Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

March 2-3 Storm Disco, Part II


stormtracker

Recommended Posts

  • Replies 1.1k
  • Created
  • Last Reply

Look guys, seriously... 18z NAM is a snowstorm.  No ifs ands or buts.  Stop playing around.

 

(Argh, think my original reply got zapped...trying again!)...

 

I finally saw this too, though the NCEP site was very slow and I was stuck around 54-h for awhile.  At that point, I admit it didn't exactly look all that great from what I saw (kind of similar to 12Z?), especially at 850-mb and the surface.  However, once I saw the entire run, yeah, we get hammered.  Basically ~9-12 hours of snow starting around dawn or pre-dawn Monday through early evening Monday.  The NAM may be a tad slower with the cold air crashing in, but it does so just before or around 12Z Monday.  There's some precip up to that time that's probably rain or a mix, I'd guess.  Then it's all snow after that, and quite a bit of it as temps plummet through the day.  As others said, about 1" liquid equivalent total.

Link to comment
Share on other sites

True. As the Euro and GFS showed, it doesn't get crankin' until after 4am or so. Then, it's on like Donkey Kong.

I worry that a lot of accumulation will get lost by the rain portions and the craptastic ratios during the changeover.  Looks like there's good wind blowing from the north to crash temps, but the timing of the crash vis-a-vis the water looks dicey.  

Link to comment
Share on other sites

   not to argue over small details that have plenty of time to be resolved, but the 18z NAM isn't as much snow as we think.   The forecast profile at DCA for 14z Monday still has a +2 layer around 800 mb.    The entire column finally supports snow by 15z, and there is still some nice snow to be had after that, but it's only about 0.3" or so liquid.

Link to comment
Share on other sites

Thanks High Risk. I had a feeling that the nam had a slower changeover than just doing the 850's thing.

 

However, it is very supportive of a wet second slug. That is probably the most important takeaway. This is a tricky evolution and not really good for the nam beyond 24-48 hours. The euro ens and gefs kinda sealed the deal for me that we are looking half decent for a mostly cold and frozen event. Snow chances are building every run.

 

Euro ens really supported the second wave of precip being fairly heavy. I think we are in good shape. 

Link to comment
Share on other sites

Yes, I can read forecast maps.  But, .3 of liquid as frozen isn't exactly crushing.  

 

it's a lot more than .3 frozen. There's prob a ton of sleet in there. It's a high impact event verbatim with heavy rates. I'm not even worried about the nam's thermal profile yet. The fact that it pummeled us with precip and crashing temps is all we really need to note. 

Link to comment
Share on other sites

it's a lot more than .3 frozen. There's prob a ton of sleet in there. It's a high impact event verbatim with heavy rates. I'm not even worried about the nam's thermal profile yet. The fact that it pummeled us with precip and crashing temps is all we really need to note. 

I don't think we actually disagree about that.  I think its the interplay of crash to precip to p-type that we're quibbling with, and that makes all the difference in the world.  

Link to comment
Share on other sites

HPC seems unimpressed.  

 

THE PRESENCE OF A LARGE UPPER VORTEX OVER EASTERN CANADA WILL PLAY
A SIGNIFICANT ROLE IN THE EVOLUTION OF THE STORM SYSTEM MOVING
EASTWARD FROM THE WEST COAST. BESIDES BEING THE SOURCE OF THE
UNUSUALLY COLD LATE WINTER AIRMASS OVER MUCH OF SOUTHERN CANADA
HEADING ACROSS THE NORTHERN TIER OF THE US...IT IS ALSO A MAIN
DRIVER FOR UPPER LEVEL CONFLUENCE AND AN INTENSIFYING UPPER LEVEL
JET ASSOCIATED WITH THE SOUTHWARD DRIFT OF THE COLD AIR WITHIN THE
ENTRANCE REGION OF THE JET. IT IS ALSO A PRIMARY REASON THAT THE
STRONG SHORTWAVE MOVING EASTWARD FROM THE WEST COAST APPEARS TO
SHEAR OUT AS IT MOVES TOWARD THE EAST COAST.

