September 2018 Discussions & Observations Thread

[LibertyBell]

12 minutes ago, bluewave said:

The two consecutive El Nino Octobers in 2014 and 2015 were active. 

hmm I wonder why...... I know we've been talking about some of our bigger storms occurring later in the season than before.

[Cfa]

0.64 final total. Finished with a nice rainbow too.

[uncle W]

1936 east coast hurricane...

http://bklyn.newspapers.com/image/52701203/

http://bklyn.newspapers.com/image/52701232

 

[Rtd208]

Picked up 0.82" of rain for the day yesterday.

[CIK62]

Next 8 days averaging 71degs., or about 6degs. AN.

Month to date is +3.1[73.3].    Should be +4.0[72.5] by the 27th.

[Rtd208]

Both the 00z & 06z GFS look pretty wet for next week. There is also a chance for severe weather on Friday.

[bluewave]

Clash of the seasons coming up over the next week to 10 days. An early fall trough arrives over the Midwest with the WAR still hanging on near the East Coast. Strong late September Great Lakes  cutter pattern along the temperature gradient to our west.

 

 

 

[donsutherland1]

During the September 1-18 period, the temperature averaged 73.3° in New York City. That makes 2018 the 19th warmest case for the first 18 days of September. Based on both the historical data and the latest guidance, the probability that 2018 will see the fourth consecutive September with a monthly mean temperature of 70° or above has increased.

Since 1869, there were 20 prior cases where the temperature averaged 73° or above during the first 18 days of September. In 16/20 or 80% of those cases, the monthly temperature averaged 70.0° or above. In all other cases, just 14% of years saw September average 70.0° or above.

Cases with a 9/1-18 Average Temperature of 73° or above:
Mean September 19-30 temperature: 66.1° (lowest: 57.5°, 1947; highest: 70.2°, 2005)
Mean September temperature: 71.3° (lowest: 68.6°, 1947; highest: 74.5°, 2015)

Cases with a 9/1-18 Average Temperature below 73°:
Mean September 19-30 temperature: 64.5° (lowest: 55.6°, 1871; highest: 74.7°, 1881
Mean September temperature: 67.4° (lowest: 60.9°, 1871; highest: 73.3°, 1881)

For those who are interested, September 1-18, 1881 had a mean temperature of 72.4°, which was the 30th warmest first 18 days of the month.

In terms of the guidance (using the first 18 days of September and the MEX MOS and EPS), the estimated mean temperature for September 2018 fell within a 70.5°-72.5° range. The implied probability of September’s having a mean temperature of 70.0° or above was 75%. In the coldest scenario, the implied probability was 64%.

Such a warm September is consistent with the long-term observed warming that has seen the return time for September cases with 70.0° or warmer average temperatures shorten.

Return Times for September Cases with Average Temperatures of 70.0° or Above (1869-2017):

Before 1980: 5.0 years
1980-2017: 3.2 years
2000-2017: 2.3 years
2010-2017: 1.6 years

1869-2017 Period: 4.4 years

Yesterday’s 1.19” rainfall brought New York City’s year-to-date precipitation to 44.90”. That ranks as the 71st highest on record in New York City. Based on this data and both the historic (1869-2017) and recent (1971-2017) periods, 2018 will very likely see 50.00” or more precipitation. 60.00” is possible. The lowest 9/20-12/31 precipitation on record is 5.68”, which occurred in 1998. Even that figure would bring the 2018 total above 50.00”.

1869-2017 Data:

Implied probability of 50.00” or more: 96%
Implied probability of 60.00” or more: 24%
Mean 9/20-12/31 Precipitation: 12.21”
Mean Annual Precipitation: 45.27”

1971-2017 Data:

Implied probability of 50.00” or more: 96%
Implied probability of 60.00” or more: 42%
Mean 9/20-12/31 Precipitation: 14.12”
Mean Annual Precipitation: 50.42”

Since 1970, in conjunction with the observed warming, the climate has also grown wetter. Extreme wet outcomes have grown more common.

This trend can be seen throughout the Northeast. Indeed, a disproportionate share of the 20 wettest years has occurred since 1970. Select data follows with the start of the climate record in parentheses:

Albany (1874): 80% of the 20 wettest cases
Bangor (1925): 60% of the 20 wettest cases
Boston (1872): 40% of the 20 wettest cases
Burlington (1884): 35% of the 20 wettest cases
Caribou (1939): 90% of the 20 wettest cases
Concord (1868): 35% of the 20 wettest cases
Hartford (1905): 75% of the 20 wettest cases
New York City (1869): 80% of the 20 wettest cases
Newark (1931): 75% of the 20 wettest cases
Philadelphia (1872): 50% of the 20 wettest cases
Portland (1871): 70% of the 20 wettest cases
Providence (1904): 65% of the 20 wettest cases
Worcester (1892): 60% of the 20 wettest cases

The following locations have seen at least 25% of their 20 wettest years occur 2000 or later: Albany, Burlington, Caribou, Concord, Hartford, New York City, Newark, Portland, and Providence.

