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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 continue for portions of the central U.S., with impactful flash flooding possible from southern Kansas to southwestern Missouri. Extremely Critical fire weather conditions will develop across the Great Basin and Southwest on Friday, with dry and windy conditions through the weekend. Dangerous heat will increase across the southern and central U.S. this weekend. Read More >

Subject: NAM3 EXPERIMENTAL Froude Number for the Central_Greens

Model run: BTV_GRID_D2D_NAM3_20260626_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)
=== ===== === ==== ==== === === === ====
Fri 06/26 00Z 0.55 2312  77  95  10 0.00
Fri 06/26 01Z 0.36 2111  72  97  10 0.01
Fri 06/26 02Z 0.29 1913  70  98  10 0.01
Fri 06/26 03Z 0.17 1714  83  98  10 0.02
Fri 06/26 04Z 0.10 1617  91  99  10 0.03
Fri 06/26 05Z 0.07 1621  96  97  10 0.07
Fri 06/26 06Z 0.11 1724  96  96  10 0.14
Fri 06/26 07Z 0.13 1726  94  96  10 0.10
Fri 06/26 08Z 0.10 1724  88  92  10 0.01
Fri 06/26 09Z 0.17 1824  90  90  10 0.00
Fri 06/26 10Z 0.16 1821  93  87  10 0.00
Fri 06/26 11Z 0.26 2017  94  83  10 0.01
Fri 06/26 12Z 0.30 2017  95  64  10 0.00
Fri 06/26 13Z 0.31 2016  94  66  10 0.01
Fri 06/26 14Z 0.33 2114  96  61  10 0.01
Fri 06/26 15Z 0.36 2213  97  67  11 0.00
Fri 06/26 16Z 0.41 2213  99  58  11 0.01
Fri 06/26 17Z 0.49 2313  97  47  11 0.00
Fri 06/26 18Z 0.57 2311  94  42  11 0.00
Fri 06/26 19Z 0.74 2211  92  54  11 0.00
Fri 06/26 20Z 1.29 2211  94  78  12 0.15
Fri 06/26 21Z 0.98 2614  93  79  12 0.28
Fri 06/26 22Z 0.49 3018  90  84  11 0.17
Fri 06/26 23Z 0.26 3216  85  64  11 0.04
Sat 06/27 00Z 0.32 3112  87  63  11 0.00
Sat 06/27 01Z 0.38 2913  92  48  11 0.00
Sat 06/27 02Z 0.36 2912  93  43  11 0.00
Sat 06/27 03Z 0.34 2913  94  44  11 0.01
Sat 06/27 04Z 0.28 3011  94  38  11 0.01
Sat 06/27 05Z 0.27 3012  94  38  10 0.01
Sat 06/27 06Z 0.20 3111  93  44  10 0.01
Sat 06/27 07Z 0.14 3211  91  54  10 0.01
Sat 06/27 08Z 0.11 3210  88  56  10 0.00
Sat 06/27 09Z 0.11 3209  84  58  10 0.00
Sat 06/27 10Z 0.10 3209  81  54  11 0.00
Sat 06/27 11Z 0.08 3310  80  48  11 0.00
Sat 06/27 12Z 0.06 3310  81  45  11 0.00
Sat 06/27 13Z 0.07 3310  83  45  10 0.00
Sat 06/27 14Z 0.08 3309  86  43  10 0.00
Sat 06/27 15Z 0.08 3307  89  43  10 0.00
Sat 06/27 16Z 0.13 3305  89  41  10 0.00
Sat 06/27 17Z 0.26 3203  89  40  11 0.00
Sat 06/27 18Z 0.28 3103  87  45  11 0.02
Sat 06/27 19Z 0.35 3103  85  47  11 0.02
Sat 06/27 20Z 0.36 3103  84  45  11 0.01
Sat 06/27 21Z 0.11 3302  83  44  12 0.01
Sat 06/27 22Z 0.06 3201  85  51  12 0.01
Sat 06/27 23Z 0.07 3202  85  61  12 0.01
Sun 06/28 00Z 0.03 3402  84  62  12 0.02
Sun 06/28 01Z 0.03 3502  83  64  12 0.01
Sun 06/28 02Z 0.02 3402  82  65  12 0.00
Sun 06/28 03Z 0.02 3402  80  64  12 0.00
Sun 06/28 04Z 0.04 0002  80  62  11 0.00
Sun 06/28 05Z 0.02 3502  81  58  11 0.00
Sun 06/28 06Z 0.02 0002  81  55  11 0.00
Sun 06/28 07Z 0.02 3402  81  53  11 0.00
Sun 06/28 08Z 0.03 3303  80  49  11 0.00
Sun 06/28 09Z 0.03 3404  79  45  11 0.00
Sun 06/28 10Z 0.02 3505  79  39  11 0.00
Sun 06/28 11Z 0.02 3506  78  40  11 0.00

Run total areal avg QPF for the Central_Greens is: 1.23 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