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December 21-22nd Winter Storm Part 2


Chicago Storm

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LOT buying into the warmer/northwest solution at this time.

I qc'ed the discussion for the storm and asked if it was okay to add in the 'there's still time for track changes as the system gets better sampled by the raob network.' Can't deny the trends today but as others have already pointed out, today could've been an overcorrection. I'm not punting on this one yet.

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MKX talking amounts now. 5-8"

 

.SATURDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.

ALL EYES ARE ON THE DEVELOPMENT OF A POTENTIALLY STRONG LOW
PRESSURE SYSTEM THAT WILL TRACK FROM THE SOUTHERN PLAINS...THEN
NORTHEAST INTO LOWER MICHIGAN BY SUNDAY. THE MAIN ENERGY WITH THIS
SYSTEM IS STILL OFF SHORE OF CALIFORNIA...BUT WILL MOVE ONSHORE ON
THURSDAY. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE 12Z
MODEL SUITE. HIGHLIGHTING THE CHALLENGE WITH THIS SYSTEM...THE
GFS...WHICH WAS THE FARTHEST SOUTH MODEL ON LAST NIGHT/S
RUN...HAS NOW BECOME ONE OF THE FARTHEST NORTH. THE ECMWF IS
PRETTY CONSISTENT AS IS THE GEM. THE CONSENSUS TRACK TAKES THE LOW
FROM SOUTHEAST MO SAT EVENING...TO NORTHEAST INDIANA SUN
MORNING...TO NORTHEAST LOWER MICHIGAN BY EARLY SUNDAY AFTERNOON.
THIS IS A PRETTY IDEAL TRACK FOR SNOW ACROSS SOUTHERN AND
PARTS OF SOUTHEAST WISCONSIN. LOOKING AT THE TEMPERATURE
PROFILE...IT SPELLS POTENTIAL TROUBLE FOR SNOW LOVERS IN THE
SOUTHEAST CORNER OF THE STATE WHERE WARM TEMPS MAY BRING A RAIN
SNOW MIX FOR THE FIRST PART OF THE EVENT...THIS INCLUDES THE
MILWAUKEE METRO AREA.

IF WE HAD TO PIN A FAVORED AXIS FOR THE HEAVIEST SNOW AT THIS
POINT...IT WOULD RUN FROM SHEBOYGAN/FOND DU LAC...BACK THROUGH
MADISON...MONROE AND MINERAL POINT. AND IF WE HAD TO PUT SOME
NUMBERS TO THAT...IT WOULD STILL BE IN THE 5 TO 8 RANGE. LESS TO
THE SOUTHEAST.

EVERY RUN AS WE GET CLOSER IS INTENSIFYING THE SURFACE SYSTEM
MORE AND MORE. LOOKING AT SOME 30 YEAR ANOMALY PRODUCTS...THE
UPPER LEVEL JET CONTINUES TO SHOW AN INTENSITY THAT IS
STATISTICALLY ONLY SEEN ABOUT ONCE EVERY 30 YEARS OR SO. THE
QUESTION WILL BE HOW FAST THE LOWER LEVELS CAN RESPOND TO THAT
UPPER LEVEL ENERGY. THE LOW WILL BE INTENSIFYING AS IT MOVES INTO
THE AREA...WHICH MAKES THIS SYSTEM EVEN MORE
UNPREDICTABLE/DANGEROUS. THE FRONTOGENESIS IS...AS
EXPECTED...VERY STRONG AND VERY DEEPLY STACKED.

NO HEADLINES WILL BE ISSUED YET. WE STILL NEED TO GET SOME
STABILITY IN THE MODEL RUNS TO GET MORE CONFIDENCE IN PLACEMENT
AND AMOUNTS.

 

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I qc'ed the discussion for the storm and asked if it was okay to add in the 'there's still time for track changes as the system gets better sampled by the raob network.' Can't deny the trends today but as others have already pointed out, today could've been an overcorrection. I'm not punting on this one yet.

 

 

Any thoughts on the ice potential in your area and whether the models could be eradicating the near-sfc cold layer a bit too quickly?  The LOT disco didn't seem to be too excited overall.

