GFS EXPERIMENTAL Froude Number for the Green Mountains

Winter Weather Advisory in Effect for Portions of Northern New York and Vermont Tonight Into Monday Morning

A Winter Weather Advisory is in effect from 8 PM this evening through 8 AM Monday for the northern Adirondack region of NY and the spine of the Green Mountains eastward in Vermont. Widespread 3-6 inches of snowfall is expected with the heaviest snow likely to fall between 1 AM and 10 AM Sunday. Elsewhere, snowfall amounts will range from 2-4 inches with rain mixing with snow Sunday afternoom. Read More >

Subject: GFS EXPERIMENTAL Froude Number for the greens Model run: BTV_GRID_D2D_GFS_20260321_0000 Using the MB925 to MB850 layer. Assumes greens are orthogonal to 270 degree winds. 925-850 mb Layer Average Wind/RH. Avg QPF over the greens. Date Time Wind RH% 700 850T QPF Day mm/dd hhZ Frd# DDFF (%) RH% (C) (in) === ===== === ==== ==== === === === ==== Sat 03/21 00Z 0.37 2416 99 69 0 0.00 Sat 03/21 03Z 0.33 2612 100 15 -1 0.01 Sat 03/21 06Z 0.17 3008 99 24 -2 0.01 Sat 03/21 09Z 0.16 3211 97 63 -5 0.00 Sat 03/21 12Z 0.20 3314 89 76 -7 0.00 Sat 03/21 15Z 0.31 3214 92 32 -9 0.00 Sat 03/21 18Z 0.51 3213 89 11 -9 0.00 Sat 03/21 21Z 0.21 3311 83 29 -8 0.00 Sun 03/22 00Z 0.05 3405 70 83 -7 0.00 Sun 03/22 03Z 0.04 2002 80 96 -6 0.02 Sun 03/22 06Z 0.08 1608 88 96 -6 0.03 Sun 03/22 09Z 0.08 1716 96 97 -5 0.11 Sun 03/22 12Z 0.12 1618 96 97 -4 0.14 Sun 03/22 15Z 0.12 1618 97 97 -3 0.11 Sun 03/22 18Z 0.12 1912 98 99 -1 0.09 Sun 03/22 21Z 0.14 2505 99 93 -1 0.07 Mon 03/23 00Z 0.04 3408 99 71 -3 0.02 Mon 03/23 03Z 0.10 0208 99 52 -6 0.01 Mon 03/23 06Z 0.11 0306 97 35 -7 0.01 Mon 03/23 09Z 0.10 0207 98 27 -8 0.01 Mon 03/23 12Z 0.07 0107 97 29 -8 0.01 Mon 03/23 15Z 0.03 0006 98 32 -9 0.01 Mon 03/23 18Z 0.15 3308 97 33 -9 0.02 Mon 03/23 21Z 0.23 3312 92 40 -9 0.02 Run total areal avg QPF for the greens is: 0.70 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