NAM3 EXPERIMENTAL Froude Number for the Central Green Mountains

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20261101_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 11/01 00Z 0.50 3015  78  45  -4 0.00
Sun 11/01 01Z 0.55 3018  82  46  -4 0.00
Sun 11/01 02Z 0.52 3119  87  25  -4 0.00
Sun 11/01 03Z 0.55 3121  89  10  -4 0.00
Sun 11/01 04Z 0.48 3121  84   6  -3 0.00
Sun 11/01 05Z 0.44 3121  79   7  -3 0.00
Sun 11/01 06Z 0.40 3121  75  10  -2 0.00
Sun 11/01 07Z 0.42 3120  76  13  -2 0.00
Sun 11/01 08Z 0.41 3120  75  14  -2 0.00
Sun 11/01 09Z 0.34 3120  69  14   0 0.00
Sun 11/01 10Z 0.31 3120  60  14   0 0.00
Sun 11/01 11Z 0.30 3121  52  14   0 0.00
Sun 11/01 12Z 0.32 3122  45  12   1 0.00
Sun 11/01 13Z 0.34 3123  41   9   1 0.00
Sun 11/01 14Z 0.36 3125  53   8   1 0.00
Sun 11/01 15Z 0.38 3126  72  10   1 0.00
Sun 11/01 16Z 0.41 3126  81  11   1 0.00
Sun 11/01 17Z 0.44 3125  83  17   2 0.00
Sun 11/01 18Z 0.51 3025  78  23   2 0.00
Sun 11/01 19Z 0.57 3025  73  25   3 0.00
Sun 11/01 20Z 0.61 2926  69  23   3 0.00
Sun 11/01 21Z 0.66 2927  67  20   4 0.00
Sun 11/01 22Z 0.71 2927  66  17   4 0.00
Sun 11/01 23Z 0.74 2928  64  17   4 0.00
Mon 11/02 00Z 0.75 2928  61  17   4 0.00
Mon 11/02 01Z 0.76 2828  59  17   5 0.00
Mon 11/02 02Z 0.77 2828  58  17   5 0.00
Mon 11/02 03Z 0.78 2829  57  18   5 0.00
Mon 11/02 04Z 0.80 2829  54  36   5 0.00
Mon 11/02 05Z 0.92 2731  54  60   5 0.00
Mon 11/02 06Z 0.99 2732  53  75   5 0.00
Mon 11/02 07Z 1.00 2731  55  80   6 0.00
Mon 11/02 08Z 1.01 2731  53  86   6 0.00
Mon 11/02 09Z 0.99 2730  55  89   6 0.00
Mon 11/02 10Z 0.94 2829  56  85   6 0.00
Mon 11/02 11Z 0.89 2828  56  79   6 0.00
Mon 11/02 12Z 0.79 2826  54  76   6 0.00
Mon 11/02 13Z 0.73 2825  51  79   7 0.00
Mon 11/02 14Z 0.70 2824  49  80   7 0.00
Mon 11/02 15Z 0.71 2824  50  78   7 0.00
Mon 11/02 16Z 0.72 2723  48  80   7 0.00
Mon 11/02 17Z 0.72 2723  50  77   8 0.00
Mon 11/02 18Z 0.71 2723  50  76   8 0.00
Mon 11/02 19Z 0.67 2722  52  77   8 0.00
Mon 11/02 20Z 0.61 2720  58  76   8 0.00
Mon 11/02 21Z 0.55 2718  64  74   8 0.00
Mon 11/02 22Z 0.55 2818  69  78   8 0.00
Mon 11/02 23Z 0.51 2717  72  73   8 0.00
Tue 11/03 00Z 0.52 2717  74  71   8 0.00
Tue 11/03 01Z 0.51 2717  75  71   8 0.00
Tue 11/03 02Z 0.51 2617  75  70   8 0.00
Tue 11/03 03Z 0.49 2617  75  71   8 0.00
Tue 11/03 04Z 0.49 2717  76  74   8 0.00
Tue 11/03 05Z 0.48 2617  75  76   9 0.00
Tue 11/03 06Z 0.46 2717  75  83   9 0.00
Tue 11/03 07Z 0.41 2715  74  86   9 0.00
Tue 11/03 08Z 0.37 2713  72  86   9 0.00
Tue 11/03 09Z 0.35 2612  69  85   9 0.00
Tue 11/03 10Z 0.34 2512  66  86   9 0.00
Tue 11/03 11Z 0.32 2411  64  82   9 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