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Any thoughts on the ice potential in your area and whether the models could be eradicating the near-sfc cold layer a bit too quickly?  The LOT disco didn't seem to be too excited overall.

 

I'm wondering if they aborted their earlier briefing they were about to prepare.  Don't see one yet on their home page.

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I qc'ed the discussion for the storm and asked if it was okay to add in the 'there's still time for track changes as the system gets better sampled by the raob network.' Can't deny the trends today but as others have already pointed out, today could've been an overcorrection. I'm not punting on this one yet.

 

 

Any thoughts on the ice potential in your area and whether the models could be eradicating the near-sfc cold layer a bit too quickly?  The LOT disco didn't seem to be too excited overall.

Was just talking about that right now with the evening public forecaster. I'm definitely concerned with ice potential during the WAA portion of the storm. If the models are too warm with surface temps and they very well might with northeast surface flow over still snow covered ground, zr/ip could become a big problem for parts of the area, likely west and north of Chicago.

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Any thoughts on the ice potential in your area and whether the models could be eradicating the near-sfc cold layer a bit too quickly?  The LOT disco didn't seem to be too excited overall.

 

I'm wondering if they aborted their earlier briefing they were about to prepare.  Don't see one yet on their home page.

It's been uploaded, just have to publish to our website. Might already be available on our YouTube channel.

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If this is solely an Ice storm i personally believe it will be hard for the Ice to accumulate near the Lake Shoreline because the Lake would regulate temperatures just enough for it be less severe than those away from the Lake. The GGEM has been consistent on its "Ice storm" idea for the GTA as compared to the other models. 

 

This storm is still days out so at this point in time any solution is viably possible. Models can be too quick in moving systems before they phase or interact. I wouldn't expect any type of consistency on the models till 0z/12z Friday. I think we need to focus on the quick hitting snowfall/mixing on Friday for the GTA too. 

 

Considering most people in Toronto do not live along the shoreline, and most public services are not along the shoreline, it would be a massive headache for 90% of the city.

 

The consistency with the ZR storm has been impressive. I would be surprised to see much snow from the Friday night storm or the weekend storm. It's going to be too warm aloft.

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:snowing: APX

 

Several periods of snow can be expected through Friday night across northern Michigan...but the main weather story is a winter storm forecast to develop across Texas Saturday and lift northeast possibly across southern Lower Michigan Sunday. This track would bring significant snowfall to northern Michigan along with gusty winds...but there is still plenty of uncertainty regarding snow amounts and perhaps even precipitation type in some areas...so be sure to pay attention to later forecasts for the latest information. One thing does seem certain...if you have plans to travel for the Christmas holiday this weekend...plan on leaving Saturday. By Sunday you may be pushing your luck.

 

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One of our local mets said his Euro output showed 4" of snow for MKE, despite a normally ideal track near Lafayette.  Since the 6am Sunday thickness was near 546, he said that's not likely snow.  Any thoughts on this aspect?  I tend to think the Euro could be overdoing temps, especially since I'm guessing we'll still have a snowpack at the time, right now we still have 5-6" on the ground.

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One of our local mets said his Euro output showed 4" of snow for MKE, despite a normally ideal track near Lafayette.  Since the 6am Sunday thickness was near 546, he said that's not likely snow.  Any thoughts on this aspect?  I tend to think the Euro could be overdoing temps, especially since I'm guessing we'll still have a snowpack at the time, right now we still have 5-6" on the ground.

Seems about right. A majority of the precip falls with 850mb temps near 0C...And likely a bit warmer above 850mb.

 

850's crash after 96hrs, but by that time <0.40" QPF is left.

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One of our local mets said his Euro output showed 4" of snow for MKE, despite a normally ideal track near Lafayette.  Since the 6am Sunday thickness was near 546, he said that's not likely snow.  Any thoughts on this aspect?  I tend to think the Euro could be overdoing temps, especially since I'm guessing we'll still have a snowpack at the time, right now we still have 5-6" on the ground.

 

 

I've seen it snow with 1000-500 mb thicknesses pushing 552 dm but that is rare.  546 can be doable for snow if you have a deep layer at or just below freezing but often times you will be mixing with that kind of thickness.  Minor changes to surface temps and nothing else wouldn't affect the thicknesses very much. 

