September 2017 Observations and Discussion

[Tom]

Who's ready for Autumn???  With the Summer season winding down and mother nature teasing us with beautiful autumnal-like air in the month of August, many of us are wondering what will September bring us???  Let's discuss the possibilities...

 

It's re-curving Typhoon season and some of the global models are suggesting a ripe atmospheric set-up in the W PAC to see plentiful systems re-curve and ultimately effect our downstream wx pattern.  In fact, almost like clock work, both GFS/EURO are showing a re-curving Typhoon during the opening days of Sept.  The 00z GFS from last nights run is suggesting a Super Typhoon to develop Day 7-10 in the W PAC and re-curve up into the N PAC.  If this track holds, it will certainly give us a clue that Week 2 in Sept could get pretty chilly and active in the Eastern CONUS.

 

 

 

 

 

 

 

[jaster220]

Iirc Tom, it was a recurving Typhoon that caused Nov 2014's early Arctic Blast. Again, it's ideal to save the best patterns for MET winter, but we don't get to order our wx, only our pizza

[Tom]

Iirc Tom, it was a recurving Typhoon that caused Nov 2014's early Arctic Blast. Again, it's ideal to save the best patterns for MET winter, but we don't get to order our wx, only our pizza

Yes, I believe so.  I agree, save this type of pattern for late Autumn.  Although, it could be a clue going forward.  We shall see what nature delivers this year.

[Tom]

Post Labor Day cold risks are being illustrated on the 12z GEFS dramatically.  Unusual ensemble run (for Sept standards) indicating above normal moisture around the GL's...lake effect rains????

 

[jaster220]

@ map above - Sept snow's not out of the question, especially across the UP and NMI's interior ridge. Earliest I personally witnessed was 9/19/95 when the ground was whitened after some heavy LES squalls near Higgins Lake SP.

[Tom]

CPC still thinking that the central CONUS will be cooler than normal through end of September...a bit dry though...

 

 

 

http://www.cpc.ncep.noaa.gov/products/predictions/WK34/gifs/WK34temp.gif

 

 

http://www.cpc.ncep.noaa.gov/products/predictions/WK34/gifs/WK34prcp.gif

[Niko]

Hello Autumn!

 

Labor Day Weekend, Halloween and ThanksGiving to follow. How time flies!

[Minny_Weather]

Met Fall will definitely start off like Summer in this region, with highs likely reaching 90 next weekend in NE before both Euro and GFS advertise a strong cold front to start off the week of 9/4.

[Tom]

Met Fall will definitely start off like Summer in this region, with highs likely reaching 90 next weekend in NE before both Euro and GFS advertise a strong cold front to start off the week of 9/4.

Ya, looks like a "puff" of very warm air for you guys out in the Plains.  Is this caused by Harvey's "venting" and an approaching front from the north resulting in sinking/compressing air??  I remember hearing this before how much Hurricane's impact the wx even though being 100's of miles away.  

 

I think after this weeks impacts on Harvey, the other big ticket item that will grab the attention of wx enthusiasts is the possibility of a Super Typhoon out in the W PAC.  Last night's 00z Euro run picked up on what the GFS was showing yesterday illustrating a monster of a storm re-curving east of Japan around the 2nd/3rd of the month.  We'll see if this trend continues.

 

 

[Tom]

Both GFS/EURO are picking up on a vigorous autumn storm system tracking somewhere across the norther tier of CONUS around Labor Day tugging down some real chilly air for the 1st full week of Sept.

 

 

 

 

 

18z GFS...Hello Autumn!

 

 

 

Not only that, but if we utilize the Bearing Sea Rule and East Asian Theory, Sept may be rocking with tons of storm systems.  I have a gut feeling this month may deliver some real unusual early season cold.

 

Over the next 10 days, the 12z Euro is showing 3 big storms tracking near the Aleutians...

Day 3...

 

 

 

Day 7...

 

 

Day 10...

 

[OKwx2k4]

Both GFS/EURO are picking up on a vigorous autumn storm system tracking somewhere across the norther tier of CONUS around Labor Day tugging down some real chilly air for the 1st full week of Sept.

 

 

 

 

 

18z GFS...Hello Autumn!

 

 

 

Not only that, but if we utilize the Bearing Sea Rule and East Asian Theory, Sept may be rocking with tons of storm systems. I have a gut feeling this month may deliver some real unusual early season cold.

