April 2023

[SnoSki14]

28 minutes ago, ILoveWinter said:

Awful, often sets up just north of Philly

It's just one day. Mid 80s by Thursday and then more 80s next week. 

Spring looks like an inferno this year as troughs keep dumping west and pump the SE ridge.

I think we could even see 90+ readings this month and definitely in May unless there's a big pattern change.

[jm1220]

11 minutes ago, SnoSki14 said:

It's just one day. Mid 80s by Thursday and then more 80s next week. 

Spring looks like an inferno this year as troughs keep dumping west and pump the SE ridge.

I think we could even see 90+ readings this month and definitely in May unless there's a big pattern change.

What we need to look for here are whether highs try to develop to our NE and/or deep troughs. If we see troughs forming over the Maritimes with a strong high in Quebec, it will try to force the back door fronts in. When those aren’t in place it will torch here like you said since the -PNA will definitely keep it warm to our south. 

[LibertyBell]

30 minutes ago, SnoSki14 said:

It's just one day. Mid 80s by Thursday and then more 80s next week. 

Spring looks like an inferno this year as troughs keep dumping west and pump the SE ridge.

I think we could even see 90+ readings this month and definitely in May unless there's a big pattern change.

<3 yes hot and dry!  We have been turning towards drier weather the last couple of springs and summers

The old pattern is back!

 

[LibertyBell]

15 minutes ago, jm1220 said:

What we need to look for here are whether highs try to develop to our NE and/or deep troughs. If we see troughs forming over the Maritimes with a strong high in Quebec, it will try to force the back door fronts in. When those aren’t in place it will torch here like you said since the -PNA will definitely keep it warm to our south. 

Hopefully the -PNA pumps all the way up to Alaska.

I have no use for cool soggy weather now.

 

[LibertyBell]

44 minutes ago, CIK62 said:

The next 8 days are averaging     57degs.(48/65) or about +4.

Reached 63 here yesterday at 3pm.

Today:    52-56, wind e., cloudy, 55 tomorrow AM.

53*(96%RH} here at 7am{was 55 overnight} FOG-about a 1/2 mile.

NOW HEAR THIS     GFS 0Z SAYS  April 13-20 will be  73(64/82) or +18 !!!

 

wow 12-20 almost every day is over 80 and 19 is close to 90...thats when it hit 96 in 2002!

 

 

[Volcanic Winter]

6 hours ago, LibertyBell said:

is there any evidence for a large airburst meteor strike though?

It’s heavily debated. I will say it’s an interesting theory, I definitely lean toward the traditional thinking but I enjoyed reading the papers on it. 

Check out the wiki for “Younger Dryas Impact Hypothesis.” Check references at bottom for the papers on it. I can link later for you if you like. 

It’s been a little bit since I reviewed the info on it, but I believe the most compelling stuff was increased platinum found in strata dating to 10,000 years ago in various locations across north and South America, which the authors argue indicates a relatively large (think it was 1ish km) asteroid exploding Tunguska style. 

It’s definitely much simpler to explain the YD as an AMOC shutdown from the melting Laurentide, and some of this evidence for a supposed impact is of course heavily contested. 

[Phillycane]

Another tornado confirmed in the Saturday outbreak. This one was an EF-1 in Bucks County PA

 

https://www.cbsnews.com/philadelphia/news/tornado-confirmed-in-bucks-county-nws-says/

 

 

[Roger Smith]

Given that GFS output for mid-April warmth, here's an average of daily highs from April to October for the four years with most impressive heat around same time, namely 1896, 1941, 1976 and 2002. 

The blue data represent daily calendar day averages Apr 1 to Oct 31. 

The orange data are slightly shifted for 1941 and 1976 so that all four have their peak day of mid-April warmth on the 18th. 1941 is shifted three days (so it runs from Mar 29 to Oct 28), and 1976 back by one day (runs Apr 2 to Nov 1). 

The most salient points would be continued relative warmth all of May and second half of June into July, not as impressive a warm signal by August, a slight recovery to warmth in early September, and a colder signal in October, although October 1941 had some record warmth in the first third. 

I also looked at rainfall amounts and those were generally dry to near end of May then mostly wet through summer and autumn months, in each case at least one month was very wet. 

[SnowGoose69]

10 minutes ago, bluewave said:

The Euro weakens the -PDO. But since it is now close to a super El Niño, we would have to deal with that warmth. So it will be interesting to see how it goes.

