
Extreme Cold Warnings and Cold Weather Advisories remain in effect across the region through 1 pm Sunday. Wind chills of 20 to 35 below zero are expected, especially this morning. The risk of frostbite and hypothermia will be elevated, especially for vulnerable populations. Use extra caution and dress appropriately if you plan to be outdoors. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260208_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)
=== ===== === ==== ==== === === === ====
Sun 02/08 12Z 0.04 3420 75 65 -21 0.00
Sun 02/08 13Z 0.04 3424 72 59 -19 0.00
Sun 02/08 14Z 0.03 3425 70 62 -19 0.00
Sun 02/08 15Z 0.03 3425 69 65 -19 0.00
Sun 02/08 16Z 0.03 3426 69 65 -18 0.00
Sun 02/08 18Z 0.03 3427 64 31 -16 0.00
Sun 02/08 19Z 0.03 3426 64 20 -15 0.00
Sun 02/08 20Z 0.03 3426 65 43 -15 0.00
Sun 02/08 21Z 0.03 3426 65 52 -14 0.00
Sun 02/08 22Z 0.02 3427 61 42 -13 0.00
Sun 02/08 23Z 0.02 3428 56 45 -12 0.00
Mon 02/09 00Z 0.02 3428 53 51 -12 0.00
Mon 02/09 01Z 0.02 3429 51 51 -12 0.00
Mon 02/09 02Z 0.02 3429 50 45 -11 0.00
Mon 02/09 03Z 0.05 3429 56 41 -11 0.00
Mon 02/09 04Z 0.07 3429 60 38 -11 0.00
Mon 02/09 05Z 0.09 3330 60 33 -12 0.00
Mon 02/09 06Z 0.11 3331 59 30 -12 0.00
Mon 02/09 07Z 0.12 3332 59 28 -12 0.00
Mon 02/09 08Z 0.10 3332 62 26 -12 0.00
Mon 02/09 09Z 0.10 3333 64 25 -12 0.00
Mon 02/09 10Z 0.09 3333 64 21 -12 0.00
Mon 02/09 11Z 0.07 3433 62 16 -11 0.00
Mon 02/09 12Z 0.07 3433 60 14 -11 0.00
Mon 02/09 13Z 0.06 3433 59 12 -11 0.00
Mon 02/09 14Z 0.05 3433 56 15 -11 0.00
Mon 02/09 15Z 0.03 3432 52 28 -11 0.00
Mon 02/09 16Z 0.03 3430 52 58 -10 0.00
Mon 02/09 17Z 0.04 3428 51 69 -11 0.00
Mon 02/09 18Z 0.08 3427 50 65 -11 0.00
Mon 02/09 19Z 0.09 3326 46 57 -10 0.00
Mon 02/09 20Z 0.10 3325 45 51 -10 0.00
Mon 02/09 21Z 0.11 3325 41 50 -9 0.00
Mon 02/09 22Z 0.10 3325 38 54 -8 0.00
Mon 02/09 23Z 0.07 3425 35 50 -8 0.00
Tue 02/10 00Z 0.08 3325 35 42 -8 0.00
Tue 02/10 01Z 0.07 3425 35 33 -8 0.00
Tue 02/10 02Z 0.07 3324 33 35 -8 0.00
Tue 02/10 03Z 0.07 3322 31 43 -8 0.00
Tue 02/10 04Z 0.06 3420 30 60 -8 0.00
Tue 02/10 05Z 0.06 3418 31 73 -8 0.00
Tue 02/10 06Z 0.05 3416 35 77 -7 0.00
Tue 02/10 07Z 0.06 3315 38 80 -7 0.00
Tue 02/10 08Z 0.10 3215 39 82 -8 0.00
Tue 02/10 09Z 0.07 3314 41 77 -7 0.00
Tue 02/10 10Z 0.10 3213 42 78 -7 0.00
Tue 02/10 11Z 0.08 3210 46 75 -7 0.00
Tue 02/10 12Z 0.09 3208 47 71 -7 0.00
Tue 02/10 13Z 0.10 3007 48 76 -7 0.00
Tue 02/10 14Z 0.11 2806 49 77 -7 0.00
Tue 02/10 15Z 0.10 2504 49 76 -7 0.00
Tue 02/10 16Z 0.13 2306 51 78 -7 0.00
Tue 02/10 17Z 0.12 2106 54 76 -6 0.00
Tue 02/10 18Z 0.12 2008 56 69 -6 0.00
Tue 02/10 19Z 0.04 1710 54 65 -6 0.00
Tue 02/10 20Z 0.07 1812 56 92 -6 0.00
Tue 02/10 21Z 0.12 1813 58 92 -7 0.00
Tue 02/10 22Z 0.04 1713 88 93 -9 0.00
Tue 02/10 23Z 0.05 1620 92 95 -8 0.01
Run total areal avg QPF for the Central_Greens is: 0.01 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