Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 221608

Area Forecast Discussion
National Weather Service Billings MT
1008 AM MDT Mon May 22 2017


Minor update to adjust pops across the area this morning and early
afternoon. Appears best shower potential has ended in Billings,
but may still get a few shower. Have tapered back likely pops to
scattered through remainder of the morning, and lowered early
afternoon pops toward isold showers. Have also raised temps
slightly for central zones, including KBIL, resulting from
possible earlier clearing. Otherwise inherited forecast appears
to be in pretty shape, with generally clearing conditions through
the afternoon/evening. AAG


.SHORT TERM...valid for Tdy and Tue...

Band of showers currently moving through most of the central and
eastern zones from north to south ahead of an approaching low
pressure system. Temps still rather warm, near 60 degrees here in
Billings at midnight. RAP analysis shows a decent 700 mb jet
punching into the region aiding winds in the vicinity of the
showers, so far we have seen these weak showers producing 30 to 45
mph winds despite their poor reflectivity signatures. Models are
fairly consistent with the current convection pushing into extreme
southern Montana and northern Wyoming by sunrise. Upper-level PV
advection and associated jet punching into the region by morning
will help increase lift from Big Horn and Yellowstone counties
westward into the mountains and foothills, as a north to south
oriented band of convection develops through the morning. East of
that main band there is a bit more instability and we could see
some isolated thunderstorms in the central and eastern zones as
CAPE increases during the early afternoon. Precip starts to become
more isolated in nature and decreasing in coverage from north to
south through the afternoon hours. Not all the models are showing
this, but there is some sign that CAPE values could increase
enough in the eastern Plains and east of the Bighorns to generate
a few stronger cells capable of producing small hail and gusty
winds during the afternoon. Ridging moves into the region on
Tuesday which will clear out the rain chances and warm
temperatures up into the low to mid 70s. Walsh

.LONG TERM...valid for Wed...Thu...Fri...Sat...Sun...

The extended forecast begins with a warm Wednesday due to
downsloping from low-level southwesterly winds. High temperatures
across the lower elevations should generally be in the upper 70s
to lower 80s. A cold front should then cross the area Wednesday
afternoon. This front can force a few showers and thunderstorms to
develop. Instability looks weak at this time so am only expecting
general, sub-severe storms. Behind this front, surface pressure
rises look impressive, close to 1 mb/hour, so think that there
should be a period of windy conditions with gusts to 40 mph late
Wednesday afternoon into the evening. Winds should taper off
overnight Wednesday night, then increase again during the day on
Thursday as surface heating leads to winds of 30-35 kt at 700 mb
mixing down to the surface.

Cyclonic flow aloft looks to generally remain over the region from
Thursday through early next week. This pattern can produce
isolated showers as disturbances rotate through the flow. A few
thunderstorms are possible in the afternoon and evening each day.
High temperatures should be in the 60s to low 70s during this
period. RMS/Walsh



Scattered showers and thunderstorms are expected today...with the
best chance from roughly KLVM-KBIL-KSHR and southwest. Small hail
and erratic gusts to 40kts can be expected with the stronger cell.
Conditions may deteriorate to MVFR at times with showers, mainly
in the foothills southwest of KBIL. Mountains will be obscured at
times today. Chambers



    Tdy Tue     Wed     Thu     Fri     Sat     Sun
BIL 067 043/073 051/078 045/063 043/062 043/065 045/069
    5/W 10/U    02/T    22/T    22/T    23/T    32/T
LVM 060 038/074 046/072 039/060 036/059 036/063 038/067
    6/W 10/U    02/T    23/T    34/T    43/T    32/T
HDN 067 042/073 047/081 045/065 042/065 042/067 043/071
    6/T 10/U    02/T    22/T    22/T    23/T    32/T
MLS 066 043/071 049/080 047/066 043/066 044/067 045/071
    4/W 10/U    02/T    21/N    12/T    23/T    32/T
4BQ 061 042/068 045/080 043/065 041/065 042/065 043/069
    6/T 20/U    02/T    21/B    22/T    23/T    32/T
BHK 059 039/065 041/074 042/062 039/063 040/064 040/066
    3/T 10/U    02/T    51/N    11/B    12/T    22/T
SHR 057 040/067 043/078 041/062 039/060 039/061 039/065
    8/T 10/U    02/T    22/T    33/T    33/T    32/T




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