National Weather Service United States Department of Commerce

Strong and gusty winds possible Sunday night and Monday

A High Wind Watch has been issued for portions of northern New York for Sunday night through Monday. South winds of 20 to 30 mph are expected with gusts up to 60 mph in the Watch area. Elsewhere, gusts up to 40 mph are possible. The strongest winds will occur between 2 AM Monday and 5 PM Monday. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260315_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 03/15 00Z 1.79 2923  89  64 -10 0.00
Sun 03/15 01Z 1.35 2823  91  51 -10 0.00
Sun 03/15 02Z 1.28 2826  95  41 -10 0.02
Sun 03/15 03Z 1.14 2926  95  14 -11 0.02
Sun 03/15 04Z 0.77 3024  94  10 -11 0.01
Sun 03/15 05Z 0.72 3024  91   9 -11 0.01
Sun 03/15 06Z 0.59 3123  86   9 -11 0.00
Sun 03/15 07Z 0.42 3122  75  10 -11 0.00
Sun 03/15 08Z 0.29 3120  62   9 -10 0.00
Sun 03/15 09Z 0.23 3118  50   8  -9 0.00
Sun 03/15 10Z 0.16 3218  38  10  -8 0.00
Sun 03/15 11Z 0.11 3315  31  11  -7 0.00
Sun 03/15 12Z 0.05 3311  26  12  -7 0.00
Sun 03/15 13Z 0.02 3406  25  37  -7 0.00
Sun 03/15 14Z 0.02 3301  26  86  -7 0.00
Sun 03/15 15Z 0.02 1402  26  97  -7 0.00
Sun 03/15 18Z 0.05 1613  39  98  -6 0.00
Sun 03/15 19Z 0.03 1615  75  98  -7 0.00
Sun 03/15 20Z 0.02 1722  77  96  -5 0.00
Sun 03/15 21Z 0.05 1628  59  91  -5 0.00
Sun 03/15 22Z 0.05 1632  52  89  -4 0.01
Sun 03/15 23Z 0.05 1734  47  88  -2 0.01
Mon 03/16 00Z 0.10 1736  42  89  -1 0.00
Mon 03/16 01Z 0.13 1739  37  77   0 0.00
Mon 03/16 02Z 0.16 1840  36  79   0 0.00
Mon 03/16 03Z 0.18 1842  39  95   1 0.00
Mon 03/16 04Z 0.15 1845  42  91   2 0.00
Mon 03/16 05Z 0.13 1747  44  74   3 0.00
Mon 03/16 06Z 0.10 1749  51  50   3 0.00
Mon 03/16 07Z 0.06 1750  68  33   3 0.00
Mon 03/16 08Z 0.06 1650  79  48   4 0.01
Mon 03/16 09Z 0.07 1650  88  62   5 0.01
Mon 03/16 10Z 0.09 1647  93  95   6 0.01
Mon 03/16 11Z 0.16 1552  94  98   7 0.01
Mon 03/16 12Z 0.15 1552  94  98   8 0.05
Mon 03/16 13Z 0.05 1651  96  57   8 0.09
Mon 03/16 14Z 0.07 1745  96  55   8 0.06
Mon 03/16 15Z 0.19 1842  97  42   8 0.07
Mon 03/16 16Z 0.29 1942  96  21   9 0.02
Mon 03/16 17Z 0.38 1943  95  12   9 0.01
Mon 03/16 18Z 0.42 1943  92   9  10 0.01
Mon 03/16 19Z 0.40 1942  95  31  10 0.01
Mon 03/16 20Z 0.37 1844  96  53  10 0.00
Mon 03/16 21Z 0.29 1845  96  71  10 0.00
Mon 03/16 22Z 0.24 1846  96  79  10 0.00
Mon 03/16 23Z 0.24 1848  96  77  10 0.01
Tue 03/17 00Z 0.24 1846  96  73  10 0.01
Tue 03/17 01Z 0.20 1747  95  72  10 0.01
Tue 03/17 02Z 0.15 1747  95  70  10 0.01
Tue 03/17 03Z 0.18 1745  96  92   9 0.01
Tue 03/17 04Z 0.14 1744  96  91   9 0.01
Tue 03/17 05Z 0.56 1931  99  98   7 0.05
Tue 03/17 06Z 0.81 2430  95  95  -1 0.07
Tue 03/17 07Z 0.90 2430  95  95  -3 0.14
Tue 03/17 08Z 1.22 2426  96  83  -6 0.09
Tue 03/17 09Z 3.70 2626  95   2  -9 0.02
Tue 03/17 10Z 5.41 2527  91   3 -11 0.02
Tue 03/17 11Z 3.57 2430  89  11 -12 0.02

Run total areal avg QPF for the Central_Greens is: 0.91 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