Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 292043
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
243 PM MDT Sun Mar 29 2015

.DISCUSSION...

Tonight through Tuesday...An upper level high pressure ridge is over
the West Coast. High level moisture associated with a shortwave
moving over the top of the ridge has been moving across the Rockies
but lower levels will remain dry. However, this shortwave will keep
a surface pressure trof in place over Alberta and keep breezy
conditions across the slopes of the Rockies through the night. The
ridge will be over the Rockies Monday and a low pressure trof will
approach the West Coast Monday night and move on shore Tuesday.
Winds aloft will strengthen as the shortwave approaches but not much
support for damaging winds except over the Northern Rockies. With
the ridge moving east of the zones Monday night, heights aloft will
be dropping and the air mass will destabilize. The approaching
shortwave has been slowed by the models over the past two days and
this slower movement will allow daytime heating ahead of the front
to further increase instability and a chance of thunderstorms will
develop Tuesday afternoon. Zelzer

Tuesday Night through Sunday...Similar to yesterday`s discussion,
latest forecast model solutions have further slowed the shortwave
trof and its associated cold front and precipitation arriving Tues.
Cold frontal passage and much of the valley rain/mtn snow are now
projected to move through our region on Tues eve and overnight.
Precip amounts haven`t changed much though, with just a few
hundredths to around a tenth of an inch expected.  Once that system
departs to the east, we`ll see cool, moist northwest flow persist
from Wed eve through Fri morning.  Some weak disturbances and
patches of moisture will move through the flow during that time,
generating periods of scattered rain/snow showers across the
region.  Again, precip amounts are expected to be minimal, with the
highest values expected to occur over the southwest counties. Models
are now in better agreement that a weak high pressure ridge will
bring more westerly flow aloft and dry conditions from Fri aftn
through Sat eve. By Sun, another Pacific weather system arrives with
more scattered showers. High temperatures will be close to seasonal
averages (low to mid 50s) each day for the remainder of this week.
Waranauskas

&&

.AVIATION...
UPDATED 1800Z.
Gusty west-southwesterly winds will continue along the Rocky
Mountain Front and adjacent plains today. Wind gusts at KCTB/KGTF of
up to 30 kts are possible with gusts 20 to 25 kts at KHVR/KLWT. Wind
gusts of 15 to 20 kts are possible at KHLN and winds will remain
light and variable at KBZN. Infrared satellite shows a Chinook Arch
developing on the lee side of the Rockies which will yield partly to
mostly cloudy skies will persist with mainly dry conditions also
expected. Overall, VFR conditions will prevail over the next 24
hours. MLV

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  70  45  69 /   0   0   0  20
CTB  42  66  42  61 /   0   0   0  10
HLN  41  70  41  68 /   0   0   0  20
BZN  32  70  36  71 /   0   0   0  30
WEY  25  57  29  60 /   0   0   0  20
DLN  36  68  39  68 /   0   0   0  20
HVR  36  69  37  72 /   0   0   0  20
LWT  40  68  43  75 /   0   0   0  20

&&

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

$$

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