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1/17 - 1/19 CO Low Winter Storm


Tom

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5 minutes ago, Tom said:

12z Euro...The one that shuts down I-80 in NE...

image.png

Convective bands in circling DSM metro. Will come down to last minute. As I have said before- get 15-25 NW of the Sleet/Rain/Mix zone and your game //// or not. It's a dice throw-- box cars or snake eyes?

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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The reason why snow totals are going to be higher in C NE is really due to temps being about 5-10 degrees colder than E NE.  It looks like temps are in the mid/low 20's when its pounding mid morning throughout the day tomorrow.  What a beautiful day time snow storm.  I expect to see many pics and vids boys!

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12Z globals are about done for defining bands outside of big winners in C.NE. This is coming down to thermals hardcore and no model will really define this until the very end. Big winners for sure are C.NE and even E.NE. C.IA is still up in the air as anything can happen.

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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Surprising to see such a wide range in model guidance with the event about 24 hours away here in Omaha; I put together a look at the last few runs of major model guidance showing snowfall in Omaha. Used 10:1 ratio maps so as not to have totals incorrectly inflated by any sleet/ZR, which some map-making services do struggle with.

As shown, the forecasted totals in Omaha range from 4" per the 12z NAM, to 13" per the 12z Euro ENS Control. Seems like a consensus is building inside a range of 6-12", probably in the vicinity of 8-10" if you want to get even more narrow. This compares to the current NWS Omaha range of 3-7" in the city.

One last note, it seems that the Omaha WFO is heavily reliant on the NBM, which appears to have the second-lowest snow totals among all model guidance shown. Wondering if both the NBM and NWS Omaha need to raise their totals to be in line with latest guidance.

oma snow analysis.png

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For the Iowa City/CR area, we'll get about 4-5 hours of precip before being dry slotted.  So any changeover to snow will have to happen very fast and come down very hard to overcome warm grounds and temperatures at or maybe even above freezing.  So all that being said, I've seen storms like this a hundred times, we'll get a half inch of sloppy crusty snow/ice.  Probably get a WWA issued even though it's basically a nothing event around here.  

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Winter Storm Warning hoisted for Omaha:

Quote

...WINTER STORM WARNING IN EFFECT FROM 6 AM WEDNESDAY TO 6 AM CST THURSDAY...

* WHAT...Heavy mixed precipitation expected. Total snow accumulations of 3 to 8 inches and ice accumulations of around one tenth of an inch. Winds gusting as high as 25 to 35 mph.

* WHERE...Portions of southwest Iowa and east central and southeast Nebraska.

* WHEN...From 6 AM Wednesday to 6 AM CST Thursday.

 

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NWS Omaha's thinking doesn't make a ton of sense to me.

The WSW above is for 3-8" of snow, which is a relatively large range, sure, but like I showed above there isn't a single operational model showing 3" of snow for Omaha, and the mean of all guidance is about 8".

Let's suppose we assume the model guidance that does show 3-5" for Omaha (looking at you, NAM) is correct. This means instead of snow, we should be expecting about half an inch of freezing rain (which doesn't appear plausible to begin with, since precip rates should be too high) and about 0.1" of sleet - again, taking the 18z NAM verbatim. But NWS Omaha of course isn't expecting nearly that much freezing rain, instead favoring less than 0.1" of ZR in the city:

StormTotalIceWeb.jpg

So if the precipitation isn't showing up via snow or freezing rain, per NWS Omaha, then the only other options are sleet and outright rain. But remember, taking the NAM verbatim, sleet is not a dominant factor in this forecast, and evaporative cooling is likely to limit sleet from getting to a significant level.

Which leaves rain as the only option. But NWS Omaha's precip type graphic keeps everything in the city as either snow or some form of wintry mix:

https://pbs.twimg.com/media/FmsEm3HacAAFNob?format=jpg&name=large

So it seems there's a mismatch here. NWS Omaha is, from what I can see, taking the low side of model guidance in snow terms, and the low side in freezing rain, and the low side in sleet, while not accounting for any rain. The only thing I can think of that the WFO expects is for precip to come in way below what model guidance is showing, a solution that (while possible, I suppose) isn't currently forecast by any global models.

