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_0600
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 06Z 0.32 2710  72   1  16 0.00
Wed 06/10 07Z 0.36 2710  75   7  15 0.00
Wed 06/10 08Z 0.34 2709  79  28  15 0.01
Wed 06/10 09Z 0.27 2707  80  56  15 0.00
Wed 06/10 10Z 0.21 2505  81  74  15 0.00
Wed 06/10 11Z 0.26 2208  82  82  15 0.00
Wed 06/10 12Z 0.27 2209  85  84  15 0.00
Wed 06/10 13Z 0.28 2210  89  83  15 0.00
Wed 06/10 14Z 0.30 2111  91  81  15 0.00
Wed 06/10 15Z 0.35 2111  92  88  15 0.00
Wed 06/10 16Z 0.36 2011  91  83  16 0.00
Wed 06/10 17Z 0.35 1911  91  87  16 0.00
Wed 06/10 18Z 0.69 2012  91  91  16 0.01
Wed 06/10 19Z 0.89 2116  90  93  16 0.02
Wed 06/10 20Z 0.51 2118  90  93  16 0.01
Wed 06/10 21Z 0.64 2119  89  86  16 0.00
Wed 06/10 22Z 0.69 2116  89  87  16 0.00
Wed 06/10 23Z 0.59 2115  91  88  16 0.00
Thu 06/11 00Z 0.44 2115  94  88  16 0.07
Thu 06/11 01Z 0.49 2118  98  91  16 0.10
Thu 06/11 02Z 0.55 2219  96  85  16 0.17
Thu 06/11 03Z 0.61 2321  97  89  16 0.11
Thu 06/11 04Z 0.51 2417  95  76  16 0.12
Thu 06/11 05Z 0.56 2418  95  81  16 0.03
Thu 06/11 06Z 0.57 2618  96  79  16 0.03
Thu 06/11 07Z 0.63 2620  97  79  16 0.02
Thu 06/11 08Z 0.57 2719  95  71  16 0.01
Thu 06/11 09Z 0.55 2719  95  63  16 0.01
Thu 06/11 10Z 0.54 2719  94  74  16 0.01
Thu 06/11 11Z 0.53 2819  95  70  15 0.01
Thu 06/11 12Z 0.46 2816  94  71  16 0.00
Thu 06/11 13Z 0.48 2816  94  69  16 0.00
Thu 06/11 14Z 0.39 2814  90  40  17 0.00
Thu 06/11 15Z 0.25 2910  83  19  17 0.00
Thu 06/11 16Z 0.30 2909  84  50  17 0.00
Thu 06/11 17Z 0.53 2710  87  62  17 0.00
Thu 06/11 18Z 0.56 2711  91  57  17 0.00
Thu 06/11 19Z 0.58 2613  96  70  17 0.03
Thu 06/11 20Z 0.55 2714  94  66  17 0.02
Thu 06/11 21Z 0.59 2615  95  70  18 0.01
Thu 06/11 22Z 0.55 2816  86  68  18 0.00
Thu 06/11 23Z 0.60 2815  91  73  17 0.00
Fri 06/12 00Z 0.59 2915  92  68  17 0.00
Fri 06/12 01Z 0.50 2814  95  68  16 0.06
Fri 06/12 02Z 0.41 2914  96  51  16 0.12
Fri 06/12 03Z 0.32 2913  93  42  16 0.01
Fri 06/12 04Z 0.29 2913  89  43  17 0.00
Fri 06/12 05Z 0.24 3012  90  52  17 0.00
Fri 06/12 06Z 0.25 3012  89  61  16 0.00
Fri 06/12 07Z 0.33 2914  92  61  16 0.00
Fri 06/12 08Z 0.38 2916  96  64  15 0.01
Fri 06/12 09Z 0.38 3017  96  64  15 0.01
Fri 06/12 10Z 0.33 3014  94  71  15 0.01
Fri 06/12 11Z 0.30 3013  88  79  16 0.00
Fri 06/12 12Z 0.26 3011  87  74  16 0.00
Fri 06/12 13Z 0.24 2909  83  56  16 0.00
Fri 06/12 14Z 0.12 2905  71  38  18 0.00
Fri 06/12 15Z 0.14 2805  67  24  18 0.00
Fri 06/12 16Z 0.27 2707  69  27  18 0.00
Fri 06/12 17Z 0.27 2808  64  33  18 0.00

Run total areal avg QPF for the Central_Greens is: 1.02 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