For New York City, the 20th highest annual figure is 53.79”. Based on the 1869-2017 data, the implied probability that 2018 will surpass that amount is 79%. Based on the wetter 1971-2017 period, the implied probability is 85%.

Farther south, Baltimore has already registered its 17th highest annual precipitation amount. There remains a possibility that Baltimore will reach or exceed its record figure by year’s end. Wilmington, NC, which has already received 86.40” precipitation, boosted by Hurricane Florence, has eclipsed its old mark. In fact, that figure is among the highest on record in North Carolina. Only a few locations in North Carolina, including the following have seen higher amounts of precipitation in a year:

Boone: 112.14”, 2013
Blowing Rock: 93.32”, 1992
Cape Hatteras: 90.84”, 1989
Coweeta Experimental Station (near Otto, NC): 93.92”, 2013
Grandfather Mountain: 89.12”, 1979
Highlands: 111.57”, 2013;
Morehead City (2 WNW): 91.51”, 2003
New Bern (3 NW): 89.45”, 1908
Rosman: 126.73”, 1961
Southport (5 N): 89.79”, 1999
Tryon: 92.76”, 1979

Cape Hatteras, Morehead City (2 WNW), New Bern (3 NW), and Southport (5N), all of those locations are in the vicinity of the Appalachian Mountains.

 

[winterwx21]

4 hours ago, Rtd208 said:

Both the 00z & 06z GFS look pretty wet for next week. There is also a chance for severe weather on Friday.

The timing of the front is late friday night, so I would think that would limit the severe potential.

[Brian5671]

13 minutes ago, winterwx21 said:

The timing of the front is late friday night, so I would think that would limit the severe potential.

it's 8 days away, plenty can change...

[CIK62]

Next 8 days averaging  70degs., or about 6degs AN.

Month to date is +3.3[73.0].   Should be +4.1[72.2] by the 30th.

(Site was down over two days)

[bluewave]

Great to see the forum back up again. The big story this month continues to be the record warm average minimum temperatures. Most stations are running +6 to +7 for the average low temperature departures. This places most stations in the top 3 warmest on record for 9/1 to 9/21.

 

[sferic]

Fantasy, but interesting on GFS, Reminds me of 10.4.87

[FPizz]

Feels cool today being in the upper 60s outside.

[winterwx21]

On 9/19/2018 at 11:24 AM, Brian5671 said:

it's 8 days away, plenty can change...

It wasn't 8 days away. He was talking about the front that came through last night. Or at least that's what I thought he was talking about. Doubt he would be talking about severe potential that was more than a week away. And next friday looks dry so I doubt he meant then. I think he meant friday's night's (last night) front. Too late at night for us to get severe.

[JustinRP37]

Withdrawals are over the site is back!!!

[LongBeachSurfFreak]

Wow, happy amx is back. Today was the quintessential early fall day! Should be an interesting week in the Atlantic.

[Santa Claus]

42 minutes ago, LongBeachSurfFreak said:

Wow, happy amx is back. Today was the quintessential early fall day! Should be an interesting week in the Atlantic.

Fall is right.  Crisp night outside.  No wind and mostly cloudy.

[sferic]

HELLO FALL !

[Snowman86]

2 hours ago, sferic said:

HELLO FALL !

Yes

[MJO812]

Winter is almost here

[RedSky]

56 minutes ago, Snow88 said:

Winter is almost here

 

[CIK62]

Next 8 days(remainder of Sept.) averaging  68degs., or about 4degs AN.

Month to date is +3.3[72 7].   Should end month at +3.5[72.0].

[bluewave]

Here we go again. More 70 degree dew points and PWAT's near 2.00 on Tuesday. So expect heavy rain potential with the storm system.

 

[Rtd208]

1 minute ago, bluewave said:

Here we go again. More 70 degree dew points and PWAT's near 2.00 on Tuesday. So expect heavy rain potential with the storm system.

 

Yeah the models look like they are pretty wet, at least the NAM/GFS.

[bluewave]

34 minutes ago, Rtd208 said:

Yeah the models look like they are pretty wet, at least the NAM/GFS.

The Euro has heavy rain potential also as the warm front slows in response to the big high over New England. We could also sneak in another 80 degree day behind the front on Wednesday with enough sun.

[doncat]

Going back to 2010, with the exception of 2013, all septembers have seen above normal temps with many significantly so. October's are similar with only 2015 near normal. Miss cool autumns.

[SACRUS]

Since Sep 7 this is day # 14 of 17 that's been mostly cloudy.  1 full sun 2  partly sunny.  What could have been on departure side with the overall ridging and higher heights.

http://mp1.met.psu.edu/~fxg1/SAT_NE/anim8vis.html

[SACRUS]

 

 

 

[SnoSki14]

7 minutes ago, doncat said:

Going back to 2010, with the exception of 2013, all septembers have seen above normal temps with many significantly so. October's are similar with only 2015 near normal. Miss cool autumns.

I think the cool autumn ship has sailed permanently. At this point we'd be fortunate just to avoid the top 10 warmest fall months.