Jump to content

Christmas Eve Potential Major Winter Storm

Tom

By Tom
in East of the Rockies

 Share

Recommended Posts

  • Replies 1k
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

Snowshoe
Snowshoe

Posted about the models on TTB 2pm EST December 19: NOAA is experiencing a large data outage that is affecting all American models including the GFS, NAM, GEFS, and GEPS. The ECMWF, CMC, JMA, and NAV

Geos
Geos

Hi-res ARW is nice looking!         NMM  

Scott26
Scott26

I'm so glad this system will pass and we will move on lol. It's been impossible to track and keep up with since day 1. Right when there was some consistency with the models they changed at the last se

Posted Images

Tom Grand Master

Tom

Posted
  • Author
Posted

LOT has already taken the warm layer into consideration...

 

 

 

THE RAPID DEEPENING AND QUICK MOVEMENT OF THE MID/UPPER LEVEL LOW
WILL LIKELY RESULT IN EXTREMELY IMPRESSIVE LARGE SCALE FORCING WITH
AN IMPRESSIVE TROWAL/DEFORMATION ZONE LIKELY TO DEVELOP ON THE
WESTERN FLANK OF THE CYCLONE. VERY STRONG LOW/MID LEVEL
FRONTOGENESIS WILL OCCUR WITHIN THE TROWAL AND COINCIDENT WITH THE
RAPIDLY STRENGTHENING CYCLONE WILL PROMOTE STRONG VERTICAL
CIRCULATION. GUIDANCE ALSO SUGGESTS WEAKLY STABLE TO UNSTABLE
CONDITIONS ALOFT WITHIN THIS TROWAL WITH NEGATIVE EPV AND STEEP
MID-HIGH LEVEL LAPSE RATES...WHICH GIVEN THE STRONG FRONTOGENESIS
WOULD TEND TO FAVOR A NARROWER BUT INTENSE PRECIPITATION BAND.
GFS/WRF-NAM BOTH INDICATE THE PRESENCE OF SOME WEAK UPRIGHT
INSTABILITY WHICH GIVEN THE FORCING COULD ALLOW FOR UPRIGHT
CONVECTION WITHIN THE DEFO BAND AND POSSIBLY A COUPLE LIGHTNING
STRIKES.

WHILE GUIDANCE IS IN PRETTY GOOD AGREEMENT ON THE ABOVE...THERE ARE
A COUPLE OF KEY AREAS OF LINGERING UNCERTAINTY. FIRST...MODEL
BOUNDARY LAYER THERMAL PROFILES ARE FORECAST TO BE QUITE MARGINAL
FOR SNOW AND EVEN MORE MARGINAL FOR ACCUMULATING SNOW. DESPITE THE
MARGINAL THERMAL PROFILES...AM FAIRLY CONFIDENT THAT DYNAMIC COOLING
WITHIN THE DEFO BAND WILL LIKELY EASILY COOL THE BOUNDARY LAYER
SUFFICIENTLY TO SUPPORT ACCUMULATING SNOW...PARTICULARLY WHERE THE
HEAVIEST PRECIP OCCURS. THE 02/07/13 SYSTEM IS A PRIME EXAMPLE OF A
CASE OF VERY STRONG DYNAMIC COOLING THAT WAS VERY POORLY HANDLED BY
THE MODELS AND RESULTED IN NEARLY 10 INCHES OF SNOW WHERE MODELS
GUIDANCE FORECAST SFC TEMPS IN THE MID TO UPPER 30S.

THE BIGGER UNCERTAINTY AND WHAT IS KEEPING ME FROM JUMPING OUT WITH
A WINTER STORM WATCH AT THIS TIME IS THE TRACK DIFFERENCES IN THE
MODELS. WHILE THEY ARE NOT HUGE AND NOT SURPRISING GIVEN THE RAPIDLY
DEEPENING NATURE OF THE SYSTEM...THEY ARE SUBSTANTIAL ENOUGH TO MAKE
IT TOUGH TO PINPOINT THE PORTION OF OUR CWA MOST AT RISK. GIVEN
COMBINATION OF STRONG FRONTOGENESIS...INSTABILITY...AND MARGINAL
THERMAL PROFILES IT SEEMS LIKELY THE AREAL EXTENT OF HEAVY SNOW
WOULD NOT BE LARGE WITH POTENTIALLY SHARP CUT OFF ON BOTH THE
WESTERN AND EASTERN FLANKS OF THE SNOW BAND...SIMILAR TO WHAT WAS
SEEN IN THE 12/01/2006 SYSTEM WHICH IS ONE OF THE STRONGEST ANALOGS
FOR THIS SYSTEM AND PRODUCED LOCALLY OVER A FOOT OF SNOW.

