Re: Long Range Thread 15.0

[sroc4]

In case anyone was wondering November is currently sitting at about normal for the month as a whole.  This map is only through the 11th but that was the coldest day as far as departure from normal thus far and is included in this reanalysis.  As you can see through the 11th at least we are actually 0.5-0.75* above normal still for the month, but if the last 3 days were allowed to be included we would be at normal to maybe -0.5* below normal through yesterday.  While the pattern continues to call for below normal temps by and large we will likely get transient periods of above normal, ie: a day or two, before going back to below normal.  As others have begun to allude to I'm not sure the pattern is quite right for a snow storm, with the period between next week Tuesday and Friday offering the best shot at it.  For now we have to see how the pattern evolves.  Yes we are looking at a -NAO trying to set up in this time frame, but the EPO region is a big question mark.  I believe Frank alluded to this previously.  We have to see how the Ridging in this area evolves.  There are hints that while the WPO will remain mod-strong neg the EPO region is going towards at least neutral.  The EPS and GEFS are a little at odds right now with this area.  I mentioned it several times in the past but the western trough will cont to be a thorn in our side for when it tucks into the WC o Canada and the N CONUS it creates a semi zonal flow off the pacific.   With a neutral or +EPO region the WC trough/Pac jet breaks off pieces of energy and shoots them east that combine with energy digging from the polar jet over the plains and the storm track remains west of us.    With a storm track cutting to the west into the GL, you get a transient warm up out ahead, followed by the cold frontal passage, and the mean trough axis sitting to our east.  The result is colder than normal temps, but dry.  It will be highly dependant on if 1) the NAO region will be strong enough neg and far enough west to hold the mean trough axis back enough leading to possibly Miller B type set up.  And/or 2) if our -WPO/-EPO ridging couplet holds strong enough.  

[algae888]

Departure through 11/13. CP -2.2, jfk -2, newark -1.5, lga -1.3.

[sroc4]

source?

[Frank_Wx]

source?

Not sure what his source is but mine is closer to Al than yours it looks like:



https://hprcc.unl.edu/maps.php?map=ACISClimateMaps

[Frank_Wx]

A visual to demonstrate just how negative the NAO is expected to go next week

[Frank_Wx]

The difference between the EPS and GEFS on Thanksgiving Week continues to be in the Pacific. Check these images out...

06z GEFS - valid NOV 22nd:



00z EPS - valid NOV 22nd:



Notice where the EPS has the Pacific trough in relation to the GEFS. It is much further east and broader, i.e. not as amplified. The GEFS amplifies the trough which typically suggests a slower/further west location which gives room for the west U.S. ridge (PNA region) to spike. Positive height anomalies encompass all of the western U.S. and western Canada while on the EPS you see negative heights beginning to invade.

Ultimately the differences here will decide whether or not Thanksgiving week will be colder than normal with a minor snow event or on the mild side. Even if the American suite is correct, I don't the pattern calls for a big snowstorm. Moderate at best but any snow before December is a welcoming sign into the holidays

[algae888]

source?

NWS monthly climate reports. Go to National Weather Service site for our region and click on climate and past weather. they have daily and monthly climate reports for all all local reporting stations

[algae888]

Frank the Euro may be onto something or it's holding energy back in the southwest as it usually it's bias. All of the guidance including the UKIE is similar to the GFS hard to go against the Euro but time will tell

[sroc4]

source?

Not sure what his source is but mine is closer to Al than yours it looks like:



https://hprcc.unl.edu/maps.php?map=ACISClimateMaps

I found it Al.  It looks like the only local station which you left off your list currently reporting above normal is Islip, +0.5, which makes sense with Franks map above if you drew a line between E Ct, RI and EMass through LI to S NJ where there are still above normal departures.  Unfortunately the site I use only had data available through the 11th as of this am, but I see it must have recently updated because I can now include the 12th, but still cannot include the 13th.  Here is the map to include the 12th as well.  This looks like what I extrapolated in my head from this mornings map as the mean departure through current.  In reality since yesterday was avg -6 from departure the map above is obviously more indicative of where we are for the month.  Frank I wish that site you posted allowed you to input specific daily dates rather than just weekly, monthly etc.  

