Tuesday, November 17, 2015

Tuesday Morning Storm Outlook: Eyeing Sunday

Good morning everyone. I am becoming more concerned that a coastal storm can develop late this weekend along the eastern seaboard. Right now this is more of a speculative post, but the trends I have seen in the last 36 hours especially with the European model hint that we need to be on the lookout.

The situation is the following. We have a big front coming through on Thursday with rain as I mentioned yesterday. In the wake of this front cold air sweeps into the region as shown by the blue colors. This is ingredient #1. Always need cold air. 



Also, we have some blocking in the jet stream to the north indicated below over Greenland. This slows down the jet stream.

The yellow circle represents energy in the northern jet stream that is projected to dive down from Canada Saturday and Sunday. Since we have an area of high pressure over Greenland and a sharper ridge than modeled previously out west this energy MIGHT dig into the east coast and consolidate into a storm.

As an example take a look at the difference between this energy on old model runs vs new ones. I want you to notice how in the new runs the ridge or red in the western US is sharper and the blue is more consolidated..

Sundays European..

Yesterday's European..

Today's European..

Again looking above notice the ridge out west gets sharper w each run and the blue near the east coast gets more focused or consolidated. This is a trend that could mean we see a coastal storm if it continues. Other models are flirting with this idea but do not have it yet, but as you all know when I see the euro start to trend I tend to take notice.

So what does it mean? At this time I say we have a 45% chance as a storm developing. IF the storm develops it looks to be rain near the coast and snow for interior New England at this time. No, I am not calling for a Mid Atlantic snowstorm, that would be way too premature given the uncertainty here. 

Regardless we got our first potential storm on the boards to track of the season! You will not hear much about this yet in mainstream until and if these trends get stronger just know we need to keep a close eye on this. 

More tonight, stay tuned. 

2 comments:

  1. Willy, most of the long-term forecasters that I'm reading still point to February as being the interesting month. For now, doesn't look like anything much outside the usual seasonal weather. Still appears to be talk of a slightly warmer December, although that's not a lock given the continued strength of the blob, the Siberian snow and the Nino's central pattern (although interestingly, sub-surface ocean temp anomalies are still pretty high near the S. American coast -- perhaps sub-surface flows are gonna keep the eastern region SSTA's from cooling down quickly after Nino peaks next month? Thus an active but still relatively warm southern jet?) For now, yea, that North Pacific blob is hanging tough. It might stay in business with all the central Nino energy radiating beneath it (but its exact shape and latitude is thus subject to question). The AO could well trend neg given that Siberian snowbank, along with the NAO (although the Gulf Stream is still bringing a lot of warm water up as far as Newfoundland, which could help maintain some coastal ridge and help push the Great Lakes trough inland -- like what I see on your GEFS 306 chart). I'm just sayin', this is gonna really be an interesting season, I don't think anyone's 1 to 3 month forecasts are particularly strong right now with this crazy set-up. But please, keep on forecasting, we all learn from the whole exercise! Once we get to the Superbowl (or at least the divisionals), the picture should be in much better focus. Keep up the good work in helping to make that happen. Jim G

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    1. Thanks Jim. Feb should be the most "active" month with this strong central based el nino that will start to weaken. December will be back and forth but I do not think its a blowtorch at all. I am seeing evidence of the seasonal variation of the jet stream evolving to our winter pattern. What I mean by that is hights slowly startnig to build to the north the Aluetan low starting to show up on the model from time to time. Trends in the eastern pacific are pretty strong to insist that the wamer water stays more west which is much different from 1997. Regardless, the strength of the el nino will still keept the season from being bitterly cold. With that active jet however and a mean ridge positon that could be over montana we could see a lot of action. People are looking at the 500mb maps and saying it looks warm but it really is not due to the ridging up there. If there was a trough up there then its a completly different story. Right now we are facing an active stream of southern moisture all season and from time to time the northern jet will interact with it and cause big storms. Whether or not those storms are just off the coast or a little inland remains to be seen.

      Bottom line its a tough seasonal forecast especially the month to month portion. The only hard stance I will take is that I do not expect a blow torch winter due to OVERALL pattern in the SSTA in pacific and atlantic. The most recent JMA and UKMET climate models support this view. 30% more snow than normal and temps 1-2 degrees below normal.

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