...on the path unwinding.

"Til we find our place, on the path unwinding."
-Circle of Life lyrics by Elton John in Soundtrack of The Lion King (Music video)



SCENARIOS AND ANALYSIS FOR SUNDAY-MONDAY EVENT 
FROM SOUTHEAST TO MID-ATLANTIC & NORTHEAST

12:15 PM EST 1/30 - UPDATED SCENARIO OVERVIEW - After a morning collaboration among members of the Winter Stormcast team in several states, we are posting revisions to our scenarios for the Sunday-Monday storm potential. This update is to account for new information received in the past 12-18 hours and reflect that insight in our projections. 

Previous scenarios and map are still available in the lower section of the post for review.

• SCENARIO A - The Powderhound favorite of "Big Kahuna" as shown below, has been reduced in probability from 50% to 40%. Large scale indications point to a more northerly track of the Low, and this outcome would hamper the chance for a significant snow event in the major metro areas. 

One of many tell-tale signs for why we think this system will NOT become a "Big Kahuna" is an expected rapid rise in the North Atlantic Oscillation. Long-time readers know this is a large scale teleconnection we have used in previous winter storm forecasting. It was this and other techniques which tipped us off to why the Dec 19-20, 2009 blizzard would not stay to our south, but also why this weekend's storm looks to trend much farther north than what is shown in Scenario A below.

• SCENARIO B - Called the "Little Bachata" depicts a light snow event in the MId-Atlantic with rain in the Carolinas as the system quickly moves out to sea. This was reduced in probability from 35% to 20%. 

• SCENARIO C - Dubbed "The Circle of Ice" is being modified to better specify what areas may be likely to see precipitation starting as frozen (snow, sleet, freezing rain), and which areas might stay primarily rain. The probability of this outcome has been raised from 15% to 40%. 

WHEN WILL WE KNOW MORE? On Saturday, we anticipate narrowing this setup down to the two most probable forecasts, and then zeroing in on timing and impacts for each based on our examination of model projections blended by a healthy serving of "probability-based, ground truthed, common sense forecasting." 

JUST CONSIDER...that given this system may have relatively higher liquid potential in these configurations. Even a quick hit from any of these scenarios with a lot of liquid converting to frozen precipitation can still be disruptive. We also invite you to review these resources at the NOAA Weather Prediction Center (WPC) for comparison:

• Short Range Surface Map Projections for Friday night to Sunday night
• Winter Weather Maps and Graphics for Days 1-3
• Heavy Snow & Ice Discussion examining Day 1-3 snow & ice probabilities

Previous statements and earlier scenarios in the next section 

9:45 PM EST 1/29 - By Lead Forecaster Mike Natoli, Advisor R. Foot and Mid-Atlantic Winter Stormcast Team

INTRODUCTION: Like the well-known lyrics from our headline song, "some of us fall by the wayside, and some of us soar to the stars"-- the next winter weather event will be marked by significant uncertainty about the final outcome for some time. That also sounds a lot like a football game, does it not? Just like weather, there is sometimes little certainly in a challenging match-up as to what side will be victorious until very end of the game. 

Thus, with millions of people gathering across the country on Sunday among friends and family to enjoy the most watched sports game of the year, we recognize the path to understand this storm will need to be marked by clear communication and easily followed by those seeking to travel it. 

THREE FACTORS guiding the development of the scenario projections: 

• 1. Based on the inherent uncertainty about the track and strength of this next storm system set to arrive Sunday-Monday, we have split the possible outcomes into 3 different scenarios. The “ground truth” for areas expecting snow will be dependent on the track the storm takes, as well as its strength. 
• 2. At issue with the evolution of this system is a "positively tilted trough." This means the base of the trough in the jet stream is further west than the top of the trough. This situation alone usually does not favor a long duration event. 
• 3. Large scale dynamics such as the North Atlantic Oscillation projected to have a sharp rise from neutral underscores what we believe is decreasing probability of a major snow event for the Mid-Atlantic.

With this already a complicated situation, we know there is "far too much to take in here," so while the sun rolls high in Friday's Sapphire sky, we will watch for clues on how the path unwinds as this next weather system approaches.

FIRST SCENARIO MAP POSTED 9:45 PM 1/29

SCENARIO A (50%) – THE BIG KAHUNA* In this scenario, the trough mentioned above digs in, but further east. This allows the storm to ramp up, but does so along a southern Mid-Atlantic track. to our south rather than to our north. As a result, a large swath of the Mid-Atlantic south of the I-76 corridor would have an opportunity to experience a significant snow event.

• LIQUID EQUIVALENTS for this scenario according to a blend of the latest model outputs ranges from about 0.60 to 0.80" 
• TEMPERATURES would start region wide in the upper 20s and end the storm in the lower 20s
• SNOW RATIOS given a colder setup would start at 10:1 for beginning of storm, near 15:1 toward the end, with 12:1 as an average. 

While it is too early to begin discussing precise snowfall amounts for any particular area, long time readers to this site from the middle 2000s will recall that the criteria used in determining a storm's eligibility to be considered a "Big Kahuna" was 6" or more. 

*What is a Kahuna?? (See once of our early posts from 2005 where Kahuna and Powderhound were first stated.) 

• You can also read this interesting analysis of our wordsmithing in another non-weather discussion board from 2010. It's cute to see how people viewed us 5 years ago. ;-) Essentially, Kahuna is a term borrowed from other cultures to assign a fun title to a significant to major winter storm, but without giving it a name.

We are not implying or explicitly stating that at this time, Scenario A will become a major winter storm. We are instead conveying that although is currently viewed as a more probable solution, that could change drastically, and as such the forecast will remain highly uncertain for several days.

SCENARIO B (35%) – THE LITTLE BACHATA - Like the evolving and rhythmically diverse Latino dance music genre, Scenario B is dubbed a "bachata" for a couple reasons:

• If the high remains strong and the trough does not dig much, then the storm will dance merrily and quickly right out to sea. 
• This would deliver a quick snow burst in the beginning, tricking Powderhounds into celebrating the long-awaited arrival of their snowstorm.  The system would produce a couple inches on Sunday
• But then just as everyone was getting accustomed to the day turning out fun and snowy, the music dies and as the system exits off stage for the much colder act to follow in its wake. 

SCENARIO C (15%) - THE CIRCLE OF ICE. Except there won't be any "wheel of fortune" coming out of this show, (other than for the insurance companies.) 

• This more hazardous travel outcome would occur if the high pressure to our north backs off, and the trough axis digs in further to our west. 
• The storm strengthens rapidly, enhanced by the digging trough and travels over or just north of central MD as shown on the map.
• The outcome for the highly populated areas of the Mid-Atlantic would be snow, turning to ice and sleet, then finally rain at the end before getting very cold after. The result would be a total slopfest of the ground covered in moisture-laden snow that will refreeze to a complete block of ice as temps drop to the teens afterwards.
• In the lyrics of our headline, not many of us would be able to sail through these troubles, and most of us would have to live with the scars, especially if all of this changes to rain and then a bitter Arctic descends right afterwards. 

WHAT'S NEXT?

Please stop in again on Friday during the day as we will be adding a wide range of linked resources, maps and charts to provide additional data-based rationale for the scenarios.

Thanks for making our team your place "Where Winter Lives."

Thanks to Powderhound Photographer Jason Germeroth 

for this beautiful scene from Snowy Run in Joppa, Maryland