Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 230917

Area Forecast Discussion
National Weather Service Billings MT
317 AM MDT TUE AUG 23 2016

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

An unseasonably deep upper low was working slowly across southern
Canada. This system has pushed a cold front through the area which
will lead to temperatures 10-15 degrees cooler than Monday. The
bulk of the coolest air will swing in this evening with a
secondary cold frontal passage. Not much in the way of moisture
around despite cyclonic flow. Today will be breezy with 850mb
winds hovering around 25kts. Dewpoints have struggled to recover
from very low readings of Monday. Not much dewpoint relief over
the north, but cooler air and ever so slightly higher dewpoints
should lead to humidity minimums in the upper teens to around 20
percent. Given reports over most of the area, that recent rainfall
has tempered fire concerns a bit, will not issue a Red Flag for
today. Looks to be a borderline event, although humidity values
might end up lower than forecast if the slightly higher dewpoint
air over northern Montana does not swing south quickly.

The main cold front will drive through this evening and this will
lead to highs struggling to get out of the upper 60s on Wednesday.
Will keep low pops over the west with low level upslope flow but
limited moisture will keep the chance of showers down. Winds will
be up again Wednesday with cold air advection and 850mb winds at
25kts. Winds will decrease Wednesday evening and lead to a cool
night with temperatures falling into the lower to mid 40s, which
would be 10-15 degrees below normal. TWH

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

Models appear to have come into better agreement for the latest
run...through about Monday...when upper level Pacific low begins
moving. ECMWF opens the trof and shifts it eastward...meanwhile
GFS deepens the low and digs south into northern Oregon before
bringing east.

Overall troffiness prevails over the area Thursday through
Friday...and several shortwaves through the flow should support
showers and isold thunder each day. Timing of waves continue to well as coverage of qpf...but looks like generally
unsettled pattern at this point. Therefore introduced more
broadbrushed pops. Temperatures will be well below normal Thursday
and Friday with readings in the lower and middle 70s.

Shortwave ridging builds in for Saturday and Sunday...with return
of dry dry conditions and temps in the 80s. Flow aloft transitions
to southwesterly Sunday night...and bringing more energy into the
high terrain...for another chance of precip across the region
Monday. Differences in models make it difficult to nail down
specific for the end of the period...but appears to be another
round of unsettled weather on tap. AAG



VFR conditions prevail across the region today...under clear to
partly cloudy skies. Northwest winds will prevail across the this
today. Some low level wind shear is possible over eastern
routes...including KMLS and KBHK terminals this morning...with 30
knot northwest winds just above the sfc. Eastern routes will see
gusts of 20 to 25 knots this afternoon. AAG



    Tdy Wed     Thu     Fri     Sat     Sun     Mon
BIL 078 051/068 049/070 051/073 051/084 055/086 055/084
    0/U 01/B    12/W    12/T    21/U    12/T    22/T
LVM 075 044/067 043/067 043/073 046/082 049/084 049/083
    1/U 12/T    22/W    22/T    21/U    12/T    22/T
HDN 080 050/071 047/073 049/075 049/084 054/087 053/086
    0/U 01/B    12/W    12/T    21/U    11/U    22/T
MLS 079 053/071 049/073 052/076 053/085 057/088 057/086
    0/N 01/N    11/B    13/T    31/U    11/U    22/T
4BQ 079 051/069 047/071 049/075 052/083 056/087 055/086
    0/U 01/B    22/T    23/T    32/T    11/U    12/U
BHK 077 050/068 045/071 048/072 049/081 053/085 054/084
    0/N 01/N    12/T    33/T    32/T    11/U    12/U
SHR 078 047/068 045/070 045/074 047/083 051/086 051/085
    0/U 01/B    23/T    32/T    21/U    11/B    22/T




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