Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 171630

Area Forecast Discussion
National Weather Service Billings MT
1030 AM MDT WED AUG 17 2016


Updated cloud and rain forecast for this morning/afternoon to
reflect area of clouds with embedded weak showers from Big Timber
to Colstrip. Forecast remains largely unchanged for this
afternoon with low to mid 90s possible for highs and isolated to
scattered showers and thunderstorms mainly confined to the
southern periphery of Montana and northern Wyoming. Showers and
thunderstorms will form along the Beartooths and Bighorns late
this afternoon and move eastward over the Plains in the early
evening. Front will approach late tonight ushering in cooler
temperatures and clouds, and increasing rain chances from Rosebud
county westward during the overnight hours. Walsh


.SHORT TERM...valid for Tdy and Thu...

Today will be the last hot day for awhile with high temperatures
expected to be in the 90s across most areas. Would not be
surprised if a few locations approach 100 degrees. Upper flow
becomes more southwesterly today with an area of low pressure at
the surface lifting through the area. Weak energy and instability
will allow for showers and thunderstorms to develop over the
mountains this afternoon, gradually spreading out onto the plains
heading into the late afternoon/evening. Gusty winds will be
possible with the thunderstorms given the large dewpoint
depressions that will be present.

Winds will turn north northeast this evening and overnight as an
initial cold front drops south through the region. Shower and
thunderstorm chances continue to increase into Thursday with
upslope flow and instability over the area. Best precipitation
chances will be over the higher terrain. Stronger storms are
possible during the afternoon and evening south of a Harlowton to
Billings to Sheridan line with models showing MUCAPEs up to 1000
j/kg and deep layer shear on the order of 30 to 40 kts.
Temperatures on Thursday will be a good 15 to 20 degrees cooler
than Wednesday with the cold frontal passage. Models have come
into much better agreement with a strong disturbance dropping
south and east through the region starting late Thursday night
bringing widespread precipitation. STP

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

No major changes were noted in the overnight model solutions
though the Friday disturbance appears to move through a little quicker.

Friday morning will be cloudy and damp with ongoing showers
across most of the forecast area as the upper level low swings
through. There is also the potential for high elevation snow
above 9000 ft, which could impact travel along the Beartooth Pass
in the morning as 1 to 3 inches of new snow is possible by early Friday
afternoon. Good forcing aloft will allow the rain to persist
through the morning and early afternoon which will keep daytime
temepratures quite low. There is still model uncertainty with max
temperatures for Friday. For this update, went just below the
ensemble mean and in the lower 60s considering the rainy and
cloudy conditions that will be prevalent over the region. The rain
should end through the day from northwest to southeast with most
of the rain out of the forecast area by the evening hours. When
all is said and done expect storm rainfall amounts of 0.50 to 1
inch over the plains with 1 to 2 inches of rain possible over the
higher terrain.

Expect a much cooler morning on Saturday with many locations
lowering into the upper 40s for the first time in over a month.
The disturbance will continue southeast through the afternoon on
Saturday with temperatures warming back into the 70s. A few
showers are possible over the far southeast.

The warm up quickly moves in Sunday and lasts through the start
of next week. Temperatures warm back into the upper 80s by next
Tuesday. Conditions are also expected to be mostly dry through at
least Tuesday. Dobbs


VFR conditions will prevail though thunderstorms will be more abundant
this afternoon from 21z-03z at KBIL and KLVM. Expect mostly light
and variable winds away from thundestorms. Winds will turn
northerly after 06z Thursday as a frontal system approaches. Dobbs


    Tdy Thu     Fri     Sat     Sun     Mon     Tue
BIL 092 062/073 051/063 047/070 050/080 055/087 057/085
    2/T 34/T    88/R    21/B    11/U    11/U    11/U
LVM 092 057/073 048/060 041/069 044/082 049/087 050/086
    2/T 34/T    76/R    21/B    11/U    11/U    11/U
HDN 093 062/077 051/065 045/072 047/082 053/089 055/087
    2/T 24/T    88/R    21/B    11/U    11/U    11/U
MLS 097 065/080 055/066 049/072 050/081 055/089 057/087
    2/T 23/T    79/R    11/B    11/U    11/U    11/U
4BQ 097 064/077 055/063 047/069 047/078 054/087 056/086
    2/T 35/T    59/R    42/R    11/B    11/U    11/U
BHK 094 061/078 052/065 045/069 046/078 050/085 053/085
    1/U 22/T    48/R    21/B    11/B    11/U    11/U
SHR 095 060/075 051/059 042/067 044/078 050/086 052/085
    3/T 35/T    68/R    41/B    11/B    11/U    11/U




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