donsutherland1

In the wake of an Arctic cold front, much colder air is pouring into the region. This air mass will cover the region tomorrow through the weekend. The weekend will be mainly dry as a storm moves offshore well to the south and east of the region. A pattern change toward persistent milder conditions could begin to evolve during the first week of February. The extended range of the EPS already shows the start of a warming trend in the closing days of January, so the timing remains somewhat uncertain. The PNA is positive and is likely to remain positive through at least January 27th. A positive PNA is associated with more frequent snowfalls in the Middle Atlantic region. However, big snowfalls typically occur when the AO is negative. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around January 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.20°C and the ENSO Region 3.4 anomaly has averaged -1.03°C. La Niña conditions will likely persist through meteorological winter. The SOI was +7.92 today. The preliminary Arctic Oscillation (AO) was +0.486. On January 18 the MJO was in Phase 7 at an amplitude of 0.364 (RMM). The January 17-adjusted amplitude was 0.429 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 96% probability that New York City will have a colder than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.5° (3.2° below normal).

Snow is starting to mix with the rain in Larchmont, NY.

Morning thoughts… Rain will end as a period of snow or flurries. 1” of snow is likely in Philadelphia, Newark, and New York City with local amounts as high as 3”. The temperature will fall throughout the day. High temperatures will likely reach the upper 30s and lower 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 39° Newark: 37° Philadelphia: 40° Normals: New York City: 30-Year: 39.1°; 15-Year: 39.7° Newark: 30-Year: 39.6°; 15-Year: 40.4° Philadelphia: 30-Year: 40.9°; 15-Year: 41.5° Tomorrow through the weekend will be cold and dry.

An advancing cold front will bring rain changing to snow overnight into midday tomorrow. A general 1"-3" snowfall is likely in Philadelphia, Newark, New York City and nearby areas. Lighter amounts are likely north and west of those cities. Much colder air will follow for the weekend. The weekend will be mainly dry as a storm moves offshore well to the south and east of the region. Generally colder than normal conditions will persist through midweek next week. A pattern change toward persistent milder conditions could begin to evolve during the first week of February. At present, the CFSv2 is somewhat faster than the EPS weeklies in bringing about that transition. The PNA is positive and is likely to remain positive through at least January 27th. A positive PNA is associated with more frequent snowfalls in the Middle Atlantic region. However, big snowfalls typically occur when the AO is negative. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around January 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.20°C and the ENSO Region 3.4 anomaly has averaged -1.03°C. La Niña conditions will likely persist through meteorological winter. The SOI was +5.75 today. The preliminary Arctic Oscillation (AO) was +0.161. On January 17 the MJO was in Phase 8 at an amplitude of 0.430 (RMM). The January 16-adjusted amplitude was 0.658 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 97% probability that New York City will have a colder than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.4° (3.3° below normal).

Arctic refers to the source region of the air mass. The Arctic has warmed quite rapidly over the past few decades, so the magnitude of cold is generally less expansive and less intense that it was then. There remain exceptions, though.

It is. Still, we'll get another look at the 0z HREF ahead of the event.

HREF for late tonight into tomorrow:

Morning thoughts… It will be variably cloudy and mild today. High temperatures will likely middle and upper 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 45° Newark: 46° Philadelphia: 49° Normals: New York City: 30-Year: 39.1°; 15-Year: 39.8° Newark: 30-Year: 39.6°; 15-Year: 40.4° Philadelphia: 30-Year: 40.9°; 15-Year: 41.5° There will be a period of accumulating snow late tonight through tomorrow morning. A general 1”-3” is likely across most of the region, including New York City, Newark, and Philadelphia.

Milder air will return early tomorrow ahead of an approaching cold front. That front will likely bring some rain and snow showers to the region. There is a chance that the precipitation ends as a period of accumulating snow in parts of the region. The potential exists for a 1"-3" accumulation in parts of the region. Much colder air will follow for the weekend. Some of the guidance hints at the development of another storm that could impact parts of the East Coast, but there remains considerable uncertainty. The PNA is positive and is likely to remain positive through at least January 27th. A positive PNA is associated with more frequent snowfalls in the Middle Atlantic region. However, big snowfalls typically occur when the AO is negative. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around January 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.20°C and the ENSO Region 3.4 anomaly has averaged -1.03°C. La Niña conditions will likely persist through meteorological winter. The SOI was -2.63 today. The preliminary Arctic Oscillation (AO) was +0.507. On January 16 the MJO was in Phase 8 at an amplitude of 0.662 (RMM). The January 15-adjusted amplitude was 0.927 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 92% probability that New York City will have a colder than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.6° (3.1° below normal).