 

April run much stronger

 

March run weaker

New April run weaker -PDO

 

Hard to believe it’ll be that strong.  Last I checked the consensus on the ENSO models was mostly around 0.8-1.0 

[Allsnow]

14 hours ago, bluewave said:

Yeah, at some point the warm spots like Newark should at least make the mid 80s this month. Could be a little higher like several years since 2010.  Especially with the -PNA and SE Ridge. I will laugh if we still that have that Western Trough next winter again even with an El Niño. Would have to be a strong enough -PDO like the 72-73 El Niño to pull that one off.

 

Amazing how persistent the -pna has been this year. We never had a sustainable pna rise at all. West getting payback on us after all those winters spent under a ridge in the mid 2000’s 

[bluewave]

10 minutes ago, Allsnow said:

Amazing how persistent the -pna has been this year. We never had a sustainable pna rise at all. West getting payback on us after all those winters spent under a ridge in the mid 2000’s 

Yeah, all Western and Central troughs since the 15-16 super El Niño.

 

[donsutherland1]

8 hours ago, LibertyBell said:

Don is there a chance to hit 90 in April this year?

 

It's too soon to be sure. The potential exists for much above normal readings around mid-month. The signal for excessive warmth shows up on the weeklies and the long-range Extreme Forecast Index (EFI). A GFS run showed readings in the high 80s at one point. The picture should become clearer as mid-month approaches. But a top 10--maybe top 5--warmest April is plausible given the guidance.

Such cases have typically seen the temperature reach or exceed 85° for the monthly high. 1921, which ranks as the 6th warmest April, is the lone exception with a monthly high of 79°.

[Allsnow]

16 minutes ago, bluewave said:

Yeah, all Western and Central troughs since the 15-16 super El Niño.

 

Last sustainable pna ridge was probably Dec 2017 into January 18?

That was also our last sustainable cold shot 

[LibertyBell]

9 minutes ago, donsutherland1 said:

It's too soon to be sure. The potential exists for much above normal readings around mid-month. The signal for excessive warmth shows up on the weeklies and the long-range Extreme Forecast Index (EFI). A GFS run showed readings in the high 80s at one point. The picture should become clearer as mid-month approaches. But a top 10--maybe top 5--warmest April is plausible given the guidance.

Such cases have typically seen the temperature reach or exceed 85° for the monthly high. 1921, which ranks as the 6th warmest April, is the lone exception with a monthly high of 79°.

Extreme Forecast Index-- is this an index that forecasts when record highs or record lows are likely to occur and doesn't default to climo like most long range forecasts do?

 

[jm1220]

56 minutes ago, bluewave said:

Yeah, all Western and Central troughs since the 15-16 super El Niño.

 

I would think with this long lived switch we’re heading back to the decadal -PDO we had in the 1960s-80s if not mistaken. Hopefully some years can have enough of a Nino influence to break that. 

[bluewave]

37 minutes ago, Allsnow said:

Last sustainable pna ridge was probably Dec 2017 into January 18?

That was also our last sustainable cold shot 

Yeah, Dec 17-18 and Jan 21 were our only 30 day periods in 20s since 15-16.

Minimum 30-Day Mean Avg Temperature 
for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.

Rank	Value	Ending Date	Missing Days
1	27.2	2018-01-19	0

 

23

29.3

2022-02-02

0

 

[Wxoutlooksblog]

NAM now gets NYC to 80 tomorrow. Maybe they'll get there. Extremely warm pattern ahead with a reasonable chance that Central Park gets to 90 degrees at some point this month.

WX/PT

[bluewave]

12 minutes ago, jm1220 said:

I would think with this long lived switch we’re heading back to the decadal -PDO we had in the 1960s-80s if not mistaken. Hopefully some years can have enough of a Nino influence to break that. 

Seems like we have been getting shorter PDO intervals since 2000 with the ups and downs. Much different from the extended cold PDO in 50s to 70s. Also the positive periods much shorter than late 70s into 90s. 

https://psl.noaa.gov/data/climateindices/

[jm1220]

10 minutes ago, Wxoutlooksblog said:

NAM now gets NYC to 80 tomorrow. Maybe they'll get there. Extremely warm pattern ahead with a reasonable chance that Central Park gets to 90 degrees at some point this month.

WX/PT

To get to 90 hopefully there can be a W or WNW downslope day to really max the heat potential without too much humidity capping it. We really heat up in the summer on those kind of days vs the much more frequent S flow these days that pump up the humidity. 

We also have many more patterns now with the ridge peaking well north of us which encourages the S and even SE flow around the south side of the high. 

[Brian5671]

Really windy here today-temps slowly falling as well-down to 52

[nycwinter]

another day chilly enough to wear a coat and i did.

[donsutherland1]

1 hour ago, LibertyBell said:

Extreme Forecast Index-- is this an index that forecasts when record highs or record lows are likely to occur and doesn't default to climo like most long range forecasts do?

