High Wind in Montana, April 5 to 9, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1225 AM MDT Sat Apr 5 2014

.UPDATE...

A relatively weak shortwave disturbance embedded within WNW flow
aloft is moving across the region this morning. Precipitation is
fairly limited with this system and mainly confined to areas near
the Continental as well as the SW MT mtns. Skies are clear to
partly cloudy across north central MT this morning and have made
some adjustments to cloud-cover. Another round of weak shortwave
energy moves into the region this afternoon, and this combined
with a more unstable airmass will likely result in a somewhat
better coverage of scattered showers over much of the forecast
area. Hoenisch

&&

.DISCUSSION...

&&

.AVIATION...
UPDATED 18Z.
Weak high pressure will build aloft today. Winds aloft will mix down
across the Rockies and adjacent plains, and cause brisk surface
winds through the afternoon and evening. A  weak disturbance will
move through area late Saturday night. Chances of precipitation will
remain over the higher terrain. VFR conditions will prevail
through the next 24 hours except for some mountain obscuration over
the Rockies after midnight Saturday night.

&&

.PREV DISCUSSION...
/ISSUED 527 AM MDT Sat Apr 5 2014/

Today through Monday...Forecast models continue to keep the
weather pattern breezy through this period with unsettled
conditions through Sunday, but the pattern becomes quieter for
Monday. Scattered showers associated with the lingering frontal
boundary over southwest Montana will decrease somewhat this
morning. However, clouds and showers will increase again this
afternoon through tonight and Sunday across much of the area as
another shortwave trough moves into Montana tonight and a
stronger one follows closely behind it on Sunday. Energy and lift
associated with this series of disturbances is only moderate at
best and moisture is only slightly high for this time of year, so
am not expecting significant precipitation with the overall
system. However, snowfall of 3 to 6 inches is possible above
mountain pass level. A weak frontal boundary will also move south
out of Canada on Sunday, which will combine with weak instability
to bring a slight chance of thunderstorms to the area during the
day. These shortwaves are embedded in a fairly breezy westerly
flow aloft, which should blanket much of the area with very breezy
westerly winds, especially during the daytime hours. Though
widespread high winds are not expected, the situation will need to
be monitored for locally strong winds in favored areas.
Temperatures through this unsettled period will generally remain
near seasonal averages. Sunday night into Monday, the shortwaves
will exit the area and an upper level ridge of high pressure will
build into the area from the west. The northwesterly flow aloft on
the leading edge of this ridge will continue to be somewhat
breezy, which should translate to breezy westerly winds across at
least north central Montana on Monday. Otherwise, the main impact
of this ridge will be to bring drier and warmer weather.
Coulston

Monday night through Saturday...A high pressure ridge will be
over the Pacific Northwest Monday night and gradually move over
the zones Tuesday. Disturbances in the flow aloft will mainly be
over Canada and the airmass over central Montana will remain dry.
However, the flow over Canada will deepen the surface low
pressure trof along the lee of the Rockies. This will strengthen
winds and trend into a very windy period late Tuesday night. A
shortwave will move over the West Coast early Wednesday and move
across the zones by Wednesday afternoon. An associated cold front
will move south out of Canada and this will bring showers across
the region and, since the air mass becomes slightly unstable
Wednesday afternoon, a slight chance of afternoon thunderstorms.
Very strong winds will continue ahead of the cold front late
Tuesday night and Wednesday morning. Winds will continue strong
near frontal passage but begin to diminish later in the day. The
shortwave will pass east and weak high pressure will build
Wednesday night. The flow aloft will remain disturbed ahead of a
low pressure trof moving over the Pacific Northwest Thursday
night. Friday will bring widespread showers with cooler
temperatures--and snow will again be expected. Some differences
are still in the model solutions at this point as the GFS is
deepens the trof more the the ECM. Overall, expect temperatures
to drop below seasonal normals as we move into the weekend.
Zelzer

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  35  52  34 /  20  20  40  20
CTB  52  34  51  33 /  20  20  30  10
HLN  55  35  54  34 /  30  40  40  10
BZN  52  31  51  29 /  40  30  50  20
WEY  45  24  44  21 /  40  30  50  20
DLN  51  32  51  31 /  30  40  40  10
HVR  59  33  55  31 /  20  20  40  20
LWT  52  31  49  30 /  20  20  50  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

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