December 2024

[Brian5671]

3 minutes ago, MJO812 said:

I guess you are ignoring every ensemble and mjo progression. Good luck.

You can't bank on anything this far out-how many times over the last 3 years has a good/great pattern been forecast only to see it fall apart as we approached?  Not saying that happens here-but caution is always advised but certainly hope for the best...look at last January-the pattern lasted a grand total of a week before it fell apart.    

[bluewave]

32 minutes ago, brooklynwx99 said:

also, if the Pacific jet is also going to be stronger than forecast for much of the winter, wouldn't that mean that the retraction on the extended guidance for late Jan into Feb is overdone, shifting the prospective Aleutian ridge more into AK and the WC, leading to a colder E US pattern?

but nobody is using that logic in that fashion for whatever reason

You have to analyze how each 500 mb pattern forecast is influenced by a faster Pacific Jet.

The long range model error in early December was the 500mb heights near Alaska were being eroded from the West by the stronger Pacific Jet. This lead to lower heights than forecast south of Alaska. It also allowed the ridge to drift east at times this month. Remember the models had the ridge anchored along the West Coast all month which didn’t work out. 

The models are now showing lower heights than forecast over the Western U.S. underneath the +PNA ridge in Canada in early January. So more jet energy is making it through near the U.S West Coast than earlier forecasts. It’s more an undercutting process further south than we initially saw in December.

The bottom line is that we are getting lower 500mb heights than forecast out West due to the faster Northern Stream of the Pacific Jet.

 

 

 

[brooklynwx99]

10 minutes ago, bluewave said:

You have to analyze how each 500 mb pattern forecast is influenced by a faster Pacific Jet.

The long range model error in early December was the 500mb heights near Alaska were being eroded from the West by the stronger Pacific Jet. This lead to lower heights than forecast south of Alaska. It also allowed the ridge to drift east at times this month. Remember the models had the ridge anchored along the West Coast all month which didn’t work out. 

The models are now showing lower heights than forecast over the Western U.S. underneath the +PNA ridge in Canada in early January. So more jet energy is making it through near the U.S West Coast than earlier forecasts. It’s more an undercutting process further south than we initially saw in December.

The bottom line is that we are getting lower 500mb heights than forecast out West due to the faster Northern Stream of the Pacific Jet.

 

 

 

they are showing that for like 24-48 hours. do you think that will be an issue after the 3-5th? honest question

[MJO812]

14 minutes ago, bluewave said:

You have to analyze how each 500 mb pattern forecast is influenced by a faster Pacific Jet.

The long range model error in early December was the 500mb heights near Alaska were being eroded from the West by the stronger Pacific Jet. This lead to lower heights than forecast south of Alaska. It also allowed the ridge to drift east at times this month. Remember the models had the ridge anchored along the West Coast all month which didn’t work out. 

The models are now showing lower heights than forecast over the Western U.S. underneath the +PNA ridge in Canada in early January. So more jet energy is making it through near the U.S West Coast than earlier forecasts. It’s more an undercutting process further south than we initially saw in December.

The bottom line is that we are getting lower 500mb heights than forecast out West due to the faster Northern Stream of the Pacific Jet.

 

 

 

The models are ? I just seen the models and they show a change to colder temps especially the ensembles.

[bluewave]

10 minutes ago, brooklynwx99 said:

they are showing that for like 24-48 hours. do you think that will be an issue after the 3-5th? honest question

The risk after the 3rd to 5th is that the trough from the west to east is too broad. We haven’t had much luck with these patterns in recent years when there has been lower heights out West under a +PNA ridge in Canada. Even if we have lower heights in the mean here in the East. Hopefully, we can get lucky this time around. But we should keep expectations low with how the fast Pacific flow has been so dominant in recent years. 

[EastonSN+]

1 hour ago, bluewave said:

The risk after the 3rd to 5th is that the trough from the west to east is too broad. We haven’t had much luck with these patterns in recent years when there has been lower heights out West under a +PNA ridge in Canada. Even if we have lower heights in the mean here in the East. Hopefully, we can get lucky this time around. But we should keep expectations low with how the fast Pacific flow has been so dominant in recent years. 

If I am not mistaken that type of pattern actually favors south of us Southeast sliders. I believe that is why the Delmarva had a lot of snow storms a couple years ago

[bluewave]

59 minutes ago, EastonSN+ said:

If I am not mistaken that type of pattern actually favors south of us Southeast sliders. I believe that is why the Delmarva had a lot of snow storms a couple years ago

Yeah, that was mid-January 2019 when they had the 12” snowstorm around DC which slid to our south. There was an upper low under the +PNA near the Southwest and one near the Northeast. The surface low couldn’t turn the corner up the coast due to the UL near the SW and east of New England.

