donsutherland1

During the 1/29 0z cycle, all of the major global models keyed in on developing a lead shortwave in a mix of multiple shortwaves. As a result, the baroclinic zone was pulled sufficiently far to the east and, along with it, the opportunity for measurable snowfall from Philadelphia to New York City. A few die-hard EPS members continued to insist on a 6" (14%) or above and 10" (10%) or above snowfall in Central Park, keeping alive a theoretical possibility of a significant snowfall. The 11z NBM showed 0.14" QPF in New York City and 0.17" at Philadelphia. For all practical purposes, the question is increasingly becoming one whether it will snow at all in Philadelphia and New York City and, if so, will a light accumulation be possible. Eastern Long Island and southeastern New England remain poised for at least some snowfall. A gusty wind and elevated high tide levels remain likely on Sunday whether or not there is snow. If the low/no snow solution plays out, one question that will linger is why multiple 6z and 18z cycles sloshed westward with their solutions only to be corrected by the subsequent 0z and 12z guidance. In any case, the 1/29 12z cycle could provide a degree of confirmation for the overnight model convergence. If the consensus holds, that agreement could be a strong signal that despite a complex set up, the guidance has keyed in on critical elements to the evolution of the weekend weather. The guidance is currently moving into its more skillful range when it comes to resolving synoptic details. The 1/30 0z cycle could put the wraps on the event or non-event. Finally, there may be a short opportunity for the temperature to reach or exceed freezing early next week in New York City.

Yes. That’s true.

Yes. It might not be until Friday before a solid consensus is achieved.

The 0z RGEM develops the lead low. Not surprisingly, it exits well south and east of the region. The earlier run developed the trailing low.

I just wanted to illustrate that it makes a difference which low will be dominant. The lead wave and the storm will almost certainly pass far too the east with little impact on most of the NYC area. If it's the second one, the storm will be more impactful.

Arctic air now covers the region. Highs will be mainly in the lower 20s through Saturday. One or more days could see highs in the teens. The last winter with more than one high in the teens was Winter 2018-19 when there were two such days. Moreover, New York City has the potential to see the temperature dip into the single digits for lows on one or more days during this period. The last winter with more than one such day was Winter 2022-23 when there were three such days. Some snow flurries or snow showers are possible Thursday night into Friday morning. Temperatures should begin to moderate on Sunday into early next week. Nevertheless, readings are likely to remain below normal into at least the start of next week. Additional snow is possible on Sunday if a developing storm passes close enough to the coast. Eastern Long Island into southeastern New England would have the greatest chance of seeing an appreciable or greater snowfall. There remains significant uncertainty about the location of the storm's development and its track. A large storm would be historic. For reference, New York City has seen just one 10" or above snowstorm one week or less following a 10" or above snowstorm: February 3-4, 1926 (10.4") and February 9-10, 1926 (12.4"). The shortest interval between 10" or above daily snowfalls is 14 days: March 2, 1896 (10.0") and March 16, 1896 (12.0"). Records go back to 1869. Overall, January 20th-February 3rd will likely be the coldest and perhaps snowiest two-week period this winter. The forecast WPO-/EPO-/AO-/PNA+ pattern is typically the coldest pattern in January and among the coldest during the first half of February. A persistently positive PNA will have above climatological risk of moderate or significant snowfalls. For perspective, the coldest two-week period this winter prior to January 20th was January 3-16, 2026 and January 4-17, 2026 with a mean temperature of 30.3°. The snowiest two-week period was December 14-27, 2025 when 7.2" of snow fell. Already, snowfall since January 20th has surpassed that figure. The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -0.7°C for the week centered around January 14. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.48°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions will likely continue into at least late winter. The SOI was +6.84 today. The preliminary Arctic Oscillation (AO) was -4.873 today. That is the lowest figure since February 15, 2025 when the AO was -5.278. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal January (1991-2020 normal). January will likely finish with a mean temperature near 30.2° (3.5° below normal). Supplemental Information: The projected mean would be 2.4° below the 1981-2010 normal monthly value.