 

The ensemble spread increases with time, which weakens long-term signals. Beyond 2 weeks, the weekly forecasts lose their skill.

The EFI places ensemble values within quantiles based on statistical occurrences.

• quantile 1 (1 in 100 occasions less than value shown),
• quantile 10 (10 in 100 occasions less than value shown),
• quantile 50 (climate (M-climate) median),
• quantile 90 (10 in 100 occasions greater than value shown),
• quantile 99 (1 in 100 occasions greater than value shown).

• EFI values between 0.5 to 0.8 (irrespective of sign) can be generally regarded as signifying that “unusual” weather is likely,
• EFI values above 0.8 (irrespective of sign) as usually signifying that “very unusual” or extreme weather is likely. 

For more information:

https://confluence.ecmwf.int/display/FUG/Extreme+Forecast+Index+-+EFI,+and+Shift+of+Tails+-+SOT

Typically, the Week 3 idea has little or no EFI signal. That there is an expansive albeit weak signal (0.3-0.5) there suggests that it is worth monitoring things. A signal between -0.3 and 0.3 is often too weak to be very useful.

Here's an EFI map from the same lead time for March 27-April 3:

Selected Outcomes for March 27-April 3:

Bismarck: 7th coldest (Start of period of record: 1875)
Flagstaff: 18th coldest (Start of period of record: 1899)
Glasgow: 11th coldest (Start of period of record: 1894)
Las Vegas: 11th coldest (Start of period of record: 1937)
Salt Lake City: 29th coldest (Start of period of record: 1875)

Ensemble forecasts can be incorrect. So one has to watch to see how things evolve. Typically, if a risk assessment is correct, the signal should hold or strengthen as the event draws closer.

 

[LibertyBell]

3 minutes ago, donsutherland1 said:

The ensemble spread increases with time, which weakens long-term signals. Beyond 2 weeks, the weekly forecasts lose their skill.

The EFI places ensemble values within quantiles based on statistical occurrences.

• quantile 1 (1 in 100 occasions less than value shown),
• quantile 10 (10 in 100 occasions less than value shown),
• quantile 50 (climate (M-climate) median),
• quantile 90 (10 in 100 occasions greater than value shown),
• quantile 99 (1 in 100 occasions greater than value shown).

• EFI values between 0.5 to 0.8 (irrespective of sign) can be generally regarded as signifying that “unusual” weather is likely,
• EFI values above 0.8 (irrespective of sign) as usually signifying that “very unusual” or extreme weather is likely. 

For more information:

https://confluence.ecmwf.int/display/FUG/Extreme+Forecast+Index+-+EFI,+and+Shift+of+Tails+-+SOT

Typically, the Week 3 idea has little or no EFI signal. That there is an expansive albeit weak signal (0.3-0.5) there suggests that it is worth monitoring things. A signal between -0.3 and 0.3 is often too weak to be very useful.

Here's an EFI map from the same lead time for March 27-April 3:

Selected Outcomes for March 27-April 3:

Bismarck: 7th coldest (Start of period of record: 1875)
Flagstaff: 18th coldest (Start of period of record: 1899)
Glasgow: 11th coldest (Start of period of record: 1894)
Las Vegas: 11th coldest (Start of period of record: 1937)
Salt Lake City: 29th coldest (Start of period of record: 1875)

Ensemble forecasts can be incorrect. So one has to watch to see how things evolve. Typically, if a risk assessment is correct, the signal should hold or strengthen as the event draws closer.

 

Thanks this is fascinating, Don!  This could also be used to assess the risks of other anomalous events-- like tornado outbreaks, high wind events, big snow or rain storms, etc.?

 

[LibertyBell]

32 minutes ago, jm1220 said:

To get to 90 hopefully there can be a W or WNW downslope day to really max the heat potential without too much humidity capping it. We really heat up in the summer on those kind of days vs the much more frequent S flow these days that pump up the humidity. 

We also have many more patterns now with the ridge peaking well north of us which encourages the S and even SE flow around the south side of the high. 

Yes that means JFK can get to 90 too!  I hate the S to SE flow events and how frequent they've become.  NW to W is my favorite wind direction in the spring and summer.

 

 

[LibertyBell]

38 minutes ago, bluewave said:

Seems like we have been getting shorter PDO intervals since 2000 with the ups and downs. Much different from the extended cold PDO in 50s to 70s. Also the positive periods much shorter than late 70s into 90s. 

https://psl.noaa.gov/data/climateindices/

whats causing these periods to become shorter do you think, Chris?

