December 2020 General Discussions & Observations Thread

[RedSky]

1 hour ago, CIK62 said:

Question:    Which model can change rain and T's in 50's, into 10" of snow and T's in the 20's----within 1 run.   (For  the 13th./14th. which has switched again)

Why it is the "GFS---I Just Dropped in to See What Condition My Forecast Was In",  model.          Bring it on!

GFS is the dude from The Big Lebowski "what condition my condition is in, man"

 

[Allsnow]

9 minutes ago, bluewave said:

These differences in handling the short term storm details really magnifies the ensemble spread by day 10. That’s  why I want to see how each individual storm verifies before looking past day 8-10. The EPS, GEFS, and GEPS all have varying solutions day 8-10.

 

 

All the ensembles now bring a piece of the TPV into Canada. This is a result of the strat hit. Looks cold mid month with no Niña pattern in sight. Look at -epo on all three of Them 

[Allsnow]

51 minutes ago, bluewave said:

That’s the retrogression showing up. But the next step after the -EPO may be a ridge pull back to the Aleutians. So you get a -EPO cool down for a few days. We would need to make the most of any overrunning potential before the EPO goes more neutral or positive a few days later.

 

51 minutes ago, bluewave said:

That’s the retrogression showing up. But the next step after the -EPO may be a ridge pull back to the Aleutians. So you get a -EPO cool down for a few days. We would need to make the most of any overrunning potential before the EPO goes more neutral or positive a few days later.

 

[Allsnow]

1 minute ago, bluewave said:

 

 

 

[wdrag]

I'll post a new topic for Friday-Sunday dual event ~5P. Confidence is much much lower than the topics of 11/11-15, and 11/30-12/01.  Ensembles are not as favorable for verifiable flood warning, wind advisory or greater, with maybe theist v reification possibilities - the I84 corridor having winter hazards (some ice or snow). Basically, if the 12z/1 EC op didn't do what it did today, I would have held off til tomorrow or beyond, to be more sure.

[MJO812]

Icon shows a big rainstorm this weekend.  Gets down to 979.

[leo2000]

4 minutes ago, bluewave said:

Day 11-15 is still outside the best range for the EPS. Especially when the model is jumping back and forth on storm details at day 4-5. Those short term errors get magnified longer range. All the guidance has a retrogression of the ridge axis from Western Canada to Alaska and then back to the Aleutians. The strength of the -EPO before it weakens will determine our overrunning potential. Then we also have to watch the strength of the ridge east of New England which the models have been underestimating. Even if we see some weakening of the PV,  it may not show up until January. But those start forecasts can be very uncertain unless we are dealing with a very strong long range signal which hit us March 2018.

Wouldn't think be a Major SSW event?

 

 

 

 

 

[Allsnow]

13 minutes ago, bluewave said:

Day 11-15 is still outside the best range for the EPS. Especially when the model is jumping back and forth on storm details at day 4-5. Those short term errors get magnified longer range. All the guidance has a retrogression of the ridge axis from Western Canada to Alaska and then back to the Aleutians. The strength of the -EPO before it weakens will determine our overrunning potential. Then we also have to watch the strength of the ridge east of New England which the models have been underestimating. Even if we see some weakening of the PV,  changes may not show up until January. But those strat forecasts can be very uncertain unless we are dealing with a very strong long range signal like Feb Mar 2018.

I’m talking about the wave 1 hit on the strat. It’s throwing a punch at the SPV and getting it off the pole. This will open the artic flood gates at a piece of the TPV goes into Hudson Bay 

[David-LI]

If it’s worth anything, 18z NAM is way different than 18z gfs at hr 80 for weekend storm. 

[nycsnow]

Icon would be a solid hit of rain and wind 

[bluewave]

First 60° temperature on record today in Caribou during meteorological winter.

 

[Allsnow]

 

[SnowGoose69]

2 hours ago, bluewave said:

Day 11-15 is still outside the best range for the EPS. Especially when the model is jumping back and forth on storm details at day 4-5. Those short term errors get magnified longer range. All the guidance has a retrogression of the ridge axis from Western Canada to Alaska and then back to the Aleutians. The strength of the -EPO before it weakens will determine our overrunning potential. Then we also have to watch the strength of the ridge east of New England which the models have been underestimating. Even if we see some weakening of the PV,  changes may not show up until January. But those strat forecasts can be very uncertain unless we are dealing with a very strong long range signal like Feb Mar 2018.

