
Severe thunderstorms will be possible from the central Plains to the Mid-Atlantic and Northeast on Monday. Hazardous heat will linger across the southern U.S. and build across the West through mid-week. Hot and dry conditions will fuel fire weather concerns for Interior Alaska and the Four Corners region through Monday. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260622_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)
=== ===== === ==== ==== === === === ====
Mon 06/22 06Z 0.13 2904 73 55 10 0.00
Mon 06/22 07Z 0.13 2604 73 52 10 0.00
Mon 06/22 08Z 0.22 2406 76 48 10 0.00
Mon 06/22 09Z 0.32 2509 78 43 10 0.00
Mon 06/22 10Z 0.33 2610 75 39 9 0.00
Mon 06/22 11Z 0.35 2609 71 36 9 0.00
Mon 06/22 12Z 0.29 2607 69 32 9 0.00
Mon 06/22 13Z 0.22 2405 67 29 10 0.00
Mon 06/22 14Z 0.22 2105 69 35 10 0.00
Mon 06/22 15Z 0.31 2006 70 35 10 0.00
Mon 06/22 16Z 0.48 2109 70 41 10 0.00
Mon 06/22 17Z 0.64 2113 74 74 9 0.00
Mon 06/22 18Z 0.42 2013 73 92 9 0.01
Mon 06/22 19Z 0.21 1913 76 97 8 0.02
Mon 06/22 20Z 0.15 1815 86 91 8 0.05
Mon 06/22 21Z 0.11 1718 92 86 9 0.08
Mon 06/22 22Z 0.12 1719 93 91 9 0.06
Mon 06/22 23Z 0.16 1520 93 95 9 0.03
Tue 06/23 00Z 0.28 1419 93 98 9 0.07
Tue 06/23 01Z 0.30 1317 92 99 10 0.11
Tue 06/23 02Z 0.34 1217 91 99 10 0.10
Tue 06/23 03Z 0.34 1217 94 99 10 0.05
Tue 06/23 04Z 0.31 1216 95 99 10 0.05
Tue 06/23 05Z 0.30 1214 96 98 10 0.06
Tue 06/23 06Z 0.21 1210 97 96 10 0.03
Tue 06/23 07Z 0.16 1006 96 95 10 0.01
Tue 06/23 08Z 0.15 0605 96 92 10 0.01
Tue 06/23 09Z 0.15 0307 95 87 10 0.01
Tue 06/23 10Z 0.13 0110 96 87 10 0.00
Tue 06/23 11Z 0.13 0111 96 86 9 0.00
Tue 06/23 12Z 0.13 0112 95 83 9 0.00
Tue 06/23 13Z 0.08 0013 92 74 10 0.00
Tue 06/23 14Z 0.07 0013 89 49 10 0.00
Tue 06/23 15Z 0.02 3513 89 38 10 0.00
Tue 06/23 16Z 0.06 3413 88 29 10 0.00
Tue 06/23 17Z 0.14 3415 86 23 10 0.00
Tue 06/23 18Z 0.24 3416 83 15 10 0.00
Tue 06/23 19Z 0.67 3316 80 11 10 0.00
Tue 06/23 20Z 0.95 3315 79 8 10 0.00
Tue 06/23 21Z 0.70 3316 83 8 10 0.00
Tue 06/23 22Z 0.30 3317 84 8 10 0.00
Tue 06/23 23Z 0.23 3318 82 10 10 0.00
Wed 06/24 00Z 0.40 3320 81 14 10 0.00
Wed 06/24 01Z 0.32 3320 86 14 9 0.00
Wed 06/24 02Z 0.28 3321 87 21 9 0.00
Wed 06/24 03Z 0.22 3322 86 20 9 0.00
Wed 06/24 04Z 0.16 3322 88 17 9 0.00
Wed 06/24 05Z 0.11 3420 91 20 9 0.00
Wed 06/24 06Z 0.05 3419 89 21 9 0.00
Wed 06/24 07Z 0.03 3417 87 21 9 0.00
Wed 06/24 08Z 0.04 3416 86 20 9 0.00
Wed 06/24 09Z 0.06 3416 86 24 8 0.00
Wed 06/24 10Z 0.09 3315 83 27 8 0.00
Wed 06/24 11Z 0.11 3315 84 28 8 0.00
Wed 06/24 12Z 0.15 3213 86 32 8 0.00
Wed 06/24 13Z 0.19 3213 88 38 8 0.00
Wed 06/24 14Z 0.19 3212 84 48 8 0.00
Wed 06/24 15Z 0.22 3212 82 46 8 0.00
Wed 06/24 16Z 0.31 3211 81 34 8 0.00
Wed 06/24 17Z 1.01 3111 83 29 8 0.00
Run total areal avg QPF for the Central_Greens is: 0.75 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