bluewave

It’s fitting that we should get one more rain event to close out December. JFK already had its wettest December on record. You can see how wet our climate has become with the top 3 wettest Decembers since 2014. Time Series Summary for JFK INTL AP, NY - Month of Dec Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 2019 7.17 3 2 2014 7.04 0 3 2018 6.76 0 4 1986 6.73 0 5 2009 6.25 0 6 1969 6.16 0 7 1983 6.14 0 8 1974 6.07 0 9 1948 6.05 0 10 1996 6.00 0

I try to go more by the actual VP anomalies especially with the GFS. The GFS can really struggle with those RMM diagrams. The Euro, CMC, and GFS all get the forcing over to phase 4-5 in early January. So with the lag, the MJO 4-5 influence about a week later. The ultimate amplitude of the MJO 4-5 is still uncertain. But we could be looking at mild to cold and back to mild temperature swings January 1-15. The exact change dates to be determined later. Forcing shifting to Maritime Continent in early January on the GFS

It looks like pretty good agreement between the Euro, GFS, and CMC on the MJO. Lingering mild phase 5-6 influence to start out January. Then a shift to colder a few days later after we go through phase 7-8. Followed by a shift back to mild with phase 4-5. So The January 1-15 progression should be mild...cold...mild. Exact dates of the quick transitions to be determined later. The GFS VP anomalies eventually get out of the the COD and over to 4-5 like the other models. The GFS can struggle with those RMM charts. That why I like to look at the VP anomalies.

Excellent post. That’s why the events this month were right in line in with recent experience You can see the emergence of this new pattern after 1981. But it became more pronounced in recent times.

There can be a lag between the MJO and its effects. But depending on the overall pattern, the results can be more in real time. So the mild start to January can be the continuation of this 5-6 influence. A cool down a few days later would be in line with 7 or even 8. Beyond that, a move back to 4-6 would cause another temperature rebound should the models be correct. But there is plenty of time to watch that. Don has an excellent discussion in the January thread.

The warm up was timed pretty well with the warm MJO 5-6 phases.

The clouds and higher dewpoints allowed the minimum temperature departures to exceed the maximums across the Northeast. Matches the recent theme of it being so wet. We needed that brief dry pattern in September for those record mid 90’s on October 2nd.

Now back to December weather. The warm minimum temperatures across the region yesterday put an exclamation point on the late December warm up. Most of our stations are back close to normal now for the month. The unusually warm minimums extended from NYC up the Hudson to Albany. So both stations experienced the warmest minimum temperature of December on the 27th. Such late minimums have become more common this decade. It’s the 5 time that NYC has a warmest December minimum after the 20th. This is unusual since the average NYC minimum temperatures drop 9 degrees from the 1st to the 31st. Warm minimums more impressive north of NYC NYC....12-27....46...+17.2...month....-0.2 ALB.....12-27...40....+22.7...month....-0.2 NYC 2010’s December warmest minimum temperature dates 12-27-19....46 12-21-18....47 12-05-17....50 12-01-16....42 12-24-15....63 12-27-14.....44....T...25th...24th 12-22-13.....61 12-03-12.....49 12-06-11....56 12-12-19...40

It’s only December 28th. I haven’t made any call about January yet. Read more and post less.

You came in here yesterday and started posting laughing emojis after numerous posts. Are you a previous member signing up under a new name to cause trouble?

It was only a 7 day forecast and not 10. That was after you started the commotion.Why don’t you go somewhere else if you want to start trouble.

You just joined yesterday and already you are derailing this thread. Specific temperature forecasts lose skill beyond beyond 5-7 days. So what is the point of posting raw day 10 temperature forecasts in the December thread. That’s what the January thread is for. Here is the raw model forecast that has been corrected for known biases. It doesn’t go out 10 days. NEW YORK CITY-CENTRAL PARK KNYC GFSX MOS GUIDANCE 12/28/2019 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168|180 192 SAT 28| SUN 29| MON 30| TUE 31| WED 01| THU 02| FRI 03| SAT 04 CLIMO X/N 53| 41 48| 41 52| 42 51| 36 47| 35 44| 40 46| 43 48 26 39

Relax. Stop thinking that everyone has an agenda. This is weather and not politics.

Does it really matter what the exact date is? All the models show a mild start to January. We now have a January thread for specific January discussion. We should put those posts in there since this is the December thread. People still want to discuss the end of December in here.

Today was the warmest departure of the month in NYC at +16. TEMPERATURE (F) TODAY MAXIMUM 54 359 PM 63 1949 40 14 44 MINIMUM 46 227 AM 6 1872 29 17 37 AVERAGE 50 34 16 41

Our successful La Niña snowfall seasons have the PAC ridge shifted closer to the West Coast and -NAO intervals.

