Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 151447

Area Forecast Discussion
National Weather Service Billings MT
847 AM MDT Sun Oct 15 2017

Winds at Livingston and Nye have decreased since last night`s weak
shortwave passage, and speeds will remain under advisory criteria
through the remainder of the day as we evolve into mixed winds,
with weaker mid level flow. Latest obs show gusts to the lower
40s, and this should decrease to 25-35 mph this afternoon. Winds
will pick back up some tonight and could see gusts back to near 50
mph. Otherwise, our weather today will be quiet with temps
moderating to the low-mid 60s, courtesy of upper level ridging and
WNW flow aloft. JKL


.SHORT TERM...valid for Tdy and Mon...

Shortwave energy was dropping southeast from southern Alberta
toward North Dakota. In response to this, a lee trough has formed
and was adequately tight enough to produce 60 mph winds from
Livingston to Nye overnight. Surface pressure rises were sliding
into North Dakota this hour, with rises behind it over southwest
Canada. This typically spells the ending process of the strong
winds for the western foothills, but local studies show the strong
winds often linger for several hours after this process starts.
Will thus, keep the advisory in place for now. May be able to
cancel it early, but will wait til it is perfectly clear that the
winds have backed off to do that.

Building heights and backing flow aloft will lead to a warmer a
dry forecast. High temperatures will reach the lower 70s on
Monday, which is some 10-15 degrees above normal. Both Sunday and
Monday will be a little breezy as 850mb winds of 20-25kts mix
down. A lee trough will form both tonight and again Monday night,
and create gusty winds from Livingston to Nye. Gradient does not
look as strong as the current gradient, so am not expecting a
highlight at this time. That being said, will need to be monitored
as gusts to 50 mph are certainly plausible. TWH

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

Forecast remains consistent with dry and unseasonably warm
conditions through the bulk of the work week under relatively
zonal, anticyclonic upper flow. An upper level Pacific trof is
progged into the region to end the work week and bring precip and
cooler temps for the weekend.

Upper air pattern lends support for lee sfc trof development over
the area, resulting in breezy conditions through much of the
period. A period of strong and gusty winds can be expected in and
around Livingston area Tuesday into Tuesday as pressure gradient
tightens over the southwestern CWA, with gusts around 50 mph

The upper-level trof, with associated FROPA should produce some
lower elevation rain showers and mountain snow showers late Friday
afternoon into Saturday. Downslope flow and dry sfc environment
will limit rain totals in plains.

Temps in upper 60s to mid 70s are expected for the the work week,
with high back to around normal for the weekend, with highs in
the 50s Saturday and lower 60s Sunday. AAG



Winds still gusting close to 40 kts this morning at KLVM but will
continue to decrease through morning. Southwest winds will
increase overnight at BIL, LVM, and MLS as a low pressure system
moves across Canada. Aside from increased wind speeds, no concerns
through the TAF period as VFR conditions are expected to prevail.



    Tdy Mon     Tue     Wed     Thu     Fri     Sat
BIL 063 041/072 044/072 044/070 044/072 046/067 040/054
    0/U 00/N    00/U    00/B    00/U    11/B    32/W
LVM 063 037/071 039/071 041/070 040/070 041/062 035/049
    0/N 00/N    00/N    00/N    11/N    13/W    52/W
HDN 064 036/074 038/075 042/073 041/075 044/070 038/056
    0/U 00/U    00/U    00/B    00/U    01/B    33/W
MLS 062 037/073 040/073 043/070 042/074 043/069 040/054
    0/U 00/U    00/U    00/B    00/U    01/B    22/W
4BQ 062 035/072 040/075 041/071 040/072 043/071 039/054
    0/U 00/U    00/U    00/U    00/U    01/B    23/W
BHK 059 035/071 039/074 042/067 041/072 042/070 039/053
    0/U 00/U    00/U    00/B    00/U    01/U    12/W
SHR 062 032/070 035/075 040/072 038/073 041/068 036/052
    0/U 00/U    00/U    00/U    00/U    01/B    33/W




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