Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 211029

Area Forecast Discussion
National Weather Service Billings MT
429 AM MDT WED SEP 21 2016

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

Wet conditions and cooler temperatures are in store for the next
several days. An upper low and trough currently moving onshore
across the Pacific Northwest coast will continue to develop and
slowly move southeast into the Great Basin area Wednesday into
Thursday. This will allow for a southwest flow aloft through the
period along with a strong area of upper level divergence across
the forecast area. Models are in fairly good agreement through the
short term so forecaster confidence is high for cooler and wetter

For this morning, we are only expecting some isolated showers as
most of the activity has shifted into the north central and
northeast areas of the state. However, shower chances will be
increasing this afternoon along and north of a Livingston-
Billings-Miles City line with a more general rain likely during
the evening and overnight hours. Rain chances will increase across
the far east and southeast toward the Dakota borders but the
likely pops will continue to be mainly along and north of the
above mentioned locations. Rain will continue to be likely
Thursday and Thursday night when an inch of rain will be possible
during the day Thursday for many areas. In addition, enough
instability will warrant the mention of an isolated thunderstorm
for both this afternoon/evening and again Thursday
afternoon/evening. Temperatures will be much cooler than the past
several days with 50s today and Thursday, with the exception of
some 60s across the far southeast areas. Hooley

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

Models continue to struggle with handling the movement of the
upper low as it moves northeast and then eastward away from the
region. Will opt for a nudge towards the ECMWF for this forecast
package because its run to run consistency has been stronger. Friday
the models are in fair agreement and this has a trend towards a
bit more dry slotting into the area so have lowered rainfall
amounts a bit. Saturday the ECMWF keeps a better wrapped up
system together over western North Dakota so expect a bit more
precipitation over southeast Montana but a bit more of a drying
trend over south central Montana and north Central Wyoming.
Temperatures will be coolest on Saturday as northwesterly flow
advects cooler air into the region.

Rest of the extended is much drier with the departing system
closing off over the northern midwest with the ECMWF both further
west than the GFS progged position. ECMWF is a bit cooler because
the further western position of the low slows the advance of the
upstream ridge keeping the northwest flow aloft longer. Pattern
becomes very blocky later next week for a nice week of dry fall
weather aiding agricultural operations. borsum



Expect increasing clouds this afternoon with lowering ceilings.
Shower activity with an isolated thunderstorm will increase
during the later afternoon hours with mountain and foothill
obscurations developing in the early evening hours. Terminal
sites should remain VFR until later this evening. borsum



    Tdy Thu     Fri     Sat     Sun     Mon     Tue
BIL 058 046/057 047/057 046/058 044/063 043/068 047/073
    3/T 77/T    88/R    54/W    31/B    01/U    11/U
LVM 057 046/056 044/053 043/055 039/062 041/069 044/073
    3/T 87/T    79/R    53/W    21/U    01/U    11/U
HDN 066 050/064 049/061 046/060 043/064 042/069 046/073
    2/T 46/T    87/R    75/W    31/B    01/U    11/U
MLS 065 052/060 049/062 049/059 044/063 041/068 045/073
    2/T 46/T    86/R    76/W    42/W    01/U    11/U
4BQ 070 052/066 052/067 048/059 043/061 039/066 043/072
    1/B 24/T    66/R    66/W    42/W    01/U    11/U
BHK 065 049/059 049/060 048/058 042/059 040/064 043/070
    1/E 23/T    66/R    76/W    42/W    11/U    11/U
SHR 066 049/068 049/065 045/058 042/061 041/067 043/073
    1/B 35/T    76/R    75/W    31/B    11/U    11/U




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