track is very crucial. Expect changes in the forecast.

[Niko]

00z NAM gives SMI near 8". Wow.

[james1976]

DMX concerned about first wave:

Snow will spread across the area on Sunday afternoon and

evening, persisting through the night before ending on Monday.

Moderate to heavy accumulations are expected. Some uncertainty

does remain with this storm. There will be an initial push of

moderate to even heavy snow from mid afternoon to mid evening.

Lighter snow will then persist through the remainder of the night.

Should snow amounts with the initial surge be lighter than

expected, snow amounts would be lighter than current forecasts.

[Tom]

00z RGEM...thru 6:00pm Monday...

 

http://www.tropicaltidbits.com/analysis/models/rgem/2017031200/rgem_apcpn_ncus_16.png

 

 

http://www.tropicaltidbits.com/analysis/models/rgem/2017031200/rgem_asnow_ncus_16.png

[Snoorani]

How does euro looks?

[GDR]

Bag full of crap

[WBadgersW]

Last nights GEM really likes the lehs potential in MKE

[Tom]

06z NAM...

 

 

http://maps1.pivotalweather.com/maps/models/nam/2017031206/060/snku_acc.us_mw.png

 

 

06z GFS...

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031206/060/snku_acc.us_mw.png

[Tom]

RPM model really develops the lake plume Tuesday morning and wobbles back and forth thru Tuesday night as it swings into NW IN Wed.  Targets Lake/Cook/Dupage counties.  Local met is forecasting additional 1-5" from Lake Effect.  Makes sense if the intense lake plume develops.  Saying isolated spots may hit 10".

[Tom]

06z NAM-4km...

 

http://www.tropicaltidbits.com/analysis/models/nam4km/2017031206/nam4km_apcpn_ncus_20.png

 

 

http://www.tropicaltidbits.com/analysis/models/nam4km/2017031206/nam4km_asnow_ncus_21.png

[Tom]

06z NAM 3km...a little higher resolution showing a lake band pounding MKE just around 6:00am Monday...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_mslp_pcpn_frzn_ncus_31.png

 

 

 

Individual lake bands begin hitting NE IL around 6:00mpm Monday...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_mslp_pcpn_frzn_ncus_41.png

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_mslp_pcpn_frzn_ncus_50.png

 

 

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_mslp_pcpn_frzn_ncus_56.png

 

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_mslp_pcpn_frzn_ncus_57.png

 

 

Tuesday morning rush hour will be interesting in Chicago...a blip of 1.00"qpf over in E Cook near downtown Chicago...this is very difficult to pin down but suggesting a very intense band.

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031206/nam3km_apcpn_ncus_20.png

[Money]

12z nam coming in south/drier 

 

http://maps1.pivotalweather.com/maps/models/nam/2017031212/030/snku_acc.us_mw.png

[WBadgersW]

Repeat of the 10th/11th "storm"? Seems like the trend has been drier

[Tom]

Reports of Heavy Snow falling in the blossoming shield of snow near Aberdeen, SD...

[Tom]

@ IndianaJohn and posters in Lake/Porter county, looks like the lake plume pounds your area around 10:00pm Tuesday.  It pushes very far inland according to the RPM.  This model handles lake snows and synoptic systems very well inside 48 hours.

[Tom]

12z NAM 3km looking good for LES up in MKE area and Chicago...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031212/nam3km_mslp_pcpn_frzn_ncus_28.png

 

 

 

The band up near MKE may push very far inland...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031212/nam3km_mslp_pcpn_frzn_ncus_30.png

 

 

 

Monday night...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031212/nam3km_mslp_pcpn_frzn_ncus_36.png

 

 

This higher-rez model is really puking snow in SE WI near Racine/Kenosha Tuesday morning...McHenry county may be in the action Tuesday morning...

 

http://www.tropicaltidbits.com/analysis/models/nam3km/2017031212/nam3km_apcpn_ncus_18.png

 

 

I've been thinking, if the models continue to show this trend tomorrow, local MKK/LOT offices may issue some sort of Lake Effect advisory/warning for lakeside counties.

[Tom]

LOT's take on the LES potential and possible headlines:

 

 

 

Several important pieces of the puzzle are coming
together to support our first organized lake effect snow event of
the season. This process will allow some very cold air to return
to the region, and will create steep low level lapse rates due to
the relatively "warm" lake. 850 Temp to lake surface temperature
differences are about 15 to 18 C, which is pretty decent. These
steep lapse rates appear to extend over a deep moist low level
layer. Lake induced CAPE values reach in excess of 500 J/KG and
equilibrium levels up to 10000 ft or so are also strongly
indicative of the potential for effective snow producers. With the
strong high to our northwest and a nor`easter low, this is a
favorable synoptic setup for our area for the development of lake
effect snow into Illinois and for the possibility of a convergent
band.