 

Over the next 10 days, the 12z Euro is showing 3 big storms tracking near the Aleutians...

 

Day 3...

 

 

 

Day 7...

 

 

Day 10...

 

I just wish this were winter with those awesome patterns.

[Minny_Weather]

Ya, looks like a "puff" of very warm air for you guys out in the Plains. Is this caused by Harvey's "venting" and an approaching front from the north resulting in sinking/compressing air?? I remember hearing this before how much Hurricane's impact the wx even though being 100's of miles away.

Funny thing is, THIS is hot for this year! Last year we were getting well into the 90s as late as 9/23, so if this is hot I'll take it!

[Tom]

To see an ensemble run showing 8-10C below normal temp maps 10+ days out is about as clear as it can get that we will be entering a potential record cold shot for the 1st week of Sept.  #EarlyFrost

 

 

 

 

 

 

00z EPS...

 

[Minny_Weather]

00z Euro advertising a VERY strong cold front on 9/5. Be glad it's not Winter!

[Tom]

00z Euro advertising a VERY strong cold front on 9/5. Be glad it's not Winter!

Crazy, right???  Last night's 00z GFS run was showing snow flurries for MN around the 9th...this cold shot is the real deal from all indications, esp if that Super Typhoon re-curves as the models are starting to figure out.

[Niko]

My highs are projected to be in the 50s and 30s for lows. That is certainly a real shot of chilly air, especially for early September standards.

[Tom]

Whether your a fan of chilly air or not, what the 00z Euro flashed last night is about as textbook "cross polar flow" as you can get...and its early Sept.  Is Nature saying something???

 

My worry about a week or two ago was that we would see something like this evolving as we opened Sept.  I think it is going to happen given what I'm seeing happen over the northern hemisphere.

 

 

 

[Thunder98]

I see a high of 59F at the very end of the forecast in Eau Claire, WI. Fall is coming early and fast!

 

https://www.wunderground.com/weather/us/wi/eau-claire/54703

 

[Niko]

I see a high of 59F at the very end of the forecast in Eau Claire, WI. Fall is coming early and fast!

 

https://www.wunderground.com/weather/us/wi/eau-claire/54703

 

fallweatheriscoming.PNG

That is a nippy forecast towards the end.

[Tom]

Labor Day weekend looks nearly perfect for many of us on here.  Might be a bit hot/humid out in the Plains but near the Lakes we will be rather comfortable.  Looking forward to closing out the summer season with some delightful weather.

 

Changes loom as we head into the later part of the holiday weekend as a rather strong cold front is still being advertised.  Still need more time to see how this pattern evolves as GFS & Euro are not agreeing on the evolution.

[Niko]

If that CF holds true after LDW, a lot of members on here will be feeling the first chill of the season. Perhaps frost and freeze warnings??!!

[westMJim]

My highs are projected to be in the 50s and 30s for lows. That is certainly a real shot of chilly air, especially for early September standards.

For GRR here is a list of the record coldest maximums for the first 12 days of September as recorded in weather threaded extremes 

 

9/1 59 in 1892 61 in 1951 61 in 1949 9/2 53 in 1974 64 in 1935 65 in 1946 9/3 58 in 1905 61 in 1974 61 in 1909 9/4 60 in 1918 62 in 2010 64 in 1984 9/5 60 in 1988 60 in 1975 64 in 1924+ 9/6 62 in 1944 63 in 1896 64 in 1988+ 9/7 55 in 1917 58 in 1924 61 in 1914 9/8 58 in 1924 60 in 1935 62 in 1914 9/9 59 in 1924 59 in 1902 59 in 1898 9/10 56 in 1940 56 in 1917 58 in 1924 9/11 55 in 1940 58 in 2006 59 in 2010 9/12 54 in 1902 57 in 1975 57 in 1943

 

and here is a list of the record lows for the first 12 days 

 

9/1 59 in 1892 61 in 1951 61 in 1949 9/2 53 in 1974 64 in 1935 65 in 1946 9/3 58 in 1905 61 in 1974 61 in 1909 9/4 60 in 1918 62 in 2010 64 in 1984 9/5 60 in 1988 60 in 1975 64 in 1924+ 9/6 62 in 1944 63 in 1896 64 in 1988+ 9/7 55 in 1917 58 in 1924 61 in 1914 9/8 58 in 1924 60 in 1935 62 in 1914 9/9 59 in 1924 59 in 1902 59 in 1898 9/10 56 in 1940 56 in 1917 58 in 1924 9/11 55 in 1940 58 in 2006 59 in 2010 9/12 54 in 1902 57 in 1975 57 in 1943

 

so yes if it came to pass that highs were in the 50's and or low in the 30's that would be very unusual for September in Michigan.

