Thursday, November 10, 2011

About that Alaska storm...

12:15 PM EST 11/10/11 HISTORIC ALASKA STORM TO IMPACT LONG RANGE PATTERNS? While many in the Meteorological community know the Gulf of Alaska is a breeding ground for major coastal storms, few people alive today can remember a time when hurricane-force driven snow struck our northernmost state with such ferocity.  Our team has posted   on the subject today because we were searching for a reasonable scientific overview from others on why this storm occurred. We wanted to provide a basis for answering two core questions we know many of our readers (and our own members)  might be asking:
  1. WHAT caused the Alaska storm to be so extreme?
  2. WHEN is the next major event? 
  3. HOW could this storm affect the winter pattern?
SYNOPSIS: Our Winter Stormcast and Long Range Teams believe the Alaska storm is another step in the "early Winter" pattern which has been evolving in the U.S. since Hurricane Irene. We anticipate a continuation of the severity and frequency of "billion dollar"  high impact events in the U.S. for the winter ahead. In 2011, fourteen events have caused over  $1 billion in reported damages,  per event.  We project the next significant to major snow event in the Eastern U.S. for the November 25 to December 5 time period. This event, if snowfall may resemble the outcome of the October 29-30, 2011 storm.  

What caused the Alaska storm to be so extreme?
OUR SHORT ANSWER: The November 2011 Alaskan Blizzard could have resulted from long term changes in the Nino-Nina pattern, as well as above normal sea surface temperatures. 
Our early hypothesis is centered on the possible global "unraveling" of energy changes in the atmosphere due to wild swings in the El Nino-La Nina pattern since Fall 2009. We combine that possible instability in the overall upper level flow with the observation that sea surface temperatures in Polar regions have been warming at a much faster rate than most other regions of the world. 
NOAA visible imagery of the blizzard
approaching Alaska on 11/8/11
Rationale: A customizable NOAA animation of how Global Sea Surface Temperatures have changed just from November 2010 to November 2011. The NOAA Sea Surface Temperature (SST) Anomaly map shown above indicates the area over which the Gulf of Alaska storm formed, prior to being designated a "blizzard," has reported SST's between 1.5 and 3.5 degrees Celsius above normal. That area of water, currently ranging in the low 50's F, would be considered relatively "cold" by most people.  However, the SST charts show the surface water temps in that region are running at least  2.7 to 6.3 degrees F above normal. Not a big difference? If you were able to bask in 70 F degree water at Ocean City, MD on Halloween, we think you would notice the water was not the normal 59-65 degree range expected that time of year.
A scientist's view: We offer this excerpt from an 11/08/11 article in Our Amazing Planet, in which Meteorologist Jim Brader from the NWS Fairbanks, AK Office stated, 
"Something that's kind of unusual in this case is that all of our computer models were in agreement of this being an extremely strong storm." 
The storm is the product of warm air in the Pacific Ocean tapping into the cold air off Siberia, picking up speed in a jet stream near there and then intensifying as it moved into the Bering Sea  –  "a place where storms typically intensify," Brader told OurAmazingPlanet.
The weird storm has an unusually long fetch length, which is the length of the wind blowing in a single direction over water. In this case it's maybe 1,000 miles (1,600 km), Brader said.

When is the next major event? 
OUR SHORT ANSWER: The Winter Stormcast and Long Range Teams still anticipate significant winter weather in the Eastern United States between November 25 and December 5. We follow the NWS definition of a significant snow as producing 4 or more inches
For comparison: Our team's criteria for a storm to be a "significant event" for the snowfall amount and resulting disruption to affect at least one metropolitan area. Although NOAA's Northeast Snowfall Impact Scale (NESIS) only ranks the October 29-30 event as a 1.75, it was - and remains an extremely disruptive to tens of millions. As of November 10, 2011 - thousands in New England remain without power due to a storm over 10 days prior. Our internal criteria points to the fact that a large portion of the Northeast U.S. received 4 or more inches of snow, which identifies the storm as having significant potential that falls just under NWS Winter Storm Watch criteria of 5 inches. 
For the record: We believe the next snow event to affect the Ohio Valley, Mid-Atlantic and Northeast  will produce a similar impact and accumulations as the October 29-30 storm.  

How could this storm affect the winter pattern? 
NOAA: Hurricane Irene
August 27, 2011
OUR SHORT ANSWER: We are not surprised to see this storm pattern evolving, as the Alaskan Blizzard is the second strong event of its kind this fall in the Northeast Pacific. We hypothesize a connection in the storm pattern moving forward from the atmospheric influences produced by Hurricane Irene. As such, we believe the East coast will be targeted again within 30 days following the sequence we outlined both in our October 1, 2011 post and our October 22, 2011 post 

RATIONALE: We believe the atmosphere has been dropping many clues to the pattern ahead. Consider this sequence of events from August 2011 forward: 
  • Late Aug: Hurricane Irene batters East coast
  • Early Sep: "Atmospheric rivers" over the Northeast U.S. tap remnants of Tropical Storm Lee, producing widespread flash floods in areas affected by Irene. 
  • Mid-late Sep: Calm period in the East, stormy in the West.
  • Early Oct: Strongest storm since 2004 strikes Pacific Northwest.
  • Mid Oct: Calm period for much of the country.
  • Late Oct: Historic early season snowstorm in the Northeast U.S.
  • Early Nov: Major snow in Colorado, historic Alaska Blizzard
PROJECTIONS: Based on our expectation of a possible 30-45 day pattern in recent major events across North America, we anticipate the following sequence going forward:
  • Mid Nov: "Indian Summer" warmup in the East, increased storminess in the West
  • Late Nov: Significant West to East storm with a strong cold front reaching the East Coast by Thanksgiving Weekend.
  • Early Dec: Pulses of cold air from the Ohio Valley to the Northeast, resulting in the next significant snow event for this region by December 5. 
  • January: May end up relatively calm and mild for the U.S., similar to January 1990.
If this all plays out, Mother Nature will have given us fair warning. Perhaps hanging the holiday lights early while it is still pleasant might save you the hassle of dealing with in after things turn nasty again...because we believe it is only a matter of time before we all "go into the zone" ahead of the next storm.

(Forecaster Foot, the Winter Stormcast and Long Range Teams)

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