The complicating factor is that these situations are highly
contigent on the development of a stronger single band for the
higher impacts, and this is highly contigent not only on the
development of a low level convergent axis, but how long that axis
lingers in one area. The GFS/GEM depict a strong convergent axis
pointed into northeast Illinois for an extended period of time.
If this were to occur in conjunction with the increasingly
favorable thermodynamic environment, some heavy snow showers would
be expected. The EC does too but is more transient. What
decreases confidence is that the NAM is more progressive with this
convergent axis and does not linger it as long, but has several
transient periods of synoptic/lake enhancement Monday night and
again Tuesday afternoon in Illinois, but has the convergent axis
focused a bit farther east more into southern Cook county
eastward into Indiana. The 6z NAM is not that impressive either.

Confidence and Headlines: We feel confident there will be lake
effect snows regardless of how long they last, but certainly
impacts hazard decisions. These situations are challenging, even
at a shorter distance, but a signal is there for a potentially
significant event if things come together. The lake effect will
also shift into Northwest Indiana where conditions remain
favorable for at least occasional snow showers through the day
Wednesday, possibly significant as well. It is possible we will
need to handle this event with a separate headline. We do taper
the advisory towards Livingston county the earliest once rates
ease and temperatures become marginal, hold onto areas away from
the core Chicago metro through the day, with the highest impacts
on the earlier side. Finally, we have not changed the end time of
the lake adjacent counties yet (late Monday evening) as this will
be the time synoptic snows ease in Indiana, while lake effect
processes begin to ramp up in WI and NE IL. Did not have high
enough confidence to do a lake effect snow/winter storm watch for
lake effect snow in NE IL just yet, though it is conceivable one
could be issued as we get closer. And for Indiana, it as mentioned
earlier significant snows could fall there from lake effect but
the time window is more Tuesday into Wednesday. It is also
possible that the advisory could be extended for a transient but
potent band of snow (note: Milwaukee has their advisory for the
whole event to cover both the synoptic and lake effect). We have
chosen to not run out a long drawn out advisory at this point as
there could be a break, and due to the higher impact potential of
round two.

 

[Snoorani]

Tom is nam an outlier croz is not showing as much as other models are

[Tom]

Tom is nam an outlier croz is not showing as much as other models are

Seems like it...lets see the rest of the 12z suite...I like paying attn to the higher rez models at this stage...

 

 

06z RGEM...thru 1:00am Tuesday...

 

http://www.tropicaltidbits.com/analysis/models/rgem/2017031206/rgem_apcpn_ncus_16.png

[Tom]

The 00z WRF had a broad band of heavy snow from S MN/N IA/S WI into N IL...

 

http://www.tropicaltidbits.com/analysis/models/wrf-nmm/2017031200/wrf-nmm_apcpn_ncus_48.png

[WBadgersW]

Still snowing in MKE, Kenosha, and Racine..

[Tom]

Still snowing in MKE, Kenosha, and Racine..qpf_acc.us_mw (1).png

D**n, that looks good!  Looks very similar to the high rez NAM...

[Tom]

The Lake Effect part of this system may be the "highlight" of the season for MKE/ORD locations...sadly, but I guess not if you enjoy the snow....

[Tom]

Latest HRRR thru 3:00am tonight...

 

http://www.tropicaltidbits.com/analysis/models/hrrr/2017031214/hrrr_apcpn_ncus_18.png

 

Temps in the low 20's should boost those snow ratios up...

 

http://www.tropicaltidbits.com/analysis/models/hrrr/2017031214/hrrr_T2m_ncus_19.png

 

 

Those just to the north of the low where the best spin in the atmosphere will get the best synoptic snows...

 

http://www.tropicaltidbits.com/analysis/models/hrrr/2017031214/hrrr_ref_frzn_ncus_18.png

[Money]

GFS:

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031212/039/snku_acc.us_mw.png

[Money]

LE doing work in MKE/Chicago after that:

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031212/054/snku_acc.us_mw.png

 

 

http://maps1.pivotalweather.com/maps/models/gfs/2017031212/054/qpf_012h.us_mw.png

[Money]

GEM:

 

http://maps3.pivotalweather.com/maps/models/ggem/2017031212/060/snku_acc.us_mw.png

[Niko]

I am thinking an advisory should be issued for my area this afternoon. I am forecasted for 3-6"+. Surprised they have not issued anything yet.