National Weather Service United States Department of Commerce

Heat Advisory in Effect for the Champlain Valley Friday

Heat and humidity will build over the next few days, with the hottest conditions expected Friday. A Heat Advisory has been issued for Friday for the Champlain Valley from 12-8 PM, when heat indices will climb into the low to mid 90s. Drink plenty of fluids, and take extra precautions if you have outdoor plans for Friday. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260610_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 06/10 12Z 0.38 2312  82  84  15 0.00
Wed 06/10 13Z 0.41 2313  80  76  16 0.00
Wed 06/10 14Z 0.41 2212  78  75  16 0.00
Wed 06/10 15Z 0.46 2110  78  86  16 0.00
Wed 06/10 16Z 0.95 2008  79  88  16 0.00
Wed 06/10 17Z 1.76 2009  80  84  16 0.00
Wed 06/10 18Z 1.81 2010  81  84  16 0.00
Wed 06/10 19Z 1.87 1909  80  81  17 0.00
Wed 06/10 20Z 1.85 1910  80  83  17 0.00
Wed 06/10 21Z 1.18 1910  82  87  17 0.00
Wed 06/10 22Z 0.87 2012  84  85  17 0.01
Wed 06/10 23Z 0.63 2216  93  87  17 0.05
Thu 06/11 00Z 0.57 2223  90  77  16 0.19
Thu 06/11 01Z 0.59 2223  96  86  16 0.02
Thu 06/11 02Z 0.57 2320  95  85  15 0.09
Thu 06/11 03Z 0.43 2415  90  79  16 0.02
Thu 06/11 04Z 0.48 2416  92  88  15 0.00
Thu 06/11 05Z 0.54 2417  95  90  15 0.01
Thu 06/11 06Z 0.54 2617  97  83  15 0.03
Thu 06/11 07Z 0.49 2616  96  69  15 0.01
Thu 06/11 08Z 0.50 2716  96  79  15 0.02
Thu 06/11 09Z 0.46 2715  95  60  15 0.02
Thu 06/11 10Z 0.50 2717  94  49  15 0.01
Thu 06/11 11Z 0.49 2716  95  49  15 0.01
Thu 06/11 12Z 0.53 2717  96  65  15 0.01
Thu 06/11 13Z 0.58 2718  96  74  15 0.01
Thu 06/11 14Z 0.49 2917  94  62  15 0.00
Thu 06/11 15Z 0.26 3114  90  52  16 0.00
Thu 06/11 16Z 0.28 3012  89  30  16 0.00
Thu 06/11 17Z 0.39 2911  90  46  16 0.00
Thu 06/11 18Z 0.36 2810  90  56  17 0.00
Thu 06/11 19Z 0.45 2712  89  58  17 0.00
Thu 06/11 20Z 0.42 2712  89  58  18 0.00
Thu 06/11 21Z 0.47 2712  91  56  17 0.00
Thu 06/11 22Z 0.44 2710  93  70  17 0.00
Thu 06/11 23Z 0.52 2712  94  86  17 0.00
Fri 06/12 00Z 0.58 2714  93  82  17 0.01
Fri 06/12 01Z 0.59 2715  94  78  16 0.08
Fri 06/12 02Z 0.44 2713  92  78  16 0.16
Fri 06/12 03Z 0.29 2810  96  71  16 0.02
Fri 06/12 04Z 0.18 3009  97  68  16 0.01
Fri 06/12 05Z 0.10 3206  98  67  16 0.01
Fri 06/12 06Z 0.09 3206  98  70  15 0.01
Fri 06/12 07Z 0.06 3205  98  69  15 0.01
Fri 06/12 08Z 0.13 3006  98  73  15 0.01
Fri 06/12 09Z 0.30 2811  98  85  15 0.03
Fri 06/12 10Z 0.33 2912  98  84  15 0.03
Fri 06/12 11Z 0.23 2909  92  76  15 0.01
Fri 06/12 12Z 0.13 2906  88  71  16 0.00
Fri 06/12 13Z 0.07 2902  85  62  16 0.00
Fri 06/12 14Z 0.10 2603  85  57  16 0.00
Fri 06/12 15Z 0.13 2503  83  49  17 0.00
Fri 06/12 16Z 0.13 2503  77  49  17 0.00
Fri 06/12 17Z 0.31 2504  76  49  17 0.00
Fri 06/12 18Z 0.64 2505  67  39  18 0.00
Fri 06/12 19Z 0.68 2506  56  22  19 0.00
Fri 06/12 20Z 1.19 2509  64  43  18 0.00
Fri 06/12 21Z 0.37 2408  77  49  18 0.00
Fri 06/12 22Z 0.38 2409  82  48  18 0.00
Fri 06/12 23Z 0.37 2509  84  47  18 0.00

Run total areal avg QPF for the Central_Greens is: 0.90 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