NAM3 EXPERIMENTAL Froude Number for the Central Green Mountains

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260603_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)
=== ===== === ==== ==== === === === ====
Wed 06/03 00Z 0.07 3517  44  28   8 0.00
Wed 06/03 01Z 0.14 3419  43  34   8 0.00
Wed 06/03 02Z 0.23 3419  44  39   8 0.00
Wed 06/03 03Z 0.17 3517  44  43   9 0.00
Wed 06/03 04Z 0.09 3514  44  43   9 0.00
Wed 06/03 05Z 0.05 3513  43  37   9 0.00
Wed 06/03 06Z 0.08 3512  43  28   9 0.00
Wed 06/03 07Z 0.17 0012  42  20   9 0.00
Wed 06/03 08Z 0.13 3510  42  16   9 0.00
Wed 06/03 09Z 0.09 3509  42  12   9 0.00
Wed 06/03 10Z 0.05 3509  42  12   9 0.00
Wed 06/03 11Z 0.04 3507  42  14   9 0.00
Wed 06/03 12Z 0.14 3309  43  18   9 0.00
Wed 06/03 13Z 0.20 3211  43  23  10 0.00
Wed 06/03 14Z 0.26 3210  44  29  10 0.00
Wed 06/03 15Z 0.72 3211  44  34  10 0.00
Wed 06/03 16Z 1.81 3211  45  36  10 0.00
Wed 06/03 17Z 2.44 3211  45  36  10 0.00
Wed 06/03 18Z 2.42 3211  45  36  11 0.00
Wed 06/03 19Z 2.38 3210  48  37  11 0.00
Wed 06/03 20Z 2.06 3108  50  37  11 0.00
Wed 06/03 21Z 1.82 3008  52  39  12 0.00
Wed 06/03 22Z 0.88 2907  54  42  12 0.00
Wed 06/03 23Z 0.52 2807  57  44  12 0.00
Thu 06/04 00Z 0.58 2609  61  47  12 0.00
Thu 06/04 01Z 0.64 2611  62  47  12 0.00
Thu 06/04 02Z 0.65 2812  61  49  12 0.00
Thu 06/04 03Z 0.55 3013  59  50  12 0.00
Thu 06/04 04Z 0.39 3113  59  49  11 0.00
Thu 06/04 05Z 0.30 3111  58  48  12 0.00
Thu 06/04 06Z 0.29 3009  54  45  12 0.00
Thu 06/04 07Z 0.32 2909  52  40  12 0.00
Thu 06/04 08Z 0.38 2809  50  35  12 0.00
Thu 06/04 09Z 0.45 2811  49  30  12 0.00
Thu 06/04 10Z 0.43 2811  48  27  12 0.00
Thu 06/04 11Z 0.43 2810  48  27  12 0.00
Thu 06/04 12Z 0.50 2813  50  28  12 0.00
Thu 06/04 13Z 0.51 2912  52  31  11 0.00
Thu 06/04 14Z 0.73 2912  54  33  11 0.00
Thu 06/04 15Z 0.79 2809  54  32  11 0.00
Thu 06/04 16Z 1.60 2709  52  30  12 0.00
Thu 06/04 17Z 2.35 2610  49  28  12 0.00
Thu 06/04 18Z 2.30 2611  48  26  13 0.00
Thu 06/04 19Z 5.42 2612  56  26  12 0.00
Thu 06/04 20Z 6.86 2613  57  25  13 0.00
Thu 06/04 21Z 5.32 2614  57  23  13 0.00
Thu 06/04 22Z 3.38 2714  58  23  13 0.00
Thu 06/04 23Z 1.46 2715  55  22  13 0.00
Fri 06/05 00Z 1.21 2717  55  21  13 0.00
Fri 06/05 01Z 0.97 2819  57  20  12 0.00
Fri 06/05 02Z 0.95 2921  59  17  12 0.00
Fri 06/05 03Z 1.05 2923  63  13  11 0.00
Fri 06/05 04Z 0.82 2923  65  12  11 0.00
Fri 06/05 05Z 0.80 3025  69  13  11 0.00
Fri 06/05 06Z 0.77 3025  71  14  11 0.00
Fri 06/05 07Z 0.69 3024  68  16  11 0.00
Fri 06/05 08Z 0.67 3023  65  18  11 0.00
Fri 06/05 09Z 0.68 3023  63  12  10 0.00
Fri 06/05 10Z 0.64 3022  61   7  10 0.00
Fri 06/05 11Z 0.66 3022  60   8  10 0.00

Run total areal avg QPF for the Central_Greens is: 0.00 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