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12/14 - 12/15 SNOWSTORM: GREAT LAKES

Looks like things could get interesting during the middle part of next week. Comments guys?

Here's the AFD out of KMKE.

AS FOR MID WEEK SYS...CANADIAN DEVELOPS QUITE A STORM FOR WED
WITH A FAVORABLE TRACK FOR SRN WI. DGEX SHOWS MORE OF A GULF LOW
PULLING OUT TO THE NE...WHILE ECMWF AND GFS SHOWING MORE OF A
PROGRESSIVE LOOKING UPR SYS ACRS NRN TIER OF STATES. WITH
THE LACK OF CONSENSUS AND LACK OF RUN TO RUN CONSISTENCY WITHIN
THE GFS POINTS TOWARDS KEEPING CHANCE GOING FOR WED/THU TIME
FRAME.
 
"Comments guys?"

Yep. Since no model had last night's half-foot+ storm until 48 hours prior to the event, I'd put a non-consensus, not-supported-by-ensemble outlook 5 days ahead on the backburner.
 
The 12Z GFS is leaning more towards the 00Z GEM solution... Right now, the key is to just look at the patterns and ensemble solutions, not much else you can do right now. As Rob said, I will put this on the back burner and re-post in this thread when the storm system seems a bit more likely - provided it's still targeting the Great Lakes.
 
I will keep it in the very back of my mind to say the least until it's nearing 60hrs out.

The run to run differences are still ridiculous with this storm. Add in some possible negative feedback issues with snowpack, and possibly adding a little more to it before the storm hits, makes for a very low confidence outlook.
 
OK, just as a note, I am using all 18Z runs of the American Models and the 12Z of the EURO...

Please ignore precip on all maps.

Lets start at the NAM:

12151.jpg


GFS:

12152.jpg


Surface map of Jan 2 1999:

12153.jpg


Look at the placement of the Highs and Lows that I have outlined...

Notice anything similar?

With the exception of the weaker pressures, this is setting up to be almost exactly the same.

Lets move down the road to 120hrs away, Low #1 and 2 have merged:

GFS:

12154.jpg


This is much weaker with everything across the board, so thats why I its placing the GL low so far north, but you still get the idea.

Here is the Surface Map:

12155.jpg


Still very similar...

Notice those 3 high pressures, If we can get those highs to be as strong as 99, I would bet money that we would have a repeat of the 99 blizzard. The EURO is very good on representing this, as you will see.

And to close my discussion about these 2 storms, The EURO:

12156.jpg


"The Ghost Of The 99 Blizzard"

This is disturbing...I received 24.5 inches of snow in southern WI on 1/2/1999 with intense thundersnow for awhile....and 65 mph wind gusts.
 
It is interesting. I'd like to see what the upper air patterns looked like for the 1999 storm to really see if there was any similarity. My guess is that the 500MB shortwaves and upper level jets were more amplified in 1999... Then again, the 1999 storm didn't really deepen all that much (996MB as it passed over lower MI).

Anyway, this event is still a ways out AND model continuity is pretty poor right now. I'd wait until the event is at most 60-72 hours away and well captured by short term models.

I really hope something happens... I can't stand the cold without anything fun happening.
 
Lots of low pressure and high pressure setups look the same - but you need to use much more than a surface plot. How's the jet stream in comparison? What did 500mb look like then vs forecast now?
 
Lots of low pressure and high pressure setups look the same - but you need to use much more than a surface plot. How's the jet stream in comparison? What did 500mb look like then vs forecast now?

I couldn't find any 500MB data - but Unisys has an archive of the 4-panel plots (SFC, 850MB, 300MB, and LI). From the 300MB plot, I gather that there were two very seperate shortwaves in 1999, with the lead shortwave being in the southern stream. The southern stream shortwave was located over southern TX, while the northern wave was located over northern MT.

With our current system, it looks like the dominant shortwave will turn out to be the northern stream wave, but that could change. Also, the models are very light with QPF - that's another difference between these two systems.

With the 1999 system, I remember watching it when it was 7 days out on the "MRF". The system seemed to get "lost" as the event got closer (it was completely gone in the day 4 to day 5 timeframe), but then reappeared. I also remember that 6HR model QPF for a big chunk of land was 0.50 to 0.75 inches. Our current system doesn't seem to carry QPF that high.
 
