
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_1800
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 18Z 0.45 2819 65 9 -15 0.00
Fri 01/16 21Z 0.36 2815 51 21 -13 0.00
Sat 01/17 00Z 0.24 2511 42 51 -11 0.00
Sat 01/17 03Z 0.24 2214 46 94 -10 0.00
Sat 01/17 06Z 0.32 2121 86 94 -10 0.00
Sat 01/17 09Z 0.29 2120 90 94 -9 0.01
Sat 01/17 12Z 0.21 2019 94 95 -7 0.01
Sat 01/17 15Z 0.20 2020 95 95 -7 0.03
Sat 01/17 18Z 0.27 2118 96 95 -6 0.03
Sat 01/17 21Z 0.40 2415 96 93 -7 0.02
Sun 01/18 00Z 0.61 2518 91 79 -7 0.01
Sun 01/18 03Z 0.63 2420 90 67 -7 0.00
Sun 01/18 06Z 0.59 2320 86 72 -7 0.00
Sun 01/18 09Z 0.75 2225 95 39 -8 0.00
Sun 01/18 12Z 0.72 2423 80 27 -10 0.02
Sun 01/18 15Z 0.86 2520 83 14 -13 0.01
Sun 01/18 18Z 1.02 2514 89 30 -14 0.00
Sun 01/18 21Z 0.68 2513 88 36 -13 0.00
Mon 01/19 00Z 0.33 2607 87 36 -13 0.00
Mon 01/19 03Z 0.25 2705 86 46 -13 0.00
Mon 01/19 06Z 0.24 2805 90 44 -13 0.00
Mon 01/19 09Z 0.23 2506 93 38 -14 0.00
Mon 01/19 12Z 0.28 2210 85 41 -14 0.00
Mon 01/19 15Z 0.62 2215 88 91 -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