 

[donsutherland1]

21 minutes ago, LibertyBell said:

Thanks this is fascinating, Don!  This could also be used to assess the risks of other anomalous events-- like tornado outbreaks, high wind events, big snow or rain storms, etc.?

 

At the short range, there are EFI tools for CAPE and CAPE Shear.  At the extended range, there is temperature, precipitation, and multi-parameter (includes a combination of temperature, precipitation, sea-level pressure, and wind gust).

[SACRUS]

 

Records:

 

Highs:

EWR: 83 (1985)
NYC: 80 (1928)
LGA: 74 (1989)

 

Lows:

 

EWR: 23 (1995)
NYC: 20 (1874)
LGA: 25 (1995)

Historical:

1936: Approximately 454 people were killed in the second-deadliest tornado outbreak ever in U.S. More than 12 twisters struck Arkansas to South Carolina. An estimated F5 tornado cut a path 400 yards wide through the residential section of Tupelo, Mississippi. At least 216 people were killed, and 700 were injured. The tornado had a 15-mile long path and did $3 million in damage. One of the survivors in Tupelo was a baby of an economically strapped family who had an infant they'd recently named Elvis Aaron Presley. Gainesville, Georgia had at least 203 fatalities and 934 injuries from an estimated F4 tornado that occurred early the following morning. 

1945 - The temperature at Eagles Nest, NM, plunged to 45 degrees below zero to establish an April record for the United States. (Sandra and TI Richard Sanders - 1987)

1955 - The Northern Rockies and the Northern High Plains were in the midst of a four day storm which produced 52 inches of snow at Lead, located in the Black Hills of western South Dakota. (David Ludlum)

1972 - A tornado, 500 yards wide at times, touched down at a marina on the Oregon side of the Columbia River, and then tore through Vancouver WA killing six persons, injuring 300 others, and causing more than five million dollars damage. It was the deadliest tornado of the year, and the worst of record for Washington. (The Weather Channel)

 

1972: An F3 tornado, touched down at a marina on the Oregon side of the Columbia River, and then tore through Vancouver, Washington. The tornado killed six people, injuring 300 others, and causing more than five million dollars damage. It was the deadliest tornado of the year and the worst on record for Washington. 

1982 - An unprecedented April blizzard began in the northeastern U.S. One to two feet of snow fell across Massachusetts and Connecticut, and up to 26 inches was reported in Maine. New York City received a foot of snow. Winds reached 70 to 80 mph during the storm, and the storm also produced numerous thunderstorms, which contributed to the heavy snow. (Storm Data)

1987 - A storm produced unprecedented April snows in the central Appalachians. Mount Mitchell NC received 35 inches of snow, and up to 60 inches (six feet) of snow was reported in the mountains along the border of North Carolina and Tennessee. The total of 25 inches at Charleston WV easily surpassed their previous record for the entire month of April of 5.9 inches. The 20.6 inch total at Akron OH established an all-time record for that location. (Storm Data) (The National Weather Summary)

1988 - Thirty-nine cities across the eastern half of the country reported record high temperatures for the date, including Saint Louis MO with a reading of 91 degrees. Laredo TX was the hot spot in the nation with an afternoon high of 100 degrees. (The National Weather Summary)

1989 - Unseasonably hot weather prevailed in the southwestern U.S. Afternoon highs of 100 degrees at Santa Maria CA and 105 degrees in Downtown Los Angeles established records for the month of April. (The National Weather Summary)

1990 - Afternoon and evening thunderstorms developing along a cold front produced severe weather in southern Oklahoma, southern Arkansas, and north central and northeastern Texas. Thunderstorms spawned a dozen tornadoes in Texas, including one at Fort Worth which caused a million dollars damage. There were nearly one hundred reports of large hail and damaging winds. Thunderstorms in Texas produced hail three and a half inches in diameter west of Fort Worth, and produced wind gusts to 80 mph at Cross Plains. (The National Weather Summary) (Storm Data)

[SACRUS]

Stuck in the clouds from CNJ on north and east

 

[Volcanic Winter]

22 minutes ago, SACRUS said:

Stuck in the clouds from CNJ on north and east

 

Yup, my home tempest is at 53 at the moment. To my immediate south and west the temperature escalated quickly. 

I’ve noticed this year a few times where even at my location at the southern extent of CNJ has avoided the warmth to the SW in the Delmarva area. 

[Stormlover74]

14 minutes ago, Volcanic Winter said:

Yup, my home tempest is at 53 at the moment. To my immediate south and west the temperature escalated quickly. 

I’ve noticed this year a few times where even at my location at the southern extent of CNJ has avoided the warmth to the SW in the Delmarva area. 

From 75 to 51 to near 80 tomorrow. Gotta love April in the northeast