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Dangerous Heat Builds and Expands; Critical Fire Weather for the Southwest; Severe Thunderstorms for Plains and Midwest

Dangerous to record breaking heat will build across the center of the nation and slowly build eastward this week. Wildfire conditions remain critical for the Southwest and portions of the Great Basin through Monday. For the northern Plains and upper Midwest, severe thunderstorms with the potential for large to very large hail and severe winds are the primary hazards. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260628_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)
=== ===== === ==== ==== === === === ====
Sun 06/28 06Z 0.04 3001  76  72  12 0.00
Sun 06/28 07Z 0.04 3203  75  69  12 0.00
Sun 06/28 08Z 0.05 3303  74  64  12 0.00
Sun 06/28 09Z 0.04 3404  73  58  12 0.00
Sun 06/28 10Z 0.04 3405  72  53  12 0.00
Sun 06/28 11Z 0.04 3506  71  49  13 0.00
Sun 06/28 12Z 0.06 0007  68  45  13 0.00
Sun 06/28 13Z 0.08 0008  68  45  13 0.00
Sun 06/28 14Z 0.14 0007  71  52  12 0.00
Sun 06/28 15Z 0.34 0006  74  57  12 0.00
Sun 06/28 16Z 0.82 0105  74  56  12 0.00
Sun 06/28 17Z 0.77 0005  71  49  12 0.03
Sun 06/28 18Z 0.55 0006  70  40  13 0.01
Sun 06/28 19Z 0.39 3505  68  29  13 0.01
Sun 06/28 20Z 0.26 3505  70  29  13 0.00
Sun 06/28 21Z 0.35 3305  71  35  13 0.00
Sun 06/28 22Z 0.22 3306  71  37  13 0.00
Sun 06/28 23Z 0.11 3307  67  39  13 0.00
Mon 06/29 00Z 0.05 3409  61  40  13 0.00
Mon 06/29 01Z 0.09 3511  58  45  13 0.00
Mon 06/29 02Z 0.20 0012  53  46  13 0.00
Mon 06/29 03Z 0.24 0112  51  43  13 0.00
Mon 06/29 04Z 0.20 0111  52  44  13 0.00
Mon 06/29 05Z 0.17 0109  58  45  13 0.00
Mon 06/29 06Z 0.12 0008  64  42  12 0.00
Mon 06/29 07Z 0.09 3508  68  37  12 0.00
Mon 06/29 08Z 0.07 3509  72  26  12 0.00
Mon 06/29 09Z 0.06 3409  73  14  12 0.00
Mon 06/29 10Z 0.06 3410  71   9  12 0.00
Mon 06/29 11Z 0.03 3510  69   5  12 0.00
Mon 06/29 12Z 0.08 3509  66   5  12 0.00
Mon 06/29 13Z 0.06 3508  67   6  12 0.00
Mon 06/29 14Z 0.10 3507  69  10  12 0.00
Mon 06/29 15Z 0.26 3505  70  15  12 0.00
Mon 06/29 16Z 0.27 3404  71  18  12 0.00
Mon 06/29 17Z 0.51 3304  71  22  12 0.00
Mon 06/29 18Z 0.84 3104  69  25  12 0.00
Mon 06/29 19Z 0.70 3204  65  22  13 0.00
Mon 06/29 20Z 0.77 3105  60  20  13 0.00
Mon 06/29 21Z 0.49 3204  57  17  13 0.00
Mon 06/29 22Z 0.24 3103  54  14  14 0.00
Mon 06/29 23Z 0.12 3102  55  10  14 0.00
Tue 06/30 00Z 0.13 2902  57   7  14 0.00
Tue 06/30 01Z 0.21 2602  60   5  13 0.00
Tue 06/30 02Z 0.25 2503  62   4  13 0.00
Tue 06/30 03Z 0.34 2404  65   4  13 0.00
Tue 06/30 04Z 0.50 2406  67   7  13 0.00
Tue 06/30 05Z 0.60 2408  67   7  13 0.00
Tue 06/30 06Z 0.68 2510  70   7  13 0.00
Tue 06/30 07Z 0.71 2511  73  10  13 0.00
Tue 06/30 08Z 0.70 2512  74  14  13 0.00
Tue 06/30 09Z 0.81 2513  77  18  12 0.00
Tue 06/30 10Z 0.91 2514  74  22  12 0.00
Tue 06/30 11Z 0.91 2517  73  26  12 0.00
Tue 06/30 12Z 0.76 2516  77  26  13 0.00
Tue 06/30 13Z 0.79 2517  77  30  13 0.00
Tue 06/30 14Z 0.83 2617  82  34  13 0.00
Tue 06/30 15Z 0.77 2514  81  36  13 0.00
Tue 06/30 16Z 1.28 2510  82  37  13 0.00
Tue 06/30 17Z 1.45 2309  80  59  14 0.00

Run total areal avg QPF for the Central_Greens is: 0.05 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