NAM3 EXPERIMENTAL Froude Number for the Central Green Mountains

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260724_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)
=== ===== === ==== ==== === === === ====
Fri 07/24 18Z 1.76 2402  67  22  11 0.00
Fri 07/24 19Z 1.13 2602  64  24  11 0.00
Fri 07/24 20Z 1.08 2702  62  25  12 0.00
Fri 07/24 21Z 0.57 2702  61  24  12 0.00
Fri 07/24 22Z 0.26 2402  60  26  12 0.00
Fri 07/24 23Z 0.15 2202  59  28  12 0.00
Sat 07/25 00Z 0.10 2101  59  30  12 0.00
Sat 07/25 01Z 0.12 2002  60  32  12 0.00
Sat 07/25 02Z 0.11 1903  61  34  12 0.00
Sat 07/25 03Z 0.12 1904  62  36  12 0.00
Sat 07/25 04Z 0.15 1905  62  38  12 0.00
Sat 07/25 05Z 0.17 2005  63  39  12 0.00
Sat 07/25 06Z 0.16 2004  63  40  12 0.00
Sat 07/25 07Z 0.12 2003  62  41  11 0.00
Sat 07/25 08Z 0.11 2202  61  41  11 0.00
Sat 07/25 09Z 0.12 2302  61  39  11 0.00
Sat 07/25 10Z 0.09 2301  61  37  11 0.00
Sat 07/25 11Z 0.08 2202  61  36  11 0.00
Sat 07/25 12Z 0.10 2003  60  36  11 0.00
Sat 07/25 13Z 0.03 1704  60  36  11 0.00
Sat 07/25 14Z 0.07 1604  63  35  11 0.00
Sat 07/25 15Z 0.09 1703  66  34  11 0.00
Sat 07/25 16Z 0.29 1603  68  30  12 0.00
Sat 07/25 17Z 0.42 1503  69  27  12 0.00
Sat 07/25 18Z 0.62 1504  69  26  12 0.00
Sat 07/25 19Z 1.01 1404  70  24  13 0.00
Sat 07/25 20Z 0.81 1505  71  24  13 0.00
Sat 07/25 21Z 0.90 1506  73  24  13 0.00
Sat 07/25 22Z 0.41 1607  74  21  13 0.00
Sat 07/25 23Z 0.14 1608  77  12  12 0.00
Sun 07/26 00Z 0.11 1609  80   7  12 0.00
Sun 07/26 01Z 0.05 1610  83  10  12 0.00
Sun 07/26 02Z 0.09 1711  84  12  12 0.00
Sun 07/26 03Z 0.22 1911  84  12  12 0.00
Sun 07/26 04Z 0.23 1910  84  11  12 0.00
Sun 07/26 05Z 0.29 2009  85  10  11 0.00
Sun 07/26 06Z 0.33 2108  86  10  11 0.00
Sun 07/26 07Z 0.37 2207  87   9  11 0.00
Sun 07/26 08Z 0.39 2307  88   9  11 0.00
Sun 07/26 09Z 0.33 2306  83   9  11 0.00
Sun 07/26 10Z 0.23 2304  80   9  11 0.00
Sun 07/26 11Z 0.14 2203  79   9  11 0.00
Sun 07/26 12Z 0.09 1903  80  10  11 0.00
Sun 07/26 13Z 0.05 1603  82  10  11 0.00
Sun 07/26 14Z 0.16 1503  84  11  11 0.00
Sun 07/26 15Z 0.26 1504  85  12  11 0.00
Sun 07/26 16Z 0.22 1504  87  14  11 0.00
Sun 07/26 17Z 0.25 1605  87  15  11 0.00
Sun 07/26 18Z 0.26 1605  86  15  11 0.00
Sun 07/26 19Z 0.25 1704  85  15  12 0.00
Sun 07/26 20Z 0.21 1704  84  15  12 0.00
Sun 07/26 21Z 0.15 1804  83  15  12 0.00
Sun 07/26 22Z 0.15 1704  82  14  12 0.00
Sun 07/26 23Z 0.10 1704  82  15  12 0.00
Mon 07/27 00Z 0.07 1704  83  17  12 0.00
Mon 07/27 01Z 0.05 1706  83  19  12 0.00
Mon 07/27 02Z 0.10 1806  83  21  12 0.00
Mon 07/27 03Z 0.21 2006  82  21  12 0.00
Mon 07/27 04Z 0.21 2105  83  19  12 0.00
Mon 07/27 05Z 0.15 2104  81  20  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