Saturday, January 31, 2015

...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:

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 



29 comments:

Andy, Southern York County Pa said...

We still look in line for a general 4-8 inch event from Baltimore City North and west with mixing issues along I-95. Confluence is not very strong with the latest trends. Low and good snows have pushed north from earlier run. Models will bounce around until game time. Right now models paint a Scenario C evolution as depicted on this page. Again a couple days left so we will see more shifts before final numbers can be nailed. Right now 40 miles of interstate could separate 2 inches and mix from 10 inches of all snow. Models are not that precise with track at this range. I still like the idea that we are tracking a 4-8 inch event.

Andy, Southern York County Pa said...

NWS BALT WASH

Long term /Sunday through Thursday/...
what was once looking like a potl snowstorm sun-Monday isnt quite so
clear anymore...as 00z guidance--incl the European model (ecmwf)--has trended warmer.
Lopres prognosticated to cross the MS river midday sun /already containing
greater than desired placement spread/ and arrives in County warning forecast area Sun night.
The track of this low looking to be somewhere north of the Virginia/NC brdr
but S of the Mason-Dixon line. That in turn bumps the track of the
800 mb low across PA...permitting warm air to penetrate region aloft.
Therefore...all sorts of ptype issues emerge.


GFS BUFKIT soundings suggest that precipitation will start as snow Sunday but change to
just rain sun evening for a large portion of the Virginia shen valley...all of
metropolitan District of Columbia...and even part of metropolitan balt. Am not ready to go that warm
just yet...but need to entertain psbltys of partial melting or even
complete melting and refreezing since wet bulbs likely will be below
32f. Do believe that sundays precipitation should be mainly snow where it isnt
too warm. Grids emphasizing afternoon...as the morning hours should be dedicated
to saturation. Will have a mixed bag for Sun night. Made the overnight hours
messier..thinking that surface cold air could seep southward on back side of
low. By 12z Monday...lopres will be offshore. At that point...ptype
becomes more certain again as enough cold air should drain down throughout
the column to support precipitation changing back to snow before ending.


Given latest trends theres too much uncertainty in the outcome to
support watches. In fact will be adjusting severe weather potential statement from accumulate snow to a more
generic winter weather. Overall...have lower than typical forecast confidence.

Jeremy S. said...

I'm beginning to despise this Winter. At least during the winter of 11-12, you could tell by long range analytics that you'd be getting nothing but mild weather for days on end. This winter, the threats are there, but event after event, your snow hopes are squandered because of marginal air, an unfortunate storm track, etc.. Yes, the models most certainly could shift back south on multiple models, but if it doesn't, this storm would just continue on with the trend of a winter of broken dreams.

kristia35 said...

Does anyone recall an instance where it shifted from north to south @ less than 2 days out. I'm sure its out there, but I cant think of any offhand.

Foot's Forecast said...

Happy Last Friday in January everyone! We are working on a revision to the scenarios today and will be polishing up the lead story to reflect some of the changes.

Check back before lunch for the next report.
-FF Team

Mike Cheuvront said...

The latest runs of the GEM AND GFS are trending the storm south giving us better chance for more snow. Stronger high to the north likely our friend. AT LEAST RIGHT NOW.

kristia35 said...

Let's hope for a 50 mile shift south. I'm feeling extra weenie-ish today 😊

Mike Cheuvront said...

What part of Md do you live in Krista?

Mike Cheuvront said...

GFS HAD RAIN SNOW LINE IN A.A. CO AND GEM HAD IT SOUTH OF THERE.

NeedaSnowday said...

::::chanting:::: I will not get sucked in... I will not get sucked in... I will not get sucked in... I will not get sucked in...

kristia35 said...

I'm in Perry Hall near the Kingsville end

Mike Cheuvront said...

Hey needa your sucked in when you follow this blog my friend. Your dying inside for a storm, you know it, you know it. :)....I'm up here near ravensbbr in north east Carroll County, Manchester. 1 mile from Hanover,Pa line. You gotta believe. It's gonna happen. If not this one, another. YEAH BABY!

NeedaSnowday said...

::::earmuffs:::: I am not listening to Mike...I am not listening to Mike...I am not listening to Mike...I am not listening to Mike!















Believe it?? Didnt think so....::just gonna peek at the models:::

kristia35 said...

We're already invested. Let's ride it out until there's no hope!

kyleZ said...

Winter storm watches for southern pa probably get nothing hear in harford but we are used to it still have some hope for something this yeAr.

genser95 said...

Don't see how it snows south of the Mason-Dixon line with this one. In fact, it's starting to look like even Southern PA is marginal.

NeedaSnowday said...

Ugh..... ::::poof:::: gone?!

kristia35 said...

It just gets worse and worse

BioPat said...

Oh well, we still haven't hit mid-February. Every season has run about 6 weeks late so I'm still hoping - hoping - hoping.

This isn't the winter of snow for me it's the winter of lousy viruses. I'd just like to feel good enough to enjoy a good snowfall so I'll wait.

Westsidehideaway said...

Foots and Team. I love the forecast scenarios. It tells us what you are looking at and what we should look for. Many Thanks. I'm gonna stack up the wood tomorrow and hope for a snow event on Sunday/Monday. But I'll keep watching Foots all the same.

Butch Dynomite said...

I'm not suck ed in..... My English teacher used to always say...esp if I asked about my grade"hope springs eternal"

Edwin Guevara said...

This "storm" will be another fart in the wind.....sad.

Edwin Guevara said...

Scenario D: raining gold coins. From 0-75% now.

Chance of good snow this winter: From 90%- Negative 3,000,000%

Foot's Forecast said...

90 north latitude greetings everyone!

We are working on the next update this morning. Engaged weather intelligence types here don't need 4 paragraphs to figure out that we're going to:

- Drop Scenario B
- Lower A to 40%
- Raise C to 60%
- Come up with 2 headlines to encapsulate both themes as part of the new scenarios.

Welcoming your thoughts on what would be a good set of lyrics, song titles or quotes for a new post focusing on A & C.

We also made some formatting tweaks to the page. We felt the page text was a teeny bit too small. Any other recommendations you have are welcome, we will effort to include those soon as we can.

-FF Leadership Team

kristia35 said...

I would say highway to hell but you probably can't use that one. that's what I feel like we've been on this winter.

Butch Dynomite said...

True Romance : (edited)

"I asked Clarence "why are things so *messed* up?"
he said: "that's just the way things go......but don't forget, sometimes they go the other way too"

Edwin Guevara said...

Why do you build me up, snow system baby , just to let me down.

FiveAlarm Photography said...

Does this system have any similarities to the Feb 14, 2007 sleet storm?

ravensbbr said...

Justin Berk hit the nail on the head with his quote about trying to predict a 50-100 mile wide storm path 48 hours out.

Prepare as best you can. Then close the blinds, watch the Super Bowl, go to sleep and the next morning it will be...
...


....


...


:-P