NAM3 EXPERIMENTAL Froude Number for the Central Green Mountains

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20261102_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 11/02 06Z 0.67 2823  62  67   6 0.00
Mon 11/02 07Z 0.78 2724  62  80   6 0.00
Mon 11/02 08Z 0.86 2725  60  87   6 0.00
Mon 11/02 09Z 0.85 2726  56  86   6 0.00
Mon 11/02 10Z 0.78 2725  55  86   7 0.00
Mon 11/02 11Z 0.72 2824  54  89   7 0.00
Mon 11/02 12Z 0.66 2822  52  84   7 0.00
Mon 11/02 13Z 0.63 2821  50  77   7 0.00
Mon 11/02 14Z 0.62 2821  49  77   8 0.00
Mon 11/02 15Z 0.61 2820  48  77   8 0.00
Mon 11/02 16Z 0.60 2720  48  76   8 0.00
Mon 11/02 17Z 0.58 2720  48  76   9 0.00
Mon 11/02 18Z 0.57 2719  46  75   9 0.00
Mon 11/02 19Z 0.60 2619  43  76   9 0.00
Mon 11/02 20Z 0.63 2620  40  73   9 0.00
Mon 11/02 21Z 0.68 2621  38  71   9 0.00
Mon 11/02 22Z 0.72 2623  38  74   9 0.00
Mon 11/02 23Z 0.69 2723  40  75  10 0.00
Tue 11/03 00Z 0.65 2722  43  78  10 0.00
Tue 11/03 01Z 0.57 2720  46  79  10 0.00
Tue 11/03 02Z 0.55 2720  48  77  10 0.00
Tue 11/03 03Z 0.51 2819  49  78  10 0.00
Tue 11/03 04Z 0.45 2817  51  80  10 0.00
Tue 11/03 05Z 0.37 2915  52  81  10 0.00
Tue 11/03 06Z 0.34 2813  52  87  10 0.00
Tue 11/03 07Z 0.33 2812  52  86  10 0.00
Tue 11/03 08Z 0.32 2611  53  87  10 0.00
Tue 11/03 09Z 0.33 2611  52  88  10 0.00
Tue 11/03 10Z 0.37 2612  51  96   9 0.00
Tue 11/03 11Z 0.38 2612  50  96   9 0.00
Tue 11/03 12Z 0.36 2512  51  90   9 0.00
Tue 11/03 13Z 0.38 2513  52  86   9 0.00
Tue 11/03 14Z 0.41 2414  57  87   9 0.00
Tue 11/03 15Z 0.47 2416  61  90   9 0.00
Tue 11/03 16Z 0.52 2418  64  91   9 0.00
Tue 11/03 17Z 0.55 2419  68  90   9 0.00
Tue 11/03 18Z 0.55 2419  66  86   9 0.00
Tue 11/03 19Z 0.59 2419  64  81   9 0.00
Tue 11/03 20Z 0.60 2419  63  82   9 0.00
Tue 11/03 21Z 0.55 2418  76  82   9 0.00
Tue 11/03 22Z 0.55 2519  80  80  10 0.00
Tue 11/03 23Z 0.59 2520  81  74  10 0.00
Wed 11/04 00Z 0.61 2521  81  68  10 0.00
Wed 11/04 01Z 0.62 2522  80  68  10 0.00
Wed 11/04 02Z 0.64 2524  79  73  10 0.00
Wed 11/04 03Z 0.66 2524  77  73  11 0.00
Wed 11/04 04Z 0.69 2525  75  66  11 0.00
Wed 11/04 05Z 0.71 2526  74  58  11 0.00
Wed 11/04 06Z 0.71 2525  72  59  11 0.00
Wed 11/04 07Z 0.70 2624  70  63  11 0.00
Wed 11/04 08Z 0.68 2624  69  51  11 0.00
Wed 11/04 09Z 0.63 2623  66  35  12 0.00
Wed 11/04 10Z 0.60 2622  65  35  12 0.00
Wed 11/04 11Z 0.56 2621  64  34  12 0.00
Wed 11/04 12Z 0.51 2619  63  35  12 0.00
Wed 11/04 13Z 0.47 2618  62  35  12 0.00
Wed 11/04 14Z 0.42 2616  62  34  12 0.00
Wed 11/04 15Z 0.39 2615  62  35  12 0.00
Wed 11/04 16Z 0.34 2613  62  29  12 0.00
Wed 11/04 17Z 0.34 2612  63  29  12 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