AS A RESULT...THE MODELS IN GENERAL APPEAR TO HAVE TRENDED COLDER
AND WEAKER/FASTER WITH THE SYSTEM AS IT MOVES EASTWARD. IT STILL
PORTENDS A SIGNIFICANT STORM OF SNOW/SLEET AND FREEZING RAIN
ACROSS THE LARGE SLICE OF THE NATION BUT MAY WORK TO PREVENT THIS
SYSTEM FROM BECOMING TOO INTENSE AS IT APPROACHES THE EAST
COAST...MINIMIZING THE LIKELIHOOD OF VERY HEAVY SNOWFALL
ACCUMULATIONS.

THE OPERATIONAL GFS APPEARS TO HAVE BECOME MORE SUPPRESSED ALONG
THE NORTHERN EDGE OF THE QPF ON DAYS 2 AND 3...WITH THE 12Z ECMWF
FOLLOWING SUIT. IN ADDITION...THE 12Z GEFS MEANS ALSO SHIFT THE
AXIS OF HEAVIEST MELTED QPF SOUTHWARD FROM WHERE IT WAS LOCATED ON
THE 06Z RUN. THAT SAID...FROM DAYS 2 TO 3...A BAND OF SIGNIFICANT
SNOW WILL EXTEND EASTWARD FROM KANSAS/MISSOURI ACROSS CENTRAL
INDIANA/OHIO ACROSS PENNSYLVANIA/NORTHERN MARYLAND/NEW JERSEY AND
SOUTHEASTERN NEW YORK. MOST OF THE AMOUNTS APPEAR TO BE IN THE 4
TO 8 INCH RANGE WITH ONLY A LOW PROBABILITY OF ANYWHERE RECEIVING
A FOOT OF SNOW.

SINCE THIS SYSTEM IS STILL IN THE 2 TO 3-DAY TIME RANGE...THERE
REMAINS ENOUGH LACK OF CONSENSUS...ESPECIALLY WITH THE
NAM/SREFMEANS/UKMET AND CANADIAN...THAT CHANGES TO THE FORECAST
ARE STILL LIKELY OVER THE NEXT DAY TO 2 DAYS.

WITH SUCH A LARGE SHALLOW ARCTIC AIRMASS...MIXED PRECIPITATION IN
THE FORM OF SLEET AND FREEZING RAIN WILL ALSO BE A LARGE
CONTRIBUTOR THE LARGE PRECIPITATION COVERAGE. THIS TRANSITION
ZONE WILL LIKELY BE MOST SIGNIFICANT ACROSS SOUTHERN
MISSOURI/NORTHERN ARKANSAS/THE OHIO RIVER AND ACROSS THE MIDDLE
ATLANTIC STATES. 

Link to comment
Share on other sites

it's a lot more than .3 frozen. There's prob a ton of sleet in there. It's a high impact event verbatim with heavy rates. I'm not even worried about the nam's thermal profile yet. The fact that it pummeled us with precip and crashing temps is all we really need to note. 

 

Yeah, that's what I was thinking.  It's quite a bit more than 0.3 of frozen.  I'd argue more than 0.3 of snow, even, though it's really hard to parse the transitions on the maps since that happens in-between times.  But again, it's parsing the NAM more than 24-48 hours out, haha!  I agree, the key take-away for now is a lot of QPF and temps crashing.

Link to comment
Share on other sites

Pretty significant shift south on 18z with the best stripe of precipitation at 15z Monday. 0.25 precip line is now DC -- BWI instead of well in PA.

 

I hate to be the a$$hole that says the GFS is usually too flat, but...

 

Edit: between the Euro and the GFS, DC is ok for now.  We're in the middle, right?

Link to comment
Share on other sites

1.1 liquid for dca. About half looks to be snow. South trend for sure but I'll take this run all day long. Not sure how much further south it can go. Our area seems to be in a good spot for this one now. heh

 

attachicon.gif18zgfsqpf2.28.JPG

 

Bob, on the NCEP maps, looks like anything after ~11z (5-6am MON) should be snow.  the first 1000-500mb blue thickness line is just south of DCA near EZF at 12z MON

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Guest
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...