Morning thoughts… It will be mostly sunny, breezy, and cold today. High temperatures will likely middle and upper 30s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 34° Newark: 36° Philadelphia: 39° Normals: New York City: 30-Year: 39.1°; 15-Year: 39.8° Newark: 30-Year: 39.6°; 15-Year: 40.5° Philadelphia: 30-Year: 40.9°; 15-Year: 41.6° Tomorrow will be milder ahead of the next cold front. There could be a period of snow or flurries early Thursday.

Most of the cold on the 30-day map is from January.

If the pattern change unfolds as shown on the latest EPS, there could be opportunities until mid-February. A faster transition would reduce the window of opportunity.

First week of February:

The powerful storm that raked coastal areas with winds gusts in excess of 60 mph and brought heavy rain to the region after some snow to some areas is now moving away. Daily precipitation amounts included: Bridgeport: 0.86" (old record: 0.77", 1994) Islip: 1.48" (old record: 0.70", 1994) New York City-JFK: 0.92" New York City-LGA: 1.06" New York City-NYC: 1.15" Newark: 1.30" Tomorrow will be blustery and colder before milder air returns early on Thursday ahead of an approaching cold front. That front will likely bring some rain and snow showers to the region. There is a chance that the precipitation ends as a period of accumulating snow in parts of the region. Much colder air will follow for the weekend. Some of the guidance hints at the development of another storm that could impact parts of the East Coast, but uncertainty is high. The PNA is positive and is likely to remain positive through at least January 27th. A positive PNA is associated with more frequent snowfalls in the Middle Atlantic region. However, big snowfalls typically occur when the AO is negative. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was -0.8°C for the week centered around January 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.20°C and the ENSO Region 3.4 anomaly has averaged -1.03°C. La Niña conditions will likely persist through meteorological winter. The SOI was -8.76 today. The preliminary Arctic Oscillation (AO) was +1.540. On January 15 the MJO was in Phase 7 at an amplitude of 0.928 (RMM). The January 14-adjusted amplitude was 1.309 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 91% probability that New York City will have a colder than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.7° (3.0° below normal).

January 2018: 31.7 Last month below 30: February 2015: 23.9

Morning thoughts… It will be partly to mostly cloudy today. Temperatures will begin to fall this afternoon. High temperatures will likely lower 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 42° Newark: 42° Philadelphia: 41° Colder air will return for tomorrow.

Probably right. I suspect that there have been some recent cases where a measurement wasn’t made when the snow stopped falling.

I heard that there was more than 0.1” at Rego Park.

Newark picked up 1.0” and Central Park saw 0.8”. LGA had 0.4” and JFK had 0.1”.

Short video of the falling snow from earlier tonight:

Mamaroneck, NY from earlier this evening.

Snow flurries in Larchmont, NY.

A strong storm will bring a period of snow or freezing rain changing to rain to much of the region late tonight into tomorrow. A moderate to significant snowfall is likely across central and upstate New York into central and northern New England. Western and Upstate New York, along with parts of Ontario and Quebec could see a significant snowfall. Some of those areas could pick up a foot or more of snow. Eastern New England and much of Long Island will likely experience mostly or all rain. High winds will produce coastal flooding especially during high tide tomorrow morning. Snowfall estimates: Allentown: 1"-3" Baltimore: 1"-3" Bridgeport: 1" or less New York City: 0.5" or less Newark: 1" or less Philadelphia: 1" or less Poughkeepsie: 2"-4" Washington, DC: 1"-3" The PNA is positive and is likely to remain positive through at least January 27th. A positive PNA is associated with more frequent snowfalls in the Middle Atlantic region. However, big snowfalls typically occur when the AO is negative. Some of the guidance suggests that the AO could go negative around or just after January 20th for a time. Overall, the cold pattern currently in place will likely last into at least the closing days of the month. The ENSO Region 1+2 anomaly was -0.9°C and the Region 3.4 anomaly was -1.1°C for the week centered around January 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.32°C and the ENSO Region 3.4 anomaly has averaged -1.05°C. La Niña conditions will likely persist through meteorological winter. The SOI was -14.46 today. The preliminary Arctic Oscillation (AO) was +0.870. On January 14 the MJO was in Phase 8 at an amplitude of 1.312 (RMM). The January 13-adjusted amplitude was 1.697 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 90% probability that New York City will have a colder than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.9° (2.8° below normal).

I love your posts. There’s always something to learn from seeing the thinking and reading the insights of someone who is truly exceptional in his field.

It’s below the radar beam.