Here is the link for the site I use in case anyone wants to bookmark: Note: this site is not the most user friendly.  
https://www.esrl.noaa.gov/psd/data/composites/day/

[jmanley32]

Well hello 12z GFS giving PA/central/northern NYS 2 feet of snow in 12-14 days LOL even NYC sees a few inches yeah I will believe it when I see it.

[Math23x7]

So the pattern the next couple of weeks looks to be cold-cuts.  In other words, It will be cold and dry except when we have a cutter, in which case we get warm precipitation with temps in the 50s and 60s.  When those cutters pass, the temperatures drop.  

As the beyond there, I am not encouraged by the latest EPS.  The end of the run shows warm air flowing in from the midwest to the East:

500 mb height anomalies:



850 mb temp anomalies:



2-meter temp anomalies:



Notice by the way that it uses the 1997-2016 anomalies rather than 1981-2010 that the NWS uses.  If you replaced it with 1981-2010, the anomalies would be higher.

I know December is still over two weeks out but I am not encouraged by how December looks at this point.

[algae888]

So the pattern the next couple of weeks looks to be cold-cuts.  In other words, It will be cold and dry except when we have a cutter, in which case we get warm precipitation with temps in the 50s and 60s.  When those cutters pass, the temperatures drop.  

As the beyond there, I am not encouraged by the latest EPS.  The end of the run shows warm air flowing in from the midwest to the East:

500 mb height anomalies:



850 mb temp anomalies:



2-meter temp anomalies:



Notice by the way that it uses the 1997-2016 anomalies rather than 1981-2010 that the NWS uses.  If you replaced it with 1981-2010, the anomalies would be higher.

I know December is still over two weeks out but I am not encouraged by how December looks at this point.

mike why are you cherry picking warm guidance.since you are using a 360 hour forecast take a look at the euro weeklies weeks 4 thru 6. roughly dec 2nd to around xmas. tell me what you see. week three on the weeklies ( week after t day) was always a relaxation from this very cold spell then reload.that's what your seeing on guidance. tell the whole story man. it's cold thru t day weekend. probably -4* by that time. that's a HUGE pattern shift!! plus it has been very active. man you have become a Debbie downer.

[algae888]

here mike this from a met from another board on warm up last few days of nov and his thoughts on dec.
"Looks like PAC is trying to begin a reload a bit more than last night's run. You can see the plains heights lower and the heights near and N of AK higher at the end of the run vs the 00z run. It would probably look better if we had a few more frames out to about day 17 or 18.
 
That kind of agrees with yesterdays weeklies where we saw the reload happening in week 3 and then week 4 was looking pretty good. So hopefully we continue to see that progression....that would be good timing as climo would be a lot more favorable by that point."

[algae888]

here is more mike from the same met which I agree totally....
"The fact that November will likely come in BN and the composite of the month will have good N PAC poleward Aleutian ridging is definitely a good sign going into December. It suggests that any relaxation of the PAC will probably be short lived."

[Frank_Wx]

A coastal storm is showing up on the models for Thanksgiving Day but it's looking to warm for any snow at this time. Since it's still a week away there is time for change. They key is the northern piece. At the moment, the GFS shows it closing off over the Great Lakes which raises heights along the east coast. We want this northern piece to dig downstream in response to the PNA ridge and phase with a southern piece of energy off our coast. That would ensure cold air is in place. Plenty of time for this to happen still.

[Frank_Wx]

500m gets a little strung out too. Need that ridge in the west to hold and not begin traveling east. It throws off the ridge-trough configuration we need for a snowstorm. Timing of Pacific energy will be important. Can't have energy crashing into the PAC NW. It will make that ridge roll.

[sroc4]

A coastal storm is showing up on the models for Thanksgiving Day but it's looking to warm for any snow at this time. Since it's still a week away there is time for change. They key is the northern piece. At the moment, the GFS shows it closing off over the Great Lakes which raises heights along the east coast. We want this northern piece to dig downstream in response to the PNA ridge and phase with a southern piece of energy off our coast. That would ensure cold air is in place. Plenty of time for this to happen still.

Yeah it is setting up to be a Miller B type set up which this early in the season will def be extremely tough to have work out along the coastal plain. Like you said still a ways out and the final soln rarely shows itself definitively this far out.