 

Here is the above list for Detroit 

 

coldest maximums 

 

9/1 61 in 1958 63 in 2003 63 in 1951+ 9/2 62 in 1974 63 in 1877 65 in 1908 9/3 65 in 1952 66 in 1883 67 in 1997+ 9/4 60 in 1885 64 in 1918 64 in 1896 9/5 62 in 1988 62 in 1891 63 in 1876 9/6 63 in 1988 63 in 1924 64 in 1896 9/7 60 in 1917 61 in 1903 62 in 1951+ 9/8 59 in 1880 60 in 1879 61 in 1995+ 9/9 57 in 1924 60 in 1914 61 in 1883+ 9/10 53 in 1917 56 in 1924 60 in 1940+ 9/11 57 in 1940 59 in 1914 60 in 1924 9/12 54 in 1902 60 in 1985 60 in 1946+

 

Coldest lows 

 

9/1 42 in 1967 42 in 1888 43 in 1970 9/2 44 in 1885 45 in 1958 45 in 1946+ 9/3 43 in 1976 43 in 1946 45 in 1877 9/4 40 in 1974 45 in 1997 45 in 1982 9/5 42 in 1984 42 in 1974 43 in 1972 9/6 38 in 1984 41 in 1976 42 in 1924 9/7 43 in 1986 44 in 1968 45 in 1988 9/8 39 in 1986 43 in 1883 44 in 1979+ 9/9 37 in 1883 40 in 1979 42 in 1986+ 9/10 40 in 1883 41 in 1972 41 in 1924+ 9/11 39 in 1917 40 in 1943 43 in 1993+ 9/12 39 in 1943 42 in 1970 43 in 1977+

[Tom]

Not just 1, but 2 big time Aleutian Low's are forecast to spin up and pump a major NW NAMER ridge to open up September.  Placement of this trough is nearly perfect to dislodge early season Frost potential.  If it were winter, well, you can imagine how cold it would be.  Just look at all that blocking in the Arctic!

 

 

 

 

 

 

 

 

Remnants of #Sanvu in the W PAC is forecast to become extra-tropical and replace the Sept 3rd storm near the Aleutian islands by Day 10...

 

[Tom]

12 GFS starting to flash a real potential for an early Frost for those in the Plains/Midwest after the 9th and likely sparked by the re-curving Typhoon #Sanvu.  Parts of the Northwoods may see their first Freeze's....fascinating pattern.  Placement of the coldest temps are likely going to change but the idea of this cold shot has been on my mind for a couple weeks already.

 

[Tom]

I'm hearing the new Euro Weeklies are cold for the entire month.  That being said, big time cool down for Week 2...

 

[Niko]

Would not be surprised if my first flakes fall in October.

[OKwx2k4]

12 GFS starting to flash a real potential for an early Frost for those in the Plains/Midwest after the 9th and likely sparked by the re-curving Typhoon #Sanvu. Parts of the Northwoods may see their first Freeze's....fascinating pattern. Placement of the coldest temps are likely going to change but the idea of this cold shot has been on my mind for a couple weeks already.

 

I see you down there by me mid-40s. Goodness that is going to feel nice.

[GDR]

This could be a December to remember for once

[Tom]

Met's starting to jump on board the "re-curving Typhoon" train in the W PAC which will aid in amplifying the N.A. wx pattern post Labor Day.  Thankfully, many of us will have a top notch closing to the official summer season this weekend.  Very much looking forward to 80's for beach/boat activities.

 

I'm going to enjoy the summery wx as much as I can this week/weekend bc next week we will be needing to dust off those light jackets/sweaters!  00z Euro driving the 540 thickness line all the way down into the Midwest next Wed/Thu morning!  #Frostymornings

 

 

 

 

 

 

[jaster220]

Yikes @ dagger plunge maps above - so much for our extended mild autumns of late. They were nice for those like myself who find "indian summer" a great time of year with the bugs gone and the aroma of leafs piling up.