There are so many pieces to the synoptic puzzle. The models are still trying to figure out how they fit together. This is a complex setup and it might not be until Friday before there is a good consensus. Several ensemble members have continued to show a 6"+ storm for NYC. That's still on the table. With greater confidence, it does appear that eastern Long Island into eastern New England have the highest chance of seeing an impactful event. Still, there's a lot of room for change.

It's a good thing he didn't add "Maybe." We'd all be paying royalties to Carly Rae Jepsen who owns the intellectual property rights to the word.

The RGEM looks promising, too.

In general, a dominant first coastal low tends to pull the baroclinic zone offshore and the trailing wave further east. The NAM makes the second low the dominant low and that's the solution that would have the best chance of bringing appreciable snows to the coastal plain, not just eastern Long Island or southeastern New England. However, the NAM is just a single model and this is a single run of that model.

Yes. At least that's the point-and-click for now. I was just commenting on the NBM's idea.

The NBM is showing a situation that would be historically unique. 1/28 13z NBM: Assuming Cape Hatteras receives 6" or more snowfall, the odds of amounts approaching 6" in New York City would likely be very low. To date, none of the 6" or greater snowstorms in Cape Hatteras saw more than 2" in New York City. While changes remain possible at the current lead time, there is no overwhelming evidence to support the historically unique solution shown on the NBM at present.

Little has changed since 6z. The deep 500 mb low that is forecast to develop will track through Alabama, Georgia and then out to sea. That's too far to the south to allow for an appreciable snowfall in the New York City area. A lighter snowfall remains plausible. The 12z Guidance: Some of the synoptic details are still subject to change. The guidance should be growing more skillful in resolving the synoptic details through the day today and especially tomorrow.

Here's the methodology from the paper that was printed when the CIPS initiative was being developed:

As noted earlier, the 1/28 0z EPS had about 20% of ensemble members showing 6" or more snow in New York City with about 10% having 10" or more. That's within the range of potential solutions, even as it might be a lower probability outcome right now. Going back in time, here are excerpts from two AFDs from another storm that enjoyed some ensemble support while the models were too far to the east. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 616 PM EST THU DEC 23 2010 IT WOULD APPEAR AS THOUGH THE THREAT FOR SUNDAY NIGHT INTO MONDAY CONTINUES TO DWINDLE...AS THE LAST HOLDOUT FOR A SIGNIFICANT WINTER STORM HAS JOINED THE MODEL CONSENSUS THIS AFTERNOON. THE 1200 UTC ECMWF RUN HAS JOINED THE MODEL CONSENSUS THIS AFTERNOON IN ALLOWING THE MID LEVEL PHASING TO OCCUR TOO LATE FOR MUCH OF AN IMPACT WITH REGARD TO SNOW FOR THE FORECAST AREA. AT THIS POINT...A CHANCE OF SNOW WILL BE RETAINED FOR SUNDAY NIGHT AND MONDAY MORNING FOR AT LEAST A PART OF THE AREA. THIS COULD BE DUE TO A BRUSH WITH THE OFFSHORE SYSTEM (AS IT BEING SHOWN BY THE ECMWF/GFS) OR THE PASSAGE OF THE CLOSED MID LEVEL SYSTEM (A BIT MORE LIKELY). IN ANY EVENT...IT NOW APPEARS AS THOUGH THE THREAT FOR A SIGNIFICANT WINTER WEATHER EVENT IS WANING. THERE WILL PROBABLY BE SOME WIGGLE ROOM ON THE TRACK (SINCE THE SHORT WAVE PUSHING THIS SYSTEM IS OVER THE FOUR CORNERS THIS AFTERNOON.)...AND EASTERN AREAS OF NEW JERSEY COAST SEE SOME SNOW ACCUMULATION. WHILE IT IS TOO EARLY TO PULL THE PLUG ON THIS SYSTEM FOR US...IT IS LOOKING MORE LIKE A GLANCING BLOW THAN A DIRECT HIT. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 656 PM EST THU DEC 23 2010 ...MAIN FEATURE TO KEEP AN EYE ON IS EVOLUTION OF COASTAL STORM AND HOW IT IMPACTS LOCAL CWA SUNDAY INTO MONDAY. MUCH DEPENDS ON PHASING OF SOUTHERN STREAM SHORTWAVE AND NORTHERN STREAM TROUGH DIGGING ACROSS THE GREAT LAKES REGION AS IT HEADS TOWARD THE NORTHEAST. THESE UPPER FEATURES NOW ENTERING DENSE OBSERVATION NETWORK...SO EACH SUBSEQUENT MODEL RUN SHOULD RESULT IN BETTER CLUSTERING OF SOLUTIONS. HOWEVER...A SLIGHT SHIFT TO THE EAST HAS BEEN OBSERVED WITH THIS 12Z RUN...ALONG WITH FASTER MOVEMENT OF SFC LOW SUNDAY INTO MONDAY PER EC/GFS/NAM. INITIALLY THE NAM/WRF REMAINS MUCH SLOWER WITH SOUTHERN STREAM SHORTWAVE AS IT MOVES ACROSS THE GULF THIS WEEKEND. LOW PRESSURE DEVELOPS AND DEEPENS OFF THE SOUTHEAST COAST SUNDAY MORNING AS THE MAIN TROUGH DIGS. LATEST NAM/WRF AND GFS TRACK THIS LOW JUST SOUTHEAST OF THE BENCHMARK...WITH MINIMAL QPF ACROSS THE CWA. LATEST ECMWF HAS SHIFTED EAST...PASSING JUST EAST OF THE BENCHMARK AS WELL. AS MENTIONED...SFC LOW MUCH FASTER TRACKING TO THE NORTHEAST. ECMWF CLIPS CWA...WITH BETTER CHANCE FOR PRECIP TO THE EAST. OVERALL...PLENTY OF ENSEMBLE MEMBERS STILL FORECASTING A FULL FLEDGED SNOWSTORM. WILL CONTINUE TO LAYER POPS FROM HIGHEST SE...TO LOWEST NW ZONES SUNDAY AFTERNOON AND SUNDAY NIGHT. AS FOR TIMING...SUNDAY AND SUNDAY NIGHT WOULD BE WHEN ANY ACCUMULATING SNOWFALL WOULD OCCUR...IF IT DOES. STORM MOVES WELL TO THE NORTH AND EAST ON MONDAY. LINGERING MID AND UPPER LEVEL TROUGH ALONG WITH AMPLE MOISTURE WRAPPING AROUND THE LOW COULD RESULT IN SCATTERED SNOW SHOWERS OR FLURRIES MONDAY.

