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Upstate NY/North Country + adjacent ON, QC, VT: End of Fall/Into Winter!


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Polar Vortex at end of GFS run. ^_^

gfs_T850_us_51.png

Latest blog post by Judah Cohen

The polar cap geopotential height anomaly plot continues to show a strong polar vortex into the foreseeable future (not shown). However some slight increase in wave activity flux in week two is predicted to perturb the stratospheric polar vortex so that it becomes less circular and more elongated (Figure 7). The counter clockwise flow around the polar vortex would help transport cold air from Siberia and drive it into North America east of the Rockies. This pattern is reminiscent of the dominant winter pattern of the past two winters that resulted in extremely cold winters in the eastern United States. The possibility of transport of cold air from Siberia into the Central and Eastern United States is something to watch as we officially begin winter. However we do not anticipate this to necessarily be the dominant winter pattern as we expect further disturbing of the polar vortex and longer term implications as we discuss in the next section.

30–day

As we have shown in our research the favored high latitude atmospheric pattern in November that follows above normal October Eurasian snow cover extent is the expansion of the Siberian high across northwest Asia with low pressure to the east near the Aleutians and a secondary area of low pressure in the northern North Atlantic; a pattern that we refer to as the tripole pattern (Cohen and Jones (2012)). The current atmospheric pattern strongly projects onto this pattern. This same pattern also favors the increase in wave activity flux or the vertical transfer of energy from the troposphere to the stratosphere during the month of December. At AER we have developed a polar vortex model that predicts the strength of the polar vortex one month in advance. It is predicting a major sudden stratospheric warming (SSW) in mid-December. We currently feel that this forecast is unlikely because the model is overly sensitive to SSW and has many false positives and because a major SSW is relatively rare in December. Still given the polar vortex model forecast and strong projection of the current atmospheric pattern onto the tripole pattern, we are more confident in increased wave activity flux in December that will result in weakening of the polar vortex in December and likely continuing into January. Also because the current dominant high latitude circulation is a wave two pattern, this would favor a polar vortex split relative to a polar vortex displacement in the event of a significant weakening of the polar vortex. One inhibiting background factor is the westerly phase of the quasi-biennial oscillation (QBO) that favors a strong vortex over a weak vortex. But if our expectations of a weakened polar vortex verify, this will likely favor an increased likelihood of severe winter weather across the continents of the Northern Hemisphere. Of course all of this is highly speculative but the purpose of this blog is to push the boundaries of what is possible in weather forecasting beyond the skillful range of the weather models.

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I see a w/nw event where are you seeing sw?

Sorry, you're definitely right. I had looked at a couple charts in class when the winds start to back out of the WSW at the end of the event, and just didn't look closer then that. Either way, GFS/ECM have been relatively consistent in their solutions, with the GFS wavering back and forth between pure Westerlies to WNW'erlies.

 

BUF has put 70% pops in for Oswego for Saturday Night-Sunday night! :)

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And BUF's AFD for those who haven't seen it. Should be interesting to see if we can actually manage of Huron connection with WNW flow. I truly haven't seen a band stay over Oswego for more than 3-4 hours in my time here, so I'm cautiously optimistic about this!

 

 

HOWEVER BY
SUNDAY MORNING...PRECIPITATION ACROSS THE SOUTHERN TIER SHOULD
RAPIDLY CHANGE ENTIRELY OVER TO SNOW AS THE LOW LIFTS ACROSS THE
OTTAWA VALLEY AND STRONG WESTERLIES WRAP COLDER AIR AND MOISTURE
BACK ACROSS THE AREA...SETTING UP WHAT MAY BE THE FIRST SIGNIFICANT
LAKE EFFECT EVENT OF THE SEASON FOR PORTIONS OF THE FORECAST AREA
ON
SUNDAY. SEE THE LONG-TERM DISCUSSION BELOW FOR MORE DETAILS...

