NAM3 EXPERIMENTAL Froude Number for the Central Green Mountains

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260602_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)
=== ===== === ==== ==== === === === ====
Tue 06/02 00Z 0.03 3405  72  66   5 0.00
Tue 06/02 01Z 0.03 3507  70  62   5 0.00
Tue 06/02 02Z 0.10 3509  69  56   5 0.00
Tue 06/02 03Z 0.17 0010  69  56   5 0.00
Tue 06/02 04Z 0.18 0011  69  65   5 0.00
Tue 06/02 05Z 0.12 3510  67  69   5 0.00
Tue 06/02 06Z 0.14 3411  66  65   5 0.00
Tue 06/02 07Z 0.18 3311  65  60   5 0.00
Tue 06/02 08Z 0.22 3213  65  65   5 0.00
Tue 06/02 09Z 0.22 3214  63  64   6 0.00
Tue 06/02 10Z 0.20 3315  60  65   6 0.00
Tue 06/02 11Z 0.18 3316  57  62   6 0.00
Tue 06/02 12Z 0.16 3316  52  54   6 0.00
Tue 06/02 13Z 0.15 3316  47  47   7 0.00
Tue 06/02 14Z 0.14 3417  42  39   7 0.00
Tue 06/02 15Z 0.63 3316  44  34   7 0.00
Tue 06/02 16Z 1.68 3317  43  24   7 0.00
Tue 06/02 17Z 2.56 3319  41  14   7 0.00
Tue 06/02 18Z 2.83 3320  40  11   7 0.00
Tue 06/02 19Z 2.55 3319  44  14   7 0.00
Tue 06/02 20Z 2.31 3320  45  26   7 0.00
Tue 06/02 21Z 1.18 3420  45  45   7 0.00
Tue 06/02 22Z 0.50 3421  45  70   7 0.00
Tue 06/02 23Z 0.07 3421  44  81   7 0.00
Wed 06/03 00Z 0.08 3523  45  69   7 0.00
Wed 06/03 01Z 0.21 3523  46  51   7 0.00
Wed 06/03 02Z 0.35 0023  44  42   8 0.00
Wed 06/03 03Z 0.37 0021  42  45   8 0.00
Wed 06/03 04Z 0.35 0019  43  47   8 0.00
Wed 06/03 05Z 0.37 0117  43  31   8 0.00
Wed 06/03 06Z 0.34 0016  43  21   8 0.00
Wed 06/03 07Z 0.28 0015  44  18   8 0.00
Wed 06/03 08Z 0.35 0014  44  23   8 0.00
Wed 06/03 09Z 0.39 0113  45  36   8 0.00
Wed 06/03 10Z 0.24 0011  45  56   8 0.00
Wed 06/03 11Z 0.11 3511  46  75   8 0.00
Wed 06/03 12Z 0.09 3510  46  75   8 0.00
Wed 06/03 13Z 0.04 3410  47  76   8 0.00
Wed 06/03 14Z 0.21 3309  49  75   9 0.00
Wed 06/03 15Z 0.71 3210  51  75   9 0.00
Wed 06/03 16Z 1.41 3210  51  72   9 0.00
Wed 06/03 17Z 1.89 3210  50  67   9 0.00
Wed 06/03 18Z 1.97 3210  50  63  10 0.00
Wed 06/03 19Z 1.72 3209  50  56  10 0.00
Wed 06/03 20Z 2.12 3109  52  54  11 0.00
Wed 06/03 21Z 1.83 3109  54  53  11 0.00
Wed 06/03 22Z 0.80 3009  56  53  11 0.00
Wed 06/03 23Z 0.47 3010  57  57  11 0.00
Thu 06/04 00Z 0.43 2909  58  53  11 0.00
Thu 06/04 01Z 0.47 2910  60  50  11 0.00
Thu 06/04 02Z 0.46 2910  61  43  11 0.00
Thu 06/04 03Z 0.45 3010  63  36  11 0.00
Thu 06/04 04Z 0.33 3110  63  31  11 0.00
Thu 06/04 05Z 0.29 3110  61  27  11 0.00
Thu 06/04 06Z 0.32 2909  58  25  11 0.00
Thu 06/04 07Z 0.40 2810  56  27  11 0.00
Thu 06/04 08Z 0.40 2810  51  31  11 0.00
Thu 06/04 09Z 0.36 2910  47  36  11 0.00
Thu 06/04 10Z 0.37 2910  48  39  11 0.00
Thu 06/04 11Z 0.38 2911  48  39  11 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