
An Extreme Cold Watch remains in effect for all of northern New York and Vermont for Saturday into Sunday afternoon. Wind chills of 20 to 40 below zero are possible, especially Saturday afternoon through Sunday morning. The risk of frostbite and hypothermia will be elevated, especially for vulnerable populations. Prepare now for the extreme cold, especially if you plan to be outdoors. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260205_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)
=== ===== === ==== ==== === === === ====
Thu 02/05 18Z 0.33 3106 82 14 -14 0.00
Thu 02/05 19Z 0.33 3107 79 14 -13 0.00
Thu 02/05 20Z 0.20 3108 75 14 -13 0.00
Thu 02/05 21Z 0.18 3109 71 14 -12 0.00
Thu 02/05 22Z 0.14 3109 69 14 -12 0.00
Thu 02/05 23Z 0.13 3109 68 14 -11 0.00
Fri 02/06 00Z 0.09 3208 68 15 -11 0.00
Fri 02/06 01Z 0.06 3207 67 18 -10 0.00
Fri 02/06 02Z 0.02 3406 67 21 -10 0.00
Fri 02/06 03Z 0.02 3505 66 24 -10 0.00
Fri 02/06 04Z 0.02 0101 65 24 -10 0.00
Fri 02/06 06Z 0.04 1404 63 19 -11 0.00
Fri 02/06 07Z 0.03 1504 59 17 -10 0.00
Fri 02/06 08Z 0.01 1704 57 14 -10 0.00
Fri 02/06 09Z 0.02 1709 61 10 -11 0.00
Fri 02/06 10Z 0.03 1712 62 8 -11 0.00
Fri 02/06 11Z 0.05 1811 63 8 -11 0.00
Fri 02/06 12Z 0.11 1911 66 9 -12 0.00
Fri 02/06 13Z 0.13 2011 72 14 -12 0.00
Fri 02/06 14Z 0.14 2010 77 37 -12 0.00
Fri 02/06 15Z 0.14 2108 77 66 -11 0.00
Fri 02/06 16Z 0.10 2006 77 84 -11 0.00
Fri 02/06 17Z 0.05 1806 80 87 -11 0.00
Fri 02/06 18Z 0.07 1708 85 88 -12 0.00
Fri 02/06 19Z 0.10 1808 88 87 -12 0.00
Fri 02/06 20Z 0.08 1807 91 86 -12 0.00
Fri 02/06 21Z 0.10 1907 91 84 -12 0.00
Fri 02/06 22Z 0.14 1907 90 83 -11 0.00
Fri 02/06 23Z 0.17 2008 89 86 -11 0.00
Sat 02/07 00Z 0.19 2009 91 89 -12 0.00
Sat 02/07 01Z 0.20 2009 93 88 -12 0.00
Sat 02/07 02Z 0.22 2010 93 89 -12 0.00
Sat 02/07 04Z 0.20 2010 92 88 -12 0.00
Sat 02/07 05Z 0.21 2010 92 87 -12 0.01
Sat 02/07 06Z 0.20 2010 92 87 -12 0.01
Sat 02/07 07Z 0.17 2009 92 86 -11 0.01
Sat 02/07 08Z 0.15 2008 92 86 -11 0.01
Sat 02/07 09Z 0.11 2006 92 86 -11 0.01
Sat 02/07 10Z 0.09 2004 92 85 -11 0.01
Sat 02/07 11Z 0.07 2102 92 84 -11 0.01
Sat 02/07 12Z 0.06 2601 92 84 -12 0.01
Sat 02/07 13Z 0.08 3204 92 83 -12 0.01
Sat 02/07 14Z 0.06 3408 91 81 -12 0.01
Sat 02/07 15Z 0.08 3411 89 81 -13 0.02
Sat 02/07 16Z 0.06 3514 89 81 -13 0.02
Sat 02/07 17Z 0.04 3415 86 82 -14 0.02
Sat 02/07 18Z 0.04 3416 85 83 -14 0.01
Sat 02/07 19Z 0.06 3318 84 83 -15 0.01
Sat 02/07 20Z 0.08 3321 84 81 -16 0.01
Sat 02/07 21Z 0.10 3323 84 82 -17 0.01
Sat 02/07 23Z 0.12 3327 85 79 -18 0.01
Sun 02/08 00Z 0.12 3328 84 74 -18 0.01
Sun 02/08 01Z 0.13 3328 83 69 -19 0.00
Sun 02/08 03Z 0.15 3327 82 64 -20 0.00
Sun 02/08 05Z 0.14 3326 80 65 -21 0.00
Run total areal avg QPF for the Central_Greens is: 0.22 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