Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 100931

Area Forecast Discussion
National Weather Service Billings MT
331 AM MDT Thu Aug 10 2017

.SHORT TERM...valid for Tdy and Fri...

A little warmer day expected today as mid level heights build a
bit from the west. Despite building heights, the state will remain
under northwest flow aloft, and this will keep temperatures ever
so slightly below seasonal averages. A weak shortwave was exiting
south central Montana at the moment. This wave did produce a few
light showers over the high county, but activity has faded with
the energy sliding southeast into northern Wyoming. Next weak
shortwave will approach the west this afternoon and shift across
the region this evening. Very limited cape progged this afternoon
and ascent was weak. Low level upslope flow would favor the
mountains and foothills for best chance of convection, so that is
where the PoPs will be located today and tonight.

A stronger shortwave trough from south central Canada drops into
northern Montana Friday. Pieces of energy, along with a cyclonic
jet max wrap around the low and eject across southern and eastern
Montana. Thus, forcing looks stronger for Friday and because of
such, will have PoPs broad brushed across most of southern Montana
and northern Wyoming. Southeast Montana will be in an area of
higher dewpoints, on the eastward side of an inverted surface
trough. Dewpoints will not be tremendous, (mid 40s to lower 50s),
but enough to produce cape around 500j/kg. Effective bulk shear
was progged around 35kts, which is on the low end for stronger
storms. Would expect the most organized storms to form over Powder
River and Carter counties, with the most likely location for
stronger storms over northeast Wyoming and northwest South Dakota
with stronger shear, higher cape, and in an area of better surface
convergence. Temperatures look to be a bit warmer on Friday
despite easterly surface winds. TWH

.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...

Saturday, upper low drops southward from Canada with entrance
region of upper jet descending into southern Montana.  By late
afternoon, 500-1000 j/kg of CAPE, 40-50 kts of bulk shear, and
freezing levels around 9 kft should allow for a few stronger
storms capable of producing gusty winds and hail mainly over
eastern MT. Strong low pressure system makes its way into the
Pacific Northwest on Sunday. An amplified ridge ahead of the
Pacific low will push through Montana Sunday and Monday,
increasing temperatures to the upper 80s and reducing
precipitation chances. Monday night into Tuesday, low pressure
system pushes across the Rockies bringing more of a widespread
threat for showers and thunderstorms. Pattern becomes more zonal
and dry as we head into the middle part of the week with
temperatures warming back toward climo. Walsh



Some lowered ceilings and fog possible east of Miles City towards
Baker for a few hours around sunrise. Otherwise VFR conditions
expected through the period with generally light easterly winds.



    Tdy Fri     Sat     Sun     Mon     Tue     Wed
BIL 083 056/084 057/083 056/087 060/088 060/084 058/085
    0/U 02/T    22/T    11/B    11/U    33/T    21/U
LVM 083 049/085 049/084 051/085 052/085 051/084 049/085
    1/U 12/T    22/T    12/T    13/T    34/T    31/U
HDN 084 056/086 055/084 055/088 059/092 059/086 057/088
    0/U 01/B    22/T    11/B    11/U    43/T    21/B
MLS 081 056/083 057/081 056/084 060/089 064/087 060/087
    0/U 03/T    22/T    10/U    01/U    44/T    21/B
4BQ 081 054/084 054/081 054/083 058/089 061/088 059/087
    0/U 14/T    23/T    11/U    11/U    25/T    41/B
BHK 077 052/079 052/076 051/078 054/083 059/085 058/084
    0/U 03/T    34/T    21/U    01/U    25/T    41/B
SHR 080 050/082 051/081 051/083 053/088 055/085 053/085
    1/U 12/T    23/T    12/T    22/T    33/T    31/B




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