
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_20260206_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)
=== ===== === ==== ==== === === === ====
Fri 02/06 00Z 0.08 3105 58 21 -10 0.00
Fri 02/06 01Z 0.05 3205 59 22 -10 0.00
Fri 02/06 02Z 0.05 3204 63 22 -11 0.00
Fri 02/06 03Z 0.02 3302 66 20 -11 0.00
Fri 02/06 04Z 0.02 0101 64 18 -11 0.00
Fri 02/06 05Z 0.03 0701 59 17 -10 0.00
Fri 02/06 06Z 0.03 1302 54 15 -10 0.00
Fri 02/06 07Z 0.02 1605 50 13 -10 0.00
Fri 02/06 08Z 0.02 1608 53 9 -10 0.00
Fri 02/06 09Z 0.02 1709 56 5 -11 0.00
Fri 02/06 10Z 0.05 1809 58 4 -11 0.00
Fri 02/06 11Z 0.05 1810 61 13 -11 0.00
Fri 02/06 12Z 0.05 1811 64 41 -12 0.00
Fri 02/06 13Z 0.07 1812 68 70 -12 0.00
Fri 02/06 14Z 0.12 1914 72 84 -12 0.00
Fri 02/06 15Z 0.14 1913 75 84 -12 0.00
Fri 02/06 16Z 0.16 1911 76 86 -11 0.00
Fri 02/06 17Z 0.17 1910 76 87 -11 0.00
Fri 02/06 18Z 0.17 1908 77 86 -11 0.00
Fri 02/06 19Z 0.25 1907 81 88 -11 0.00
Fri 02/06 20Z 0.12 1807 84 91 -11 0.00
Fri 02/06 21Z 0.07 1707 87 89 -11 0.00
Fri 02/06 22Z 0.09 1808 87 85 -11 0.00
Fri 02/06 23Z 0.11 1809 88 85 -11 0.00
Sat 02/07 00Z 0.11 1810 89 88 -11 0.00
Sat 02/07 01Z 0.14 1911 93 90 -11 0.00
Sat 02/07 02Z 0.18 1912 94 87 -11 0.00
Sat 02/07 03Z 0.21 1913 93 87 -11 0.01
Sat 02/07 04Z 0.21 1913 92 87 -11 0.01
Sat 02/07 05Z 0.20 1913 92 86 -11 0.02
Sat 02/07 06Z 0.19 1913 92 85 -11 0.02
Sat 02/07 07Z 0.17 1912 92 85 -11 0.02
Sat 02/07 08Z 0.17 1911 92 84 -11 0.02
Sat 02/07 09Z 0.17 2009 92 84 -11 0.01
Sat 02/07 10Z 0.15 2006 92 84 -12 0.01
Sat 02/07 11Z 0.14 2304 92 84 -12 0.01
Sat 02/07 12Z 0.10 3204 92 83 -12 0.02
Sat 02/07 13Z 0.06 3408 90 82 -13 0.02
Sat 02/07 14Z 0.06 3512 88 82 -13 0.02
Sat 02/07 15Z 0.03 3414 87 82 -14 0.01
Sat 02/07 16Z 0.04 3415 86 82 -14 0.01
Sat 02/07 17Z 0.05 3415 84 83 -15 0.01
Sat 02/07 18Z 0.06 3317 84 83 -16 0.01
Sat 02/07 19Z 0.08 3319 83 82 -17 0.01
Sat 02/07 20Z 0.10 3322 83 81 -17 0.01
Sat 02/07 21Z 0.10 3323 85 80 -18 0.00
Sat 02/07 22Z 0.09 3325 85 77 -18 0.00
Sat 02/07 23Z 0.09 3327 85 74 -19 0.00
Sun 02/08 00Z 0.09 3328 84 72 -19 0.00
Sun 02/08 01Z 0.10 3329 84 72 -19 0.00
Sun 02/08 02Z 0.11 3328 83 71 -19 0.00
Sun 02/08 03Z 0.12 3327 82 73 -20 0.00
Sun 02/08 04Z 0.12 3326 81 73 -19 0.00
Sun 02/08 05Z 0.11 3326 81 73 -19 0.00
Sun 02/08 06Z 0.12 3326 80 68 -19 0.00
Sun 02/08 07Z 0.13 3326 79 62 -20 0.00
Sun 02/08 08Z 0.14 3327 78 58 -20 0.00
Sun 02/08 09Z 0.16 3229 76 54 -21 0.00
Sun 02/08 10Z 0.16 3231 72 49 -21 0.00
Sun 02/08 11Z 0.15 3331 69 33 -21 0.00
Run total areal avg QPF for the Central_Greens is: 0.25 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