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Severe Weather and Flooding Threats for the Central U.S.; Fire Weather Concerns for the Western U.S.

Severe weather and flooding threats will continue for portions of the central U.S. through Thursday, focused from the central High Plains to the Mid-Mississippi Valley. Hot and dry conditions will fuel fire weather concerns for the Intermountain West, and dry thunderstorms may spark additional wildfires. Dangerous heat will build across the southern U.S. Friday into the weekend. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260625_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)
=== ===== === ==== ==== === === === ====
Thu 06/25 00Z 0.67 3015  78  57  10 0.00
Thu 06/25 01Z 0.99 2918  77  49  10 0.00
Thu 06/25 02Z 1.05 2920  78  41  10 0.00
Thu 06/25 03Z 0.99 2920  77  46  10 0.00
Thu 06/25 04Z 0.72 2920  79  52  10 0.00
Thu 06/25 05Z 0.61 2919  76  60  10 0.00
Thu 06/25 06Z 0.54 3018  73  62  10 0.00
Thu 06/25 07Z 0.54 3017  69  58  10 0.00
Thu 06/25 08Z 0.52 2915  65  39  10 0.00
Thu 06/25 09Z 0.46 2913  64  29  10 0.00
Thu 06/25 10Z 0.45 3012  62  30  10 0.00
Thu 06/25 11Z 0.39 3011  62  39  10 0.00
Thu 06/25 12Z 0.31 3008  63  47  10 0.00
Thu 06/25 13Z 0.27 3006  62  46  10 0.00
Thu 06/25 14Z 0.34 2804  63  46  10 0.00
Thu 06/25 15Z 0.87 2504  64  49  10 0.00
Thu 06/25 16Z 1.61 2405  64  46  10 0.00
Thu 06/25 17Z 3.00 2305  64  44  11 0.00
Thu 06/25 18Z 3.86 2306  65  47  11 0.00
Thu 06/25 19Z 4.58 2207  65  52  11 0.00
Thu 06/25 20Z 4.01 2208  66  53  11 0.00
Thu 06/25 21Z 2.77 2108  65  53  11 0.00
Thu 06/25 22Z 2.03 2108  63  57  11 0.00
Thu 06/25 23Z 0.82 2109  63  57  11 0.00
Fri 06/26 00Z 0.51 2010  61  70  11 0.00
Fri 06/26 01Z 0.55 2012  63  86  11 0.00
Fri 06/26 02Z 0.54 2014  68  94  11 0.00
Fri 06/26 03Z 0.39 1914  68  92  11 0.00
Fri 06/26 04Z 0.38 1914  75  88  11 0.00
Fri 06/26 05Z 0.43 1917  79  82  11 0.01
Fri 06/26 06Z 0.45 1920  84  87  10 0.01
Fri 06/26 07Z 0.41 1920  89  93  10 0.03
Fri 06/26 08Z 0.28 1919  91  93  11 0.10
Fri 06/26 09Z 0.21 1919  93  94  11 0.01
Fri 06/26 10Z 0.27 1923  95  95  11 0.09
Fri 06/26 11Z 0.35 2023  93  94  10 0.15
Fri 06/26 12Z 0.30 1920  92  90  10 0.01
Fri 06/26 13Z 0.32 2017  99  84  10 0.02
Fri 06/26 14Z 0.36 2214 100  72  10 0.04
Fri 06/26 15Z 0.33 2310  98  65  10 0.01
Fri 06/26 16Z 0.31 2408  97  41  10 0.00
Fri 06/26 17Z 0.37 2508  97  42  10 0.00
Fri 06/26 18Z 0.44 2608  95  54  10 0.00
Fri 06/26 19Z 0.45 2606  93  49  11 0.00
Fri 06/26 20Z 0.54 2606  92  48  11 0.00
Fri 06/26 21Z 0.42 2504  92  64  11 0.01
Fri 06/26 22Z 0.29 2505  92  88  12 0.10
Fri 06/26 23Z 0.29 2706  91  60  12 0.09
Sat 06/27 00Z 0.33 2808  93  65  12 0.03
Sat 06/27 01Z 0.28 2908  90  65  12 0.01
Sat 06/27 02Z 0.26 2908  89  69  11 0.00
Sat 06/27 03Z 0.24 2907  92  53  11 0.00
Sat 06/27 04Z 0.26 2808  94  43  11 0.00
Sat 06/27 05Z 0.28 2808  96  40  11 0.01
Sat 06/27 06Z 0.21 2706  94  37  11 0.01
Sat 06/27 07Z 0.19 2606  92  38  10 0.00
Sat 06/27 08Z 0.11 2703  92  37  10 0.00
Sat 06/27 09Z 0.10 2803  93  37  10 0.00
Sat 06/27 10Z 0.04 3001  91  35  10 0.00
Sat 06/27 11Z 0.03 0001  91  36  10 0.00

Run total areal avg QPF for the Central_Greens is: 0.74 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