
An expansive storm system will bring widespread storms with a threat for flash flooding and severe weather to much of the central to eastern U.S. into early this week. Critical fire weather conditions are expected across interior Alaska this weekend. Elevated fire conditions also expected in the Southwest U.S.. Conditions will remain uncomfortably hot across the southern Plains and the Southeast. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260621_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)
=== ===== === ==== ==== === === === ====
Sun 06/21 00Z 0.57 2913 92 80 9 0.00
Sun 06/21 01Z 0.64 2816 95 88 8 0.05
Sun 06/21 02Z 0.62 2918 95 91 8 0.08
Sun 06/21 03Z 0.66 2919 94 88 8 0.03
Sun 06/21 04Z 0.57 2918 92 91 8 0.01
Sun 06/21 05Z 0.54 2918 92 90 8 0.01
Sun 06/21 06Z 0.44 2916 87 86 8 0.00
Sun 06/21 07Z 0.45 2916 88 91 8 0.01
Sun 06/21 08Z 0.50 2816 91 88 8 0.01
Sun 06/21 09Z 0.43 2815 90 84 8 0.01
Sun 06/21 10Z 0.44 2816 89 78 8 0.00
Sun 06/21 11Z 0.44 2816 85 76 8 0.00
Sun 06/21 12Z 0.44 2917 88 75 8 0.00
Sun 06/21 13Z 0.43 2916 90 82 8 0.00
Sun 06/21 14Z 0.44 3014 92 77 8 0.00
Sun 06/21 15Z 0.77 2913 94 74 7 0.00
Sun 06/21 16Z 0.98 2812 96 79 8 0.00
Sun 06/21 17Z 0.75 2813 96 84 8 0.02
Sun 06/21 18Z 0.74 2813 95 82 8 0.03
Sun 06/21 19Z 0.81 2814 93 79 9 0.04
Sun 06/21 20Z 0.65 2914 91 67 9 0.02
Sun 06/21 21Z 0.80 2914 93 70 9 0.03
Sun 06/21 22Z 1.25 3014 90 71 9 0.02
Sun 06/21 23Z 0.70 3014 89 71 9 0.02
Mon 06/22 00Z 0.44 3013 89 64 9 0.02
Mon 06/22 01Z 0.49 3015 89 64 9 0.04
Mon 06/22 02Z 0.40 3014 87 60 9 0.00
Mon 06/22 03Z 0.29 3113 86 58 9 0.00
Mon 06/22 04Z 0.22 3111 83 58 9 0.00
Mon 06/22 05Z 0.19 3110 80 52 9 0.00
Mon 06/22 06Z 0.17 3108 78 51 9 0.00
Mon 06/22 07Z 0.18 3007 77 45 9 0.00
Mon 06/22 08Z 0.14 3006 76 39 9 0.00
Mon 06/22 09Z 0.15 2905 77 36 9 0.00
Mon 06/22 10Z 0.18 2805 77 34 9 0.00
Mon 06/22 11Z 0.21 2705 76 35 9 0.00
Mon 06/22 12Z 0.17 2804 72 35 9 0.00
Mon 06/22 13Z 0.09 2902 69 34 9 0.00
Mon 06/22 14Z 0.03 3000 71 32 10 0.00
Mon 06/22 15Z 0.09 1802 78 29 9 0.00
Mon 06/22 16Z 0.14 1804 83 28 9 0.00
Mon 06/22 17Z 0.24 1806 83 24 10 0.00
Mon 06/22 18Z 0.32 1908 82 28 10 0.01
Mon 06/22 19Z 0.27 1810 80 37 10 0.00
Mon 06/22 20Z 0.23 1910 87 74 9 0.02
Mon 06/22 21Z 0.11 1608 92 94 8 0.11
Mon 06/22 22Z 0.20 1412 91 96 8 0.10
Mon 06/22 23Z 0.28 1316 94 98 8 0.11
Tue 06/23 00Z 0.34 1318 93 99 8 0.11
Tue 06/23 01Z 0.36 1220 94 98 8 0.12
Tue 06/23 02Z 0.39 1222 95 97 9 0.10
Tue 06/23 03Z 0.35 1221 96 97 9 0.25
Tue 06/23 04Z 0.47 1225 97 95 9 0.22
Tue 06/23 05Z 0.42 1223 97 91 9 0.23
Tue 06/23 06Z 0.32 1318 97 94 10 0.16
Tue 06/23 07Z 0.24 1314 97 93 11 0.10
Tue 06/23 08Z 0.22 1310 98 93 11 0.07
Tue 06/23 09Z 0.16 1207 98 94 11 0.09
Tue 06/23 10Z 0.11 1404 98 92 11 0.07
Tue 06/23 11Z 0.10 1501 98 95 11 0.05
Run total areal avg QPF for the Central_Greens is: 2.37 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