Frank whats the actual difference between a wave 1, wave 2, and wave 3 attack on the stratosphere? Is it strictly the geographic location for which the attack occurs?

[algae888]

got this from another board. ffor what ever reason the euro is struggling with this pattern...

[algae888]

more on euro. my question is how does the trough over central Canada move east instead of dropping into central U.S.. look at the dif. between euro and gfs....
euro


gfs


with the west based block and 50/50 low it makes sense for the next s/w/trough to dig into U.S. heartland. it should not move east. let's see if there is a correction on the next few runs of euro.

[sroc4]

more on euro. my question is how does the trough over central Canada move east instead of dropping into central U.S.. look at the dif. between euro and gfs....
euro


gfs


with the west based block and 50/50 low it makes sense for the next s/w/trough to dig into U.S. heartland. it should not move east. let's see if there is a correction on the next few runs of euro.

There are a couple of differences Al.  First is the GFS has the northern stream energy a little stronger vs the euro.  The second and more significant is the interaction and placement of the southern piece of energy.  Here are the GFS and euro and you can see by 00z the 21st look at the difference in position and amt of interaction the GFS vs the euro has.  The GFS clearly has much more interaction between the N and S pieces by this time because the S piece is much further east when compared to the euro.  This allows the PNA ridge to be a little taller which allows the N piece to dig a little more and interact with the southern branch.




 The result is a much stronger system that cuts.  The euro on the other hand holds back the energy in the west (a known bias) therefore the N piece doesnt dig and interact nearly as much resulting in a Low that passes N and W and the two branches remaining unphased for the most part.  Honestly we need to have the southern energy to slight out ahead of the N energy rather than the reverse like the GFS shows where its just behind.  The way its currently modeled by both models will result in warm out ahead of the cutter followed by cold frontal passage and below normal behind the front.  








Of course 12z GFS has a COMPLETELY different look compared to the 6z meaning dont trust it.  Euro has been consistent at least with holding back the energy.    

[amugs]

The Wpo remains strong which is a good sign and will have downstream effects. If we can get rid of the stubborn troughing in w canada/e pac, we would be ready to roll. With all things considered though, it’s not a bad look. EPS raising height in the 10 day plus, good sign there. Maybe onto the MJO wave. If we can get that we roll and like I said in banter it usually pops up in a short time frame with this huge perturbation in the pattern.
Sitting tight and Al just know you are the third person here to call Miey Math23x7 out about the warmth. Heat Miser??
Anyway , like the polar extension from the top pac and we have a warming in the PV that will perturbation it for latter Nov and early Dec. Where it sets up on the side of the world will be important. To far weat and it opens up the SE Ridge to a degree for the coast. Set up in Alberta and good location to a degree. Beat is HB west shore.
Good discussion here lads and keep it up. Lots of changed coming with the transition.

[sroc4]

Great points Mugs. Some hints that the Strat vortex might shift back to the other side and strengthen. Big trouble if it does. Still in the Lr though so we’ll see.

[Isotherm]

Previous w2 hit now transitioning into a largely suppressed vertical wave driving regime for the upcoming 7 days, as the strengthening PNJ / SPV will project onto the troposphere by D7-10 with a neutralization of the NAM. However, a robust w1 constructive interference will occur D10-15 which will converge on the vortex by the end of this month, resulting in about a 40-45% (or potentially more) reduction in mean zonal winds at 10hpa. I expect these effects to downwell one week following, bringing us to late in the first week of December or the second week. By that point, a contemporaneous shift in low-frequency tropical forcing will once again initiate Aleutian ridging, coupled w/ an increase in hi-lat blocking. So I do expect this transitional phase to in fact be a legitimate "relaxation," preceding a more auspicious pattern henceforth.

[sroc4]

Previous w2 hit now transitioning into a largely suppressed vertical wave driving regime for the upcoming 7 days, as the strengthening PNJ / SPV will project onto the troposphere by D7-10 with a neutralization of the NAM. However, a robust w1 constructive interference will occur D10-15 which will converge on the vortex by the end of this month, resulting in about a 40-45% (or potentially more) reduction in mean zonal winds at 10hpa. I expect these effects to downwell one week following, bringing us to late in the first week of December or the second week. By that point, a contemporaneous shift in low-frequency tropical forcing will once again initiate Aleutian ridging, coupled w/ an increase in hi-lat blocking. So I do expect this transitional phase to in fact be a legitimate "relaxation," preceding a more auspicious pattern henceforth.

