Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 161528

Area Forecast Discussion
National Weather Service Billings MT
928 AM MDT Wed May 16 2018


No update necessary for short term forecast this morning. AAG


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

Will be transitioning to a more unsettled pattern to close out
the week. The upper ridge that gave the state a near cloudless sky
on Tuesday was weakening and sliding into the western Dakotas
this morning. This process was allowing mid level moisture and
weak energy to work into the western part of the forecast area.
The main upper low driving ascent today was in Idaho at the moment
and progged to move northeast toward Great Falls. Convection has
been mainly on the northeast segment of the low, but can not rule
out cyclonic flow and increasing capes producing a few showers or
thunderstorms today for the entire forecast area, with the best
chance being over the west.

The patterns gets pretty messy for Thursday and Thursday night.
The upper low mentioned above works into northern Montana but
opens up southwest flow for southern Montana. Capes will be on the
rise as moisture gradually returns. Meanwhile, a northern trough
approaches northwest North Dakota and pushes a cold front into
Montana. Winds will switch to the northwest Thursday afternoon,
but the strongest cooling will come late Thursday night and
Friday. All of this will combine for an increasing chance of
convection. Some of the storms could be briefly strong, especially
over the east where higher capes and shear will reside. The front
will come through Thursday evening with gusty northwest winds and
bring a much cooler day for Friday. TWH

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

Cool and wet conditions can be expected for Friday into Saturday
as height falls and weak upslope flow produce periods of showers
and thunderstorms. Greatest precipitation chances continue to be
over western and central areas. Overall drier conditions are then
expected Sunday into early next week as heights build aloft.
Another cut- off upper low moving into the Great Basin and
eventually north and east looks to put the region under diffluent
southerly flow aloft, sending moisture and energy north,
increasing shower and thunderstorm chances for the middle portion
of the week. Quite a bit of model uncertainty does exist in the
timing of the waves of energy rounding the upper low and advecting
into the region. High temperatures look to range from the 50s and
60s on Friday and Saturday, before a warming trend starts for the
remainder of the long term with mainly 70s for highs. Low
temperatures mainly in the 40s can be expected most

With the warm temperatures causing mountain snowmelt, we will
continue to monitor river levels over the coming days, with many
rivers expected to crest by the end of the week. STP



Mainly VFR conditions will prevail today with isolated showers and
thunderstorms sweeping across the area this afternoon and evening
as a disturbance lifts out of the Great Basin. Mountains will have
best shower potential and will be occasionally obscured. AAG/STP



    Tdy Thu     Fri     Sat     Sun     Mon     Tue
BIL 082 053/079 049/055 040/058 043/071 048/076 052/078
    2/T 34/T    56/W    53/W    12/W    12/T    22/T
LVM 076 046/073 046/055 037/056 040/068 043/073 047/074
    4/T 36/T    77/W    63/W    23/T    23/T    23/T
HDN 084 052/081 050/056 041/061 044/073 047/078 052/080
    2/T 34/T    56/W    53/W    11/B    11/B    12/T
MLS 084 056/082 052/056 040/061 044/070 048/076 054/080
    1/U 33/T    55/W    41/E    01/B    01/U    12/T
4BQ 083 054/081 052/060 039/058 042/068 046/076 052/077
    2/T 23/T    46/W    42/W    11/B    01/U    12/T
BHK 082 053/080 051/058 038/060 040/066 044/072 051/076
    1/U 23/T    53/W    31/B    01/U    01/B    12/T
SHR 081 048/078 049/056 039/055 040/068 044/074 049/075
    2/T 33/T    46/W    53/W    12/W    12/T    23/T




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