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Area forecast discussion
National Weather Service Billings Montana
253 am MDT Sat may 27 2017

Short term...valid for tdy and sun...

An upper low over southern Canada and the Great Lakes region will
continue to provide a cyclonic flow aloft across the eastern half
of Montana today continuing into Sunday. At the same time, high
pressure ridging and its associated axis will remain over the
Pacific northwest. This will all result in a continued northwest
flow aloft across our forecast area through the weekend. There
will continue to be some weak disturbances within this unsettled
northwest flow that will bring continued chances for isolated
showers and thunderstorms. There isn't really any organization
with these weak disturbances and models are just placing isolated
showers with light qpf across the forecast area. Therefore, we
will maintain a slight shower and isolated thunderstorm chance for
most areas mainly during the afternoon and evening today and
Sunday.

The upper ridge and its axis over the Pacific northwest will
slowly shift east over the weekend bringing rising heights and
warmer temperatures. Expect readings in the upper 60s to lower 70s
today with mainly lower 70s for Sunday. Hooley

Long term...valid for Mon...Tue...Wed...Thu...Fri...

Extended models were in good agreement through Wednesday of next
week, but then diverge greatly from there. The GFS has diverged
from previous solutions and will lean toward the more consistent
European model (ecmwf) for this package. Overall, a warming trend in store with
fairly limited precipitation chances.

Northwest flow will be over the state through Tuesday with an
amplified ridge axis to the west. The flow aloft will weaken over
time as the axis shifts east. Models continue the thought of weak
shortwave streaming southeast across the forecast area Monday and
Tuesday for weak ascent. Low levels will be pretty dry with
dewpoints in the 30s to lower 40s and models want to focus the
best chance of showers over the higher terrain and around the
foothills. The upper ridge axis will slide over the forecast area
on Wednesday and this will keep most locations dry again. The flow
backs on Thursday and will increase the chance of showers and
thunderstorms Thursday and Friday as a shortwave trough moves
across the northern rockies.

Temperatures will steadily warm up with an upper ridge sliding in
place. Highs will approach the lower 80s Wednesday and may well
reach the mid 80s Thursday as mid level flow backs with the ridge
axis shifting east. The warmer temperatures will likely hold into
Friday. The European model (ecmwf) builds a ridge back over the following weekend
for a continuation of the warm and mainly dry pattern. This
extended period of warmth from the middle of next week on, will
likely cause rises on main steam rivers with increased mid and
high level snowmelt. Will have to keep an eye on area waterways
through the end of next week. Twh

&&

Aviation...

VFR conditions are expected today across Montana. A weak
disturbance will slide through the area today and generate a few
showers and isolated thunderstorms. The best chance for rainfall
will be over the mountains and along the foothills. Local MVFR
conditions are possible in the heavier showers, along with
occasional mountain obscurations. Twh

&&

Preliminary point temp/pops...

Tdy sun Mon Tue Wed Thu Fri
-------------------------------------------------------
bil 072 049/074 047/075 050/078 051/080 052/082 054/083
2/T 13/T 21/u 11/u 11/u 11/b 12/T
lvm 070 041/072 040/074 043/077 044/077 044/079 045/079
2/T 13/T 22/T 11/u 11/b 12/T 32/T
hdn 072 046/075 045/077 046/080 048/082 049/083 050/083
2/T 12/T 21/u 00/u 01/u 11/b 12/T
mls 074 049/075 044/075 045/078 048/080 050/082 053/082
2/T 12/T 00/u 00/u 00/u 01/u 12/T
4bq 070 046/073 043/073 043/076 047/079 048/080 051/080
2/T 22/T 20/u 00/u 00/u 12/T 13/T
bhk 069 043/071 040/069 039/073 043/074 045/076 048/076
2/T 12/T 00/u 00/u 00/u 02/T 12/T
shr 066 044/070 041/072 043/076 044/076 046/079 047/080
2/T 22/T 21/u 01/u 11/b 11/b 12/T

&&

Byz watches/warnings/advisories...
Montana...none.
Wyoming...none.

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