Both the 12z ECMWF and 12z GFS are showing a break in the polar vortex- a significant development that may lead to the much-anticipated pattern change. Another thing we're seeing in these 8-10 day height anomaly outlooks are trough patterns in the Southwest as well as offshore the Southeast. This means that the cutoff low pattern may return to the Southwest and bring some snowy weather to the Plains. Possibly. A lot has to be determined, but it does match up with my theory of cutoff lows returning.
Friday, December 30, 2011
January 3-5 Lake Effect Snow (Great Lakes Affected)
Hour 90 of 12z GFS |
The snowfall from the lake effect snow may put down up to a foot of snow up in the far northern reaches of Michigan. Lake Michigan may put down up to 6 inches of snow, with lesser accumulation in the eastern Great Lakes.
January 2-4 Snow Event (Midwest, Great Lakes Affected)
Hour 42 of 12z GFS |
Hour 48 of 12z GFS |
There are two sides to this storm: precipitation and temperatures. Here's 850mb temperatures from the ECMWF.
Hour 48 of ECMWF |
Hour 72 of ECMWF |
Hour 96 of ECMWF |
Icy Mix Possible This Evening in the Northeast
PrecipCAST from intellicast.com Time valid for 10:00 PM EST |
Map is not interactive |
Full Winter Update, Snowstorm Predictions, Long Range Predictions
We are seeing a major stratospheric warming event take place in the last several days. We are seeing some big temperature anomalies from the 30mb level up to the 1mb level. The big part is that the warming is occurring over Alaska. Because the warming is occurring over Alaska, we might be seeing the semi-permanent low pressure system over Alaska weaken as the warming may progress down into the troposphere. If this warming continues, the pattern change would definitely be helped along. The warmth may be able to propagate into the North Pole, where a disruption in the Polar Vortex could break the stubborn +AO/+NAO regime which has been producing a snow drought over the East US.
Here we have the 0z ECMWF 500mb analysis over the far North Hemisphere. We see the strong low pressure systems right over the North Pole. We can see the strong low pressure system over Alaska, where we are seeing warming occurring. Now let's skip ahead to hour 168.
At hour 168, we are seeing a ridge from Asia pump north into the polar vortex and interrupt it for a little bit. This ridge will be pulled north into the main polar vortex and disrupt the vortex. Essentially, the NAO and AO will also be disrupted. The AO, which is based in the North Pole, is the biggest piece that will be affected. If the vortex breaks, the extremely cold air that has been locked up may flow southward as the vortex breaks. Moving ahead to hour 240 is seeing the low pressure system over Alaska take a big weakening hit, which may bring some active weather into the US. However, no model does well at 10 days out, so take this as something to watch.
But let's say that this disruption does happen. Well, what would happen to the all-important NAO?
The old 0z ECMWF shows the point of when the expected break in the polar vortex is, as well as the effects of the polar vortex break. The new 12z ECMWF does now show the downward trend, but an up-and-down pattern similar to what we have outlined as the time when the vortex breaks. We are still seeing a more persistent ridge break into the polar vortex, however, so the NAO image above should not be discounted.
The NAO has been wildly swinging. With stronger systems bringing stronger positive NAO values, this means the potential for lower NAO values, going off of Newton's laws: With every action there is an equal and opposite reaction. If we use that law, it can be determined that a strong +NAO value will eventually lead into a strong -NAO sometime this winter.
SNOWSTORM PREDICTIONS---
Pre note: Confidence is low on these predictions. It is entirely possible that these snowstorms will not happen. In other words, don't hold me to these.
January 6-11: An active period is already setting up that should lead into the first couple weeks of January, if not longer. Among those possibly affected include the North Plains and the Northeast.
January 14-18: A couple shots of low pressure systems into the Southwest could make for a good snow somewhere in the Plains or Midwest.
LONG RANGE PREDICTIONS---
A quick start to January will continue as the deep low pressure system over Alaska weakens as the ridge interrupts the polar vortex in the early new year. Late January may bring a deep chill to much of the country as the Arctic Oscillation dips far enough into negative territory to unleash pure Arctic air. Using Newton's Laws mentioned above, we can expect a BIG snowstorm for the Northeast sometime this winter when the NAO goes negative in response to a very positive NAO so far this winter.
Here we have the 0z ECMWF 500mb analysis over the far North Hemisphere. We see the strong low pressure systems right over the North Pole. We can see the strong low pressure system over Alaska, where we are seeing warming occurring. Now let's skip ahead to hour 168.
At hour 168, we are seeing a ridge from Asia pump north into the polar vortex and interrupt it for a little bit. This ridge will be pulled north into the main polar vortex and disrupt the vortex. Essentially, the NAO and AO will also be disrupted. The AO, which is based in the North Pole, is the biggest piece that will be affected. If the vortex breaks, the extremely cold air that has been locked up may flow southward as the vortex breaks. Moving ahead to hour 240 is seeing the low pressure system over Alaska take a big weakening hit, which may bring some active weather into the US. However, no model does well at 10 days out, so take this as something to watch.
But let's say that this disruption does happen. Well, what would happen to the all-important NAO?
OLD 0z ECMWF |
The NAO has been wildly swinging. With stronger systems bringing stronger positive NAO values, this means the potential for lower NAO values, going off of Newton's laws: With every action there is an equal and opposite reaction. If we use that law, it can be determined that a strong +NAO value will eventually lead into a strong -NAO sometime this winter.
SNOWSTORM PREDICTIONS---
Pre note: Confidence is low on these predictions. It is entirely possible that these snowstorms will not happen. In other words, don't hold me to these.
January 6-11: An active period is already setting up that should lead into the first couple weeks of January, if not longer. Among those possibly affected include the North Plains and the Northeast.
January 14-18: A couple shots of low pressure systems into the Southwest could make for a good snow somewhere in the Plains or Midwest.
LONG RANGE PREDICTIONS---
A quick start to January will continue as the deep low pressure system over Alaska weakens as the ridge interrupts the polar vortex in the early new year. Late January may bring a deep chill to much of the country as the Arctic Oscillation dips far enough into negative territory to unleash pure Arctic air. Using Newton's Laws mentioned above, we can expect a BIG snowstorm for the Northeast sometime this winter when the NAO goes negative in response to a very positive NAO so far this winter.
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