Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 041742
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1042 AM MST Wed Mar 4 2015

.UPDATE...Overall forecast is in generally good shape but have
updated to increase winds along the Rocky Mountain Front for the
entire short term period. Cross-barrier flow aloft is expected to
be generally 30 to 40 mph though this period. Additionally,
surface pressure gradients increase above 100 microbars per
kilometer by early Thursday morning. This combination will bring
wind gusts through favored canyons and passes quite near to high
wind criteria so this will be monitored for potential highlights.
Have also decreased cloud cover for today to be more in keeping
with satellite observations and newest model runs. Temperatures
remain on-track and no precipitation is expected through the
period. mpj

&&

.AVIATION...
UPDATED 01741Z.
High pressure is building aloft and the airmass is beginning a
lengthy period of warming and drying. A weak disturbance will move
through the flow aloft Thursday and help strengthen surface winds
across the Rockies and adjacent plains. VFR conditions will prevail
thought the next 24 hours.

&&

.PREV DISCUSSION...
/ISSUED 447 AM MST Wed Mar 4 2015/
Wednesday through Friday...Upper level high pressure ridge will
begin building in from the west as the early week low pressure
trough and its associated snow and cold move off to the
east/southeast. There are a few embedded disturbances riding
through the ridge that will keep skies partly to mostly cloudy
through the remainder of the week, however with limited moisture
available, chances of any precipitation are low. As the ridge
begins to build in aloft, a surface low pressure trough will
develop along the east side of the Rocky Mountain Front. The
resulting Chinook winds will usher in some warmer air for a
warming trend that will continue through the end of the week.
Temperatures are expected to be near to slightly above seasonal
averages Thursday and Friday.

Friday Night through Wednesday...Period begins with weak shortwave
trof working its way through MT, bringing widespread clouds but only
expected precipitation will be light, occasional snow showers along
the Rocky Mtn Front and over parts of the central/southwest mtn
ranges.  Our region remains under northwest flow aloft through the
weekend, then gradually shifts more westerly as broad high pressure
ridge along the Pacific Coast moves into the Great Basin and
Northern Rockies. The portion of the ridge over MT and southern
BC/Alberta is flattened a bit on Mon/Tues as a deep Gulf of Alaska
trof begins to dig south along the BC coast.  Forecast models, which
had been in good agreement up to this point, diverge late Tues into
Wed with the GFS bringing a sharp cold front and widespread light
snow into the state, while the ECMWF keeps the low pressure system
along the West Coast, with the ridge and its dry conditions
persisting over MT.  Forecast grids lean more toward the EC solution
at this point, but do have a mention of slight chance for showers
along the Hiline and Rocky Mtn Front Wed aftn/eve.  Finally, the
dominant ridge pattern will produce above normal temperatures for
most of this forecast period, with upper 40s to mid 50s for weekend
and mid-upper 50s for early next week.
Waranauskas

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  30  19  45  27 /   0   0   0   0
CTB  30  20  45  27 /   0   0   0   0
HLN  35  18  47  29 /   0   0   0   0
BZN  30  12  44  22 /   0   0   0   0
WEY  30   3  35   9 /   0  10   0   0
DLN  35  15  47  24 /   0   0   0   0
HVR  26  12  45  23 /   0   0   0   0
LWT  25  15  44  26 /   0   0   0   0

&&

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

$$

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