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Area forecast discussion 
National Weather Service Billings Montana
319 am MDT Sat Apr 18 2015

Short term...valid for today and sun...

We are still anticipating a vigorous short wave clipper type
system in the northern stream moving quickly through Montana this
morning. This feature dives east/southeast today phasing with the
upper low coming out of the central/southern rockies by tomorrow

Current indications are a frontal passage at Billings around 930 am
this morning...and through the entire forecast area before late
afternoon. Pressure tendencies do not look impressive with
pressure rises only up to 5 mb per 6 hours behind the front...and
850mb winds are well below 50 kts for the most part. Thus...I
still do not see a need for any wind highlights. We should see
initial strong gusts and switch to northerly winds with the
front...then some stronger gusts again in the afternoon with
subsidence and 700mb winds increasing.

Despite the weather highlights do not look necessary
as humidities never get a good chance to bottom out. There
continues to be some decent q vector forcing associated with the
system...and some of this runs into the moisture swinging up from
the upper low over the central rockies. So proggs continue to
paint quantitative precipitation forecast over the higher terrain and eastern border counties
while keeping our north central zones pretty dry. We have had this
handled pretty good so there was little change to the probability of precipitation for
today and tonight. Might be some isolated thunder in the east
late...but left it out for now as unsure if instability from
southern moisture will be enough to counter subsiding air later
behind front. Air behind system is not very snow should
be limited to higher mountains...going into tonight while
precipitation ends over the plains before midnight.

As the short wave phases with the upper low on the plains Sunday
our region falls under a brisk northwest flow. Some instability
is apparent and may produce some light precipitation over the
mountains and nearby foothills...with a little energy still
affecting our far eastern border zones as well. Otherwise...look
for a bit cooler day with brisk winds...especially in the east. Bt

Long term...valid for Monday...Tue...Wed...Thu...Fri...

Northwest flow dominates the early part of the extended period as
an upper level ridge entrenches itself over the western Continental U.S..
freshened up the forecast to tweak temperatures and winds ever so
slightly based on most recent model guidance. Based on slower
model solutions...the warmest temperatures at 850 mb will now occur on
Wednesday...averaging around 15c across the western and central
zones. That will translate into a pretty nice day Wednesday...with
Mercury readings well into the 70s at most locations. As far as
impacts go...there are not many to write about. Chances for precipitation
are few and far between...with the best opportunity coming very
late in the period with the onset of larger trough with an
associated vorticity maximum over western Montana. Singer


VFR conditions should prevail at all terminals through the day
today. Light winds will give way to gusty northerly winds with the
onset of a cold front that will move in from the west by the
early afternoon. All terminals could see gusts upwards of 40 miles per hour
with the frontal passage. Singer


Preliminary point temp/pops...

Today sun Monday Tuesday Wednesday Thursday Friday
bil 061 035/056 034/060 037/071 041/074 043/071 041/068
2/west 10/b 00/b 00/u 00/u 13/west 33/west
lvm 060 032/055 033/064 035/073 038/076 039/073 038/067
3/west 22/west 01/b 00/u 11/b 24/west 33/west
hdn 063 033/058 033/063 035/072 035/076 036/073 034/072
2/west 10/north 00/b 00/u 00/u 12/west 22/west
mls 066 034/056 032/060 034/070 036/072 038/070 036/067
1/north 10/north 00/u 00/u 00/b 11/b 22/west
4bq 065 031/055 029/058 032/069 033/071 036/071 035/066
2/west 10/north 01/b 00/u 00/b 11/b 22/west
bhk 064 033/051 028/055 030/067 032/067 033/063 032/058
3/west 12/west 01/u 00/b 00/b 11/north 22/west
shr 060 032/053 031/059 032/067 036/072 037/072 037/067
3/west 20/north 01/b 00/u 00/u 13/west 34/west


Byz watches/warnings/advisories...



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