
An Extreme Cold Watch has been issued for all of northern New York and Vermont for Saturday into Sunday afternoon. Wind chills of 20 to 35 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_1200
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 12Z 0.23 3013 79 8 -13 0.00
Thu 02/05 13Z 0.22 3116 82 4 -14 0.00
Thu 02/05 14Z 0.20 3116 82 19 -13 0.00
Thu 02/05 15Z 0.17 3215 78 27 -13 0.00
Thu 02/05 16Z 0.15 3112 68 17 -12 0.00
Thu 02/05 17Z 0.16 3112 60 8 -12 0.00
Thu 02/05 18Z 0.17 3112 53 7 -11 0.00
Thu 02/05 19Z 0.17 3112 47 7 -11 0.00
Thu 02/05 20Z 0.15 3111 44 8 -11 0.00
Thu 02/05 21Z 0.13 3111 42 8 -11 0.00
Thu 02/05 22Z 0.09 3210 41 7 -10 0.00
Thu 02/05 23Z 0.06 3209 41 7 -9 0.00
Fri 02/06 00Z 0.04 3308 43 8 -9 0.00
Fri 02/06 01Z 0.02 3407 46 9 -10 0.00
Fri 02/06 02Z 0.01 3404 46 10 -10 0.00
Fri 02/06 03Z 0.01 0400 47 11 -10 0.00
Fri 02/06 04Z 0.03 0601 43 11 -10 0.00
Fri 02/06 05Z 0.03 1302 40 11 -10 0.00
Fri 02/06 06Z 0.02 1604 35 9 -9 0.00
Fri 02/06 07Z 0.02 1706 32 8 -9 0.00
Fri 02/06 08Z 0.04 1806 33 12 -9 0.00
Fri 02/06 09Z 0.05 1906 33 25 -9 0.00
Fri 02/06 10Z 0.06 1907 35 41 -10 0.00
Fri 02/06 11Z 0.06 1908 36 69 -10 0.00
Fri 02/06 12Z 0.05 1809 39 83 -10 0.00
Fri 02/06 13Z 0.04 1809 42 80 -10 0.00
Fri 02/06 14Z 0.07 1810 48 81 -11 0.00
Fri 02/06 15Z 0.09 1910 53 67 -11 0.00
Fri 02/06 16Z 0.09 1909 58 42 -11 0.00
Fri 02/06 17Z 0.11 1908 61 34 -11 0.00
Fri 02/06 18Z 0.16 2007 63 53 -11 0.00
Fri 02/06 19Z 0.21 2006 67 69 -11 0.00
Fri 02/06 20Z 0.16 2005 68 76 -11 0.00
Fri 02/06 21Z 0.11 1906 72 87 -11 0.00
Fri 02/06 22Z 0.11 1907 76 92 -11 0.00
Fri 02/06 23Z 0.13 1908 80 89 -11 0.00
Sat 02/07 00Z 0.17 1910 86 91 -12 0.00
Sat 02/07 01Z 0.17 1910 91 87 -12 0.00
Sat 02/07 02Z 0.21 2011 92 86 -12 0.01
Sat 02/07 03Z 0.25 2011 93 88 -12 0.01
Sat 02/07 04Z 0.31 2112 92 87 -12 0.01
Sat 02/07 05Z 0.28 2112 92 88 -12 0.01
Sat 02/07 06Z 0.23 2111 92 87 -11 0.01
Sat 02/07 07Z 0.20 2109 91 87 -11 0.01
Sat 02/07 08Z 0.16 2008 91 87 -11 0.02
Sat 02/07 09Z 0.11 1907 91 86 -11 0.02
Sat 02/07 10Z 0.05 1805 91 85 -11 0.01
Sat 02/07 11Z 0.02 1704 91 85 -12 0.01
Sat 02/07 12Z 0.02 1603 92 85 -12 0.01
Sat 02/07 13Z 0.05 2700 92 84 -12 0.02
Sat 02/07 14Z 0.04 3405 91 82 -13 0.02
Sat 02/07 15Z 0.09 3408 90 81 -13 0.02
Sat 02/07 16Z 0.07 3411 89 81 -13 0.01
Sat 02/07 17Z 0.04 3413 86 82 -14 0.01
Sat 02/07 18Z 0.06 3315 85 83 -15 0.01
Sat 02/07 19Z 0.07 3317 84 83 -15 0.01
Sat 02/07 20Z 0.08 3319 83 83 -16 0.01
Sat 02/07 21Z 0.09 3321 83 83 -17 0.01
Sat 02/07 22Z 0.10 3323 83 82 -18 0.01
Sat 02/07 23Z 0.10 3325 83 79 -19 0.01
Run total areal avg QPF for the Central_Greens is: 0.27 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