Saturday, November 12, 2011

Welcome to the Winter Stormcast Zone

4:00 PM EST 11/12/11 | As we approach end of the 2011 Atlantic Tropical Cyclone Season, and begin a transition to Winter Operations, the Winter Stormcast Team wishes to recognize the contributions and leadership of the multi-state Tropical Zone Team

During this season, our Tropical Forecasters have managed 18 named storms, which has become the third most active season behind 2005 and 1995. We salute the dedication of Tropical Team Director Daniel Ross, Tropical Team Coordinator Jason Mitchell, Forecast Advisor Forrest Palmer and their 6-member team for unfailing service to the readers in a challenging tropical season. We recognize Meteorologist Randall Hergert, Forecasters Ross Harris in NC, Kurt Hansen in VA, Nikki Byers in MD, Matt Bolton  in FL and Meteorologist Advisor Dr. Pete Winstead in MD for over one hundred forecasts this year in our Tropical Zone on Facebook. We hope the winter will afford you all time to rest up!  

As cold weather approaches, we know the Powderhounds out there are excited to see a relaunch of this winter weather forecast page which received millions of hits the past two winters. The Winter Stormcast Zone began in 2009, and by the February 2010 "Snowmageddon" readers poured into by the hundreds of thousands for a inside scoop on what our team predicted. With the Northeast having been clocked by the Shocktober Storm, and a potentially major storm to impact the Northern U.S. next week...we figured it was time to get it started in here.  

RECENT TEAM REPORTS: Read "About that Alaska storm" for a potential timeline of events for the winter kickoff and into January 2012. 

WE'RE NOT JUST IN THE MID-ATLANTIC: This page is the school-side version of what we post in facebook. For our other Winter zones, search for "Winter Stormcast" in facebook, to discover what our team has in the Northeast, Ohio Valley, Great Lakes and more on the way... it's a big planet, we got a lot of snow to cover.

Winter 2011-12 Forecast: Overview  

3:00 PM EST 11/11/11 | PART 1: INTRODUCTION | After extensive collaboration over three months and across 5 states, the Winter Stormcast Team has prepared this overview of the Winter Forecast, We are also assembing a data-focused technical version that details the projected seasonal precipitation amounts for selected locations  similar to our "Storm Grade Amounts" approach. Part 2 is identifed as "Projections" to be released on or before December 1. This quantifiable method will establish specific amounts we project to occur, and then we can track the accuracy of that projection throughout the season as compared to climatology for that location. (Lead Forecasters Jason M., Connor M. and Lead Advisor Mr. Foot)

La Nina Projections for 2011-12
THE MAJOR PLAYER: La Nina. In a typical La Nina winter, the East Coast normally experiences below average snowfall and precipitation along with above average temperatures. The Climate Prediction Center currently expects a moderate La Nina this winter continuing into Spring, as stated in this recent report published 11/10/2011 and in the Weekly ENSO Diagnostic Report posted each Monday by the CPC.  

A La Nina Backgrounder on NOAA's page about the oceanic temperature phenomenon. 

We expect atmospheric teleconnections such as the North Atlantic Oscillation (NAO) and the Arctic Oscillation to be in phases that are conducive for below average temperatures at times this winter. This should mainly be the case for the first half of the winter. Thus, we expect below average temperatures with several chances for accumulating snow in December, with moderating temperatures later in the winter.

Overall for the Mid Atlantic, we expect slightly above average snowfall with near average precipitation and average temperatures. For northern portions of the Mid Atlantic, we expect the next significant snowfall event by December 5, with the remainder of the region receiving significant snow by the middle of December. 

Areas in the Southeast U.S. should experience below average precipitation and above average temperatures. Our team is predicting below average temperatures and above average snowfall for the Pacific Northwest. Statements on the winter in different regions are in progress from our other Winter Stormcast Teams, and will be posted when complete.  

Prepared 11/7/2011, Updated 11/11/11
by the Mid-Atlantic Winter Stormcast Team. 

Lead Forecaster Jason M. 