I've noticed the GFS when we have favorable patterns in the East for cold has always had a serious bias to tend to want to pull the ridge back west and dump cold air masses into the west or Plains Day 8-9 and beyond.  Its been showing that the last few days consistently and the EPS wants no part of it.

[the_other_guy]

Inlaws have 10 inches of snow on ground in Cleveland.

We are talking about another week in the 50s and a rainstorm

[bluewave]

18 minutes ago, SnowGoose69 said:

I've noticed the GFS when we have favorable patterns in the East for cold has always had a serious bias to tend to want to pull the ridge back west and dump cold air masses into the west or Plains Day 8-9 and beyond.  Its been showing that the last few days consistently and the EPS wants no part of it.

Even the EPS drops the cold into Montana in about 8-10 days. But the GEPS and GEFS dig a little more into the Rockies. Montana and surrounding areas have really been the focus of what little cold departures there have been in recent years.

[qg_omega]

6 minutes ago, bluewave said:

Even the EPS drops the cold into Montana in about 8-10 days. But the GEPS and GEFS dig a little more into the Rockies. Montana and surrounding areas have really been the focus of what little cold departures there have been in recent years.

So much for the western ridge

[Allsnow]

30 minutes ago, bluewave said:

Even the EPS drops the cold into Montana in about 8-10 days. But the GEPS and GEFS dig a little more into the Rockies. Montana and surrounding areas have really been the focus of what little cold departures there have been in recent years.

Initially it will dump there as the ridge rolls forward and pac reshuffles. Show those maps pass that hour lol 

[donsutherland1]

December started off with balmy early morning readings in the region. Afterward, temperatures fell throughout the afternoon. In northern New England, the temperature reached 60° in Caribou this evening ahead of the push of colder air. That broke the daily record high figure of 48°, which was set in 1975 and tied in 1991. It also set a new monthly record. The prior monthly record was 58°, which was set on December 5, 1950 and tied on December 12, 1950. That makes December the second consecutive month on which Caribou set a new monthly record high temperature.

On the other side of North America, a wild storm was pounding southeast Alaska with high winds, heavy rain, along with exceptionally mild conditions. As of 4 pm AKS, the high temperature at Juneau was 48°. That tied the daily record set in 1906 and tied in 1997. In addition, 3.09" rain had fallen. That smashed the daily record of 1.44", which was set in 1997. In addition, that figure was just below the December precipitation record of 3.11", which was set on December 19, 1937.

A large-scale hemispheric pattern change is now evolving. A sustained period of cooler than normal to near normal temperatures will commence in coming days. A fairly sharp cold shot is possible during the second week of December. There remains considerable uncertainty about the timing of the next change toward milder conditions. The development of a AO-/PNA+ pattern has shifted the outlook toward colder temperatures during the first half of December (consistent with statistical guidance). Exceptional cold is unlikely through mid-December. The duration of the AO-/PNA+ pattern will be key to how long the colder pattern persists.

Meanwhile, an extended duration much warmer than normal regime is now developing in parts of western Canada. Tomorrow through Friday could see record high temperatures in that region.

Statistical guidance based on the ENSO state and teleconnections would typically favor a colder regime for the first half of December in the Middle Atlantic and southern New England regions. Both historic experience following exceptionally warm November cases suggest that a warmer than normal December remains the base case even if the first half of the month winds up colder than normal. Almost 90% of cases with a November mean temperature of 51.5° or above in Central Park (2020 saw the temperature average a record 52.9° in November) went on to record a warmer than normal December and just over three-quarters of such cases saw December register a monthly mean temperature of 40.0° or above.  

The ENSO Region 1+2 anomaly was -1.0°C and the Region 3.4 anomaly was -1.0°C for the week centered around November 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.87°C and the ENSO Region 3.4 anomaly has averaged -1.40°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +21.23.

Today, the preliminary Arctic Oscillation (AO) figure was +0.303.

On November 30 the MJO was in Phase 4 at an amplitude of 0.848 (RMM). The November 29-adjusted amplitude was 0.809.

Based on the latest guidance, no significant stratospheric warming event is likely through the middle of the second week of December. Some warming above 2 mb is likely toward the latter part of the first week of December on account of Wave 1 activity.  

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 10/11 (91%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. A predominant EPO+/AO+ pattern is very likely for winter 2020-21. It is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with below normal snowfall.

 

[Allsnow]

29 minutes ago, qg_omega said:

So much for the western ridge

We are not going to sustain a ridge out there for weeks on end. Need to make the most of our opportunities when we have it. A ridge kissing the west coast up into the artic works also. Which is what the ensembles have. 

[NEG NAO]

36 minutes ago, donsutherland1 said:

It is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with below normal snowfall.

 

Hope you are wrong.............

Hoping for this:

[donsutherland1]

35 minutes ago, NEG NAO said:

Hope you are wrong.............

Hoping for this:

I hope I am wrong, too. December will probably provide good insight into how things may evolve. If blocking breaks down after mid-December that could be an indication that winter will wind up warmer and less snowy than normal.

[donsutherland1]

With 3.24” rain through 5 pm AKS, Juneau has now set a new December daily precipitation record. The old record was 3.11”, which was set on December 19, 1937.

[wdrag]

From what I can sense through 00z/2 ensembling... it looks like there is going to be a cold intrusion next week into the northern tier with the next large scale storm toward the 14th (after this weekends).   After that... no super warming immediately modeled prior to the 16th. However, it is LaNina with AGW.  I might be seeing some sort of blocking trying to get going up by Greenland. Unsure if that is going to occur.

[CIK62]

The next 8 days are averaging 42degs.(38/45).           Making it 37degs., or -3.0.

There is No Snow on the 3 primary models except for a Trace near the 7th.       Mid-month deal is back to rain in the 60's.

38*(60%RH) here at 6am.        43* by Noon.

[Allsnow]

2 hours ago, wdrag said:

From what I can sense through 00z/2 ensembling... it looks like there is going to be a cold intrusion next week into the northern tier with the next large scale storm toward the 14th (after this weekends).   After that... no super warming immediately modeled prior to the 16th. However, it is LaNina with AGW.  I might be seeing some sort of blocking trying to get going up by Greenland. Unsure if that is going to occur.

That’s a legit cold shot coming with the wave 1 strat hit. We should have shots at snow between the 10th-20th. Looks like overrunning stuff and clippers 

[donsutherland1]

Morning thoughts...

The warm air that sent temperatures soaring on the closing day of November in the region, produced yesterday’s monthly record high temperature at Caribou, is now located in Atlantic Canada. Earlier today, Halifax (59°) and Charlottetown (58°) set daily record high temperatures. Meanwhile, at 7:55 am, a band of snow stretched northward from approximately Elmira, NY to central Ontario and was headed eastward.

Today will be variably cloudy, breezy, and cool. Temperatures will likely reach the lower and middle 40s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 43°

Newark: 46°

Philadelphia: 46°

Tomorrow and Friday will be somewhat milder.

[MJO812]

1 hour ago, CIK62 said:

The next 8 days are averaging 42degs.(38/45).           Making it 37degs., or -3.0.

There is No Snow on the 3 primary models except for a Trace near the 7th.       Mid-month deal is back to rain in the 60's.

38*(60%RH) here at 6am.

Where do you get your info from ?

[CIK62]

Info mostly from WeatherBell charts.

Where is your disagreement?     UC snow?

I want some snow but no actionable or bettable events are out there.

The only likely weather worthy event I see now, is Tampa's 32 month stretch w/o a BN one may end.

Snowstorms will be by accident this winter, I believe.      Meanwhile our last 'measureable' snow was Jan.18.

What is your guess for a measurable event?

[NEG NAO]

9 minutes ago, CIK62 said:

Info mostly from WeatherBell charts.

Where is your disagreement?     UC snow?

I want some snow but no actionable or bettable events are out there.

The only likely weather worthy event I see now, is Tampa's 32 month stretch w/o a BN one may end.

Snowstorms will be by accident this winter, I believe.      Meanwhile our last 'measureable' snow was Jan.18.

What is your guess for a measurable event?

If we don't get at least an event that is  measurable this month that will be by accident IMO . Plenty of cold enough air available and the indicies are mostly  favorable going forward and  an active southern stream coming in our direction - the cold enough air at all levels and the southern moisture will eventually phase together in NYC metro most models have shown runs in recent days suggesting this after this week.....

[MJO812]

31 minutes ago, CIK62 said:

Info mostly from WeatherBell charts.

Where is your disagreement?     UC snow?

I want some snow but no actionable or bettable events are out there.

The only likely weather worthy event I see now, is Tampa's 32 month stretch w/o a BN one may end.

Snowstorms will be by accident this winter, I believe.      Meanwhile our last 'measureable' snow was Jan.18.

What is your guess for a measurable event?

Accident with the pattern ahead ?