Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 242045

Area Forecast Discussion
National Weather Service Billings MT
245 PM MDT TUE MAY 24 2016

.SHORT TERM...valid for Wed and Thu...

Stationary upper low continues to spin over southern Saskatchewan,
but the door has opened up to SW flow aloft with energy lifting
out of the great basin and a little moisture advection up the
high plains. Ascent will increase over the next several hours and
we will see an increase in shower and isold ts from S to N through
the late afternoon and evening. Sfc dew pts remain only in the
upper 30s to lower 40s, with similar values upstream in NE WY and
SW SD, so although we are seeing instability increase it will not
be enough to produce severe weather in our SE, which would be more
favored if higher theta-e air existed, though a strong-ish storm
is possible. Much greater severe threat is to the SE of our CWA.
Cooler Canadian air and temps only in the 50s to lower 60s are
noted in our western CWA, so looking for mainly showers with
perhaps isold ts in this area. Pcpn will increase across our east
tonight into early Wednesday as shortwave moves through, with
latest models suggesting a bit further west track, and this is
consistent with main upper trof axis to our west in western MT. So
have raised/expanded pops further west thru the night, keeping at
least likely pops across our east half. There is some model
disagreement regarding how fast ascent will exit as a mid level
circulation may develop over eastern MT tomorrow morning, so have
raised pops 12-18Z Wednesday as well. Overall a fairly wet period
of weather for our CWA over the next 18 hours, especially for our
east where some areas should receive a half inch to locally an
inch of rain.

We will remain under the influence of slow-evolving upper low to
our north and cyclonic flow aloft tomorrow and Thursday. This will
result in continued daily chances of showers and a few
thunderstorms, along with temps a little below late May normals.
Convection the next two days will be non-severe but given the
fairly low freezing levels cannot rule out some small hail in any
stronger cells.


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

Weak shortwave ridging over the area will be short-lived as
models continue to prog an upper low to drop out of BC and into
the Pac Northwest, bringing a chance for showers and thunderstorms
on Friday, highest across western areas where height falls will
be greatest.

Heading into the weekend, the models have come into better
agreement. The upper low will gradually lift north and east
through Tuesday with a few shortwaves rotating around the low
affecting the area. One of these aforementioned shortwaves will
swing through the area on Saturday, continuing shower and
thunderstorm chances. Weak ridging behind the shortwave will bring
a fairly dry Sunday to much of the area with just a slight chance
for showers and thunderstorms. Monday, another shortwave is
progged to approach the area bringing a chance for showers and
thunderstorms, eventually shifting east through Tuesday as its`
parent upper low shifts north and east. There is enough
instability around to include showers and the mention of thunder
in the forecast every afternoon and evening, although it is hard
to nail down which day has the best instability and dynamics at
the moment.

Unsettled weather and below to near normal temperatures will be
the norm through the long term. STP


Scattered showers were forming over the higher terrain across
western areas this afternoon. Isolated thunderstorms are possible
as well. Showers will become likely near KSHR and southeast of
KBIL after 00z. A few storms may be strong across the southeast
late this afternoon and evening, capable of producing hail and
gusty winds. Mountains will be obscured at times through tonight
with cigs lowering to MVFR to possibly IFR later tonight,
especially across the east where precipitation will be more
widespread. STP



    Wed     Thu     Fri     Sat     Sun     Mon     Tue
BIL 046/065 046/068 047/069 047/067 047/069 046/069 047/070
    54/T    43/T    34/T    44/T    43/T    33/T    33/T
LVM 039/062 040/065 041/063 040/060 040/064 040/064 042/067
    46/T    44/T    45/T    54/T    43/T    33/T    33/T
HDN 046/066 043/071 043/073 047/070 046/071 046/072 047/074
    64/T    33/T    34/T    44/T    43/T    33/T    33/T
MLS 049/066 047/070 049/074 052/074 051/073 049/073 052/076
    88/T    24/T    23/T    34/T    43/T    33/T    33/T
4BQ 046/064 042/070 043/073 048/074 048/073 048/073 048/075
    75/T    23/T    23/T    34/T    43/T    33/T    33/T
BHK 046/063 043/069 044/072 047/074 048/073 046/072 047/074
    89/T    34/T    23/T    33/T    33/T    33/T    33/T
SHR 043/063 040/068 040/070 044/068 044/069 043/070 045/072
    65/T    44/T    34/T    44/T    43/T    33/T    33/T




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