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fxus65 kbyz 260253 
afdbyz

Area forecast discussion...updated
National Weather Service Billings Montana
853 PM MDT Thu may 25 2017

Update...
for the forecast this evening, have adjusted pops based on
decreasing trends on radar and adjusted winds which have come
down over the central and west. Clouds were also decreasing over
the area as a weak secondary cold front and upper trough push
east out of the region. Clouds will be on the increase again late
tonight with precipitation chances moving into the western
mountains as an upper low, seen over the Pacific northwest on water
vapor, moves southeast toward SW Montana. This feature will bring scattered
showers and isolated thunderstorms to areas west and S of kbil Fri.
Afternoon as lapse rates and moisture increase over portions of
the area. The winds will be much lighter than they were today.
Arthur

&&

Short term...valid for Fri and Sat...
trowal on back side of upper low in southern Saskatchewan
continues to wrap some light showers into our cwa. This activity
has not amounted to much, and pcpn will diminish quickly this
evening as drier air advects from the northwest. Gusty west-northwest winds
will also diminish this evening. Satellite imagery shows western
portion of split trof dropping into eastern Oregon. Ascent from
this feature will brush our Southwest Mountains late tonight and
Friday morning, with some mid level frontogenesis as winds turn
easterly, so expect some pcpn over the beartooth absarokas over
the next 18-24 hours. This shortwave will then continue to sag
toward the central rockies and further from our area by Friday
night. Expect snow showers and a little accumulation for those
traveling over Beartooth Pass as it opens Friday.

Diurnal instability with cyclonic flow aloft will allow for
isolated to scattered showers mainly over our western/southern
mountains and foothills tomorrow afternoon and evening. Eastern
areas will see drier northwest winds. Temps on Friday will remain below
normal with highs mainly in the 60s, with 50s along the foothills.

Weak shortwave in northerly flow aloft will bring potential for a
few showers on Saturday. Heights will begin to climb as strong
ridge establishes itself along the Pacific coast, so expect temps
to climb to near normal with highs in the mid 60s to lower 70s.

Jkl



Long term...valid for sun...Mon...Tue...Wed...Thu...
longwave pattern sun-Tue will be characterized by a strong ridge
along the Pacific coast and cold trof over the northern plains and
Great Lakes, leaving our region under northwest flow aloft. A
series of weak shortwaves will bring an opportunity for at least
isolated diurnal showers/tstms mainly over our western areas each
day. More stable air associated with surface ridging over the
northern plains will keep our east drier. Temps will be seasonal
with highs mainly lower to mid 70s. No severe weather is
anticipated from this weekend through the first part of next week.

Model consensus, though not perfect, suggests that the upper level
ridge to our west will finally move east by the middle of next
week as westerly flow develops along the Pacific coast. This will
open the door to warmer temperatures and perhaps a better chance
of thunderstorms by next Wed-Thu.

Jkl
&&

Aviation...
gusty northwest winds will continue to diminish this evening with
light winds overnight. Showers will increase again late tonight
into Friday over the high country. Look for VFR conditions to
prevail overnight with perhaps some occasional mountain
obscuration late. Bt &&

Preliminary point temp/pops...

Fri Sat sun Mon Tue Wed Thu
-----------------------------------------------------------
bil 042/065 045/072 049/074 049/074 047/076 049/082 053/085
11/b 12/T 13/T 22/T 11/b 11/b 12/T
lvm 035/062 037/069 041/072 041/073 042/075 043/081 044/082
13/T 23/T 23/T 22/T 12/T 11/b 13/T
hdn 039/066 042/072 045/074 045/074 045/078 046/083 049/086
11/b 12/T 12/T 22/T 11/u 00/b 12/T
mls 042/068 044/072 048/074 046/072 044/075 048/081 052/087
10/b 12/west 12/T 00/u 00/u 00/u 12/T
4bq 040/066 043/069 046/072 044/071 042/073 045/079 049/084
11/b 12/T 12/T 10/u 00/u 00/u 11/b
bhk 039/065 041/068 044/070 041/067 037/070 042/074 046/080
20/u 02/west 22/T 00/u 00/u 00/u 01/u
shr 037/060 039/066 044/070 042/070 041/073 044/079 046/084
13/T 22/T 23/T 22/T 11/u 11/b 12/T

&&

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

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