[Tom]

Yikes @ dagger plunge maps above - so much for our extended mild autumns of late. They were nice for those like myself who find "indian summer" a great time of year with the bugs gone and the aroma of leafs piling up.

We will have some Indian Summer days this Autumn just like almost every year.  Although, it will likely come in earlier this year than previous years given how cold it looks to get in early Sept.  I have to agree with you in terms of the bugs and I hope to see them gone after we get through the first week of Sept.  If the Euro is right, HP will cause clear skies and calm winds to produce some widespread Frosts if the forecast verifies.

[Niko]

September is looking to be a chilly month tempwise. Lets see if that holds true.

[Minny_Weather]

Model inconsistencies are huge as we get into later next week. On the same day as 00z Euro shows highs not getting out of the low 60s here, 00z GFS shows highs in the mid-80s. On the same night as lows around 40 here are shown by Euro, GFS shows lows barely into the 50s. GFS is definitely warm-biased as it has been all Summer, add in Euro's very slight cool bias, and next week may STILL be historic temp-wise in some areas. Both do agree on a strong cold front early next week, however. Will be interesting looking at this afternoon's AFDs to see how the different offices interpret it.

[Thunder98]

Early Autumn weather is coming around September 5th-11th time frame? Highs in the 50's and 60's while lows in the 30's and 40's? Fall weather is coming early this year.

 

 

 

 

 

 

 

 

[jaster220]

Model inconsistencies are huge as we get into later next week. On the same day as 00z Euro shows highs not getting out of the low 60s here, 00z GFS shows highs in the mid-80s. On the same night as lows around 40 here are shown by Euro, GFS shows lows barely into the 50s. GFS is definitely warm-biased as it has been all Summer, add in Euro's very slight cool bias, and next week may STILL be historic temp-wise in some areas. Both do agree on a strong cold front early next week, however. Will be interesting looking at this afternoon's AFDs to see how the different offices interpret it.

 

GRR has leaned warm-biased all summer, only conceding in the final 24 hrs when it's "a lock". I expect they'll continue that way. Easy to understand though, since last holiday season when all the "cold shots" on the d10 maps somehow managed to fade as we approached d0

[jaster220]

 

Early Autumn weather is coming around September 5th-11th time frame? Highs in the 50's and 60's while lows in the 30's and 40's? Fall weather is coming early this year.

 

Must be leaning towards the GFS (or at least a blend). For those far north cities, those temps would be nothing special. As said, I've seen a late afternoon temp of 35º in NMI on 9/19/95

[westMJim]

Must be leaning towards the GFS (or at least a blend). For those far north cities, those temps would be nothing special. As said, I've seen a late afternoon temp of 35º in NMI on 9/19/95

There was wide spread frost and freezing temperatures around Michigan on 9/23/95.  It did not get that cold again until mid October.  November and December were cold and somewhat snowy. January and February were below average temperature wise with less than average snow fall. March was cold and snowy. And April was still cold.

[Tom]

Here is a nice illustration of the mechanics involved to produce our post Labor Day cold shot; 

 

 

 

 

 

Saw this post from a met and I'm seeing more '67/'76/'11 analogs...

 

 

 

PNA forecast approaching +2.5 standard deviations via morning CMC data. Its only happened 7 times in Sept. 1951,67,76 & 2011.

[Minny_Weather]

Not so fast for us plainsers. We'll get the cold shot, but beforehand we are getting the West Coast death ridge for a couple days during this next weekend. Won't be too far above normal, but it'll still feel hot because it's been so pleasant recently! I'm typing this as I have the windows open, it is in the upper 70s out, and my AC is off.

[Tom]

Not so fast for us plainsers. We'll get the cold shot, but beforehand we are getting the West Coast death ridge for a couple days during this next weekend. Won't be too far above normal, but it'll still feel hot because it's been so pleasant recently! I'm typing this as I have the windows open, it is in the upper 70s out, and my AC is off.

I know exactly what your feeling, esp when I flew back from 118F heat in June in AZ and upper 90's with humidity in mid July from the Monsoon.  Enjoy it bud!

 

Meantime, 12z Euro advertising record breaking low temps later next week as a major trough amplifies over the GL's region Day 8-10.