Add in the 18z NBM sending snow totals way up in the city so that the expected snow total is above the high water mark in the warning text (attached image), and either NWS Omaha is seeing something I'm not, or their forecast is going to bust pretty substantially. They're trained meteorologists so I won't pretend I know which side is right, but I do know there's a mismatch between model guidance and the WFO.

nbm-conus-nebraska-total_snow_10to1-4172800.png

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6 minutes ago, The Snowman said:

NWS Omaha's thinking doesn't make a ton of sense to me.

The WSW above is for 3-8" of snow, which is a relatively large range, sure, but like I showed above there isn't a single operational model showing 3" of snow for Omaha, and the mean of all guidance is about 8".

Let's suppose we assume the model guidance that does show 3-5" for Omaha (looking at you, NAM) is correct. This means instead of snow, we should be expecting about half an inch of freezing rain (which doesn't appear plausible to begin with, since precip rates should be too high) and about 0.1" of sleet - again, taking the 18z NAM verbatim. But NWS Omaha of course isn't expecting nearly that much freezing rain, instead favoring less than 0.1" of ZR in the city:

StormTotalIceWeb.jpg

So if the precipitation isn't showing up via snow or freezing rain, per NWS Omaha, then the only other options are sleet and outright rain. But remember, taking the NAM verbatim, sleet is not a dominant factor in this forecast, and evaporative cooling is likely to limit sleet from getting to a significant level.

Which leaves rain as the only option. But NWS Omaha's precip type graphic keeps everything in the city as either snow or some form of wintry mix:

https://pbs.twimg.com/media/FmsEm3HacAAFNob?format=jpg&name=large

So it seems there's a mismatch here. NWS Omaha is, from what I can see, taking the low side of model guidance in snow terms, and the low side in freezing rain, and the low side in sleet, while not accounting for any rain. The only thing I can think of that the WFO expects is for precip to come in way below what model guidance is showing, a solution that (while possible, I suppose) isn't currently forecast by any global models.

Add in the 18z NBM sending snow totals way up in the city so that the expected snow total is above the high water mark in the warning text (attached image), and either NWS Omaha is seeing something I'm not, or their forecast is going to bust pretty substantially. They're trained meteorologists so I won't pretend I know which side is right, but I do know there's a mismatch between model guidance and the WFO.

nbm-conus-nebraska-total_snow_10to1-4172800.png

 

I'm guessing they are going heavily on their own model blend forecast.  This shows much lower totals in Omaha.  The NWS is typically highly conservative with snow totals anymore.  And frankly, models do very frequently overdo moisture and snowfall, so a % less than the models show is probably not a bad idea.  What that % is, is hard to say though. 

 

 

snowfall_acc-imp.us_c.png

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Been a very long time since I have seen a map like this. Nearly the entire state of Nebraska is under a WSW. 

Lastly, here is what's being forecasted in Central Nebraska at Ord. Pretty impressive stuff! 

Tonight
Snow likely, mainly after 5am. Cloudy, with a low around 22. Northeast wind 5 to 15 mph, with gusts as high as 25 mph. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
Wednesday
Snow. The snow could be heavy at times. Widespread blowing snow, mainly after 5pm. High near 25. Blustery, with a north northeast wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 100%. New snow accumulation of 10 to 16 inches possible.
Wednesday Night
Snow, mainly before midnight. Patchy blowing snow. Low around 16. Blustery, with a north wind 20 to 25 mph, with gusts as high as 35 mph. Chance of precipitation is 90%. New snow accumulation of 1 to 3 inches possible.

Screen Shot 2023-01-17 at 2.52.25 PM.png

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NWS Blend brings most if not all back to reality .... let's be honest--- 2' of snow in C.NE in one event happens about 1 in 33 years. ( NW NE is different) --- -- same thing here in C.IA -- a 6" event is about once every 2-3 years. Don't have my hopes up-- other than convective potential which don't happen much. That's all I'am really looking forward to as the actually synoptic snows will be will NW...