I wouldn't bet money on anything. January 1999 was an interesting phasing of two systems that evolved into one significant extra-tropical cyclone (I remember it well, we were *supposed* to get 10" in Kansas City and we ended up with maybe an inch)... the interaction of two systems is never "given"... The interaction is dependent on so many things and you can either end up with one significant vorticity max that allows the development of a robust surface cyclone/anticyclone couplet supporting ingredients for possible blizzard conditions.... or you can get a sort of fuji-wara of two vorticity maximas that end up rotating around each other... and you get two surface responses close to each other.. destroying your good pressure gradient for a significant and widespread snow+wind event... right now I see the ecmwf and gfs favoring more the latter. In fact there will probably be three disturbances at play here... and if they don't interact in the "perfect way" you just get a messy, disorganized winter storm with some snow and maybe a little wind... with a 1000 low here, a 1009 trough axis there, and a 1027 high to the west... To get a major blizzard, there needs to be incredible anticyclogenesis OR cyclogeneis to get the strong pressure gradient, of course.... right now I just see "decent" cyclogenesis and a poor signal of robust anticyclogenesis or absence of a huge arctic 1040+ high in close proximity to the north or northwest.

This is why predicting blizzards is extremely difficult. It takes a very delicate balance of ingredients with cold air, moisture, jet streak dynamics, etc etc etc... on all atmospheric scales... which I honestly say we can't predict easily at all even 2 to 3 days in advance... So I put my money on a wait and see :) Models right now are changing so much... just look at all the little purturbations on a north american water vapor loop right now... it's extremely chaotic.

If you can say explosive deep tropospheric cyclogensis will occur with a singular dominant h5 vort center, with one dominant mid-upper jet streak involved allowing just one surface cyclonic/anticyclonic couplet to vigoroustly develop at h+120... then you are a better forecaster than I am :)

Mike U
 
Models right now are changing so much... just look at all the little purturbations on a north american water vapor loop right now... it's extremely chaotic.

That's for sure. Not only do the models not handle phasing all that well - but with the shortwaves still over the ocean, I doubt they were well sampled.

As of right now, I'm not really "feeling it" in terms of a big snowstorm or blizzard... In other words, my hopes aren't high at all. But then again, even if the majority of the models DID have "the storm of the century", my hopes still wouldn't be that high. The fact is, with the system still being a solid 84 to 102HR's out, things WILL change.

FWIW... The latest NAM and GFS show two seperate shortwaves at 500MB exhibiting a slight Fujiwara effect that Mike U. was talking about.
 
Some pretty big differences right now just between the NAM and GFS. At 78hrs, the NAM has the 850 freezing line in central WI, while at the same time the GFS is in southern IL!!
 
Now that the system is nearing the 60hr mark, I guess it can be taken more seriously now, well at least for me lol. The GFS and NAM have become a little more similar to each other than previous runs. The NAM still has a small wedge of warm air ahead of the main trough, just above the surface, but is much less bullish on the amount of warm air compared to previous runs. The GFS has been the most consistant.

The bottom line is, this whole storm system looks to be pretty complex, so there's still a very good chance certain issues won't be resolved for another 30-42hrs.

If we can close off a decent low at the southern end of the trough there could be quite a snowstorm for someone, but right now that doesn't look like it's going to happen.
 
Models seem to be coming into BETTER agreement... But as you said Joel, there are still some small differences (small differences in terms of placement, timing, evolution - the "better" agreement means that we are all on the same page with a storm, LOL) that will have a big effect on what ultimately happens. I'm really liking how the models are trending towards a single vorticity maximum, versus three. I'm also likeing the less-progressive system, so areas that do see snow will see a longer shot of it.

There are still two main SFC reflections though - one in the MS Valley and one near the Gulf. If we can get those to phase a bit further south or at least the southern wave ride north along the slow moving baroclinic zone / front, someone may be looking at pretty heavy snowfall. Not really concerned about blizzard conditions at this moment in time, but heavy snow looks like a possibility for someone.

Reading over NWS discussions, DTX mentions that various snowfall techniques are showing 6-8 inches at a 15:1 ratio, with the potential for convective snow. Obviously that's not the forecast, just sort of a "what if" situation.
 
Things look pretty complex with this system (or systems). The main SFC low situates itself across the WI/MN area... While a secondary low forms near the East Coast. This gives us two main areas of high QPF values (at least on the NAM) - one near the main SFC low, and another area along the track of the East Coast low. Areas in between have rather dry QPF amounts.

As for MI... Latest 12Z NAM now shows <0.25 inch of QPF where it originally had over 0.75 inches over central lower MI. Of interest though is the East Coast low, which has been tracking further west with each run. My specific location shows a QPF of around 0.50 inches, while 45 miles to the east QPF's are 1.00 inch.

