
Periods of light snow will develop tonight and continue into tomorrow night. Rutland and Windsor counties will see between 2 and 6 inches. The rest of the region should mostly see between a half inch and 2 inches, with slightly higher totals in the mountains. Use caution if driving. A Winter Weather Advisory is in effect for Rutland County from 1 AM to 7 PM Saturday. Read More >
Subject: GFS EXPERIMENTAL Froude Number for the greens
Model run: BTV_GRID_D2D_GFS_20260116_1200
Using the MB925 to MB850 layer.
Assumes greens are orthogonal to 270 degree winds.
925-850 mb Layer Average Wind/RH. Avg QPF over the greens.
Date Time Wind RH% 700 850T QPF
Day mm/dd hhZ Frd# DDFF (%) RH% (C) (in)
=== ===== === ==== ==== === === === ====
Fri 01/16 12Z 0.57 2920 97 85 -20 0.00
Fri 01/16 15Z 0.49 2820 90 53 -18 0.01
Fri 01/16 18Z 0.45 2819 62 7 -14 0.00
Fri 01/16 21Z 0.39 2716 47 18 -12 0.00
Sat 01/17 00Z 0.28 2512 43 50 -11 0.00
Sat 01/17 03Z 0.28 2215 53 94 -10 0.00
Sat 01/17 06Z 0.32 2120 86 94 -10 0.01
Sat 01/17 09Z 0.27 2120 92 92 -8 0.01
Sat 01/17 12Z 0.18 2019 95 96 -7 0.02
Sat 01/17 15Z 0.17 2020 96 96 -7 0.02
Sat 01/17 18Z 0.34 2119 96 96 -7 0.02
Sat 01/17 21Z 0.55 2418 95 82 -7 0.01
Sun 01/18 00Z 0.72 2520 93 71 -7 0.00
Sun 01/18 03Z 0.69 2420 94 79 -7 0.00
Sun 01/18 06Z 0.64 2319 89 76 -7 0.00
Sun 01/18 09Z 0.74 2225 88 65 -7 0.00
Sun 01/18 12Z 0.75 2421 94 39 -10 0.02
Sun 01/18 15Z 0.82 2518 82 12 -12 0.02
Sun 01/18 18Z 1.18 2515 86 21 -13 0.00
Sun 01/18 21Z 0.64 2510 85 36 -13 0.00
Mon 01/19 00Z 0.56 2708 85 53 -13 0.00
Mon 01/19 03Z 0.46 2910 89 61 -14 0.00
Mon 01/19 06Z 0.49 2812 87 57 -14 0.00
Mon 01/19 09Z 0.40 2610 87 45 -14 0.00
Run total areal avg QPF for the greens is: 0.14 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