
Significant heat is expected to build today and Friday. Hot temperatures and high humidity will allow heat index values to reach into the lower to mid 90s this afternoon and again Friday afternoon in the Champlain Valley and Connecticut River Valley. Heat index values elsewhere will be in the upper 80s to low 90s. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260611_1800
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)
=== ===== === ==== ==== === === === ====
Thu 06/11 18Z 1.00 2905 87 55 17 0.00
Thu 06/11 19Z 1.38 2806 86 54 17 0.00
Thu 06/11 20Z 1.36 2608 86 57 17 0.00
Thu 06/11 21Z 0.71 2508 89 62 17 0.00
Thu 06/11 22Z 0.53 2609 91 66 17 0.08
Thu 06/11 23Z 0.47 2610 91 70 17 0.01
Fri 06/12 00Z 0.29 2709 78 77 18 0.03
Fri 06/12 01Z 0.25 2707 71 71 19 0.00
Fri 06/12 02Z 0.39 2610 74 73 18 0.00
Fri 06/12 03Z 0.51 2512 83 74 18 0.00
Fri 06/12 04Z 0.54 2414 88 69 18 0.00
Fri 06/12 05Z 0.38 2412 85 61 18 0.00
Fri 06/12 06Z 0.30 2410 79 58 19 0.00
Fri 06/12 07Z 0.25 2408 78 56 19 0.00
Fri 06/12 08Z 0.23 2507 81 66 18 0.00
Fri 06/12 09Z 0.19 2706 87 67 17 0.00
Fri 06/12 10Z 0.10 3004 88 76 17 0.00
Fri 06/12 11Z 0.05 0102 88 68 17 0.00
Fri 06/12 12Z 0.03 3401 92 72 17 0.00
Fri 06/12 13Z 0.04 2801 94 75 16 0.00
Fri 06/12 14Z 0.10 2602 95 75 16 0.00
Fri 06/12 15Z 0.12 2203 92 65 17 0.00
Fri 06/12 16Z 0.14 2103 88 55 17 0.01
Fri 06/12 17Z 0.51 2204 85 50 17 0.00
Fri 06/12 18Z 1.51 2306 81 53 18 0.00
Fri 06/12 19Z 2.18 2306 77 42 18 0.00
Fri 06/12 20Z 3.47 2409 79 35 18 0.00
Fri 06/12 21Z 2.02 2410 83 23 18 0.00
Fri 06/12 22Z 0.88 2313 85 44 18 0.00
Fri 06/12 23Z 0.76 2317 91 78 18 0.02
Sat 06/13 00Z 0.84 2520 89 60 17 0.02
Sat 06/13 01Z 0.73 2722 82 61 16 0.03
Sat 06/13 02Z 0.60 2824 56 50 17 0.01
Sat 06/13 03Z 0.52 2923 63 13 16 0.00
Sat 06/13 04Z 0.43 3023 61 10 15 0.00
Sat 06/13 05Z 0.39 3024 54 10 15 0.00
Sat 06/13 06Z 0.40 3025 53 10 14 0.00
Sat 06/13 07Z 0.39 3126 52 9 14 0.00
Sat 06/13 08Z 0.38 3126 53 11 13 0.00
Sat 06/13 09Z 0.36 3126 53 11 13 0.00
Sat 06/13 10Z 0.31 3126 56 12 13 0.00
Sat 06/13 11Z 0.27 3225 55 12 13 0.00
Sat 06/13 12Z 0.32 3224 60 16 12 0.00
Sat 06/13 13Z 0.36 3122 65 14 12 0.00
Sat 06/13 14Z 0.42 3118 64 13 12 0.00
Sat 06/13 15Z 0.49 3016 61 13 12 0.00
Sat 06/13 16Z 1.04 2913 66 9 12 0.00
Sat 06/13 17Z 3.99 2812 76 5 12 0.00
Sat 06/13 18Z 6.14 2713 79 6 12 0.00
Sat 06/13 19Z 7.17 2712 76 10 13 0.00
Sat 06/13 20Z 7.90 2713 73 13 13 0.00
Sat 06/13 21Z 6.39 2711 68 17 13 0.00
Sat 06/13 22Z 3.95 2611 66 14 14 0.00
Sat 06/13 23Z 1.47 2511 65 17 14 0.00
Sun 06/14 00Z 1.38 2515 64 38 14 0.00
Sun 06/14 01Z 1.05 2518 63 50 14 0.00
Sun 06/14 02Z 0.89 2519 63 43 14 0.00
Sun 06/14 03Z 0.69 2518 60 43 15 0.00
Sun 06/14 04Z 0.54 2517 53 42 15 0.00
Sun 06/14 05Z 0.60 2519 44 37 15 0.00
Run total areal avg QPF for the Central_Greens is: 0.21 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