This is still quite a ways out there (48-60HR), but it could get real interesting if that East Coast low continues to show a more westward / phased track.
 
Looks like the northeast half of Iowa could get a nice heavy wet snow later tonight and tomorrow. It will be interesting to see where the rain/snow line sets up and how it moves throughout the storm. North-central and northeast Iowa look to be in the bullseye for snow totals.

For me it's going to be a nail biter. The snow looks like it may try to change to rain at some point tomorrow, which could really shut down accumulations. Man it will be kind of weird seeing rain after it being so cold! :wink:
 
Okay... yeah... Very complex... LOL

Most of the 12Z models (06Z UKMET, 00Z ECMWF) agree that the main shortwave won't consolidate all of the vorticity. What appears to be happening is the "left over" vorticity streaming down the backside of the shortwave trough creates sort of a "Fujiwara" effect (as mentioned earlier). The secondary area of vorticiy then dives east/southeastward into the developing +150KNT upper level jet - which ultimately becomes responsible for SFC low along the Gulf.

The BIG question is... How close in proximity to the main shortwave will the secondary shortwave rotate around? 12Z guidance has that shortwave closer to the main wave, bringing the Gulf low further west. In fact, the NAM has been trending furth west with each run since yesterday's 12Z stuff.

That has a big impact for regions of MI, OH, etc.. If that Gulf low DOES track further west, we'd be looking at storm total (+30 hour) QPF's in excess of an inch with a "one two punch" situation (main burst of precipitation with the main shortwave, then the secondary wave blowing up to the east/southeast). If that Gulf low remains further east, we're talking about <0.25 inches...

Given the complexity and very low confidence - I doubt the NWS offices will be issuing any watches anytime soon.
 
Here in east-central IA where I'm at...

Summary:

Snowfall will start in Cedar Rapids around 11 PM, and a mixture of snow, rain, and freezing rain will start in Iowa City around the same time. Between 12AM and 3AM, expect a period of moderate freezing rain in Washington, Iowa, and Benton Counties; with ice accumulations of around 0.1". During the same period, precipitation should remain all snow N of US-30 in ERN IA with a mixture to the S and all rain to the W of the aforementioned counties. A changeover to all snow will take place over the entire area by 6AM tomorrow. Precipitation will linger trough 6PM Wednesday, at which time it will taper to flurries.

Snowfall accumulation:
Iowa City: 2"
Cedar Rapids: 3" (Eastern Iowa Airport), 6" in the north portions of the city.

Discussion:

Concerns: precipitation type, especially early on in the system as an area of freezing rain will develop, and the amount of snowfall. Currently, SFC low pressure centered in ND, with associated trough extending SWRD and a WF bisecting IA from SE to NW. Strongest pressure falls are taking place in SERN ND, while a band of strong WAA is taking place as evidenced by 30kt 850mb LLJ advecting a 304k airmass into the ERN Dakotas. An interesting phasing of the NRN and SRN stream waves will take place over the planes from 0Z Wed through 12Z Wed, with upper flow then developing into a cut-off low that will linger over the Great Lakes through the end of the week. ATTM, it seems like two QPF maxes will occur with this system, with highest amounts to the NW and the SE of the ERN IA as areas of frontogenesis develop in each of these areas. In ERN IA, go with 6:1 snow/water ratio N of US-30, taper down to 3:1 S of I-80 where much of the precipitation will be liquid. Forcing is increasing, as noted in several fields: Q-vector divergence, tropopause-level PV advection, and omega fields.

Guidance is in decent agreement, with the 12Z GFS somewhat faster then the 12Z ECMWF and 12Z MAM. All are fairly close with regard to overall placement of features, and the latest runs have slowed down the onset of the precipitation by several hours. The ECMWF has had the best run-to-run consistency the last few days, and will side with it. Concerning precipitation type, forecast soundings indicate temperatures near 30F at the SFC but with temps above freezing at 850mb, so freezing rain will be a concern during the first portion of the precipitation period before colder mid-level temperatures advect into the area. By mid-afternoon, Wednesday, dry-slotting should work in from the SW, ending precipitation S of I-80 in ERN IA.

- bill
 
I decided to plot of the 12-HR QPF differences between the 00Z NAM and the 12Z NAM. The light green is +0.25 inches, with each color interval being another 0.10 inches.

precip.gif
 
This storm is making me lose my hair lol. It's going to be a VERY close call in my immediate area. The new 18z NAM is even warmer than before. (Although I'm not a fan of the midday runs).

