
A Cold Weather Adviosry is in effect for portions onorthern New York and Vermont this afternoon through Sunday morning. Cold wind chills of -15F to -25F are expected. A Winter Storm Warning is in effect across Vermont and northern New York starting 1 PM Sunday through 1 AM Tuesday. Total snow accumulations between 8 and 16 inches will create very hazardous conditions for travel. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260124_1800
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)
=== ===== === ==== ==== === === === ====
Sat 01/24 18Z 0.27 3115 71 20 -24 0.00
Sat 01/24 19Z 0.34 3018 66 19 -24 0.00
Sat 01/24 20Z 0.40 3019 67 17 -24 0.00
Sat 01/24 21Z 0.45 2921 67 13 -23 0.00
Sat 01/24 22Z 0.46 2922 66 11 -23 0.00
Sat 01/24 23Z 0.39 3022 62 10 -22 0.00
Sun 01/25 00Z 0.34 3022 60 10 -21 0.00
Sun 01/25 01Z 0.29 3122 57 11 -21 0.00
Sun 01/25 02Z 0.25 3122 53 12 -20 0.00
Sun 01/25 03Z 0.21 3121 49 11 -19 0.00
Sun 01/25 04Z 0.18 3119 44 9 -19 0.00
Sun 01/25 05Z 0.16 3117 40 8 -18 0.00
Sun 01/25 06Z 0.14 3216 36 7 -18 0.00
Sun 01/25 07Z 0.10 3214 35 7 -17 0.00
Sun 01/25 08Z 0.08 3212 33 7 -17 0.00
Sun 01/25 09Z 0.08 3210 32 10 -16 0.00
Sun 01/25 10Z 0.06 3106 33 17 -16 0.00
Sun 01/25 11Z 0.04 3003 31 32 -16 0.00
Sun 01/25 12Z 0.03 2601 29 47 -15 0.00
Sun 01/25 13Z 0.03 2102 27 66 -15 0.00
Sun 01/25 14Z 0.02 1704 27 84 -15 0.00
Sun 01/25 15Z 0.04 1808 34 87 -16 0.00
Sun 01/25 16Z 0.02 1608 53 88 -16 0.00
Sun 01/25 17Z 0.06 1509 74 87 -16 0.00
Sun 01/25 18Z 0.07 1512 85 87 -15 0.02
Sun 01/25 19Z 0.09 1412 85 86 -14 0.03
Sun 01/25 20Z 0.17 1214 86 88 -14 0.03
Sun 01/25 21Z 0.18 1319 85 90 -15 0.06
Sun 01/25 22Z 0.22 1423 85 90 -15 0.08
Sun 01/25 23Z 0.25 1426 85 89 -15 0.09
Mon 01/26 00Z 0.36 1330 86 89 -15 0.08
Mon 01/26 01Z 0.41 1232 85 90 -14 0.07
Mon 01/26 02Z 0.39 1230 86 91 -12 0.05
Mon 01/26 03Z 0.35 1126 86 92 -11 0.05
Mon 01/26 04Z 0.32 1123 86 93 -11 0.04
Mon 01/26 05Z 0.37 1023 86 90 -12 0.05
Mon 01/26 06Z 0.43 1026 86 89 -12 0.04
Mon 01/26 07Z 0.45 1026 85 89 -12 0.03
Mon 01/26 08Z 0.44 1126 86 92 -12 0.01
Mon 01/26 09Z 0.47 1026 88 89 -12 0.01
Mon 01/26 10Z 0.43 1023 87 88 -12 0.02
Mon 01/26 11Z 0.40 1021 87 88 -12 0.02
Mon 01/26 12Z 0.40 1020 88 87 -12 0.02
Mon 01/26 13Z 0.40 1020 87 86 -12 0.02
Mon 01/26 14Z 0.38 1018 88 86 -12 0.02
Mon 01/26 15Z 0.36 1016 89 85 -12 0.01
Mon 01/26 16Z 0.37 1014 90 87 -12 0.00
Mon 01/26 17Z 0.37 1112 90 88 -12 0.00
Mon 01/26 18Z 0.36 1110 90 88 -12 0.01
Mon 01/26 19Z 0.45 1109 91 87 -12 0.01
Mon 01/26 20Z 0.47 1008 91 87 -12 0.01
Mon 01/26 21Z 0.29 1006 92 85 -12 0.02
Mon 01/26 22Z 0.17 0804 92 85 -12 0.02
Mon 01/26 23Z 0.09 0602 91 84 -12 0.03
Tue 01/27 00Z 0.07 0402 91 83 -12 0.02
Tue 01/27 01Z 0.05 3503 91 82 -13 0.02
Tue 01/27 02Z 0.05 3307 89 81 -13 0.03
Tue 01/27 03Z 0.11 3213 88 81 -14 0.02
Tue 01/27 04Z 0.19 3221 87 81 -15 0.01
Tue 01/27 05Z 0.30 3226 87 80 -17 0.01
Run total areal avg QPF for the Central_Greens is: 1.06 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