National Weather Service United States Department of Commerce

Winter Weather Advisory Issued for Most of Northern New York

A Winter Weather Advisory is in effect from 7 PM this evening to 7 PM Thursday for most of northern New York. Total snow accumulations between 3 and 7 inches are expected. Precipitation will initially start as rain before quickly changing over to snow with sharply falling temperatures. Travel could be very difficult. The hazardous conditions could impact Thursday commutes. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260114_0000
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 01/14 00Z 0.30 2025  67  54  -1 0.00
Wed 01/14 01Z 0.37 2028  63  92   0 0.00
Wed 01/14 02Z 0.51 2032  63  95  -1 0.00
Wed 01/14 03Z 0.75 2136  76  92  -3 0.00
Wed 01/14 04Z 0.57 2134  87  91  -1 0.03
Wed 01/14 05Z 0.68 2136  71  73  -1 0.00
Wed 01/14 07Z 0.81 2233  69  77  -1 0.00
Wed 01/14 08Z 0.80 2332  73  83  -1 0.00
Wed 01/14 09Z 0.78 2331  76  69  -1 0.00
Wed 01/14 10Z 0.73 2330  78  74  -1 0.00
Wed 01/14 11Z 0.68 2328  80  65   0 0.00
Wed 01/14 12Z 0.66 2328  78  64   0 0.00
Wed 01/14 13Z 0.66 2328  78  56   0 0.00
Wed 01/14 14Z 0.65 2327  78  49   0 0.00
Wed 01/14 16Z 0.61 2324  78  42   0 0.00
Wed 01/14 17Z 0.67 2324  79  60   0 0.00
Wed 01/14 18Z 0.69 2223  79  79   0 0.00
Wed 01/14 19Z 0.74 2222  80  77  -1 0.00
Wed 01/14 20Z 0.67 2221  80  84  -1 0.00
Wed 01/14 21Z 0.62 2220  83  89  -1 0.00
Wed 01/14 22Z 0.52 2118  87  93  -1 0.00
Wed 01/14 23Z 0.42 2117  92  96  -1 0.00
Thu 01/15 00Z 0.30 2015  96  94  -1 0.00
Thu 01/15 01Z 0.28 2017  97  94  -1 0.00
Thu 01/15 02Z 0.21 1918  98  94   0 0.01
Thu 01/15 03Z 0.14 1820  96  94   0 0.01
Thu 01/15 04Z 0.11 1821  91  93   0 0.03
Thu 01/15 05Z 0.09 1721  92  92   0 0.03
Thu 01/15 06Z 0.08 1719  96  95   0 0.03
Thu 01/15 07Z 0.05 1719  98  97  -1 0.01
Thu 01/15 08Z 0.07 1718  98  94  -1 0.01
Thu 01/15 09Z 0.16 1817  98  96  -1 0.02
Thu 01/15 10Z 0.21 1916  98  94  -1 0.04
Thu 01/15 11Z 0.22 1917  98  92  -1 0.04
Thu 01/15 12Z 0.18 1916  98  92  -1 0.03
Thu 01/15 13Z 0.28 1917  98  91  -2 0.04
Thu 01/15 14Z 0.37 2016  99  81  -2 0.03
Thu 01/15 15Z 0.50 2215  99  72  -3 0.01
Thu 01/15 16Z 0.53 2315  98  65  -4 0.01
Thu 01/15 17Z 0.48 2315  97  64  -4 0.02
Thu 01/15 18Z 0.41 2416  96  60  -5 0.02
Thu 01/15 19Z 0.40 2515  95  40  -7 0.02
Thu 01/15 20Z 0.51 2516  95  23  -9 0.02
Thu 01/15 21Z 0.85 2518  94  10 -11 0.01
Thu 01/15 22Z 1.05 2519  88  11 -13 0.01
Thu 01/15 23Z 2.45 2521  83  21 -14 0.01
Fri 01/16 00Z 3.47 2521  87  29 -16 0.01
Fri 01/16 01Z 4.29 2519  90  38 -16 0.00
Fri 01/16 02Z 2.47 2519  86  45 -17 0.00
Fri 01/16 03Z 2.33 2519  83  48 -17 0.00
Fri 01/16 04Z 1.63 2619  83  46 -18 0.00
Fri 01/16 05Z 2.54 2618  84  49 -19 0.00
Fri 01/16 06Z 4.36 2718  81  69 -20 0.00
Fri 01/16 07Z 4.09 2719  84  77 -20 0.00
Fri 01/16 08Z 5.20 2819  85  81 -21 0.01
Fri 01/16 09Z 5.30 2821  85  80 -21 0.01
Fri 01/16 10Z 3.63 2822  86  76 -21 0.00
Fri 01/16 11Z 2.60 2723  86  75 -21 0.00

Run total areal avg QPF for the Central_Greens is: 0.52 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