I think a band of 6-8" of heavy wet snow will line up along a line from Waterloo IA to Dubuque, and towards Rockford IL.

The combination of warm air intrusion just above the surface, and dry slotting makes the forecast along the I-80 corridor very scary. If anything changes either way, it could go from a 2" snow, to an 8" one very easily, or visa versa.

Much of MN and WI are going to see a long duration light snow event, which could gradually pile up pretty nicely too for them.


For you guys out east, well, this storm is obviously very complex, so I guess it's just a waiting game for now. But it's fun watching things change from run to run! 8)
 
Sitting here just west of Milwaukee I am forecasting 4-7 inches for my general area. I think the 4 is the bare minimum and most people around my area will get 5-7 inches. Liquid should be about 0.4 to 0.55 or 0.6 maybe if some of the more robust solutions pan out. Been broadcasting a solid 12:1 ratio here for awhile with various techniques. NAM is definately the lightest but I don't trust its winter snowfall prediction. NGM has a broad area of +0.5 inches which by my calculations would mean 6 inches or more. Time to wait for the 14/00Z GFS run and other models to leak in.

ARX wrote a great discussion this afternoon. I'd recommend reading it if u want to get a hold on the situation.

...Alex Lamers...
 
Still very complex for us folks a bit further east between 06Z THU and 18Z THU.

It looks like the moisture from the Gulf / Coastal system will make it into the eastern third of lower MI, and the dryslot now appears to be delayed. The column gets saturated between the SFC and 600MB at 06Z THU and remains so until 18Z THU. Strong omega values are also present during that entire 12HR period within that moist layer... The only drawback I see is that that moisture doesn't extend to 500MB, and the best omega / RH values are located within the -10C to -14C thermal layer through 12Z. Between 12Z and 18Z, the thermal profile becomes more favorable for snow growth (-15C to -20C).

Moving on... Substantial CSI (100MB thick) exists during the above mentioned 12HR period centered around 700-600MB. That's also within the region of strong omega and frontogenesis.

And then on to model QPF... The NAM shows around 0.60 to 0.75 inches across portions of MI. The Canadian GEM is very similar, with portions of MI receiving 0.80 inches - in fact, the GEM has quite a bit more moisture located farther west than any of the other models. The NGM (though the entire model looks odd) shows around 0.50 inches. The FSL RUC comes in at 0.50 to 0.75 inches...

I'll update my post in a few minutes when the GFS is in... Currently out to F48 and it shows 700MB moisture / omega much further west than the 12Z run...

Update: Okay, GFS is in... It looks nearly identical to the GEM. The Gulf / Coastal system tracks further west - phasing significantly will the main SFC low before pulling off. It brings in QPF's of 0.75 to 1.00 inch across eastern/northern lower MI.

The event still has plenty of time to evolve, but as of now I'm liking the trends.
 
Watching the potential for a nice glaze ice/freezing rain event with this system on the eastern side of the Appalachians. Good wedging setup with warm air stuck on the west side of the mountains and cold air entrenched on the east side.

NWS hasn't pulled the trigger on a watch/warning yet, but I'm gearing up for another trip into the Blue Ridge around Christiansburg/Wytheville. Who said there was nothing to chase in the winter :)
 
Originally posted by Dan Robinson
Watching the potential for a nice glaze ice/freezing rain event with this system on the eastern side of the Appalachians. Good wedging setup with warm air stuck on the west side of the mountains and cold air entrenched on the east side.

NWS hasn't pulled the trigger on a watch/warning yet, but I'm gearing up for another trip into the Blue Ridge around Christiansburg/Wytheville. Who said there was nothing to chase in the winter :)

Yeah, the slightly further west track of the NAM / GFS really supports an ice storm with that cold air damming. I'm just hoping the models don't all of a sudden reverse their trend, and with a few more model runs left - it does worry me.

For my area - It wouldn't be the first time that all of the models kept a dry slot at bay, only for it to really blast through and choke everything off.

My prediction is that NWS DTX won't be issuing a WSW with the AM/morning package. I have a feeling this event won't be preceded by a watch. I also doubt the NWS GRR will issue a WSW either, with even less confidence that moisture will stick around. With all of the models showing the same thing - I would probably go with a watch for areas east of a JYM/LAN to MCD (Mackinac) in line with the GFS QPF fields. --> http://69.14.190.10/images/winter_watch.gif
 
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