National Weather Service United States Department of Commerce

Wind Advisory in effect for most of the region from 8 AM to 8 PM Tomorrow for strong Gusty Winds

A Wind Advisory is in effect for majority of the region from 8AM to 8PM Tomorrow for southerly winds gusts between 45 and 55 MPH. There will be two rounds of gusty winds with the first tomorrow morning for most of the area and the second mainly over northern New York. The strongest winds will be between 9AM and 1PM in the CPV, western facing slopes of the higher terrain and the St. Lawrence Valley Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260617_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)
=== ===== === ==== ==== === === === ====
Wed 06/17 18Z 1.77 1909  67  86  10 0.00
Wed 06/17 19Z 1.69 1909  65  82  10 0.01
Wed 06/17 20Z 1.88 1910  64  75  11 0.00
Wed 06/17 21Z 0.42 1709  63  60  11 0.00
Wed 06/17 22Z 0.46 1710  63  68  11 0.00
Wed 06/17 23Z 0.34 1812  63  89  11 0.00
Thu 06/18 00Z 0.34 1813  65  88  11 0.00
Thu 06/18 01Z 0.30 1814  67  79  11 0.00
Thu 06/18 02Z 0.37 1818  70  78  11 0.00
Thu 06/18 03Z 0.39 1820  78  84  11 0.00
Thu 06/18 04Z 0.34 1923  90  93  11 0.05
Thu 06/18 05Z 0.42 2023  93  63  11 0.07
Thu 06/18 06Z 0.42 2119  94  53  11 0.00
Thu 06/18 07Z 0.44 2120  96  63  11 0.01
Thu 06/18 08Z 0.45 2121  93  56  11 0.01
Thu 06/18 09Z 0.45 2122  92  83  11 0.01
Thu 06/18 10Z 0.44 2023  92  90  11 0.04
Thu 06/18 11Z 0.23 1922  89  90  12 0.02
Thu 06/18 12Z 0.10 1728  92  88  12 0.02
Thu 06/18 13Z 0.15 1734  92  98  13 0.04
Thu 06/18 14Z 0.25 1839  88  89  14 0.10
Thu 06/18 15Z 0.33 1842  88  88  14 0.02
Thu 06/18 16Z 0.35 1840  95  94  13 0.16
Thu 06/18 17Z 0.42 1936  97  71  13 0.13
Thu 06/18 18Z 0.46 1932  97  72  14 0.04
Thu 06/18 19Z 0.45 1929  96  55  15 0.03
Thu 06/18 20Z 1.11 2026  93  69  15 0.08
Thu 06/18 21Z 1.25 2533  91  73  14 0.53
Thu 06/18 22Z 1.61 2433  89  50  13 0.04
Thu 06/18 23Z 2.33 2433  87  57  12 0.01
Fri 06/19 00Z 2.82 2533  86  62  11 0.01
Fri 06/19 01Z 1.84 2532  89  69  10 0.00
Fri 06/19 02Z 1.73 2532  92  69  10 0.01
Fri 06/19 03Z 1.38 2532  93  65  10 0.01
Fri 06/19 04Z 1.22 2531  96  70   9 0.01
Fri 06/19 05Z 1.16 2630  96  74   9 0.01
Fri 06/19 06Z 1.15 2531  96  71   8 0.01
Fri 06/19 07Z 1.16 2632  97  73   8 0.01
Fri 06/19 08Z 1.12 2632  96  68   8 0.01
Fri 06/19 09Z 1.01 2732  94  61   8 0.01
Fri 06/19 10Z 0.90 2733  89  56   9 0.00
Fri 06/19 11Z 0.87 2633  91  51   9 0.00
Fri 06/19 12Z 0.86 2631  89  42   9 0.01
Fri 06/19 13Z 0.95 2630  91  48   9 0.01
Fri 06/19 14Z 0.98 2628  94  46   9 0.01
Fri 06/19 15Z 1.07 2628  95  45   9 0.01
Fri 06/19 16Z 1.26 2626  95  43   9 0.01
Fri 06/19 17Z 1.50 2625  94  48   9 0.01
Fri 06/19 18Z 2.98 2624  93  44   9 0.01
Fri 06/19 19Z 4.76 2624  91  49  10 0.01
Fri 06/19 20Z 6.18 2624  89  42  10 0.01
Fri 06/19 21Z 7.98 2525  86  41  10 0.00
Fri 06/19 22Z 7.91 2527  81  37  10 0.00
Fri 06/19 23Z 4.60 2529  76  34  10 0.00
Sat 06/20 00Z 3.16 2632  79  38   9 0.00
Sat 06/20 01Z 2.19 2731  85  43   8 0.03
Sat 06/20 02Z 1.76 2731  84  56   8 0.04
Sat 06/20 03Z 1.45 2730  84  64   8 0.01
Sat 06/20 04Z 1.33 2730  90  71   7 0.01
Sat 06/20 05Z 1.18 2629  93  67   7 0.01

Run total areal avg QPF for the Central_Greens is: 1.70 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