Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 031526
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
926 AM MDT Mon Aug 3 2020

.UPDATE...
Current forecast looks in pretty good shape. Only change was to
speed up the convective start time for the eastern parts of south
central Montana this afternoon. The latest 12z model runs and
regional mosaics were showing activity a little more active to the
west than previous runs. Otherwise the chance of severe looks
good toady with the storms that roll in, with the main threat
being wind. TWH

&&

.DISCUSSION...
Today through Tuesday...

Dry conditions and ridging over the area this morning will give
way to increasing chances for showers and thunderstorms this
afternoon and evening, as a shortwave trough and associated
Pacific cold front approach and move through the region. Shower
and thunderstorm activity will first start over the west this
afternoon, eventually shifting east overnight, with showers and
thunderstorms lingering perhaps along the Dakotas border and the
higher terrain on Tuesday. Otherwise, Tuesday will be cooler
behind the front with northwest winds.

With easterly low level winds over the area out ahead of the
approaching trough, PWATs will be around an inch today. Ample
moisture, along with good instability and shear, and forcing from
the approaching trough will combine to produce a risk of strong to
severe storms over western and central areas (including Billings)
later this afternoon and evening. Main threat will be strong
winds, with large hail to a lesser extent. Highs will range from
the 90s most places today, cooling into the 80s for Tuesday. STP


Tuesday night through Sunday...

A drier and more stable air mass associated with a building upper
level ridge will bring us quiet weather Tuesday night through
Wednesday night. Cannot rule out a few weak diurnal thunderstorms
over the mountains on Wednesday, otherwise this should be a dry
period.

We will see some monsoonal and high plains moisture return on
Thursday as a weak trof moves through the great basin and induces
gradual height falls. This wave should bring our next real
opportunity for thunderstorms Thursday afternoon and evening.
Thursday will be hot (90s) and low level lapse rates steep, so
there is a risk of strong wind gusts w/ Thursday`s convection.
Something to think about with regard to fire weather moving
forward.

Models diverge in details Friday and beyond, but the overall theme
is a shift to zonal flow and lower precipitable waters than we
have seen lately. This should yield mostly dry days, near to
slightly above normal temps, and afternoon humidity getting to the
teens many places. EC hints at keeping some higher moisture in our
far east, and some thunderstorm activity cannot be ruled out there
and over the mountains. GFS shows a deeper trof moving into the
northern Rockies Sunday, but this is a real outlier compared to
the majority of ensembles (as well as the other operational
models).

JKL
&&

.AVIATION...

In general, VFR conditions are expected to prevail with showers
and thunderstorms spreading over the area from west to east this
afternoon and evening as a front moves through. The stronger
thunderstorms will be capable of MVFR conditions along with wind
gusts in excess of 50 kts and large hail. Mountains will be
obscured at times later today and tonight. Easterly surface winds
today will shift to the northwest overnight, continuing into
Tuesday. LLWS over southeast Montana will decrease this morning. STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 095 062/087 059/090 062/095 063/089 058/090 059/089
    3/T 51/U    01/U    12/T    21/U    11/U    11/B
LVM 093 053/086 050/090 054/093 054/087 049/089 051/087
    4/T 41/U    01/U    13/T    22/T    11/U    11/U
HDN 097 062/087 057/090 059/097 061/091 056/092 058/090
    4/T 41/U    10/U    12/T    21/U    11/U    10/U
MLS 091 063/087 058/086 060/094 065/091 059/090 060/088
    0/B 42/T    10/U    01/U    21/U    11/U    10/U
4BQ 090 062/086 058/087 060/095 064/092 059/092 061/090
    0/B 43/T    11/U    02/T    21/U    11/U    11/U
BHK 085 058/085 055/085 055/091 061/092 056/089 057/088
    0/N 33/T    10/U    01/U    22/T    22/T    21/U
SHR 095 058/086 055/090 056/096 059/092 055/092 057/090
    4/T 53/T    22/T    12/T    22/T    21/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings


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