THE CURRENT SNOWFALL FORECAST MAP WAS CREATED BLENDING VARYING
MODEL TRACK SOLUTIONS TOGETHER WHICH YIELD SNOWFALL AMOUNTS THAT
WILL LIKELY BE TOO LOW WHERE THE HEAVIEST SNOW FALLS AND TOO HIGH
OUTSIDE OF THAT BAND...BUT LIKELY THE BEST COMPROMISE THAT CAN BE
DONE FROM THIS DISTANCE GIVEN WHAT LOOKS TO BE A MESOSCALE HEAVY
SNOW THAT WILL SET UP. WHERE THE HEAVY SNOW BAND SETS UP...THINK IT
IS PRETTY LIKELY THAT VSBYS OF 1/4SM OR LESS WITH HEAVY WET SNOW ARE
LIKELY WITH SNOWFALL RATES >/= 2 INCHES PER HOUR POSSIBLE. THE PEAK
INTENSITY OF THE SNOW LOOKS TO COINCIDE WITH THE DAYTIME HOURS WHEN
MANY PEOPLE WILL LIKELY BE TRAVELING...SO ASSUMING THE BAND SETS UP
AS EXPECTED...IT COULD MAKE TRAVEL EXTREMELY DIFFICULT TOMORROW
AFTERNOON. SOME MODELS ARE AS FAR WEST AS NW IL INTO RFD (PARALLEL
GFS AND WRF-NMM) RANGING TO AS FAR EAST AS NORTHWEST INDIANA (00Z
ECMWF). WOULD TEND TO FAVOR THE MORE WESTERN SOLUTIONS AS RAPIDLY
DEEPENING CYCLONES TYPICALLY TEND TO END UP FARTHER WEST THAN
PROGGED WHICH COULD FAVOR CHICAGO AREA OR POINTS JUST WEST FOR THE
HEAVY SNOW THREAT. BUT WITH A STILL RELATIVELY LARGE SPREAD IN TRACK
SOLUTIONS WOULD BE DIFFICULT TO PIN POINT A SPECIFIC AREA FOR A
WINTER STORM WATCH WHEN IN REALITY THE HEAVY (6"+) SNOW AMOUNTS
COULD BE CONFINED TO INTERNALLY...WITH NEIGHBORING WFOS...AND WPC HAVE OPTED TO JUST HIT
THE THREAT HARD IN UPDATED SPS AND HOPEFULLY MORNING MODEL RUNS WILL
NARROW DOWN THE THREAT AREA ENOUGH TO ALLOW HEADLINES TO BE ISSUED
BY MIDDAY.

IZZI

 

 

IZZI pretty confident on the threat of potential Thundersnow!  There you go Tim, you can at least use only one of your 2 favorite words for this storm...Thundersnow.  Hopefully the "B" word will be used at least once this season.  Haha.  Anyway, kinda smart of him to use past experience and mention last winter's storm that dumped more snow than models progged.  Should be interesting to see what the HRRR models shows later tonight.

  • Like 1
Link to comment
Share on other sites
Tony Enthusiast

Tony

Posted
Posted

Nam is usually within its range under 24hrs out and I like to compare it to the other hi-res models(just for accuracy sake)otherwise I think it is a terrible model. The 12z has backed off a bit on its qpf, but not by much. I can see where the very heavy banding does setup of getting rates of up to or greater than 2" per hour as LOT has mentioned. Heavy cement pasted snow will look like a snow globe once it is all done.

 

As far as totals, the heavy rates of snowfall will easily overcome the warm ground issues and depending on how fast the turnover is, some areas could see 10"+ out of this. Of course this is just my thinking and I could be way off but the dynamics of this storm really look impressive and I could easily see it take off. GOM moisture will be plentiful and looking quite impressive.

 

Looking forward to the hi-res models as the day progresses.

Link to comment
Share on other sites
WildWisconsinWeather Newbie

WildWisconsinWeather

Posted
Posted

993 in E. IN at HR 27. Moves more NE rather than N

 

No one sees snow this run really. Temps look too warm in the Chicago area. 

 

If trends hold, looks like the GFS and its ensembles failed a bit as well.  As of yesterday's 18z suite, almost all of the ensembles were wrapped up storms tracking into SW Lower Michigan or over LM.

Link to comment
Share on other sites
Scott26 Newbie

Scott26

Posted
Posted

993 in E. IN at HR 27. Moves more NE rather than N

 

No one sees snow this run really. Temps look too warm in the Chicago area. 

GFS clearly can't handle mesoscale factors like dynamic cooling. That is why looking at global models at this point is pretty pointless.

  • Like 2
Link to comment
Share on other sites
Money Proficient

Money

Posted
Posted

If trends hold, looks like the GFS and its ensembles failed a bit as well.  As of yesterday's 18z suite, almost all of the ensembles were wrapped up storms tracking into SW Lower Michigan or over LM.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122312/gfs_mslp_pcpn_frzn_us_5.png

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122312/gfs_mslp_pcpn_frzn_us_6.png

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
 Share
Go to topic listing
×
×
  • Create New...