
Severe thunderstorms and heavy rain are expected across the central High Plains into parts of the central and southern Plains and in the the Mid-Atlantic today. Intense, dangerous heat will persist across the West, Southwest, and Southern Plains into the end of the week. Elevated to critical fire weather conditions expected in the Great Basin and Four Corners region. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260623_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)
=== ===== === ==== ==== === === === ====
Tue 06/23 00Z 0.28 1416 93 99 8 0.00
Tue 06/23 01Z 0.29 1421 94 99 9 0.03
Tue 06/23 02Z 0.15 1520 96 93 10 0.03
Tue 06/23 03Z 0.05 1620 97 95 10 0.02
Tue 06/23 04Z 0.07 1719 98 98 11 0.03
Tue 06/23 05Z 0.11 1815 99 99 11 0.03
Tue 06/23 06Z 0.10 1910 99 98 11 0.03
Tue 06/23 07Z 0.07 1907 99 96 11 0.03
Tue 06/23 08Z 0.05 1804 99 95 11 0.03
Tue 06/23 09Z 0.05 1902 99 92 10 0.03
Tue 06/23 10Z 0.04 2801 99 86 10 0.01
Tue 06/23 11Z 0.05 3204 99 79 10 0.01
Tue 06/23 12Z 0.04 3407 99 70 10 0.00
Tue 06/23 13Z 0.04 3409 97 60 10 0.00
Tue 06/23 14Z 0.03 3409 95 40 10 0.00
Tue 06/23 15Z 0.03 3410 93 24 10 0.00
Tue 06/23 16Z 0.04 3411 90 15 10 0.00
Tue 06/23 17Z 0.04 3412 88 12 10 0.00
Tue 06/23 18Z 0.08 3412 86 8 10 0.00
Tue 06/23 19Z 0.11 3412 86 6 10 0.00
Tue 06/23 20Z 0.17 3312 86 6 10 0.00
Tue 06/23 21Z 0.15 3313 85 5 10 0.00
Tue 06/23 22Z 0.20 3314 86 6 10 0.00
Tue 06/23 23Z 0.18 3315 89 5 10 0.00
Wed 06/24 00Z 0.21 3318 93 7 10 0.00
Wed 06/24 01Z 0.24 3319 91 11 10 0.01
Wed 06/24 02Z 0.21 3318 88 10 10 0.01
Wed 06/24 03Z 0.15 3319 85 12 10 0.01
Wed 06/24 04Z 0.14 3321 90 15 10 0.01
Wed 06/24 05Z 0.10 3421 94 20 9 0.00
Wed 06/24 06Z 0.07 3420 94 22 9 0.00
Wed 06/24 07Z 0.06 3418 93 21 9 0.00
Wed 06/24 08Z 0.07 3417 91 21 9 0.00
Wed 06/24 09Z 0.14 3317 89 24 9 0.00
Wed 06/24 10Z 0.21 3217 87 27 9 0.00
Wed 06/24 11Z 0.29 3118 85 28 8 0.00
Wed 06/24 12Z 0.34 3118 87 30 8 0.00
Wed 06/24 13Z 0.38 3118 87 30 8 0.00
Wed 06/24 14Z 0.55 3118 86 34 7 0.00
Wed 06/24 15Z 1.06 3017 86 34 7 0.00
Wed 06/24 16Z 3.32 2915 86 37 8 0.00
Wed 06/24 17Z 5.10 2815 88 48 8 0.00
Wed 06/24 18Z 5.34 2815 86 44 8 0.00
Wed 06/24 19Z 5.87 2815 85 43 9 0.00
Wed 06/24 20Z 4.00 2816 85 40 9 0.00
Wed 06/24 21Z 3.35 2917 85 40 9 0.00
Wed 06/24 22Z 2.62 3018 83 41 9 0.00
Wed 06/24 23Z 1.31 3018 83 38 9 0.00
Thu 06/25 00Z 0.95 3019 83 39 9 0.00
Thu 06/25 01Z 1.12 3018 84 36 9 0.00
Thu 06/25 02Z 0.97 3018 88 36 9 0.00
Thu 06/25 03Z 0.84 3019 87 35 9 0.00
Thu 06/25 04Z 0.67 3019 84 38 9 0.00
Thu 06/25 05Z 0.49 3118 82 38 9 0.00
Thu 06/25 06Z 0.36 3217 79 38 10 0.00
Thu 06/25 07Z 0.31 3215 78 40 10 0.00
Thu 06/25 08Z 0.21 3313 77 39 10 0.00
Thu 06/25 09Z 0.17 3311 77 40 10 0.00
Thu 06/25 10Z 0.12 3307 76 39 10 0.00
Thu 06/25 11Z 0.10 3305 76 39 10 0.00
Run total areal avg QPF for the Central_Greens is: 0.32 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