Collaborating Forecasters: 

Connor M. (MD); Ross H. (NC); Mitch D. (PA); Mike N. (MD); Daniel R.(GA); Mark I. (WA)


Current status

2. La Nina/El Nino

Review and Results:
October 29-30, 2011 Storm

The historic winter-like storm that brought unprecedented October snowfall amounts to the Northeast will be remembered by many for decades to come.  NOAA ranked the event on the Northeast Snowfall Impact Scale (NESIS) as having a Category 1 level impact as compared to a "Category 5-level" impact for the March 1993 Superstorm. 

STORM GRADE VERIFICATION: A preliminary review of our Storm Grade Amounts as as verified by NWS Local Storm reports shows a 60% average accuracy for the 6 selected major cities in our forecast. Many thanks to Storm Chaser/Forecaster Kelton Halbert of in Nashville, Tennessee for conducting the independent verification of our forecast results. Kelton, a high school junior, was selected for this role because he was outside the forecast area of the storm and not involved in the prediction process. Additional storm data is available upon request via: footsforecast AT

Several key factors were in place that contributed to this historic event. Following a strong cold frontal passage on Thursday, an anomalously cold area of high pressure set up over New England and southern Quebec. This allowed for early winter-like temperatures to descend over the Mid Atlantic and Northeast. 

DEVELOPMENT: A storm system began to develop Friday over the Tennessee Valley. A strong area of high pressure was also anchored over Greenland, and this “Greenland Block” helped to keep the storm on a southerly track through the Southeast. By early Saturday, the storm system reemerged off the Carolina coast. With favorable upper level dynamics in place, the storm rapidly intensified off the Mid Atlantic coast by the early afternoon hours. 

EVOLUTION: The high pressure to the north of the storm kept cold air in place over inland areas, and precipitation over portions of the Northeast quickly changed from rain to snow. The coastal storm continued to bomb (rapidly deepen over a 24 hour period) during the evening hours, and this allowed tremendous snowfall rates to persist over portions of New Jersey and Connecticut. 

IMPACTSTemperatures in the lower to middle 30s allowed for low snow-to-liquid ratios, and the snow was very heavy. As a result of the heavy snowfall consistency, considerable tree damage occurred in many areas, and millions of people were without power. 

COMPUTER MODELSAs with nearly all nor’easters, there was plenty of computer model disagreement in advance of the storm. However, our review of model verification showed that the European Center for Medium-Range Weather Forecasting (ECMWF) model consistently projected this major coastal storm for several days. (Forecaster Jason M.)

October Snowstorm 
Latest team analysis

11:30 PM EDT 10/28/11 | STORM SYNOPSIS | Reposted from the Mid-Atlantic Winter Stormcast Zone in facebook by Forecaster Jason and the WSC Team: We are just hours away from a potentially record-breaking October snowstorm for interior portions of the Mid Atlantic. Although the main focus is on snow, wind and coastal flooding will also be hazards for other portions of the region. As the coastal storm deepens in classic fashion, winds will increase throughout the day over the Mid Atlantic. 

For the Atlantic beaches in Maryland, Delaware, and New Jersey, there will likely be a several hour period with sustained winds of 25-35 mph and gusts to 45 mph. Areas near the Chesapeake Bay should experience winds of 15-25 mph with gusts of 30-35 mph. 

Fortunately, winds will be a bit weaker in areas that will receive heavy snow. However, 10-20 mp may still be enough to help knock down leaf-covered tree limbs that are snow covered. Our Storm Grade Amounts for selected cities are listed below, many thanks to Forecasters Jason and Dakota for organizing the data for this chart. 

(Author: Forecaster Jason M. Collaborators: Forecasters Dakota S., Connor M., Mitchell D., Advisors Foot, Krichinsky)

What started as a simple experiment that received just 200 hits a day in December 2009 grew by exponential rate to February 24, 2010 when nearly 150,000 individuals visited the Winter Stormcast Zone. By the winter of 2010-11, this page had become the go-to source for thousands on winter storm events. The Christmas Weekend Blizzard of 2010, the Southeast Ice Storm of January 8-10 and the January 26, 2011 "snow monsoon"  in the Mid-Atlantic among other events further cemented our "Winter Stormcast Team" as a reliable source for winter weather forecasting. 

No comments: