Dec 11-13 MW/Lakes/OV snow event part 4

[The_Global_Warmer]

18Z UK going NAM and intensifying the low and tracking it farther N along the MN/IA border. MPX is going to get hit hard.

Public Enemy #1

JK

[baroclinic_instability]

that's what i suspected but you put it better.

For an even more in-depth discussion, what an ensemble is is a collection of model runs in which the initial conditions of the "control member" have been "perturbed" using a mathematical formulation which perturbs them to account for the natural limitations and errors one can expect in a data assimilation system. In other words, you are accounting for chaos as Lorenz discussed in the 60s in "Deterministic Nonperiodic Flow". An ensemble mean is good to account for trends as well as understand the amount of variability in a forecast, but they are not useful for the actual true forecast since the mean QPF blends everything together which is not realistic. Mesoscale effects such as potential banding in SREF runs are not well defined in the mean run and things such as dry slots are not shown well either.

[Hoosier]

I live in Fond du Lac. Have no idea how to add my location though.

Click the drop down menu at the top right (where your name is). Click on my profile and then on the button that says "edit my profile" (located at the right). Then fill in your location.

[Chicago WX]

I live in Fond du Lac. Have no idea how to add my location though.

Go to your profile, hit "Edit profile" and at the bottom of the next page there is a box labeled "Location". Wa la.

[baroclinic_instability]

Base on current location and pressure falls alone, looks like central iowa is more likely, but if it really cranks off here, i guess IA/MN border is still in play.

Definitely going to be interesting. When the PV Anomaly ejects over the plains, that is when rapid cyclogenesis begins and the self development process starts. All models dive the surface low SE before either tracking straight east (GFS) or taking it a tad NE (NAM/SREF/18zUK).

[A-L-E-K]

FOr an even more in-depth discussion, what an ensemble is is a collection of model runs in which the initial conditions of the "control member" have been "perturbed" using a mathematical formulation which perturbs them to account for the natural limitations and errors one can expect from data assimilation system. In other words, you are accounting for chaos as Lorenz discussed in the 60s in "Deterministic Nonperiodic Flow". An ensemble mean is good to account for trends as well as understand the amount of variability in a forecast, but they are not useful for the actual true forecast since the mean QPF blends everything together which is not realistic. Mesoscale effects such as potential banding in SREF runs are not well defined in the mean run and things such as dry slots are not shown well either.

This was new to me thanks.

[TheWeatherPimp]

No way this thing makes it up into Southern Minnesota, a track across Central Iowa is much more likely based on current obs, trends IMO

[Moneyman]

Thank you. Should be good to go now.

[MadTown]

looks like mke is banking on it stayin down in ill

[The_Global_Warmer]

I have been tracking this all day at work.

as sick as it is I have done nothing and will have to work this weekend, oh well, it's 1 mile from home and I can focus on weather there easier then at home.

anyways...the ruc has basically been trending south all day. I mean, almost no East advancement, the 300mb Jet and H5, H7, H8 troughs all south. exp the H3 & H5 troughs.

Even the surface low has went south about 50 miles.

[OceanStWx]

As an example of why we went with the blizzard watch here at DVN, here is an image from the GFS at 12z Sunday morning.

The fill is 0-0.5km lapse rate (roughly approximating sfc to 925mb), the blue lines are 925 wind speed, and the yellow lines are 6 hour pressure change. The center of the image shows a 60+ kt 925 wind nearly centered over the Quad Cities, with lapse rates approaching dry adiabatic. The general idea is that there is a shallow layer of near DALR, but if it extends to the top of the mixed layer there isn't much more to go to reach the ground. Even taking a fraction of that wind puts us well within blizzard conditions.

[prinsburg_wx]

No way this thing makes it up into Southern Minnesota, a track across Central Iowa is much more likely based on current obs, trends IMO

doesn't matter if it does track across c ia...s mn still gets nailed...even the ukie shows that

[csnavywx]

Haha, I find that really funny. Is that the scientific way of figuring it out?

BTW, not an attack or anything, just think its funny that METS would figure that out, and figure it out in a simple manner such as that.

Operational forecasting is loaded with this type of stuff.

[Paweatherguy1]

Operational forecasting is loaded with this type of stuff, also known as "Thumb Rules".

I guess it makes things a lot easier.

[Hoosier]

As an example of why we went with the blizzard watch here at DVN, here is an image from the GFS at 12z Sunday morning.

The fill is 0-0.5km lapse rate (roughly approximating sfc to 925mb), the blue lines are 925 wind speed, and the yellow lines are 6 hour pressure change. The center of the image shows a 60+ kt 925 wind nearly centered over the Quad Cities, with lapse rates approaching dry adiabatic. The general idea is that there is a shallow layer of near DALR, but if it extends to the top of the mixed layer there isn't much more to go to reach the ground. Even taking a fraction of that wind puts us well within blizzard conditions.

I don't have any maps like that but I've been checking out soundings around northern IL and this basically translates east throughout the day, so I think 50-60 mph gusts are likely throughout all of northern IL.

[A-L-E-K]

unisys updates

[patrick7032]

As an example of why we went with the blizzard watch here at DVN, here is an image from the GFS at 12z Sunday morning.

The fill is 0-0.5km lapse rate (roughly approximating sfc to 925mb), the blue lines are 925 wind speed, and the yellow lines are 6 hour pressure change. The center of the image shows a 60+ kt 925 wind nearly centered over the Quad Cities, with lapse rates approaching dry adiabatic. The general idea is that there is a shallow layer of near DALR, but if it extends to the top of the mixed layer there isn't much more to go to reach the ground. Even taking a fraction of that wind puts us well within blizzard conditions.

I agree with that (good post btw)....and I don't know about your area....although I would assume so....but for my area Bufkit shows hints of slight to moderate elevated instability above 400mb. Did you see any such examples in your CWA?

[OceanStWx]

I don't have any maps like that but I've been checking out soundings around northern IL and this basically translates east throughout the day, so I think 50-60 mph gusts are likely throughout all of northern IL.

That was our assessment too, more or less sweeping the strongest winds right through the heart of our CWA and into Illinois more or less along I-80.

[buckeye]

just looking at the 18z...

the digging of the 5h continues... not sure how anyone under the path of that closed upperlevel low makes it out without gett'n all white

[Sidewinder]

Those bars are so close together, I have never seen anything like this. Thanks for posting that pic, Ocean.

[Justin]

Based on the images Alek posted appears the central low should be in consolidation mode very shortly and pressure falls would take it right down I80 or so I'd say. Definitely a hair South of the consensus the WFO's were using. This may have implications in Southern WI causing their forecasted snow amounts to be on the low side. I only wish this was another 100 to 150mi further South but we will get ours eventually.

[prinsburg_wx]

Based on the images Alek posted appears the central low should be in consolidation mode very shortly and pressure falls would take it right down I80 or so I'd say. Definitely a hair South of the consensus the WFO's were using. This may have implications in Southern WI causing their forecasted snow amounts to be on the low side. I only wish this was another 100 to 150mi further South but we will get ours eventually.

here's a closeup....i'm still learning here but wouldn't the best snows fall n of the 700 850 L's.? thanks

[patrick7032]

Based on the images Alek posted appears the central low should be in consolidation mode very shortly and pressure falls would take it right down I80 or so I'd say. Definitely a hair South of the consensus the WFO's were using. This may have implications in Southern WI causing their forecasted snow amounts to be on the low side. I only wish this was another 100 to 150mi further South but we will get ours eventually.

You prob will "get yours" this storm....I wish that I was in a Blizzard Watch....but think DTX will drop the watch south once more data is analyzed.

[The_Global_Warmer]

Based on the images Alek posted appears the central low should be in consolidation mode very shortly and pressure falls would take it right down I80 or so I'd say. Definitely a hair South of the consensus the WFO's were using. This may have implications in Southern WI causing their forecasted snow amounts to be on the low side. I only wish this was another 100 to 150mi further South but we will get ours eventually.

How will the low maintain an Easterrly course, while the H5 low drops SSE?

[csnavywx]

How will the low maintain an Easterrly course, while the H5 low drops SSE?

It's occluding pretty early.

[Moneyman]

Green Bay Forecast Discussion:

AS FAR THE ACTUAL FCST OF THE INCOMING WINTER STORM...INITIAL

CONCERN IS MOISTURE. 12Z RAOBS WERE QUITE DRY FM WI DOWN TO THE

GULF. SOME RETURN FLOW STARTING...BUT GIVEN WHAT/S OUT THERE NOW

THE MODEL QPFS LOOK AWFULLY AGGRESSIVE. WE/LL SEE WHAT THE 00Z

BALLOON LAUNCHES REVEAL. OF THE VARIOUS MODEL SOLNS AVAILABLE...12Z

CANADIAN REGIONAL SEEMED THE MOST REASONABLE TO ME...SO USED THAT

FOR THE 00Z TAFS.

Anyone else see this problem happening?

[msp]

lol, how the heck does MSP now keep getting snowstorm after snowstorm like this? i'd have given and arm and a leg to even get half this much by mid-dec. the last few years. looks like eden prairie should see double digits again. maybe 12-14 inches if lucky.

23/13 and overcast at flying cloud right now. i'll be eagerly watching traffic cams through the night.

[baroclinic_instability]

How will the low maintain an Easterrly course, while the H5 low drops SSE?

Surface lows don't always follow the exact track of the upper low, especially in this case where the dominant forcing will be in the low levels along the fronts with the low level convergence rising into the upper low/strongly divergent region in the upper levels. Won't bother with dynamics. Come on Friv we have discussed this a lot here

[baroclinic_instability]

lol, how the heck does MSP now keep getting snowstorm after snowstorm like this? i'd have given and arm and a leg to even get half this much by mid-dec. the last few years. looks like eden prairie should see double digits again. maybe 12-14 inches if lucky.

23/13 and overcast at flying cloud right now. i'll be eagerly watching traffic cams through the night.

Ah, you are in EP. Wondering where you were from. I was born there, now in Shaktown.

[cyclone77]

Wow, I was basically starting to write this thing off late last night. That's two storms in a row I wrote off too early. Guess that's why I'm not a met lol.

Anyway, this is starting to look like a pretty scary situation for many parts of the Midwest. I'm becoming much more concerned with the wind than anything else at this point. With 40-60mph wind gusts there is a high likelihood of at least scattered power outages. That combined with very cold air roaring in will make any prolonged periods without power somewhat dangerous with the loss of home heating ability. Repair crews would likely have a hard time getting out to locations in a timely manner to repair things as well.