Thanks, Tom. The ENSO blog summed up several of the points we mentioned here going back to the fall of 2018. They discuss the warmest SST departures over the WPAC relative to further east. Another recent paper showed how the rapid expansion of that warm pool shifted the MJO to more frequent phase 4-6 episodes. https://www.climate.gov/news-features/blogs/enso/csi-enso-case-missing-central-pacific-rainfall The following figure shows how sea surface temperatures in the fall of 2018 differed from those of a typical El Niño of similar strength (1). Compared with a typical El Niño, the fall of 2018 featured a warmer sea surface in the western Pacific and a cooler sea surface in the eastern Pacific. This signifies an enhancement of the east-west sea surface temperature gradient relative to typical El Niño conditions. In other words, we failed to see the eastward movement of the warmest surface waters that we usually see with El Niño. It looks like this suspect fits the profile! The September–November difference in sea surface temperature between 2018 and a typical El Niño of similar strength. The typical El Niño sea surface temperature pattern was determined as a scaled average of all events since 1979 (13 total). In 2018, the sea surface temperature was warmer than typical over the western Pacific but cooler than typical over the eastern tropical Pacific, which indicates a stronger east-west temperature gradient than typically experienced during an El Niño fall. The white boxes indicate regions used to define a gradient index (west minus east) that measures the strength of the east-west temperature gradient. Climate.gov figure from ERSSTv5 data.

We really need to lose that Niña-like ridge north of Hawaii for an improved storm track. All the storms since last winter have been cutting or hugging. Each storm kicks up the SE ridge out ahead of it. This is probably related to the warmest SST departures west of the date line and cooler near South America. The warm SST departures in the WPAC also lead to more MJO phase 4-6 forcing. This winter so far Last winter La Niña 500 mb composite Current SST departures

Yeah, looks like a mixed bag for the next storm coming in Sunday night into Monday.

Not your ideal ski conditions today.

You know it’s warm when the NYC low of 46 is 6 degrees warmer than the normal high of 40.

bluewave, that is an interesting concern. I have read, from a couple mets, that the desire for colder outcomes in the East eventually rested in part to a weakening of the record +IOD. I did not come across any mentions of weaker IOD influence leading to more amplified forcing in those unfavorable phases. Unless, I misunderstood what Webb posted, I thought that when the IOD weakened it would enable more traditional and assertive West Pac forcing to arise, and even the possibility of increased -NAO phases. I would appreciate why you feel the weakening + IOD might be a concern. Honestly, I was happy to see the + IOD weaken, now you have me concerned. The +IOD was associated with subsidence near the Maritime Continent during the first half of December. As the +IOD weakened, forcing returned there the last 10 days. It coincided with all the record warmth across the US this week. Now the Euro has forcing returning to phases 4-5 in early January. But there is a lag with the MJO. So the first few days of of January will have a lingering mild phase 5-6 influence. Then a colder pattern following the phase 7 passage. Finally, that cool down may be followed by a phase 4-5 warm up. The pertinent forcing changes are all within the more reliable day 1-10 period.

Yeah, it was a steep +IOD decline over the last few weeks. This coincided with our late December warm up and mild MJO 4-6 forcing. Looks like the first few days of January have a lingering mild 6 pattern .By Jan 5h, models are producing more of a phase 7 look. This could mean a return to normal or below normal temperatures. Beyond the 5th, models are hinting at forcing returning to the Maritime Continent 4 -5 phases. Obviously, these day 11-15 forecasts have been very low skill. But my concern is that the weaker IOD influence may eventually lead to more amplified forcing in those unfavorable phases.

Snowfall totals from NYC out along the South Shore of Long Island were on the low side this month. The Pacific Jet has still been very fast with the record low pressure in California and rainfall in Seattle. The mean Pacific ridge position has been stuck north of Hawaii since last winter. Maybe we need a stronger El Niño development down the line to flip the Pacific out of this stagnant pattern. But it seems like all the warm PAC SSTs west of the DL are mismatched with the El Niño development. Those same warm WPAC SSTs amp up the MJO in the unfavorable phases.

The main problem since last winter has been the unfavorable Pacific with plenty of cutter and hugger storm tracks. The temperature departures haven’t been the big issue. A cold first 3 weeks of December was only able to produce 2.5 inches of snow in NYC. Areas Inland from the coastal plain can did much better. Even last January that went -0.1 in NYC was only able to produce 1.1 inches of snow. It’s no coincidence that the best snowfall rates this December and last January in NYC were snow squalls.