
A Winter Weather Advisory is in effect until 8 AM Monday for the northern Adirondack region of NY and the spine of the Green Mountains eastward in Vermont. Most snow should taper off this afternoon changing to rain and freezing drizzle. Freezing drizzle is expected to form this evening into Monday morning with icing amounts ranging from a glaze up to 0.05". Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260323_0000
Using the MB925 to MB850 layer.
Assumes Central_Greens are orthogonal to 260 degree winds.
925-850 mb Layer Average Wind/RH. Avg QPF over the Central_Greens.
Date Time Wind RH% 700 850T QPF
Day mm/dd hhZ Frd# DDFF (%) RH% (C) (in)
=== ===== === ==== ==== === === === ====
Mon 03/23 00Z 0.11 3311 96 48 -2 0.00
Mon 03/23 01Z 0.05 3311 95 29 -2 0.00
Mon 03/23 02Z 0.06 3311 93 19 -2 0.00
Mon 03/23 03Z 0.03 3411 92 17 -3 0.00
Mon 03/23 04Z 0.06 0010 92 15 -3 0.00
Mon 03/23 05Z 0.12 0210 91 13 -3 0.00
Mon 03/23 06Z 0.14 0308 91 11 -4 0.00
Mon 03/23 07Z 0.18 0509 91 10 -4 0.00
Mon 03/23 08Z 0.23 0510 92 10 -4 0.00
Mon 03/23 09Z 0.21 0608 93 12 -5 0.00
Mon 03/23 10Z 0.25 0709 94 13 -6 0.00
Mon 03/23 11Z 0.30 0710 96 15 -7 0.00
Mon 03/23 12Z 0.34 0810 97 17 -7 0.01
Mon 03/23 13Z 0.33 0809 98 17 -8 0.01
Mon 03/23 14Z 0.35 0609 97 20 -8 0.00
Mon 03/23 15Z 0.39 0608 97 21 -8 0.00
Mon 03/23 16Z 0.35 0605 97 34 -8 0.00
Mon 03/23 17Z 0.15 0502 97 41 -8 0.00
Mon 03/23 18Z 0.09 0201 97 45 -8 0.00
Mon 03/23 19Z 0.07 3203 97 39 -8 0.01
Mon 03/23 20Z 0.12 3207 97 37 -8 0.01
Mon 03/23 21Z 0.15 3210 95 40 -8 0.01
Mon 03/23 22Z 0.15 3312 95 42 -8 0.01
Mon 03/23 23Z 0.12 3316 95 40 -8 0.01
Tue 03/24 00Z 0.09 3420 96 51 -9 0.01
Tue 03/24 01Z 0.08 3422 96 64 -9 0.01
Tue 03/24 02Z 0.10 3425 94 72 -9 0.01
Tue 03/24 03Z 0.11 3425 89 72 -10 0.01
Tue 03/24 04Z 0.09 3425 84 71 -10 0.00
Tue 03/24 05Z 0.07 3425 84 57 -11 0.00
Tue 03/24 06Z 0.08 3423 86 44 -11 0.00
Tue 03/24 07Z 0.13 3421 87 35 -11 0.00
Tue 03/24 08Z 0.17 3320 88 22 -11 0.00
Tue 03/24 09Z 0.13 3418 87 5 -11 0.00
Tue 03/24 10Z 0.19 3318 87 3 -12 0.00
Tue 03/24 11Z 0.19 3318 85 7 -12 0.00
Tue 03/24 12Z 0.18 3318 82 9 -12 0.00
Tue 03/24 13Z 0.19 3315 80 10 -12 0.00
Tue 03/24 14Z 0.18 3312 73 9 -12 0.00
Tue 03/24 15Z 0.87 3111 76 7 -12 0.00
Tue 03/24 16Z 0.82 2908 69 5 -11 0.00
Tue 03/24 17Z 0.93 2708 60 7 -10 0.00
Tue 03/24 18Z 0.81 2508 50 7 -9 0.00
Tue 03/24 19Z 0.51 2310 44 6 -8 0.00
Tue 03/24 20Z 0.89 2314 44 5 -8 0.00
Tue 03/24 21Z 1.01 2417 46 8 -8 0.00
Tue 03/24 22Z 0.97 2421 49 10 -7 0.00
Tue 03/24 23Z 1.08 2426 45 25 -7 0.00
Wed 03/25 00Z 1.54 2531 39 47 -7 0.00
Wed 03/25 01Z 2.45 2632 44 82 -8 0.00
Wed 03/25 02Z 5.54 2730 61 85 -9 0.00
Wed 03/25 03Z 1.77 2729 79 36 -10 0.00
Wed 03/25 04Z 1.13 2828 84 8 -9 0.00
Wed 03/25 05Z 0.95 2827 80 7 -9 0.00
Wed 03/25 06Z 0.73 2826 72 6 -8 0.00
Wed 03/25 07Z 0.54 2824 62 7 -7 0.00
Wed 03/25 08Z 0.51 2923 60 6 -7 0.00
Wed 03/25 09Z 0.46 2922 55 7 -6 0.00
Wed 03/25 10Z 0.42 2921 53 10 -6 0.00
Wed 03/25 11Z 0.35 2919 44 9 -5 0.00
Run total areal avg QPF for the Central_Greens is: 0.11 inches.
Froude Number (Frd#):
Frd# < 0.5 Flow is subcritical and blocked.
Upslope clouds/precip backed farther upwind of and up to mtn crest.
W Upslope snow favors eastern Champlain Valley, BTV, and Western slopes.
Gap winds possible.
Frd# 0.5-1 Flow is subcritical/slow moving/blocked.
Upslope clouds/precip falls immediately upwind of mtn crest.
W Upslope snow favors western slopes to the Green Mt. spine including:
Montgomery,Underhill,Jericho,Bolton,Richmond,Huntington,Lincoln.
Gap winds possible.
Frd# 1-2 Flow is critical.
With strong winds, Mountain waves/downslope winds possible.
Precip falls close to mountain ridge crests and on lee side.
W Upslope snow favors Green Mt Spine,Jay,Stowe,Waterbury,NE Kingdom.
Froude > 2 Flow is supercritical/unblocked(rapid flow).
Air flows freely over terrain.
Persistent upslope snow not favored. Scattered snow showers and flurries.
Relative Humidity (RH):
925-850 mb RH > 90% needed for upslope precipitation.
with 700mb RH > 70% favors upslope snow.
with 700mb RH > 90% greater amounts of W upslope snow possible.
850mb Temperature (T degC) Westerly Upslope Snow Ratios: (Avg=28:1)
T > -11 10-15:1
T -11 to -15 25-35:1
T < -15 15-20:1