Nov 28-30th Post Turkey Day Wintry Potential

[michsnowfreak]

3-6" seems like a good call for Detroit.

[Chambana]

4.6” final call. Chicagoland looks locked and loaded for a solid 6-9” event

[michsnowfreak]

1 hour ago, AWMT30 said:

Solid start to the models today! A nice Chicago to Detroit sweeping Winter Storm with 6-10" 

Chicago saw under 20 last winter. I dont mind that they'll get more than us this storm. Regardless looks like a widespread advisory to warning criteria snowstorm. Thats on top of the early November 9-10 snowfall and cold as far as the eye can see...excellent start to winter!

[fluoronium]

I've never used the RRFS for snow before but it's interesting to see it hinting at thundersnow.

I have noticed that the lightning algorithm on the HRRR has been completely worthless for predicting thundersnow (or at least the algorithm CoD uses)

[cyclone77]

Can't recall any other warning criteria events here when the winds were from the southeast predominately.  Gonna be kind of strange lol.

[ChiTownSnow]

Seems like the higher end totals may depend o solely on instability and thunderstorm like convection that happens locally.  

[donsutherland1]

For reference:

The 33.5 cm snowfall at Toronto on November 30, 1940 is the biggest daily snowfall on record for November. The 10.0" for Milwaukee on November 30, 1940 is the second biggest daily snowfall on record for November.

[hawkeye_wx]

The Euro is stronger/sharper with the shortwave at 500 mb than the rest of the models.  I was expecting the 12z run to fade south and weaker just a bit, but it actually ticked farther north.

Here are the resulting snow maps for the south UK, middle GFS, and north Euro.

[Radtechwxman]

4 minutes ago, hawkeye_wx said:

The Euro is stronger/sharper with the shortwave at 500 mb than the rest of the models.  I was expecting the 12z run to fade south and weaker just a bit, but it actually ticked farther north.

Yeah it definitely is. I wouldn’t want it anymore north than that. Hugs that mixing line right against me. Oof. My biggest worry is the marginal temps and ratios during day Sat. If rates are high enough it will help mitigate it somewhat but I do anticipate some level of melting and compaction. Hoping that warm nose can stay south enough to avoid a changeover. But that sfc low does get pretty north. 

[ILSNOW]

Happy Thanksgiving to all!!!!

[Baum]

1 hour ago, ILSNOW said:

Happy Thanksgiving to all!!!!

I’ve decided to withhold my reply until Saturday evening 

[Chicago Storm]

Today’s trend has been to reverse yesterday’s trend.

Yesterday’s we saw guidance come in less phased, less amped and flatter with the main wave…thus, weaker, south and drier. Today’s trend reversed all of that.

[sbnwx85]

Could cash in on lake effect bonus Sunday. 12”+ in play. 

[cyclone77]

HRRR 18z is a beautiful sight to behold.  

[Baum]

7 minutes ago, Chicago Storm said:

Today’s trend has been to reverse yesterday’s trend.

Yesterday’s we saw guidance come in less phased, less amped and flatter with the main wave…thus, weaker, south and drier. Today’s trend reversed all of that.

Hold.

[Sciascia]

4 minutes ago, cyclone77 said:

HRRR 18z is a beautiful sight to behold.  

Let’s behold it together (thru noon Saturday)

[Harry Perry]

Winter storm watch for the entire GRR CWA. Local P&C showing 8” and still snowing by Sunday. Looks like gusty winds in the 30-40 mph range, so blizzard conditions at times.
 

Still some time for the rug to get yanked but I feel pretty confident in a solid 6-10”+ throughout the sub. 

 

[andyhb]

500 mb evolution with this does remind me a good deal of a slightly less impressive version of GHD II. Trough/jet streak matures in a very similar way and the thermos aren't terribly far off from that either. More likely to taper out with eastward extent though.

[hawkeye_wx]

I would, of course, love for the 18z HRRR to be correct, but it is likely too strong and juiced.  It has a 1004 mb low, whereas the globals have a 1008-1012 mb low.  This HRRR run would probably finish with 16+" in Cedar Rapids, which I very much doubt.  Half of that is more likely.  The CAMs will probably come back to earth as the start approaches.

[Harry Perry]

1 minute ago, andyhb said:

500 mb evolution with this does remind me a good deal of a slightly less impressive version of GHD II. Trough/jet streak matures in a very similar way and the thermos aren't terribly far off from that either. More likely to taper out with eastward extent though.

Ironically enough I was going to mention this myself as well. Definitely some similarities. 

[jlauderdal]

Let’s behold it together (thru noon Saturday)

Eye candy that won't materize, GFS does this in the tropics on a regular basis. Heavy rain at my place ahead of a cold front, last rain and 80s I will see for a few days. I'm holding my 7.5 prediction for Western burbs. One more shot to adjust tomorrow.

[Chicago Storm]

500 mb evolution with this does remind me a good deal of a slightly less impressive version of GHD II. Trough/jet streak matures in a very similar way and the thermos aren't terribly far off from that either. More likely to taper out with eastward extent though.

This is a very good and valid point.

[weathafella]

Clown range 18z NAM shows a trend to have better mid levels.  That can really improve output regardless of modeled qpf (which is decent as is).

[andyhb]

6 minutes ago, Chicago Storm said:

This is a very good and valid point.

IIRC that wave had a deepening trend closer to verification as well as the PV lobe became better resolved, I remember having some back and forth with @RCNYILWX about it at the time.

The issue this time is that the upstream ridge isn't quite as amplified as that, and there's a bit more phasing required here for a higher end outcome.

[hawkeye_wx]

Can always count on the 18z NAM/3kNAM to go extra weenie.