 

 

Data for January 12, 2019 through January 13, 2019
Click column heading to sort ascending, click again to sort descending.

MD	CLARKSBURG 2.1 NE	CoCoRaHS	12.2
MD	DAMASCUS 3 SSW	COOP	11.8
MD	ROCKVILLE 2.8 WNW	CoCoRaHS	11.5
VA	WASHINGTON DULLES INTL AP	WBAN	10.6
VA	WFO STERLING	COOP	10.6
VA	OAK HILL 0.3 WSW	CoCoRaHS	10.5
VA	WASHINGTON REAGAN NATIONAL AIRPORT	WBAN	10.2

[Rjay]

2 hours ago, MJO812 said:

I guess you are ignoring every ensemble and mjo progression. Good luck.

You've busted on everything for years at this point 

[donsutherland1]

Parts of the region experienced light snow. Into this evening, snowfall amounts included:

Boston: 0.5"
Bridgeport: 0.4"
New York City: Trace
Newark: Trace
Philadelphia: Trace

Light snow is likely tonight into tomorrow. A coating to an inch of snow is likely in the Philadelphia to New York City region overnight into tomorrow. Boston will likely pick up a storm total 1"-3" of snow.

Last winter, New York City's first measurable snowfall occurred on January 6, 2024. The prior winter, it occurred on a record late February 1, 2023. The last earlier first measurable snowfall occurred on December 16, 2020. Normal is December 13th.

Afterward, the coldest air so far this season will pour into the region. The temperature will fall into the teens for the first time this season in New York City and Philadelphia on Sunday morning and then again on Monday morning. Many areas outside those cities will likely experience single-digit lows.

The cold will begin to recede around the middle of next week.  December will likely close with above normal temperatures. The opening days of January will likely also begin with above normal temperatures, but it will start to turn colder. Snowfall prospects will remain limited through the end of December.

On account of a lack of snowfall, 2023-2024 will likely set a new records for the lowest snowfall over a two-year period for Boston and New York City.

Boston: 2023-2024 Total to Date: 21.5"; Record: 38.2", 1979-1980
New York City: 2023-2024 Total to Date: 9.8"; Record: 17.4:, 1997-1998

In past days, an occasional run of the operational GFS showed a significant snowstorm from Washington, DC to New York City. However, the pattern makes such an event very unlikely for this region. Since 1950, there were 5 December snowstorms that brought 6" or more snow to all three of these cities. Four (80%) occurred with a PNA+/NAO- pattern. The NAO is forecast to be positive. In addition, three (60%) occurred when the MJO was in Phase 8, which is not likely over the next 10 days. Only the December 23-25, 1966 event produced 6" or more snow in all three cities with a positive NAO, but the AO was strongly negative (< -2.000), which is not likely during the next 10 days. In sum, the interior sections will be far more favored for an appreciable or perhaps greater snowfall than the Washington-Baltimore-Philadelphia-New York City area over the next 10 days. A smaller snowfall remains plausible. One example will be the ongoing light snowfall in parts of the region.

The NAO fell to a preliminary -2.751 on September 24th (all-time September record: -2.371, September 12, 1971). That was the 9th lowest value on record. La Niña winters following September cases where the NAO fell to -1.900 or below featured a predominantly positive NAO. The most recent such winters were 2016-2017 and 2022-2023. The mean temperatures for those winters in New York City were 39.3° and 41.0° respectively. The 1991-2020 normal value is 36.2°. A warmer to much warmer than normal outcome is favored by the November run of the ECMWF for Winter 2024-2025.

The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around December 11. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.17°C and the ENSO Region 3.4 anomaly has averaged -0.27°C. Neutral ENSO conditions may still evolve into a La Niña event during the winter. Uncertainty as to whether a La Niña will actually develop continues to increase. Currently, 47% of dynamical models and 22% of the statistical models forecast the development of a La Niña.

The SOI was +24.81 today.

The preliminary Arctic Oscillation (AO) was +0.671 today.

Based on sensitivity analysis applied to the latest guidance, there is an implied 81% probability that New York City will have a colder than normal December (1991-2020 normal). December will likely finish with a mean temperature near 37.4° (1.7° below normal).

