BLOG SONG: "Blame" by Calvin Harris
This is a 2-part blog. The 1st part will talk about the overall pattern in the medium to long range. The 2nd part will discuss individual storm systems over the next 10 days.
Don't blame it on the night. Blame it on the NAO/QBO!
Long Range Pattern
The Stratosphere has been a big problem so far this winter. The QBO has been extremely negative due to mean zonal winds staying stubbornly westerly instead of reversing easterly like we typically see by mid-winter. There has been no SSWE (Sudden Stratospheric Warming Event) yet, but we have seen SSW at 10 hPa which has helped temporarily displace or split the PV a couple times already. The graphic above shows the PV progression in the Stratosphere at 50 hPa. As time goes on, the Stratospheric PV is shifting into Eurasia and warming is taking place over Canada, the Davis Straits, and Greenland. This should allow for positive heights to build in the Troposphere over the AO region which could finally bring our AO into a permanent negative state. The NAO will definitely neutralize and might even trend slightly negative, but I am not yet convinced it reaches an anomalous negative state like many predicted this winter. Until the QBO reverses, expect an NAO mainly around neutral to positive.
This progression is also apparent at the 30 hPa level. The lag effect for this to reflect at H5 is usually 7-10 days, which would take us into late Jan/early Feb.
Like the Stratosphere, the MJO has also not cooperated as well as we would have liked given that we're (supposedly) in a weak El Nino ENSO. Some have argued that the extremely negative QBO or the active sun are the culprits to why our atmosphere has not responded to the +ENSO. There is probably merit in those theories. The Pacific Jet has been unusually amplified which has taken a toll on our Pacific pattern this season. The PNA has struggled to stay consistently positive despite the +PDO in the east-northeast Pac. The STJ has been weak with little to no influence on our upper air pattern yet this winter.
Currently we're in phase 7 of the MJO which promotes higher heights in the west U.S. and the northeast Pac. This signals for a -EPO/+PNA couplet. It also suggests there should be higher heights into the Arctic and NAO regions but there is some resistance there given the current state of the Stratosphere. Both the GFS and EURO want to take the MJO into the COD (circle of death) next week, but the biggest difference is the GFS comes out again into phase 8 then 1, while the EURO stays in the COD. An MJO in the COD has no influence on our upper air pattern. Given the struggles we have seen with the Pacific Jet and the lack of blocking, we absolutely want the MJO to have an influence on our pattern going forward so it's imperative the GFS verifies here.
Put it this way: if what I said about the Stratosphere comes to fruition with the PV shifting into Eurasia, then there will no longer be resistance in the Arctic and NAO regions for higher heights to build there. An MJO in phases 8-1 typically bring about a -AO/-NAO. This may be our only shot in trying to overcome the -QBO.
That being said, OLR anomalies show active tropical weather or convection east of the Dateline over the next 6-10 days. This is why we're currently seeing an MJO pulsing in phase 7. The big question then becomes...can this convection continue its propagation eastward? It's hard to say right now since these are current observations, but seeing convection building again over the Indian Ocean in the Day 11 range with suppressed conditions closing in on the Dateline again does NOT look favorable to me. The GEFS have done a much better job than the EURO this season, so maybe they're seeing something I'm not, so lets hope they verify and the MJO can get into phase 8. As the composite graphic shows, an MJO in phase 8 supports a continues -EPO/+PNA with a stronger signal for a -AO/-NAO to develop.
The 00z EPS show a nice -EPO/+PNA pattern in the west with a mean trough on the east. The issue remains the AO/NAO where they both look to remain mainly positive this run. Keep in mind the EURO has the MJO collapsing into the COD, so of course it will show lower heights over those regions compared to the GEFS.
Here were the 06z GEFS and they have noticeably higher heights extending into the Arctic and even Greenland.
Let me be clear about something: The pattern going into the end of this month and early February is NOT screaming Godzilla. It is, however, a much improved pattern than where we have been so far this winter and for that matter the potential to get at least a moderate snowfall is higher. The flow on the east is still too fast, so we would have to get good timing with the ridge axis in the west and the northern/southern stream phase on the east. I can see a Miller B type of storm come out of this pattern.
If one thing is certain, it will be that the cold air has staying power and the month of January is likely to end well below normal. Anytime Pacific blocking develops that is a signal for arctic air masses to intrude into the eastern CONUS. Expect below normal cold through the end of the month.
Potential Storm Systems
Wednesday January 21st Clipper:
There has been a lot of waffling on latest guidance on the intensity of this clipper storm. Since this is all northern stream driven, to what degree the energy digs and consolidates will determine how much it deepens and where it tracks.
Today's 12z GFS is doing pretty much what the 00z EURO did last night. There are two pieces of northern stream energy, one over the Mid-Atlantic and the other over the Midwest, that remain separate and de-amplify the east coast trough. The clipper would have looked much better at the surface if those energies consolidated because the trough axis would sharpen up and a storm would try to come up the coast. At this point, I probably would not expect more then a minor event in the order of a coating to an inch or two for the area. If future runs show better consolidation over the next couple of days, this could turn into a 2-4/3-6 ordeal. I would bet against that for now, but I'll be sure to keep you updated.
January 24th-27th Storm:
This is the next time frame to watch for a bigger storm to develop.
The 12z GFS looks very progressive in this time period with a trough axis positioned too far east and minimal northern stream energy interaction.
The GFS Ensembles have a large spread and are not so much in agreement. They at least develop the coastal storm but do so too far off the coast. You can tell when guidance is struggling with a storm system when the time frames are all mixed up. Some have it on the 24th, others on the 26th. The various upper air energies circulating the country makes this a complex situation for the models to handle. Once they realize which vort to focus on, we'll begin to see more agreement.
The 00z EURO from last night looked much better. A sharper looking trough with northern stream energy digging in for a phase, but the storm tracked too far off the coast. Better ridge orientation in the west would have brought the storm up the east coast. You can see both models differ on where to place the main axis of the western ridge. It actually almost looks like a Rex Block with a High Pressure dome over a low pressure off of Baja. They look very much like the GEFS. For now, just realize the potential is there.
Even beyond January 27th there are more threats to look out for. Like I explained in the long range section, if we can get the Stratosphere and MJO to cooperate, it would greatly put our upper air pattern in a better position to deliver us a storm. I still feel a moderate snowstorm is possible between January 24th and February 5th, possibly of the Miller-B variety. We'll see if this pattern can deliver. If not, managing to reach an average snowfall season will reach a higher level of difficulty.
Enjoy the rest of your day.
-Frank
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