December 2024

[qg_omega]

5 hours ago, bluewave said:

The UHI in Manhattan has been in effect since the 1890s and Queens since the 1930s to 1950s. But it’s just more obvious when we have calm winds. Plenty of strong high pressure this month for radiational cooling.

 

Big change from last year which is enabling lows to actually be normal to below normal for a change

[BoulderWX]

47 minutes ago, Cfa said:

Fake cold. Went from the teens to the 30’s almost instantly.

I’ve seen a lot of interesting/crazy posts on this forum but “fake cold” may be the funniest. Thanks for that, I legit laughed out loud. 

[winterwx21]

45 degrees here. Nice recovery from the mid teens this morning. Feels comfortable out there. 

[EastonSN+]

January looks chilly at least the first couple weeks. Wonder when the last time we had back to back below average temperature months.

[Rjay]

13 minutes ago, EastonSN+ said:

January looks chilly at least the first couple weeks. Wonder when the last time we had back to back below average temperature months.

Not just chilly.  Ensemble guidance continues to look good for some actual winter weather threats.  

[bluewave]

1 hour ago, EastonSN+ said:

January looks chilly at least the first couple weeks. Wonder when the last time we had back to back below average temperature months.

The last back to back below average temperature winter months were December 2017 into January 2018.

 

NYC

Feb 24…+4.2

Jan 24..+3.3

Dec 23..+5.5

…………..+4.3

 

Feb 23…+5.2

Jan 23…+9.8

Dec 22…-0.6

…………..+4.8

 

Feb 22….+1.4

Jan 22….-3.2

Dec 21….+4.7

……………..+1.0

 

Feb 21….-1.7

Jan 21….+1.1

Dec 20…+1.7

…………..+0.4

 

Feb 20…+4.8

Jan 20….+6.5

Dec 19….+0.8

…………….+4.0

 

Feb 19….+0.9

Jan 19….-0.1

Dec 18…+2.6

…………….+1.1

 

Feb 18…+6.7

Jan 18….-0.9

Dec 17…..-2.5

…………….+1.1

 

Feb 17…..+6.3

Jan 17….+5.4

Dec 16….+0.8

…………….+4.2

 

Feb 16….+2.4

Jan 16….+1.9

Dec 15….+13.3

…………….+5.9

[NorthShoreWx]

2 hours ago, Cfa said:

Fake cold. Went from the teens to the 30’s almost instantly.

This temperature inversion won't quit.  Did anyone else notice the haze this afternoon?

[the_other_guy]

22 minutes ago, NorthShoreWx said:

This temperature inversion won't quit.  Did anyone else notice the haze this afternoon?

Looks like a haze summer day crossing the bridge

[BxEngine]

My fake snow wont melt. Who do i call?

[donsutherland1]

It will turn noticeably milder tomorrow as wetter weather moves in. New York City's northern and western suburbs could see some freezing rain late tonight or early tomorrow morning. By late in the day, the temperature will push into the lower and middle 40s in New York City

December will close with above normal temperatures and additional periods of rain. The temperature will likely peak in the 60s in Washington, Baltimore, and Philadelpia and the 50s in New York City and Boston. 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. However, the pattern could become more favorable for moderate or perhaps larger snowfalls as the cold returns during the first week of January. The second week of January will likely feature widespread cold anomalies in much of the eastern half of the CONUS and Canada south of the Hudson and James Bays. The potential exists for widespread cold anomalies of 6°-10° below normal during that week in that region.

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: 26.7"; Record: 38.2", 1979-1980
New York City: 2023-2024 Total to Date: 12.6"; Record: 17.4", 1997-1998

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 -0.8°C for the week centered around December 18. 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 -0.35°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 persists. On the December 19 outlook, 56% of dynamical models but 0% of the statistical models forecast the development of a La Niña.

The SOI was -0.57 today.

The preliminary Arctic Oscillation (AO) was +0.650 today.

Based on sensitivity analysis applied to the latest guidance, there is an implied 99% 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).