
Cold temperatures and gusty winds will occur Friday night and Saturday. Temperatures between -10 and -20 with sustained winds between 5 and 15 mph will cause wind chills between -20 and -40 for most areas Friday night and Saturday morning. Stronger gusts will cause it to feel colder at times. Winds decrease on Saturday and temperatures rise modestly, raising wind chills into the -10 to -20 range. Read More >
Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens
Model run: BTV_GRID_D2D_NAM3_20260121_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)
=== ===== === ==== ==== === === === ====
Wed 01/21 12Z 0.58 2624 73 2 -17 0.00
Wed 01/21 13Z 0.57 2524 68 2 -16 0.00
Wed 01/21 14Z 0.55 2524 67 24 -16 0.00
Wed 01/21 15Z 0.49 2421 65 56 -15 0.00
Wed 01/21 16Z 0.48 2421 61 70 -15 0.00
Wed 01/21 17Z 0.48 2321 55 82 -14 0.00
Wed 01/21 18Z 0.46 2222 49 87 -14 0.00
Wed 01/21 19Z 0.49 2123 49 87 -14 0.00
Wed 01/21 20Z 0.46 2124 62 88 -13 0.00
Wed 01/21 21Z 0.38 2027 66 88 -11 0.00
Wed 01/21 22Z 0.35 1931 86 89 -11 0.00
Wed 01/21 23Z 0.43 2036 89 90 -10 0.03
Thu 01/22 00Z 0.61 2040 88 93 -11 0.02
Thu 01/22 01Z 0.71 2141 87 87 -11 0.00
Thu 01/22 02Z 0.73 2142 92 91 -10 0.01
Thu 01/22 03Z 0.73 2140 96 89 -9 0.01
Thu 01/22 04Z 0.72 2137 96 92 -8 0.01
Thu 01/22 05Z 0.67 2134 96 91 -7 0.01
Thu 01/22 06Z 0.71 2234 97 88 -7 0.02
Thu 01/22 07Z 0.74 2233 96 93 -7 0.01
Thu 01/22 08Z 0.77 2332 96 70 -7 0.01
Thu 01/22 09Z 0.81 2332 96 50 -7 0.01
Thu 01/22 10Z 0.82 2331 95 59 -7 0.01
Thu 01/22 11Z 0.84 2331 95 75 -7 0.01
Thu 01/22 12Z 0.95 2333 94 81 -8 0.01
Thu 01/22 13Z 1.15 2434 95 86 -9 0.01
Thu 01/22 14Z 1.60 2434 91 76 -10 0.01
Thu 01/22 15Z 2.00 2532 93 49 -11 0.00
Thu 01/22 16Z 2.85 2528 92 49 -11 0.00
Thu 01/22 17Z 9.79 2525 87 46 -12 0.00
Thu 01/22 18Z 13.34 2523 83 41 -12 0.00
Thu 01/22 19Z 10.94 2423 83 45 -11 0.00
Thu 01/22 20Z 3.08 2424 88 37 -11 0.00
Thu 01/22 21Z 2.06 2427 92 53 -11 0.01
Thu 01/22 22Z 4.86 2531 81 53 -12 0.01
Thu 01/22 23Z 2.27 2631 84 41 -12 0.01
Fri 01/23 00Z 1.70 2630 81 38 -13 0.01
Fri 01/23 01Z 1.90 2631 84 37 -14 0.00
Fri 01/23 02Z 1.76 2631 82 41 -15 0.00
Fri 01/23 03Z 1.53 2532 84 45 -15 0.00
Fri 01/23 04Z 1.43 2631 86 43 -16 0.00
Fri 01/23 05Z 1.28 2629 84 39 -16 0.00
Fri 01/23 06Z 1.23 2629 88 40 -17 0.01
Fri 01/23 07Z 1.41 2628 83 39 -17 0.00
Fri 01/23 08Z 1.17 2626 82 38 -17 0.00
Fri 01/23 09Z 1.26 2525 90 40 -18 0.00
Fri 01/23 10Z 1.39 2526 92 47 -18 0.00
Fri 01/23 11Z 1.09 2526 87 52 -17 0.00
Fri 01/23 12Z 0.93 2428 78 41 -16 0.00
Fri 01/23 13Z 1.10 2333 89 31 -16 0.00
Fri 01/23 14Z 1.76 2436 93 23 -17 0.00
Fri 01/23 15Z 8.49 2534 92 19 -17 0.00
Fri 01/23 16Z 14.25 2530 88 19 -17 0.00
Fri 01/23 17Z 17.08 2627 69 17 -18 0.00
Fri 01/23 18Z 16.31 2625 70 23 -18 0.00
Fri 01/23 19Z 15.02 2624 74 30 -19 0.00
Fri 01/23 20Z 12.06 2623 75 39 -19 0.00
Fri 01/23 21Z 9.48 2723 75 49 -19 0.01
Fri 01/23 22Z 5.57 2723 77 58 -20 0.01
Fri 01/23 23Z 3.22 2825 79 60 -20 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