Saturday, October 22, 2011

Wet Halloween...White Thanksgiving?

Snow for the 1989 Macy's
Thanksgiving Day Parade in NYC.  
9:30 PM EDT 10/22/11 As the golden days of October wane toward thoughts of Turkey and early season snow, our Winter Stormcast Team have been analyzing long range climate patterns. We have also reviewed NOAA's Winter Outlook* and are encouraged to see reference to the Arctic Oscillation as a factor which will influence 2011-12 winter weather in North America. *Link to summary article by Meteorologist H. Michael Mogil, an Advisor to the U.S. Team of Foot's Forecast and former NOAA/NWS forecaster. 

LOOKING AHEAD TO DECEMBER A detailed analysis and rationale of our early winter forecast will be posted in our new Winter Stormcast Zone in development this weekend. In the interim, we wanted to share some projections for the 6-week period ahead (first outlined on September 30)
  • Wet Halloween? Energy from tropical disturbances in the western Caribbean may develop into a named system and could move into the southern Gulf of Mexico by Friday 10/26. Long range U.S. and European computer models show copious moisture reaching the Carolina/Mid-Atlantic coast just after Halloween. The Midwest, Mid-Atlantic and Northeast may get a dry run at trick-or-treating next Sunday or Monday, but probably not the Southeast.  
  • November Flip-flops: Starts cold then a mid-month warmup, ending cold and stormy. Following the late October coastal storm, another high pressure ridge establishes in the Eastern U.S., allowing an early month cold snap that eventually warms, but could lead to another deep trough moving east by end of the month. We believe this setup is the continuation of a long range pattern initiated by Hurricane Irene.    
  • I"ll be home for...Thanksgiving?: By the 11/18-20 period, the deep trough may move east bringing a strong cold front. Passage of the front would be followed by another cold high pressure dome building south from Canada. We envision very cold air from this dome reaching the Eastern seaboard before Thanksgiving weekend. Any fast moving clipper system could "overrun" the dome, generating a significant early season snowfall by Turkey Day or Black Friday from the Ohio Valley into the Northeast.

TARGET DATE FOR FIRST SIGNIFICANT SNOW: (defined as 4 or more inches of snow for an event, following NWS criteria). Our Winter Stormcast Team has targeted the period between November 25 to December 5 for the first significant snowfall should occur from the Ohio Valley to the Mid-Atlantic and Northeast. Long-time readers will remember what happened for our December 5, 2009 call first made on October 30, 2009. 

THE SCIENTIFIC RATIONALE? We have an extensive report currently posted in several of our Winter Stormcast Zones for the Northeast, Ohio Valley and Western Great Lakes. That report will be reposted in our soon-to-be launched U.S. Winter Stormcast Zone.  For the hard-core scientists among our readers, we have assembled a headache-inducing review of Northern Hemisphere Snow Cover, the Arctic Oscillation, oceanic factors of La Nina, the Pacific Decadal Oscillation, Solar output and a host of other climate teleconnections. *Image (right) from National Geographic Magazine as posted on the website of the North Carolina State Climate Office explaining the Arctic Oscillation.

It takes some time to sanitize all that into a format which won't send running from the computer screaming, (unless it's too late), so check back later this weekend for the full report. (Advisor Mr. Foot, Winter Stormcasters Jason M., Connor M., Nic R.)

No comments: