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das

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    February 10-12 event obs

    in Mid Atlantic

    Posted

    33°F/32°F in Clarksburg with SN. Dirty snow is white again, new snow on all elevated surfaces. 
     

    Man, the radar sure looks juiced to the WSW entering WV along the low level jet. It will be interesting to see where the heaviest snow sets up running west-east in MD. 

    • Like 2

    1/31 - 2/2 Obs. / Nowcast

    in New England

    Posted

    1 hour ago, powderfreak said:

    That NWS met now has 11.4” Storm total in Milton and only 1” last hour lol.

    I think we are around 6.5” here in Stowe Village. Steady snow still going.

    It was pretty vigorous.  I just passed 7" here in Charlotte and 3.5" of it came in 1h45m from 3:45pm to 5:30pm.  The convergence was definitely greater 20mi to the north in Milton so it's likely a legit measurement as they were under it for like 3 hours and they started with 4 or or so already while I only had a measly 2.5" when it started.  Steady snow still going here.  It's going to be a nice 24 hours upcoming as waves of moisture continue to wrap around the GOM low.

    • Like 1

    1/31 - 2/2 Obs. / Nowcast

    in New England

    Posted

    1 hour ago, powderfreak said:

    Starting to crank back this way.  A NWS MET just text me 2.9” in 1-hour in Milton just north of BTV.

    7E5D500C-2E96-4C7B-8467-720075D7411F.gif.93b7d4cb15a82fe076414fb72b8e0fed.gif

    The valley convergence has pushed far enough south down the valley to just now reach me.  1/8mi. visibility, it looks like.  I'd guess this is 2"/hr rates.  We'll see in a bit....  24ºF/19ºF, N23G31, it's howling out there.

    BTV_Loop.thumb.gif.ce258c882b2eac8203c39af1815b0b83.gif

     

    1/31 - 2/2 Obs. / Nowcast

    in New England

    Posted

    10 hours ago, Drz1111 said:

    As an aside, if I ever went back to school the project I want to do is applying this to the west to see if you can use it to untangle the different rain shadows and such.  The simple rain shadow / terrain explanation doesn't do a very good job of predicting Western climate. 

    If ever you think about it seriously, talk to the NWS Burlington team. They do serious work in this area on nearly a daily basis during the winter. For example, here’s their AFD from this evening: 

    000
FXUS61 KBTV 020336
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1036 PM EST Mon Feb 1 2021

.SYNOPSIS...
Accumulating snow will make for difficult travel conditions
across the area, especially during the Tuesday morning commute.
Southern areas will only see light snow Tuesday night, but
northern areas will have the best chance for accumulating snow
and continued difficult travel conditions through Wednesday.
Overall looking at six to twelve inches of snow tonight through
Tuesday night with slightly less amounts for portions of the
Saint Lawrence Valley and parts of northeast Vermont.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 1003 PM EST Monday...Overall, no significant changes were
made to the forecast. Only small tweaks were needed to speed up
arrival of precipitation by an hour so as snow is already being
reported at Rutland and Lebanon, NH. This precipitation shield
will continue to move into northern NY and VT overnight.
Interesting to note that east of the Greens temps and dewpoints
are in the 20s while the northern Champlain Valley and northern
New York remain firmly in the single digits/low teens. Have
adjusted the temp forecast accordingly based on these latest
observations. Still thinking that as the warm front continues to
move northward these locations will warm into the 20s by
morning.

Previous Discussion...Forecast remains on track for widespread
snow event across the North Country tonight through Tuesday
night. Only change to headlines will be to include eastern
Clinton County in the Winter Storm Warning. All other warnings
and advisories remain in place. Bottom line much of the area
will see six to twelve inches of snow with slightly less amounts
over parts of the Saint Lawrence Valley and northeast Vermont.

Snow spreads from south to north tonight and especially after
midnight and continuing through the morning commute on Tuesday.
Looking at a period of difficult travel conditions during this
time period. Main mechanism for the snow during this period will
be pronounced 700 mb frontogenesis lifting northward across the
area. In addition, favorable alignment of omega and snow growth
support the idea of a burst of steadier snow...around an inch
per hour. The snow will taper off from south to north during the
late morning and afternoon hours with best forcing lifting to
the north. However, flow will become more northerly Tuesday
night and moisture wrapping around the upper low will support
the idea of snow becoming more widespread across far northern
New York and northern Vermont. Northerly flow and very low
Froude numbers support the idea that snow should also be in the
Champlain Valley and not just confined to the higher terrain.

&&

     

    1/31 - 2/2 Obs. / Nowcast

    in New England

    Posted

    2 hours ago, Typhoon Tip said:

    I'm sorry ... "froude number"   ?

    Continuum fluid dynamics defined as the ratio of the flow inertia (at the boundary layer) to the external field (at the crest level) that calculates blocking.  

    image.png.17eae66c6d98ce171d09dddba9916e74.png

    BTV has experimental output they use to determine if snows will fall on the lee side of the crest, the windward side or, under extreme blocking conditions (ie., <0.50), back up into the valley.  It's found here:

    https://www.weather.gov/btv/froudeALL

    I posted this earlier, I think, but here's the primer on it:

    https://www.weather.gov/btv/froude

    More scholarly reading:

    https://web.stanford.edu/~fringer/publications/mayer-jfm-2017.pdf

    • Like 1
    • Thanks 1

    1/31 - 2/2 Obs. / Nowcast

    in New England

    Posted

    -5°F / -11°F here just south of Burlington. Probably not much mixing with the storm here. :^P  Virga is now only 3 counties to the south away. It’s going to be a long day of radar hallucinations waiting. 
     

    For those of you struggling with the NWS “upgrade” of the radar page, here’s my favorite mosaic from Univ of Washington. Change the number of frames there in the link for longer or shorter loops and to auto if you want it to auto refresh every 6 minutes:
    https://a.atmos.washington.edu/~ovens/wxloop.cgi?radar_us_full+30+-noauto


    And, if any of you want to pass the virga watching time and read up on Froude numbers for blocked flow, here’s an excellent primer from the team at NWS Burlington:

    https://www.weather.gov/btv/froude

    January 1-2 Kitchen Sink Obs/Nowcast

    in New England

    Posted

    16 hours ago, Damage In Tolland said:

    Did you guys up north that got 2” or more melt today or did it stay below freezing? Not Phin or Freak who are in their own microclimates. I mean normal locations. 

    Topped out at 31°F yesterday with minimal sun only as it was setting. It’s all still here in the Champlain Valley. 

    • Thanks 1

    January 1-2 Kitchen Sink Obs/Nowcast

    in New England

    Posted

    3.1” here in Charlotte with 32dBZ returns overhead and more incoming from the WSW. Looking at correlation coefficient, the mix line stalled just south of Middlebury and recently shunted east as winds veered. Nice morning so far. 

    Edited to add:  30.9°F here at the house. Going out for a run!

    December 2020 Discussion

    in New England

    Posted

    1 hour ago, 40/70 Benchmark said:

    Oh, agreed. Its not a concern for snowfall. Frankly, if you need 24 to drop over a foot of snow, than then you have some paltry dynamics.

    Totally unrelated but I had a crash course in this.  In the 72 hours ending at 3am this morning, there were 52 hourly obs of snow here in Charlotte and a temp that ranged from 24F to 29F.  For a whopping 3.6" of snow.  And, a max of 2.9" OTG.

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