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734
FXUS65 KBYZ 291535
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
935 AM MDT Thu Sep 29 2016

.UPDATE...
No significant changes to the forecast this morning. BT

&&

.SHORT TERM...valid for Tdy and Fri...

Mid level flow has backed to the southwest with an amplified
ridge shifting into the central plains. This will allow monsoon
like moisture to work into the forecast area from Utah today.
Precipitable water values have risen to around .75 inches at Salt
Lake City, which are 2-3 standard deviations above normal. This
mid level moisture will work into southern Montana today and
combine with disorganized energy streaming up from the southwest
to generate a few showers and isolated thunderstorms. Most of the
activity will be confined to the west today due to the lack of
shear, but enough mid level instability to sustain a few showers
onto the plains into the evening hours.

The disorganized area of energy will continue to stream across
southern Montana and northern Wyoming on Friday. The deeper
moisture, with precipitable water values over .75 inches, shifts
into eastern Montana. Have added low pops over parts of the
southeast as vorticity slow to clear the state. High temperatures
today should be warmer than yesterday, but increasing clouds could
play a role in keeping readings a touch cooler than forecast.
Similar temperatures expected Friday. TWH

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


A shortwave moving through southwest flow aloft will bring shower
and thunderstorm chances to the area on Saturday with high
temperatures in the 70s and lower 80s. Models continue to prog an
upper trough and associated low to move onto the west coast on
Sunday. As the trough and associated low move inland, moisture and
energy will be advected over the region bringing increasing shower
and thunderstorm chances through early next week. Models have come
into much better agreement with the overall track of the upper
trough and low. As the trough moves into the interior west, models
prog the associated low to lift north and east through Wyoming on
Tuesday, eventually moving through far southeast Montana and into
the Dakotas by Wednesday. Models show the area drying out
Wednesday into Thursday as the aforementioned system moves off to
the northeast, and high pressure begins to build into the west.

Although the GFS and ECMWF have come into better agreement with
the overall track of the system, there is still quite a bit of
uncertainty in the details. GEFS plumes show a large spread in
precipitation amounts. In any case, it looks like cooler and
unsettled weather will impact the Northern Rockies late this
coming weekend into early next week. High temperatures will drop
from the 70s and 80s on Saturday to the middle to lower 50s by
early next week. STP

&&

.AVIATION...


Mainly VFR conditions can be expected across the area today. A
weak disturbance moving in from the southwest will bring
increasing middle to high level clouds through the day with
possible showers and thunderstorms, mainly over the southwest
mountains. RMS/BT

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 081 057/082 054/080 052/066 049/058 044/053 040/054
    0/B 21/B    11/U    33/T    45/T    55/W    42/W
LVM 080 052/080 047/076 043/064 042/056 042/052 036/054
    2/T 22/T    23/T    33/T    45/T    55/W    32/W
HDN 081 053/082 051/082 051/068 050/061 044/052 040/054
    0/B 21/B    11/U    33/T    45/T    55/W    42/W
MLS 083 055/082 054/081 055/069 052/066 047/053 040/055
    0/U 21/B    10/U    33/T    55/T    55/W    53/W
4BQ 083 056/081 053/082 053/069 051/069 047/053 039/055
    0/U 22/T    10/U    22/T    45/T    55/W    44/W
BHK 077 052/078 048/077 051/069 049/067 047/056 040/052
    0/N 32/T    10/U    23/T    55/T    55/W    54/W
SHR 082 050/081 049/080 049/068 048/063 043/048 038/051
    1/B 21/B    10/U    22/T    35/T    55/W    42/W

&&

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

&&

$$
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