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS SATURDAY`S LOW MOVES OFF INTO QUEBEC SUNDAY...ALL OF THE
INGREDIENTS APPEAR TO BE IN PLACE FOR A BRIEF BUT POTENTIALLY
SIGNIFICANT LAKE EFFECT EVENT ACROSS THE WESTERN SOUTHERN TIER AND
OFF OF LAKE ONTARIO ACROSS THE TUG HILL PLATEAU
. ENSEMBLES ARE IN
EXCELLENT AGREEMENT ON THE SYNOPTIC SETUP ACROSS THE REGION WITH A
SURFACE/MID-LEVEL LOW LIFTING OFF TO THE NORTHEAST ACROSS QUEBEC AND
A SHARP UPPER LEVEL TROUGH UPSTREAM ACROSS THE CENTRAL GREAT LAKES.
COLD AIR WRAPPING IN BEHIND THE SURFACE/MID-LEVEL FEATURES WILL
ADVECT ACROSS THE LAKES ON WESTERLY FLOW AND AS 850MB TEMPS FALL TO -
10C...EQUILIBRIUM LEVELS WILL CLIMB ABOVE 15KFT BY DAYBREAK
SUNDAY MORNING. WHILE DIURNAL EFFECTS SHOULD HAMPER BAND
DEVELOPMENT TO SOME EXTENT DURING THE DAY ON SUNDAY...SYNOPTIC
LIFT FROM THE UPPER LEVEL TROUGH MAY COMPENSATE FOR THIS AS IT
MOVES THROUGH BY SUNDAY EVENING WITH A BRIEF PERIOD OF POTENTIAL
UPSTREAM CONNECTION OFF OF LAKE HURON AS FLOW VEERS TO THE WNW
LATER IN THE DAY AND INTO SUNDAY EVENING
. INCREASING SHEAR SUNDAY
NIGHT IN THE WAKE OF THE UPPER LEVEL TROUGH PASSAGE SHOULD BRING
AN END TO THE BULK OF THE SNOW BY MONDAY MORNING OFF OF LAKE ERIE
AND AROUND MIDDAY OFF LAKE ONTARIO.

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And BUF's AFD for those who haven't seen it. Should be interesting to see if we can actually manage of Huron connection with WNW flow. I truly haven't seen a band stay over Oswego for more than 3-4 hours in my time here, so I'm cautiously optimistic about this!

 

Yeah, you should be in a good spot for this. Maybe just north of your location. Keep us updated!

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BUF is at +7.4 for the month.  I don't see this changing too much with another big time warm-up looking likely around T'giving.  I would be interested in what the analogs say for winter temp/snowfall after such a torch November.  

 

Strong El Ninos almost always mean a warmer winter, snowfall is unpredictable though, especially because lake effect represents 50-60% of our snowfall.

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Strong El Ninos almost always mean a warmer winter, snowfall is unpredictable though, especially because lake effect represents 50-60% of our snowfall.

 

Persistent snow cover will probably be tough to have - hope ski country can get through this OK. But an open lake in Feb/Mar might give us plenty of opportunities in what are typically lower snowfall months.

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The lake effect may start out on a SW flow before veering Sunday Afternoon, but there is another shortwave moving in very early Monday morning which may swing the band back north and provide some synoptic lift to the band as temps should still be cold enough until the afternoon where dry air moves in and chokes the band off.

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Ever used this one for snowfall prediction/probs? It tends to be a lot more accurate;

http://www.wpc.ncep.noaa.gov/pwpf/wwd_accum_probs.php?fpd=24&ptype=snow&amt=1&day=2&ftype=probabilities

No, I haven't found the WPC 24/48/72 maps produced in Maryland 2x daily to show more predictive accuracy than the maps produced by the Buffalo WFO. It's nice that they harmonize between WFOs - I know that the disjuncts on map edges between offices drive some people bonkers - but professional mets at local forecast offices tend to have a better understanding of local conditions in general, and with the peculiarities of lake weather, that means even more at the Buffalo office.

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No, I haven't found the WPC 24/48/72 maps produced in Maryland 2x daily to show more predictive accuracy than the maps produced by the Buffalo WFO. It's nice that they harmonize between WFOs - I know that the disjuncts on map edges between offices drive some people bonkers - but professional mets at local forecast offices tend to have a better understanding of local conditions in general, and with the peculiarities of lake weather, that means even more at the Buffalo office.

Maybe that works if you live at 'ground zero' for a great WFO like Buffalo. For me, right at the far boundary of three different ones (and directly subject to the worst of the three), the WPC maps are always more accurate. Buffalo is a (semi) close second if I punch in the zip code three miles west of me.

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Maybe that works if you live at 'ground zero' for a great WFO like Buffalo. For me, right at the far boundary of three different ones (and directly subject to the worst of the three), the WPC maps are always more accurate. Buffalo is a (semi) close second if I punch in the zip code three miles west of me.

Yeah, you're subject to that special frustration of map edges. And it doesn't surprise me that some WFOs do a poor job outside what they see as the key population or weather origination areas, so it makes sense that the WPC forecasters, just by weighing every area equally, do a better job. That sucks, and if you're getting higher accuracy from less frequent larger scale forecasting, that is a flaw in the system.

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