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Dangerous Heat in the East; Critical Fire Weather in the Southwest

Dangerous, record-breaking heat will intensify across most of the central and eastern U.S this week. Heat indices will likely exceed 100 degrees. Heat is likely to continue across the eastern U.S. through the Independence Day holiday weekend. Critical fire weather conditions will continue today and likely Tuesday across portions of the Four Corners and northern High Plains. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260629_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)
=== ===== === ==== ==== === === === ====
Mon 06/29 06Z 0.08 0005  67  72  13 0.00
Mon 06/29 07Z 0.05 3404  67  66  13 0.00
Mon 06/29 08Z 0.10 3305  69  65  13 0.00
Mon 06/29 09Z 0.16 3206  73  64  13 0.00
Mon 06/29 10Z 0.15 3308  75  58  13 0.00
Mon 06/29 11Z 0.13 3309  74  47  13 0.00
Mon 06/29 12Z 0.09 3310  71  33  13 0.00
Mon 06/29 13Z 0.06 3410  70  21  13 0.00
Mon 06/29 14Z 0.07 3408  72  20  13 0.00
Mon 06/29 15Z 0.12 3406  74  20  13 0.00
Mon 06/29 16Z 0.36 3307  72  25  13 0.00
Mon 06/29 17Z 0.41 3308  71  37  13 0.01
Mon 06/29 18Z 0.29 3408  66  35  13 0.02
Mon 06/29 19Z 0.43 3307  63  25  14 0.01
Mon 06/29 20Z 0.39 3307  58  14  14 0.00
Mon 06/29 21Z 0.34 3307  55  13  14 0.00
Mon 06/29 22Z 0.12 3406  52  16  14 0.00
Mon 06/29 23Z 0.10 3307  52  26  14 0.00
Tue 06/30 00Z 0.13 3306  52  18  14 0.00
Tue 06/30 01Z 0.24 3205  54   7  14 0.00
Tue 06/30 02Z 0.25 3003  57  14  14 0.00
Tue 06/30 03Z 0.45 2504  60  14  14 0.00
Tue 06/30 04Z 0.48 2405  62  16  14 0.00
Tue 06/30 05Z 0.59 2307  63  12  14 0.00
Tue 06/30 06Z 0.77 2409  64  11  14 0.00
Tue 06/30 07Z 0.88 2511  65  12  14 0.00
Tue 06/30 08Z 0.85 2513  63  13  14 0.00
Tue 06/30 09Z 0.84 2613  65  16  13 0.00
Tue 06/30 10Z 0.88 2614  65  21  13 0.00
Tue 06/30 11Z 0.69 2613  67  36  14 0.00
Tue 06/30 12Z 0.65 2514  71  46  14 0.00
Tue 06/30 13Z 0.63 2513  74  42  14 0.00
Tue 06/30 14Z 0.65 2413  78  55  14 0.00
Tue 06/30 15Z 0.73 2312  81  59  14 0.00
Tue 06/30 16Z 2.03 2313  80  70  14 0.00
Tue 06/30 17Z 2.34 2211  78  69  15 0.00
Tue 06/30 18Z 0.84 2016  74  84  15 0.00
Tue 06/30 19Z 1.24 2119  78  72  16 0.00
Tue 06/30 20Z 2.80 2219  85  79  15 0.00
Tue 06/30 21Z 1.00 2219  82  81  16 0.00
Tue 06/30 22Z 0.83 2220  87  55  17 0.00
Tue 06/30 23Z 0.82 2323  93  43  17 0.00
Wed 07/01 00Z 0.91 2425  94  39  17 0.00
Wed 07/01 01Z 0.90 2426  97  36  17 0.01
Wed 07/01 02Z 0.88 2526  97  34  17 0.01
Wed 07/01 03Z 0.94 2529  98  48  18 0.05
Wed 07/01 04Z 0.81 2629  92  49  19 0.12
Wed 07/01 05Z 0.81 2630  92  30  19 0.03
Wed 07/01 06Z 0.82 2631  89  43  19 0.02
Wed 07/01 07Z 0.73 2729  89  40  20 0.02
Wed 07/01 08Z 0.72 2728  92  24  20 0.02
Wed 07/01 09Z 0.67 2727  91  15  20 0.01
Wed 07/01 10Z 0.57 2826  85  15  21 0.02
Wed 07/01 11Z 0.48 2823  77  19  21 0.02
Wed 07/01 12Z 0.37 2920  67  24  23 0.01
Wed 07/01 13Z 0.32 2917  63  31  23 0.01
Wed 07/01 14Z 0.30 2815  62  33  23 0.01
Wed 07/01 15Z 0.31 2815  61  35  23 0.00
Wed 07/01 16Z 0.30 2814  62  40  23 0.00
Wed 07/01 17Z 0.29 2712  65  38  23 0.00

Run total areal avg QPF for the Central_Greens is: 0.40 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