 

[Allsnow]

2 hours ago, bluewave said:

Yeah, that was mid-January 2019 when they had the 12” snowstorm around DC which slid to our south. There was an upper low under the +PNA near the Southwest and one near the Northeast. The surface low couldn’t turn the corner up the coast due to the UL near the SW and east of New England.

 

 

Data for January 12, 2019 through January 13, 2019
Click column heading to sort ascending, click again to sort descending.

MD	CLARKSBURG 2.1 NE	CoCoRaHS	12.2
MD	DAMASCUS 3 SSW	COOP	11.8
MD	ROCKVILLE 2.8 WNW	CoCoRaHS	11.5
VA	WASHINGTON DULLES INTL AP	WBAN	10.6
VA	WFO STERLING	COOP	10.6
VA	OAK HILL 0.3 WSW	CoCoRaHS	10.5
VA	WASHINGTON REAGAN NATIONAL AIRPORT	WBAN	10.2

I believe the mjo briefly went into p8 which helped with the airmass for that system in the Mid Atlantic. After that system SE ridge took over and the winter ended. I believe we got some slop system In early March 

[MJO812]

2 hours ago, Rjay said:

You've busted on everything for years at this point 

I listen to smart people 

[Stormlover74]

Just now, MJO812 said:

I listen to smart people 

Who also have busted. DT, JB...oh wait you said smart people

[MJO812]

Just now, Stormlover74 said:

Who also have busted. DT, JB...oh wait you said smart people

For when  ? Winter isn't over yet.

[Stormlover74]

Just now, MJO812 said:

For when  ? Winter isn't over yet.

The past few years

[MJO812]

[bluewave]

1 hour ago, Allsnow said:

I believe the mjo briefly went into p8 which helped with the airmass for that system in the Mid Atlantic. After that system SE ridge took over and the winter ended. I believe we got some slop system In early March 

Yeah, the 18-19 winter was when the Northern Stream of the Pacific Jet began to act as the spoiler. It was a great example of a January which averaged close to normal at 32.5° and only delivered a 1.0” snow squall for the month. The heaviest storm that month was a cutter with over 1.00” of rain around the 20th with highs around 60°. Then a strong Arctic outbreak later in the month with near 0° lows. 

[Wxoutlooksblog]

10 hours ago, brooklynwx99 said:

by the way, the Pacific jet actually trended weaker for early Jan, not stronger. it was significantly stronger a few days ago

It's definitely getting weaker. You can see weather systems moving significantly slower all across the country. 

WX/PT

[bluewave]

7 hours ago, Wxoutlooksblog said:

It's definitely getting weaker. You can see weather systems moving significantly slower all across the country. 

WX/PT

The most interesting part of the recent runs which may provide some snowfall hope in January is the much stronger blocking NE of Hudson Bay. This may be a feedback process related to the low sea ice. Chances would increase for a 4”+NYC  event January 1-15 if we can get a +PNA and -AO at the same time. Even if we have to deal with a broad trough from the west to the east. 
 

New run

Old run

 

[LibertyBell]

11 hours ago, bluewave said:

Yeah, the 18-19 winter was when the Northern Stream of the Pacific Jet began to act as the spoiler. It was a great example of a January which averaged close to normal at 32.5° and only delivered a 1.0” snow squall for the month. The heaviest storm that month was a cutter with over 1.00” of rain around the 20th with highs around 60°. Then a strong Arctic outbreak later in the month with near 0° lows. 

This is a common occurrence, during the 80s we had many such Januarys where we averaged in the 20s with very little snowfall.

[LibertyBell]

2 minutes ago, bluewave said:

The most interesting part of the recent runs which may provide some snowfall hope in January is the much stronger blocking NE of Hudson Bay. This may be a feedback process related to the low sea ice. Chances would increase for a 4”+NYC  event January 1-15 in if we can get a +PNA and -AO at the same time. Even if we have to deal with a broad trough from the west to the east. 
 

New run

Old run

 

Correct me if I'm wrong but la ninas with less than 3 inches of snow in December, dont usually result in snowy winters, Chris?

 

[bluewave]

14 minutes ago, LibertyBell said:

Correct me if I'm wrong but la ninas with less than 3 inches of snow in December, dont usually result in snowy winters, Chris?

 

While it generally means below average seasonal snows, there have still been nice snowstorms following such Decembers. That’s why I am hoping we can maximize the potential January -AO +PNA window. We have seen decent snows following under 3” Decembers in January 2000 and February 2008 to name a few.

