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Area forecast discussion...updated 
National Weather Service Billings Montana
930 am MDT Sat Apr 25 2015


An upper low and trough currently over the forecast area along
with a surface low over northeast Wyoming will slowly shift east
today taking the bulk of the precipitation with it. Satellite showing
mostly cloudy skies across southern Montana and the northern half
of Wyoming. Expect a mostly cloudy day today but some breaks in
the clouds can be expected this afternoon across our central and
western areas. Radar is currently showing an area of light to
moderate rain across Big Horn...Yellowstone and Treasure counties
moving north with mostly dry conditions east and west of this
area. As a result...will keep likely probability of precipitation across these areas
through this morning with the rain shifting east to Miles City and
Baker this afternoon. The rain is expected to end by noon for the
Billings area with only an slight shower chance for the afternoon.
Only made a few minor adjustments to the previous forecast. Hooley


Short term...valid for today and sun...

Active weather through the weekend will bring many areas some
much-needed precipitation. Two separate systems will impact our
County Warning Area.

Moist SW flow has brought periods of shower activity to areas from
Pryor to Billings and Ingomar westward since yesterday evening. We
are starting to see another surge of cloud top cooling in response
to shortwave lifting out of southeast Idaho...and blx radar is
showing increasing echoes from the S-SW as of 09z. Surface temperatures have
cooled such that a mix with snow is being observed at Livingston
and Judith Gap. Precipitation across our west will extend beyond 12z so
have adjusted probability of precipitation up from 12-15z...after which upper divergence
and middle level frontogenesis will shift across our east through
the remainder of the day...along with a cold frontal passage.
Subsidence west/ drier surface ridge will slide in from the west behind
this energy... in advance of trough digging to our we will
see a break in precipitation in central zones including Billings later
today into this evening. Temperatures today will be quite a bit cooler
than yesterday with highs mostly in the 50s...with low 60s
prefrontally near the Dakotas border.

Trough over the Pacific northwest today will dig to the central and southern
rockies on Sunday. Track of this low is not ideal for a
significant upslope precipitation event but initial period of ascent along
with deepening easterly/upslope winds should yield some precipitation
across our western foothills late tonight through Sunday. Models
have trended a bit cooler and this is not just dynamically
induced...see 00z 850mb temperature of -2c at Edmonton Friday evening...
so believe there is a fair chance of some wet snow along the
foothills at such places as Nye...Red Lodge and story early
Sunday. Will need to watch model trends here. Higher up...east
slopes of the beartooths and bighorns should see at least a few
inches of snowfall but this will also depend on how quickly the
upper low pushes south. Focus of precipitation will shift to our
east Sunday and Sunday night per inverted surface trough and a period of
low level moisture advection under diffluent southerly flow aloft.
Locations in our east could see a half inch of precipitation or more by
the time the northern split wave passes on Monday. With confidence
have raised probability of precipitation a bit more across our east Sunday afternoon and
night. Sunday should be the coolest day over the next seven days
with highs ranging from the upper 40s to upper 50s.


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

Long term forecast is dominated by ridging from Monday through
Thursday. This will bring sunny dry conditions with temperatures
rising from the upper 60s on Monday to the lower 80s by Thursday.
Longwave trough develops along the West Coast Thursday into Friday
with energy also pushing across southern Canada breaking down the
ridge. This combination will allow Pacific air to push in from the
southwest. With some low Level Plains moisture and some Pacific
moisture aloft have climatology type probability of precipitation in for the later
extended...along with slightly cooler temperatures. Overall pretty
quiet for this time of year. Chambers


Moist southerly flow combined with strong energy moving through
aloft will bring scattered to numerous showers to western and
central zones this morning...shifting into eastern areas this
afternoon. MVFR ceilings will prevail over the area for most of
the day...with local IFR conditions near areas of heavier
precipitation. Rain will be the main precipitation type...mixed
with snow in the foothills. Snow can be expected in the mountains.
Mountain and pass obscuration can be expected and will persist
into this afternoon. Conditions will improve from southwest to
northeast this afternoon as the system pushes through...with VFR
conditions expected across the area by this evening. Chambers


Preliminary point temp/pops...

Today sun Monday Tuesday Wednesday Thursday Friday
bil 057 038/054 038/063 039/072 046/078 048/073 049/075
3/west 36/west 31/b 00/u 01/u 12/west 22/west
lvm 056 035/052 031/059 033/069 042/074 043/069 042/070
4/west 67/west 31/b 00/u 01/u 13/west 22/west
hdn 058 037/057 037/064 039/072 045/079 048/075 050/078
6/west 26/west 41/b 00/u 00/u 12/west 22/west
mls 056 036/058 039/063 040/071 045/079 049/075 051/078
7/west 15/west 51/b 00/u 00/u 11/u 22/west
4bq 056 037/053 038/060 037/068 043/077 047/076 048/078
5/west 37/west 72/west 00/u 00/u 02/west 22/west
bhk 061 036/055 038/058 038/066 042/073 046/072 048/076
7/west 67/west 72/west 00/u 00/u 11/u 22/west
shr 055 036/049 035/057 036/067 040/073 045/072 046/074
3/west 37/west 62/west 00/u 00/u 11/u 22/west


Byz watches/warnings/advisories...



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