GFS EXPERIMENTAL Froude Number for the Green Mountains

Winter Storm Warning and Winter Weather Advisory for Most of Northern New York

A Winter Storm Warning and Winter Weather Advisory is in effect from until 7 PM Thursday for most of northern New York. Total snow accumulations between 3 and 8 inches are expected. Precipitation will initially start as rain before changing over to snow with sharply falling temperatures. Travel could be very difficult, including the Thursday commutes. Read More >

Subject: GFS EXPERIMENTAL Froude Number for the greens Model run: BTV_GRID_D2D_GFS_20260115_0600 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) === ===== === ==== ==== === === === ==== Thu 01/15 06Z 0.18 1410 99 96 -2 0.00 Thu 01/15 09Z 0.09 1610 99 96 -1 0.08 Thu 01/15 12Z 0.07 1611 99 92 -1 0.08 Thu 01/15 15Z 0.16 2011 99 82 -2 0.04 Thu 01/15 18Z 0.23 2112 99 62 -4 0.02 Thu 01/15 21Z 0.56 2318 92 55 -7 0.04 Fri 01/16 00Z 0.80 2618 89 44 -13 0.02 Fri 01/16 03Z 0.88 2617 91 48 -15 0.01 Fri 01/16 06Z 1.07 2715 95 61 -18 0.00 Fri 01/16 09Z 0.67 2818 96 91 -18 0.01 Fri 01/16 12Z 0.59 2820 96 73 -18 0.01 Fri 01/16 15Z 0.45 2819 78 11 -16 0.01 Fri 01/16 18Z 0.43 2817 52 19 -14 0.00 Fri 01/16 21Z 0.35 2713 54 25 -13 0.00 Sat 01/17 00Z 0.24 2312 47 80 -11 0.00 Sat 01/17 03Z 0.31 2119 81 94 -11 0.00 Sat 01/17 06Z 0.41 2222 83 87 -10 0.01 Sat 01/17 09Z 0.33 2119 72 52 -9 0.00 Sat 01/17 12Z 0.24 2019 80 89 -8 0.00 Sat 01/17 15Z 0.24 2118 92 95 -7 0.00 Sat 01/17 18Z 0.25 2114 96 95 -7 0.00 Sat 01/17 21Z 0.34 2312 95 97 -7 0.02 Sun 01/18 00Z 0.60 2518 95 91 -7 0.01 Sun 01/18 03Z 0.77 2519 91 69 -8 0.00 Run total areal avg QPF for the greens is: 0.36 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