
A Flood Watch remains in effect for south-central Vermont and eastern slopes of the Adirondacks due to the potential for heavy rain. Additional rainfall amounts of 1-3 inches with localized amounts of 3-5 inches along the spine of the southern Greens could produce excessive runoff and cause flooding in low-lying or flood prone areas. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260729_0600
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)
=== ===== === ==== ==== === === === ====
Wed 07/29 06Z 0.04 1615 94 96 13 0.00
Wed 07/29 07Z 0.09 1620 95 94 13 0.00
Wed 07/29 08Z 0.11 1622 94 95 13 0.01
Wed 07/29 09Z 0.19 1523 92 93 13 0.01
Wed 07/29 10Z 0.30 1427 91 91 13 0.01
Wed 07/29 11Z 0.35 1429 88 86 13 0.01
Wed 07/29 12Z 0.29 1428 84 80 13 0.01
Wed 07/29 13Z 0.28 1424 87 72 13 0.01
Wed 07/29 14Z 0.39 1323 84 62 13 0.00
Wed 07/29 15Z 0.59 1323 89 66 13 0.00
Wed 07/29 16Z 0.72 1223 92 70 12 0.01
Wed 07/29 17Z 0.81 1224 95 75 12 0.01
Wed 07/29 18Z 0.72 1223 95 78 12 0.02
Wed 07/29 19Z 0.75 1123 94 79 12 0.02
Wed 07/29 20Z 0.74 1123 92 83 12 0.03
Wed 07/29 21Z 0.64 1123 89 83 12 0.02
Wed 07/29 22Z 0.59 1023 83 84 12 0.01
Wed 07/29 23Z 0.57 1023 81 85 12 0.01
Thu 07/30 00Z 0.58 0922 83 86 12 0.01
Thu 07/30 01Z 0.62 0823 85 89 12 0.01
Thu 07/30 02Z 0.60 0823 82 94 12 0.01
Thu 07/30 03Z 0.58 0822 80 96 12 0.00
Thu 07/30 04Z 0.58 0821 82 96 12 0.00
Thu 07/30 05Z 0.52 0720 84 95 12 0.00
Thu 07/30 06Z 0.52 0619 84 98 12 0.01
Thu 07/30 07Z 0.57 0620 88 97 11 0.04
Thu 07/30 08Z 0.58 0620 91 97 11 0.03
Thu 07/30 09Z 0.53 0519 93 93 11 0.03
Thu 07/30 10Z 0.50 0519 92 89 11 0.03
Thu 07/30 11Z 0.48 0419 91 91 11 0.03
Thu 07/30 12Z 0.46 0420 87 91 11 0.01
Thu 07/30 13Z 0.49 0420 81 93 11 0.01
Thu 07/30 14Z 0.48 0420 76 91 12 0.00
Thu 07/30 15Z 0.55 0320 82 91 11 0.00
Thu 07/30 16Z 1.13 0219 86 87 11 0.00
Thu 07/30 17Z 0.92 0218 89 92 11 0.00
Thu 07/30 18Z 0.88 0219 94 98 11 0.01
Thu 07/30 19Z 0.63 0221 93 98 11 0.02
Thu 07/30 20Z 0.64 0222 92 95 11 0.01
Thu 07/30 21Z 0.56 0321 87 88 11 0.00
Thu 07/30 22Z 0.58 0321 89 81 11 0.00
Thu 07/30 23Z 0.53 0420 89 79 11 0.00
Fri 07/31 00Z 0.48 0420 89 84 11 0.00
Fri 07/31 01Z 0.45 0418 90 81 11 0.00
Fri 07/31 02Z 0.37 0415 90 76 11 0.00
Fri 07/31 03Z 0.30 0313 89 80 11 0.00
Fri 07/31 04Z 0.26 0213 90 82 11 0.00
Fri 07/31 05Z 0.22 0213 89 79 11 0.00
Fri 07/31 06Z 0.19 0113 86 71 11 0.00
Fri 07/31 07Z 0.19 0114 87 66 11 0.00
Fri 07/31 08Z 0.20 0115 90 64 11 0.00
Fri 07/31 09Z 0.22 0115 90 56 11 0.00
Fri 07/31 10Z 0.24 0215 88 51 11 0.00
Fri 07/31 11Z 0.20 0114 87 50 11 0.00
Fri 07/31 12Z 0.16 0113 88 53 11 0.00
Fri 07/31 13Z 0.17 0113 91 56 11 0.00
Fri 07/31 14Z 0.18 0110 93 58 11 0.00
Fri 07/31 15Z 0.15 0109 93 58 11 0.00
Fri 07/31 16Z 0.13 0008 92 57 11 0.00
Fri 07/31 17Z 0.03 3508 91 56 12 0.00
Run total areal avg QPF for the Central_Greens is: 0.45 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