Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 271205
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
605 AM MDT FRI MAY 27 2016

UPDATED AVIATION SECTION

.DISCUSSION...
Today through Sunday...The airmass remains unstable today as an
upper trof begins to push into the area from the west. The
southwest flow aloft will become increasingly diffluent this
afternoon. Additionally, the trof will push a cold front across
the area this afternoon. Showers and thunderstorms will develop
behind the front. Models indicate the best chances for convective
activity will be east of a Cut Bank to Great Falls to Helena line.
Severe storms are not anticipated as CAPE values are generally
less than 200 J/kg and bulk wind shear values will be in the 30
to 35 kt range. QPF amounts will likely fall between a quarter
inch to a half inch. Convective activity will push into the
eastern portion of the county warning area this evening before
ending by daybreak Saturday. West winds Saturday will bring drier
air to the area though a few lingering showers will persist over
the western and southwest mountains. Another upper trof will move
east of the continental divide Sunday bringing another round of
scattered showers and/or thunderstorms to the western and
southwest mountains Sunday afternoon. Temperatures will remain
near to slightly below seasonal averages through the period.

Sunday Night through Friday...A shortwave trough is forecast to
cross the PacNW Sunday night. This will produce showers and
thunderstorms across North-central and Southwest MT on Memorial Day.
Model solutions begin to vary on Monday with the intensity and speed
of motion for this wave. Have followed WPC`s lead and opted for a
model blend and keeping rainfall generally below 0.5 inch.  Snow
will be possible again Sunday night and Monday night at elevations
above 7000 feet. Tuesday`s forecast presents a challenge due to the
differences in which models carry the trough away to the east. A
strong and resilient upper level ridge is anticipated to develop
sometime on Wednesday and persist through next weekend. Temperatures
will finally move above average, with  a slight chance for mainly
mountain showers and isolated thunderstorms. PN

&&

.AVIATION...
UPDATED 1205Z.
The airmass will destabilize after 18z as an upper level disturbance
and a surface cold front move across the area. Showers and/or
thunderstorms will develop again after 20z and continue through 04z.
VFR conditions prevail with MVFR conditions possible in the vicinity
of showers and/or thunderstorms. Gusty erratic winds are also
possible near thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  41  62  40 /  50  50  10  10
CTB  61  37  60  38 /  20  30  10  10
HLN  61  41  63  42 /  60  50  20  10
BZN  62  39  62  38 /  60  70  20  10
WEY  54  34  53  32 /  40  50  20  10
DLN  58  38  60  38 /  60  60  20  10
HVR  67  45  65  42 /  40  60  20  10
LWT  62  42  61  41 /  60  70  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/greatfalls


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