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You guys are certainly making this sound apocalyptic. Based purely on the latest EURO output, 2m temps seem way too marginal (-0.2C) to allow for such a copius amount of precip (0.86") to freeze on surfaces properly. Then we steadily warm up to a whopping +7.3C in the next 12 hours. There would definitely be some accretion but I think it would have a hard time really building up beyond the 12Z mark Sunday. We saw this in the April icestorm in Guelph where ice accretion at -1C could not keep up with the rainfall rate and a lot of the damage was mitigated. Of course there would still be numerous issues given the busy time of year but I doubt we would see the entire 0.86" + 0.11" of water turn to ice.

 

Also this is base purely on this run of the EURO, any subsequent colder runs could spell trouble and the other models will need to be taken into account as well (ex. the GEM has been quite steady on a heavy ice event).

 

Agree 100%. Getting a historic ice threat is going to be difficult for the GTA. First of all you need thermals to line up perfectly or a lot of the QPF is spent on PL/SN/RN. If BL temps are too cold, you get more in the way of PL/SN with the initial burst of precip before a change over. If Sfc/BL temps torch then we get a cold rain after a period of ZR. I do however think that this period of ZR is going to be quite significant for the GTA which isn't used to these types of freezing rain accums(15-35mm potentially). The flow is lined up nicely for some significant ZR, even if its only about 60-80% of the total QPF for YYZ. Once you get north of about the 0.3" mark, you start getting into some major problems with downed power lines/trees in the GTA. Key is going to be that northern branch feature and how much CAD occurs at the surface. Definitely think parts of S ontario have a heightened risk of a potentially devastating ice storm with the guelph/ K-W/ brantford area up towards caledon/bolton/newmarket getting the worst of the ice.

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one interesting thing to note...even those crazy warm and west solutions of todays 12z GFS and Euro (the 18z gfs has already cut back) have a brief few-hour spike to 50F at DTW but that is AFTER the rain ends...nearly all the precip, even in those warm solutions, falls with temps in the low 30s. I did a snow core sample (the amount of water in the snowpack) and we right now have a depth of 8" with a water equivalent of 0.84" (basically while the snow settles some we have lost none of the liquid in the snow since the first coating was laid down Dec 8th), and yes the ground underneath is rock hard frozen solid. We would either be looking at a rock hard glacier with 2-1 ratio once the storm passes or one hell of a flood. The snowpack is deep and dense enough that it will be able to absorb a lot of cold rain, but if it melts the water literally has nowhere to go.

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one interesting thing to note...even those crazy warm and west solutions of todays 12z GFS and Euro (the 18z gfs has already cut back) have a brief few-hour spike to 50F at DTW but that is AFTER the rain ends...nearly all the precip, even in those warm solutions, falls with temps in the low 30s. I did a snow core sample (the amount of water in the snowpack) and we right now have a depth of 8" with a water equivalent of 0.84" (basically while the snow settles some we have lost none of the liquid in the snow since the first coating was laid down Dec 8th), and yes the ground underneath is rock hard frozen solid. We would either be looking at a rock hard glacier with 2-1 ratio once the storm passes or one hell of a flood. The snowpack is deep and dense enough that it will be able to absorb a lot of cold rain, but if it melts the water literally has nowhere to go.

50 degrees will wipe out the snow. No question about it. 

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Seems about right. A majority of the precip falls with 850mb temps near 0C...And likely a bit warmer above 850mb.

 

850's crash after 96hrs, but by that time <0.40" QPF is left.

 

It looked to me like most of the precip was falling with 850s just below 0C and surface temps very slightly above freezing when I looked at the output, which could be a cake mixer, but obviously way too close for comfort.

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50 degrees will wipe out the snow. No question about it. 

Everyone better sure hope it doesnt hit 50F then...because there would be a massive flood. Once we add in the mix of rain, freezing rain, and snow from tomorrow, we will have at least 1" of water in the snowpack when the storm begins Saturday. Then that rain/freezing rain would further get absorbed into the snowpack and your talking a 2-3" water content snowpack that, if it rapidly melts, has absolutely nowhere to runoff on the frozen ground. Staying under 40F would save all of those problems.

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