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October 2017 Discussion


Hoosier

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30 minutes ago, Hoosier said:

I would argue there is a pretty clear trend since the 1980s, but a lot of it may come down to site location and land development changes.  It would be interesting to take some rural sites and see what that looks like.

Yep.  Plus, I don't think "first freeze" is the best metric to use for these types of discussions.  Although first freeze is an easy thing to calculate, it's not always representative of the larger picture (i.e. there could be several cool nights in 30s but if none of then happens to be 32 or lower, it will seem like a warm Fall when in reality it wasn't...or the opposite situation where there happened to be an early freeze...but then most nights were 40s/50s...in which case the avg Sep/Oct min temp is warm despite the early freeze).  

I am more talking about consistently cool mornings in the Fall.  It just seems recently (say 2000-present) that it takes forever to get cool Fall mornings at ORD...like until mid-November.  And it's even worse in downtown Chicago.  They probably haven't dropped into the 40s all season...and may not do so until the 3rd or 4th week of October.  Downtown Chicago probably has the longest growing season in all of Illinois, which is crazy when you think about it.

Case in point - normal low for ORD today is 46, yet ORD hasn't dropped below 48 all season...and probably won't for another week.  Considering the "normal distribution" of daily lows...for every min temp of 50, you'd expect one of 42...but that hasn't been happening in recent years.  80-90% of Sept/Oct mornings seem to range from "slightly above normal" to "much above normal".  ORD just doesn't get any normal cool Fall mornings consistently over the past several years...not just 2017.  I hope that makes sense.

Not meant to be a "complaining" situation...just strange.  Can it all be UHI??  Or is something else going on?   

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35 minutes ago, beavis1729 said:

Yep.  Plus, I don't think "first freeze" is the best metric to use for these types of discussions.  Although first freeze is an easy thing to calculate, it's not always representative of the larger picture (i.e. there could be several cool nights in 30s but if none of then happens to be 32 or lower, it will seem like a warm Fall when in reality it wasn't...or the opposite situation where there happened to be an early freeze...but then most nights were 40s/50s...in which case the avg Sep/Oct min temp is warm despite the early freeze).  

I am more talking about consistently cool mornings in the Fall.  It just seems recently (say 2000-present) that it takes forever to get cool Fall mornings at ORD...like until mid-November.  And it's even worse in downtown Chicago.  They probably haven't dropped into the 40s all season...and may not do so until the 3rd or 4th week of October.  Downtown Chicago probably has the longest growing season in all of Illinois, which is crazy when you think about it.

Case in point - normal low for ORD today is 46, yet ORD hasn't dropped below 48 all season...and probably won't for another week.  Considering the "normal distribution" of daily lows...for every min temp of 50, you'd expect one of 42...but that hasn't been happening in recent years.  80-90% of Sept/Oct mornings seem to range from "slightly above normal" to "much above normal".  ORD just doesn't get any normal cool Fall mornings consistently over the past several years...not just 2017.  I hope that makes sense.

Not meant to be a "complaining" situation...just strange.  Can it all be UHI??  Or is something else going on?   

I looked up temps of 39F or lower at ORD since 1980.  It's happened 39 times in September (so about 1 per year on average) and 433 times in October (over 11 per year on average). A lot of time yet to go this month but I kind of doubt we will get 11 such days.

Just to be clear, this is only back to 1980 to attempt to minimize the issues with site location changes (the exact location of the measuring site has moved around on the grounds of ORD over the years, but you'd expect that to have less impact than a move from some entirely different location in Chicago).

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Originally was looking good for over 1", and maybe 2" of rain around here this weekend, but I'm not sure.  I think it probably comes down to what happens tonight and tomorrow.  If that struggles, then it will be tough to get over 1" as the Saturday stuff should be fairly progressive.

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38 minutes ago, cyclone77 said:

So far the rains have been another disappointment.  Have a few sprinkles falling now, but that's about it.  

Radar is an abomination.  The stuff in southern IA/northern MO looks decent but probably going to mostly skirt south of us unless something changes.  

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Continuing with the first freeze talk from yesterday, I do agree that first freeze isn't necessarily a metric. I can remember many 33s where seemingly the rest of the area had a freeze. So I looked up avg # of days in the 30s in Oct for Detroit. Once again, the trend is undeniable...the 1970s-80s were a cold blip in the longterm trends from both before and after. 1870s and 2010s data obviously not complete.

The latest that a temp in the 30s was first seen for the season was 1900. The first low in the 30s wasn't until a low of 35F on Nov 6, 1900. The earliest was 1982, when a low of 38F was seen on Aug 29, 1982.

1870s: 13

1880s: 9

1890s: 8

1900s: 10

1910s: 8

1920s: 7

1930s: 11

1940s: 9

1950s: 9

1960s: 11

1970s: 14

1980s: 15

1990s: 11

2000s: 11

2010s: 8

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27 minutes ago, snowlover2 said:

0z NAM brings the remnants to W KY before a sharp east turn through southern Ohio. Farthest west I've seen it go thus far. Brings a soaker to most of OH/KY/SE IN.

I tried to isolate just Nate's remnants on here.  Very healthy rains, and it should be an efficient rainmaker as this is a legit tropical airmass.  NAM has precipitable water around 2.25" into Indiana/Ohio, which is ridiculous for October.  Track could shift of course.  NHC track is still farther east, but there's a good amount of model/ensemble spread to not dismiss a western solution yet.

qpf_048h.us_mw.thumb.png.7cb1e463e65f9b52d9cddacd3044985a.png

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48 minutes ago, cyclone77 said:

Looks like Hawkeye did pretty well again tonight.  Some passing showers this evening managed to get us up to 0.44" for the day.  Not great but we'll take it.

The heavy rain this evening largely missed me nw, just barely.  I picked up 0.34" earlier today, then another 0.33" this evening.  Just a mile or so nw received a total of an inch, while just nw of that 1.5+ inches.

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4 minutes ago, Jim Martin said:

 

pwat.us_mw.png

If it doesn't happen tonight, then there should be another shot at 00z tomorrow night as the moisture plume associated with Nate moves northward.  So it's not out of the question that record could be broken more than once in the next day or two.

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1 hour ago, Hoosier said:

Pretty impressive warm signal next weekend, especially near/south of I-80. Actually, it'd be pushing the bounds of what's ever been recorded in mid October.   Will be interesting to see if that backs off at all in coming days.

It will back down.

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