...on an Underwood Portable Typewriter.

Here' the forecast assessment for the Boxing Day Blizzard: https://www.wpc.ncep.noaa.gov/winter_storm_summaries/event_reviews/2010/December25_27_2010_Blizzard.pdf

Yes, during the second half of February, PNA- is better for significant or major snowfalls due to the shortening of wave lengths.

The 1/28 0z ECMWF develops and tracks an impressive 500 mb low in Tennessee through Alabama and Georgia and then off the southeast coast. That track would favor an out-to-sea solution, as shows up on the surface maps. Model skill in resolving synoptic details should be improving today and tomorrow. So, if these solutions begin to lock in with the improved-skill output later today and especially tomorrow, the risk of snow in such cities as Philadelphia and New York City would diminish on Sunday. It's worth noting that about 20% of individual EPS members showed 6" or more snow in New York City and just over 10% had 10" or above amounts. In short, a significant snowfall, while decreasing in probability, is still a low probability not zero probability outcome. On a separate note, temperatures have been somewhat higher than modeled yesterday and again this morning. Friday and Saturday still look to be the coldest days with highs struggling toward 20°, lows in the single digits in New York City and some subzero lows in the colder suburbs. The opening week of February will likely start off dry but still colder than normal.

Yes, I believe that’s the case.

The record is 56 consecutive days (December 24, 1947 through February 17, 1948). The 2010-11 streak was the third longest.

BWI finished at 11.3".

As noted earlier, IMO writing the event off completely goes beyond what can reasonably be supported by the models and their ensembles. Indeed, there has been some improvement during the 18z cycle.

A number of those were high-impact storms i.e., 12/20/2009, 12/27/2010, 2/9/2013, 1/24/2016, 1/29/2022, etc.

That was the area I was most uncertain about. I overdid the impact of the warm air aloft. Hopefully, I'll do better next time.