Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 261502

Area Forecast Discussion...Updated
National Weather Service Billings MT
902 AM MDT FRI AUG 26 2016

No significant changes to the forecast package this morning.
Vorticity max moving through the bottom of the trough aloft is
providing some forcing for showers and thunder across the SE
section of our CWA. We did have some small hail reported near
Sonnette in Powder River County this morning. This is probably due
to the cool low level temps which were not warm enough to melt the
graupel before reaching the surface. Instability and cold pool at
500mb this afternoon may result in some more small hail or graupel
this afternoon with some of the stronger cells. BT


.SHORT TERM...valid for Tdy and Sat...

Water vapor imagery and upper air analysis shows troffing/cyclonic
flow over the northern Rockies with a strong upstream ridge over
the north Pacific and ridging over the eastern CONUS. A couple
shortwaves will impact our cwa today and bring us a greater chance
of showers/tstms than yesterday . Energy in central/eastern WY may
produce a few showers across our southeast early this morning.
Additional energy dropping out of Alberta in NW flow aloft will
aid in diurnal convection this afternoon and evening. Forecast
soundings suggest convective temps in the lower to mid 70s which
should be achievable, and afternoon CAPES on the order of a few
hundred j/kg. Wet bulb zero heights remain relatively low at
around 10kft msl, so could see some small hail with any stronger
cells, and mixed pcpn can be expected over the higher peaks.
Activity will end from west to east tonight as PV exits and flat
ridge builds in from the west. This ridge will bring dry/warmer
conditions with increased downslope winds on Saturday and RHs back
down to the teens. After high temps only in the lower to mid 70s
today, we will see 80s on Saturday. JKL

.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...

A return to summer conditions will prevail during the extended
period. Noted the GEFS/GFS were in decent agreement through Fri.,
while the ECMWF ensembles showed lower confidence in the pattern
beginning on Tuesday. The deterministic GFS/ECMWF were in better
agreement than they were last night.

Rising heights and zonal flow will give way to upper ridging over
the area by Monday. The upper ridge remains over the area through
Tue., then shifts east on Wed. allowing SW flow to move into the
area ahead of a Pacific trough. Above normal temperatures will
prevail, with 90s returning on Tuesday. Despite some waves moving
through the flow, the airmass looked too dry to support
precipitation through early Wednesday. However, the highest
elevations of the SW mountains may have a few thunderstorms Sun.
afternoon. Brought slight chances for thunderstorms into the western
and central zones Wed. afternoon under the more active SW flow.

SW flow continues for the rest of the period with model
differences in moisture and trough movement. Thus opted for climo
PoPs for Thursday through Friday. Checking CAPES and Bulk Shear
showed little potential for any severe weather at this time.
Temperatures will continue above normal for the remainder of the
period. Arthur



Isolated showers this morning will give way to scattered showers
this afternoon with a few thunderstorms. Localized MVFR conditions
are possible with the thunderstorms. There will be localized to
areas of mountain obscuration through the day. Isolated to
scattered showers and thunderstorms will gradually end from W to E
tonight. Again, localized MVFR conditions are possible in
thunderstorms. Mountain obscurations will decrease from W to E
tonight. Arthur



    Tdy Sat     Sun     Mon     Tue     Wed     Thu
BIL 074 051/086 058/088 056/087 058/092 059/090 058/086
    2/T 30/B    00/B    00/U    11/U    12/T    22/T
LVM 073 043/085 050/087 049/089 050/091 052/088 049/085
    2/T 20/N    01/U    01/U    11/U    12/T    22/T
HDN 076 047/087 055/090 054/090 056/093 058/093 057/089
    2/T 30/U    00/U    00/U    11/U    12/T    22/T
MLS 076 051/085 057/090 057/090 060/094 061/093 061/089
    3/T 30/U    00/B    00/U    11/U    11/B    22/T
4BQ 075 049/085 056/091 056/091 059/094 060/094 060/090
    5/T 30/U    00/U    00/U    11/U    11/U    12/T
BHK 074 048/082 054/089 055/087 057/091 058/089 058/087
    4/T 30/U    00/B    00/U    11/U    11/U    12/T
SHR 073 044/085 052/089 052/089 053/092 054/091 055/089
    2/T 30/U    00/U    00/U    11/U    12/T    22/T




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