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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13 minutes ago, Grizzcoat said:

NWS Blend brings most if not all back to reality .... let's be honest--- 2' of snow in C.NE in one event happens about 1 in 33 years. ( NW NE is different) --- -- same thing here in C.IA -- a 6" event is about once every 2-3 years. Don't have my hopes up-- other than convective potential which don't happen much. That's all I'am really looking forward to as the actually synoptic snows will be will NW...

Last time I can recall was in March of 2006. I got 2 feet of snow, places out by ord got 30”.  I think you’re right though 2 ft might be a little high. Will see, I’ll gladly take what we can get. 

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7 minutes ago, hawkstwelve said:

Seems like most models so far today have cut back totals on the northern edge of the system (NAM cut in half, RGEM cut by 2 inches, Canadian in half vs yesterday's 12z, etc.) yet the 18z NBM is among it's highest totals yet for FSD at 7.2 inches with 10:1 ratios. Isn't that model a combination of many of the models we are looking at individually? The GFS is the only model still showing 8+ inches so it's kind of odd the NBM almost doubled totals on it's 18z run and ends up just shy of what the GFS is showing.

At this point things are obviously a lock for almost all of Nebraska (save the very SW corner) and most of E IA. I think those of us on the fringes, either north or south, will mostly be a nowcast scenario to see either a) how far north the heavier band can reach and b) how much mixed precip plays into the southern edge. It'll be tough for models to nail either of those aspects down prior to the onset of the system. 

Congrats on another warning!!-- ( Shovel that snow down street from your driveway -- in fact -- make a small "C" on the the upward side where the plow comes from) this makes all the difference in clearing a driveway after MANY snow plows have gone through. Grew up in Minny. But don't blow your snow in the street- that's Iowa like-- please refrain .

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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IF -- big IF, MSP receives 6" from this event; MSP; will be ahead of all time snowfall seasonal records. Albeit- 1982 in a few days changes that. But still... Amazing stat.

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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DSM take 4--- love the 3-9" in Council Bluffs (WTF?)-- they have no clue. Like 1-3 inches of rain in the summer over night---  -- that stats wise is really not a forecast--

StormTotalSnow.jpg

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The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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3 hours ago, Grizzcoat said:

IF -- big IF, MSP receives 6" from this event; MSP; will be ahead of all time snowfall seasonal records. Albeit- 1982 in a few days changes that. But still... Amazing stat.

Through 1/17/14 my total was at 47.8" (96% of annual avg), with another major storm that hit 9 days later on the 25th. January for mby in far south Lwr MI was an incredible 42.8"! There's a reason we are sitting on the sidelines watching The Plains get their turn as the pendulum swings both ways in this Sub. 

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Winter 2023-24 Snow Total = 52.8" (89% Normal Season)  Largest Storm: 12" (1/12-13)   Oct: 0.1 Nov: 2.9 Dec: 7.5 Jan: 31.7 Feb: 6.0 Mar: 4.1 Apr: 0.0

Avg = 59.2"  (Harrison): 2023-24 = xx.x" 

Avg = 45.0"  (KDTW): 2022-23 = 33.5"   2021-22 = 35.6"    

Avg = 49.7"  (KRMY): 2020-21 = 36.2"   2019-20 = 48.0"   2018-19 = 56.1"   2017-18 = 68.3"    2016-17 = 52"    2015-16 = 57.4"    2014-15 = 55.3"    2013-14 = 100.6" (coldest & snowiest in the modern record!)  2012-13 = 47.2"    2011-12 = 43.7"

Legit Blizzards (high winds and dbl digit snows): Feb 2011, Dec 2009, Jan 2005, Dec 2000, Jan 1999, Mar 1998, Nov 1989, Jan 1982, Jan 1978, Jan 1977, Apr 1975, Mar 1973, Jan 1967, Feb 1965, Jan 1918

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