Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 300926

Area Forecast Discussion
National Weather Service Billings MT
326 AM MDT Tue May 30 2017

.SHORT TERM...valid for Tdy and Wed...

A ridge of high pressure and its associated axis will be situated
over the northern Rockies for the next couple of days. This will
result in sunny to mostly sunny skies and dry conditions today and
Wednesday. The exception will be over the mountains where some
weak instability may exist allowing for a very slight chance for
an afternoon/evening shower or isolated thunderstorm. Temperatures
will continue to warm above normal with readings in the middle to
upper 70s today with lower to middle 80s Wednesday. Hooley

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

Ridging will slide east on Thursday and cause mid level flow to
back. This will provide strong downslope warming and high
temperatures will reach the mid to upper 80s on Thursday. A cold
front will slide into the area from the west Thursday evening as
an upper trough moves in and drives the upper ridge east. The
chance of showers and thundestorms will increase with the
shortwave trough. Cape values look higher over the east with more
persistent low level southeast winds allowing for higher dewpoints
there. Can`t rule out a strong or severe storm over the east
Thursday evening, but timing seems a little slow for the strongest
ascent for severe convection. Did lower temperatures a bit more
for Friday per latest guidance based on strong cold frontal
passage Thursday evening.

Models diverge greatly for Friday as the GFS brings a secondary
trough across northern and central Montana for strong ascent over
northern zones of our county warning area. The ECMWF was much
farther north and weaker with this wave and provided downslope
flow for a dry forecast. Trimmed back PoPs a bit for Friday, but
still carried low chance to isolated. The forecast gets
complicated for Saturday and beyond as the models try deal with
another upper trough moving into Idaho for the Sunday and Monday
time frame. Timing and position differences lends to low
confidence on the forecast beyond Saturday, and will thus not make
many changes, mainly cosmetic.

Still expecting aggressive rises on area rivers late this week
into the weekend, in response to temperatures rising above 80
degrees Wednesday and Thursday. The strong cold frontal passage
Thursday evening will provide cooler weather for the weekend, and
this cool down is expected to continue into early next week and
likely temper some of the rises. River guidance was bringing the
Yellowstone at Livingston and the Clarks Fork of the Yellowstone
at Belfry and Edgar very close to flood stage Thursday and Friday,
and holding high values into the weekend. Will let the day shift
evaluate the current ESF or potential watches based on updated
guidance from the MBRFC late this morning. In the mean time, will
issue a HWO to highlight rising water levels late in the week and
emphasize the two rivers mentioned above. TWH



VFR conditions with generally light winds expected today.
Isolated showers or thunderstorms area possible over the
Beartooth/Absarokas this afternoon and evening. TWH



    Tdy Wed     Thu     Fri     Sat     Sun     Mon
BIL 078 052/085 057/089 056/078 052/079 052/080 053/076
    0/U 01/U    12/T    33/T    21/U    11/B    22/T
LVM 077 045/084 049/081 048/073 043/076 043/075 044/072
    1/U 11/U    13/T    32/T    30/U    02/T    32/T
HDN 078 047/087 051/091 054/080 050/080 050/082 049/078
    0/U 00/U    12/T    34/T    21/U    11/B    22/T
MLS 074 047/085 057/092 060/081 053/079 051/080 051/078
    0/U 00/U    00/U    34/T    22/W    10/U    23/T
4BQ 074 044/084 053/092 056/080 051/078 050/079 050/078
    0/U 00/U    00/U    24/T    21/B    11/U    23/T
BHK 069 039/078 049/088 056/078 050/075 046/075 046/073
    0/U 00/U    01/U    25/T    23/W    21/U    23/T
SHR 074 044/083 048/088 052/076 047/076 046/078 047/077
    1/U 11/U    12/T    33/T    21/B    12/T    23/T




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