Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 270805

Area Forecast Discussion
National Weather Service Billings MT
205 AM MDT SAT AUG 27 2016

.SHORT TERM...valid for Tdy and Sun...

Some showers and a few lightning strikes remain from Rosebud
County eastward at 2 am, in response to PV moving through eastern
MT. This activity will exit our region by around 12z. Onset of
flat ridging from the west and increasing downslope winds will
then yield a dry day today. Temps will respond accordingly, with
700mb temps near +10c resulting in afternoon highs into the mid to
upper 80s.

Fire weather concerns will elevate as RHs fall to the lower teens
and ridgetop/mixed winds increase over the Gallatin NF and
Beartooth RD. 700mb flow around 25 kts will yield some modestly
gusty afternoon winds, and will stress the warmer/drier/breezy day
in our morning fire weather forecast. As surface and mid level
flow backs to a WSW direction, we will likely see an increase in
smoke over our cwa from upstream wildfires in western MT and
northwest WY.

Shortwave skirting across southern Canada tonight into Sunday will
not produce any pcpn in our cwa, but will result in a shift in
surface winds to the NW-NE Sunday afternoon and evening. Upslope
and convergence along sfc trof may be enough for isolated showers
over our western mountains/foothills from 21-03z Sunday. Dry
conditions will prevail across the cwa otherwise. Temps on Sunday
will continue to run above normal especially in our east with near
90F expected. Wind shift should bring in some slightly higher
boundary layer moisture, but still expecting afternoon humidity to
fall to the mid or upper teens.


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

As would be expected, the ensembles showed lots of model spread
regarding the pacific trough moving into the area late in the
period. The deterministic models also showed differences in trough
strength and timing. This period will be monitored to see if the
trough slows down, as it often does in high amplitude patterns.

Otherwise, noted the guidance was trending higher with
temperatures on Tue. and Wednesday. It will be very warm on Mon.,
as well, with temperatures of 85 to 90 under a strong upper
ridge. The upper ridge remains anchored over the area on Tue., on
the ECMWF while the GFS shifts it eastward. Either way, the dry
forecast continues with highs on Tue. now in the 90s. Both models
had SW flow increasing over the area on Wed., and precipitable
waters increasing to /0.5/ inches to /0.75/ inches over previously
dry western portions of the area. Thus continued slight chances
for thunderstorms over western and central parts of the area.
Highs on Wed. will also reach the 90s.

SW flow with energy moving through the flow and decent
precipitable waters will be over the area Thu. and Fri.,
supporting slight chance PoPs across the area. The upper trough
moves E on Sat. with the ECMWF showing a splitting trough. Active
SW flow continues over the area with a cold front moving through
the region. Had PoPs across the area with the highest PoPs closest
to the trough, behind the front. Temperatures were forecast to be
in the 70s and 80s. As previously mentioned, this timing of the
system could change, so will continue to monitor model trends.



Isolated showers and thunderstorms will move out of SE MT by
12Z today. Localized MVFR conditions are possible with any
thunderstorms. Otherwise, VFR will prevail today and tonight.
Surface winds will become gusty from the W over KLVM this
afternoon, with gusts in the 20s. Mountain peaks will be hidden by
mid clouds from time to time through tonight. Arthur



    Tdy Sun     Mon     Tue     Wed     Thu     Fri
BIL 087 059/088 056/088 058/093 061/092 060/089 059/086
    0/B 00/B    00/U    01/U    12/T    22/T    22/T
LVM 086 050/087 048/089 051/093 053/090 051/086 050/083
    0/N 01/B    10/U    01/U    12/T    23/T    32/T
HDN 088 054/090 053/091 056/095 059/094 058/092 057/089
    0/B 00/U    00/U    01/U    12/T    22/T    22/T
MLS 088 058/091 058/090 061/096 064/095 062/094 061/090
    0/U 00/B    00/U    01/U    11/U    22/T    22/T
4BQ 086 056/091 057/090 059/093 062/093 061/093 060/091
    0/U 00/U    00/U    11/U    11/U    12/T    22/T
BHK 083 053/090 055/085 057/090 060/090 059/090 058/089
    0/U 00/B    00/U    11/U    11/U    12/T    22/T
SHR 086 052/090 052/090 054/092 056/092 056/090 056/088
    0/U 00/U    00/U    11/U    12/T    22/T    22/T




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