
A warm front will approach Friday afternoon. A brief wintry mix or rain in warmer valleys is possible before a quick transition into moderate or heavy snow takes place during the Friday evening commute. 1 inch per hour snowfall rates are possible in northeastern New York and much of Vermont. Difficult travel is likely to be the main concern. Light snow will continue Friday night into Saturday. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260219_0600
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 02/19 06Z 0.21 0312 56 17 -6 0.00
Thu 02/19 07Z 0.30 0413 55 9 -6 0.00
Thu 02/19 08Z 0.21 0509 46 4 -6 0.00
Thu 02/19 09Z 0.14 0406 36 2 -5 0.00
Thu 02/19 10Z 0.12 0406 33 2 -5 0.00
Thu 02/19 11Z 0.13 0406 33 4 -5 0.00
Thu 02/19 12Z 0.10 0504 31 5 -5 0.00
Thu 02/19 13Z 0.10 0704 29 5 -4 0.00
Thu 02/19 14Z 0.06 0802 28 6 -4 0.00
Thu 02/19 15Z 0.06 0802 27 6 -4 0.00
Thu 02/19 16Z 0.05 0902 29 7 -4 0.00
Thu 02/19 17Z 0.06 1002 32 9 -4 0.00
Thu 02/19 18Z 0.02 1502 38 15 -4 0.00
Thu 02/19 19Z 0.02 1603 43 25 -4 0.00
Thu 02/19 20Z 0.07 1903 49 39 -5 0.00
Thu 02/19 21Z 0.13 2105 53 54 -4 0.00
Thu 02/19 22Z 0.14 2106 52 61 -4 0.00
Thu 02/19 23Z 0.13 2206 47 45 -3 0.00
Fri 02/20 00Z 0.12 2205 48 34 -3 0.00
Fri 02/20 01Z 0.08 2104 55 26 -3 0.00
Fri 02/20 02Z 0.08 2005 64 27 -4 0.00
Fri 02/20 03Z 0.14 2007 74 28 -4 0.00
Fri 02/20 04Z 0.20 2109 82 28 -5 0.00
Fri 02/20 05Z 0.27 2211 87 28 -5 0.00
Fri 02/20 06Z 0.18 2209 88 22 -3 0.00
Fri 02/20 07Z 0.19 2210 90 20 -3 0.00
Fri 02/20 08Z 0.15 2208 88 18 -2 0.00
Fri 02/20 09Z 0.13 2207 86 16 -2 0.00
Fri 02/20 10Z 0.05 1904 85 20 -2 0.00
Fri 02/20 11Z 0.03 1805 85 24 -2 0.00
Fri 02/20 12Z 0.03 1707 85 28 -2 0.00
Fri 02/20 13Z 0.02 1707 83 30 -2 0.00
Fri 02/20 14Z 0.03 1609 79 24 -2 0.00
Fri 02/20 15Z 0.02 1711 78 24 -2 0.00
Fri 02/20 16Z 0.02 1612 78 25 -2 0.00
Fri 02/20 17Z 0.04 1713 78 35 -2 0.00
Fri 02/20 18Z 0.03 1714 79 76 -2 0.00
Fri 02/20 19Z 0.05 1514 90 93 -1 0.01
Fri 02/20 20Z 0.11 1417 95 96 0 0.04
Fri 02/20 21Z 0.15 1420 96 98 0 0.03
Fri 02/20 22Z 0.18 1421 96 98 0 0.05
Fri 02/20 23Z 0.21 1422 95 98 -1 0.10
Sat 02/21 00Z 0.22 1322 95 99 -1 0.15
Sat 02/21 01Z 0.26 1323 95 98 -2 0.09
Sat 02/21 02Z 0.30 1323 96 97 -3 0.07
Sat 02/21 03Z 0.31 1321 96 97 -4 0.05
Sat 02/21 04Z 0.34 1320 95 95 -6 0.06
Sat 02/21 05Z 0.33 1419 95 85 -7 0.03
Sat 02/21 06Z 0.22 1517 95 93 -7 0.03
Sat 02/21 07Z 0.07 1615 94 95 -7 0.03
Sat 02/21 08Z 0.06 1714 94 96 -7 0.02
Sat 02/21 09Z 0.10 1812 95 95 -7 0.02
Sat 02/21 10Z 0.14 1812 97 96 -7 0.02
Sat 02/21 11Z 0.14 1911 98 95 -7 0.02
Sat 02/21 12Z 0.14 1909 98 94 -7 0.02
Sat 02/21 13Z 0.18 2009 97 91 -7 0.03
Sat 02/21 14Z 0.20 2108 97 89 -7 0.03
Sat 02/21 15Z 0.22 2207 97 88 -7 0.02
Sat 02/21 16Z 0.26 2407 97 87 -7 0.01
Sat 02/21 17Z 0.24 2406 98 83 -7 0.01
Run total areal avg QPF for the Central_Greens is: 0.94 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