Tom what's the actual difference between a wave 1, wave 2, and wave 3 attack on the stratosphere? Is it strictly the geographic location for which the attack/EPV flux occurs?

[GreyBeard]

Previous w2 hit now transitioning into a largely suppressed vertical wave driving regime for the upcoming 7 days, as the strengthening PNJ / SPV will project onto the troposphere by D7-10 with a neutralization of the NAM. However, a robust w1 constructive interference will occur D10-15 which will converge on the vortex by the end of this month, resulting in about a 40-45% (or potentially more) reduction in mean zonal winds at 10hpa. I expect these effects to downwell one week following, bringing us to late in the first week of December or the second week. By that point, a contemporaneous shift in low-frequency tropical forcing will once again initiate Aleutian ridging, coupled w/ an increase in hi-lat blocking. So I do expect this transitional phase to in fact be a legitimate "relaxation," preceding a more auspicious pattern henceforth.

Trying to read your posts is like trying to read a foreign language. Perhaps you can say what you want to say in terms that the average reader can understand. I, for one, haven't a clue.

[sroc4]

Previous w2 hit now transitioning into a largely suppressed vertical wave driving regime for the upcoming 7 days, as the strengthening PNJ / SPV will project onto the troposphere by D7-10 with a neutralization of the NAM. However, a robust w1 constructive interference will occur D10-15 which will converge on the vortex by the end of this month, resulting in about a 40-45% (or potentially more) reduction in mean zonal winds at 10hpa. I expect these effects to downwell one week following, bringing us to late in the first week of December or the second week. By that point, a contemporaneous shift in low-frequency tropical forcing will once again initiate Aleutian ridging, coupled w/ an increase in hi-lat blocking. So I do expect this transitional phase to in fact be a legitimate "relaxation," preceding a more auspicious pattern henceforth.

Trying to read your posts is like trying to read a foreign language. Perhaps you can say what you want to say in terms that the average reader can understand. I, for one, haven't a clue.

Simply stated a wave 1(w1) attack on the stratospheric vortex initiated by the very potent MJO wave we saw the last 10days of Oct combined with two recurving typhoons in the same timeframe caused a disruption to the strat vortex such that it was weakened and became elongated and even split for a brief time and positioned on our side of the globe which led to the establishment of high latitude blocking (WPO/EPO regions) over the Aleutian islands and Alaska extending into the arctic.  The result of this positioning of the strat vortex on the north american side of the N hemisphere elongated as such, and the resultant high lat blocking set up in the WPO/EPO region (Aleutian Island/Alaska) allowed the cold air to be discharged into the mid latitudes of north America.  The arctic blast we saw around the 7-9th and the below normal temps since then were the result of that.

A wave 2 attack on the strat vortex (w2) occurred in the first 5-7days of November which is leading to additional disruption to the strat vortex such that high latitude blocking in the north Atlantic(NAO) region is becoming established.  However, we may be losing the high lat blocking in the Aleutian Island/alaska location while simultaneously establishing the blocking in the N Atlantic/Greenland location.  

There will likely be a relaxing period after the Thanksgiving through the first to second week of December, aka a loss of high lat blocking in the N Atlantic AND/OR N Pac, and the strat will likely get stronger for a period, tighten up, and shift away from north America and possibly onto the Asian side of the N Hemisphere for a period.  This will likely result in a period of a couple of weeks that will go back to warmer than normal temps overall for most of us...

BUT he believes a strong wave 1(w1) attack is imminent on the strat vortex once again in the 10-15 day time frame, the result of which will lead to the distruption/weakening of the strat vortex once again such that the high latitude blocking in the troposphere(where we live) re-establishing itself around the Aluetian Islands once again which will hopefully discharge the cold air into the mid latitudes of north America (our back yards) for the later half of December.

[sroc4]

Even more simply stated:

We will likely cont below normal to normal temps between now and Thanksgiving. After that time there is a good chance, but not definite that we go to above normal to maybe normal temps for a period of about two weeks +/-. Beyond that we may go back to below normal temp regime for the latter half of the month of Dec.

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