[MJO812]

BRRR

[forkyfork]

10 days to get a miracle 1.2"

[SACRUS]

 

29 / 18 colder period in progress, snow moving out deeper cold moving in the next 3 days.  Some places sub or at freezing the next 3 days and not above till Tuesday afternoon.  Peak cold in the teens metro/costal and singe digits inland. Little reinforcing cold shot Christmas eve that could trigger some snow showers and flurries around the afternoon.  Warmer close to the month dry the next 7 days outside some flurries on the eve.

 

Snow on the visible as the clouds head northeast

 

[SACRUS]

 

Records:

Highs:

EWR: 64 (2013)
NYC: 65 (2013)
LGA: 62 (2018)
JFK: 59 (2011)

Lows:

EWR: 0 (1942)
NYC: -2 (1871)
LGA: -1 (1942)
JFK: 12 (2004)

Historical:

 

1892 - Portland, OR, was buried under a record 27.5 inches of snow. (21st-24th) (The Weather Channel)

1929 - An exceptional storm produced snow from the Middle Rio Grande Valley of Texas to southern Arkansas. The storm produced 26 inches of snow at Hillsboro TX, 18 inches at El Dorado AR, and 14 inches at Bossier LA. (21st-22nd) (David Ludlum) (The Weather Channel)

1964 - A great warm surge from the Pacific Ocean across Oregon and northern California brought torrential rains on a deep snow cover resulting in record floods. (David Ludlum)

1987 - High winds continued along the eastern slopes of the Rockies. During the morning hours winds gusted to 64 mph at Cheyenne WY, and reached 97 mph near Boulder CO. Gale force winds prevailed across the Great Lakes Region. (The National Weather Summary) (Storm Data)

1988 - Seven cities in the eastern U.S. reported record high temperatures for the date, including Charleston SC with a reading of 78 degrees. A storm in the northwestern U.S. produced 22 inches of snow at Idaho City ID in two days, and up to two feet of snow at Happy Camp CA. Ski resorts in Idaho reported three to six feet of snow on the ground. (The National Weather Summary) (Storm Data)

1989 - Forty cities in the north central U.S., including thirteen in Iowa, reported record low temperatures for the date. Havre and Jordan, MT, tied for honors as the cold spot in the nation with morning lows of 43 degrees below zero, and the temperature remained close to 40 degrees below zero through the daylight hours. Dickinson ND reported a morning low of 33 degrees below zero and a wind chill reading of 86 degrees below zero. The high for the date of 16 degrees below zero at Sioux Falls SD was December record for that location. (The National Weather Summary)

1998 - Cold air spread into the southern San Joaquin Valley of California. For the next four nights, temperatures in the agricultural portions of Fresno, Tulare, and Kern counties dropped below 28 degrees for several hours at a time. In some locations, temperatures dipped into the teens. The California citrus industry suffered more than $600 million in damages due to the extreme cold.

[EastonSN+]

14 hours ago, bluewave said:

Yeah, the 18-19 winter was when the Northern Stream of the Pacific Jet began to act as the spoiler. It was a great example of a January which averaged close to normal at 32.5° and only delivered a 1.0” snow squall for the month. The heaviest storm that month was a cutter with over 1.00” of rain around the 20th with highs around 60°. Then a strong Arctic outbreak later in the month with near 0° lows. 

In my opinion the 2018/2019 winter was underrated for snowfall. We were below average snowfall wise but not by that much. The two March snowstorms really made up for a lot of ground.

[SACRUS]

 

Winter Solstice 

 

NYC

sun rose at : 7:16 AM
Sun set : 4:32 PM  (1632) / 9:15:16 length 

 

 

[EastonSN+]

2 hours ago, bluewave said:

The most interesting part of the recent runs which may provide some snowfall hope in January is the much stronger blocking NE of Hudson Bay. This may be a feedback process related to the low sea ice. Chances would increase for a 4”+NYC  event January 1-15 if we can get a +PNA and -AO at the same time. Even if we have to deal with a broad trough from the west to the east. 
 

New run

Old run

 

It's really good to see the same setup appearing in all three ensemble guidance.

[bluewave]

11 minutes ago, EastonSN+ said:

It's really good to see the same setup appearing in all three ensemble guidance.

Hopefully, we can maximize any window we get in early to mid-January. 

[SnowGoose69]

11 minutes ago, EastonSN+ said:

It's really good to see the same setup appearing in all three ensemble guidance.

The MJO plots now show both the Euro/GFS trying to go stronger through 8 and 1 as well.