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And we begin


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At this time of year, freezing ice releases latent heat and there is usually a spike or two as it does. There was some talk about this in the Arctic Ice thread.

 

That may be true, but there is no surface ice being formed north of 80 degrees this time of year.  The spikes are typically due to weather systems moving the cold air out of that area and into regions further south.  That's what happened during the first 50 days of the year as well.  

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This is probably a little remedial if not obvious, but how is Eurasia defined for the purposes of the SAI? The entire Eastern Hemisphere north of 60N?

 

For the SAI, it's essentially all of Europe and Asia, but south of 60N instead of north of 60N.  Specifically, it's 25-60N and 0-180E 

 

See http://web.mit.edu/jlcohen/www/papers/CohenandJones_GRL11.pdf

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Today and Sept 30th

Big Gains on our side .

The Oct 3 map shows snow covering the northern half of Minnesota. I cans find no snow on webcams there and only found one observation of light snow with temps in the mid 30's yesterday. Calls into question the accuracy of the whole map IMO.

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NWS Central Illinois

"We don't want to alarm you, but snow was reported in parts of northern Illinois this morning. Rockford reported its 2nd earliest snowfall on record, and Chicago had its third earliest. Parts of the Quad Cities metro area also reported light snow. So far nothing of that sort this far south, although we did see wind chills in the 20s earlier this morning north of I-74. Winter is not too far away..."

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NWS Green Bay

"Some locations saw their first (light) snowfall late night into this morning. 0.8" was reported in Arbor Vitae and 0.4" in Merrill. Did you see any in your location? If so, how much? Send us a pic if you can!

Any snow will change over to rain by this afternoon. Rain chances end later today, then a very chilly night is expected with lows in the upper 20s to middle 30s."

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We're near the bottom. Season melt season least robust since 2006 but no thank you on that winter.

attachicon.gifimage.jpg

Hard saving the snow progression. Let's see it grow in the coming weeks especially as we approach October.

attachicon.gifimage.jpg

 

 

Pretty cool to see how much we've progressed in under a month. Of course what matters though is what happens south of 60 N in Eurasia.

 

cursnow.gif

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Is there any way to illustrate the depth of the snow...how exactly is this data captured by remote sensing technology?

Try Instant weather maps. They have the GFS forecast depth and extent changes which can be quite useful. http://www.instantweathermaps.com/GFS-php/showmap-nh.php?run=2014101212&var=SNOD_sfc&hour=000

 

Today

 

post-451-0-81441900-1413142606_thumb.gif

 

T+180

 

post-451-0-47883000-1413142624_thumb.gif

 

Some good gains in both depth and extent forecast, especially south of 60ºN

 

post-451-0-84860500-1413142774_thumb.gif

 

Can't vouch for accuracy (in depth) though.

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Try Instant weather maps. They have the GFS forecast depth and extent changes which can be quite useful. http://www.instantweathermaps.com/GFS-php/showmap-nh.php?run=2014101212&var=SNOD_sfc&hour=000

 

Today

 

attachicon.gif NH_SNOD_sfc_000-1.gif

 

T+180

 

attachicon.gif NH_SNOD_sfc_180.gif

 

Some good gains in both depth and extent forecast, especially south of 60ºN

 

attachicon.gif NH_SNOWCPER_sfc_180.gif

 

Can't vouch for accuracy (in depth) though.

The depth is directly based off the snow depth parameter in the GFS model, without any post-processing. Oftentimes the observed time-0 snow depth can be a bit off (such as showing a placeholder amount of an inch or two when actually a lot more fell but no confirmed observations have happened yet), but not much can be done about that without compromising my maps' equality with the raw model output.

 

ETA: Looked at old data. this is pretty good. No clue what I was talking about

 

NH_SNOD_sfc_384.gif

You probably meant to post the image below. For bandwidth and archival reasons we don't allow hotlinking of our images. I highly encourage posting of images from my site, though; just use a site like Imgur to rehost them instead of directly linking. There is a wonderful Firefox addin that turns the uploading into a one-click task as well.

AFG1pad.gif

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Current SAI. Values plotted are snow extent in Eurasia south of 60N. Like last year, we are starting with above normal snow extent. Let's see where things go over the next 21 days.

Based on that chart , it seems our very high starting level will severely limit the ability for the SAI to be very favorable unless we finish October with Record extent. But based on other posts, it looks like there is significant reason to think Mid to Late October will have above normal extent in Siberia which could lead to the second year in a row that Cohen has the SAI and SCE  are conflicting.

 

And to be clear, our starting point at 150 instead of 50 is a starting point 3x higher than ave so the % of increase obviously is crippled in a very big up hill battle to get near normal when starting at a level 3x the average base.

 

As another poster pointed out when the SAI /and SCE are conflicting and SCE is very high I would run SAI including beginning of week 39, since the correlations seem to be more representative of what the data was trying to measure (snow cover increase as winter begins in Siberia)  instead of just a magic Oct 1 date.  

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The depth is directly based off the snow depth parameter in the GFS model, without any post-processing. Oftentimes the observed time-0 snow depth can be a bit off (such as showing a placeholder amount of an inch or two when actually a lot more fell but no confirmed observations have happened yet), but not much can be done about that without compromising my maps' equality with the raw model output.

 

AFG1pad.gif

Cheers for that info. I had suspected as much regarding the T+0 snow depth chart. Love the strat charts btw!

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