Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 181755
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1155 AM MDT Fri Apr 18 2014

UPDATE TO AVIATION

.UPDATE...

Decreased pops over the plains west of I-15 and southwest valleys
today and kept highest pops in the mountains and areas east of I-15.
Isolated to scattered showers will remain possible east of I-15
today as an upper-level disturbance moves across the area. Strong
westerly winds will continue along the Rocky Mountain Front and
adjacent plains and have kept current High Wind Warnings in effect
through 06z Saturday. The remainder of the forecast is on track
and made no further changes. MLV

&&

.AVIATION...
UPDATED 1755Z.
Windy conditions will continue to increase through the afternoon
ahead of a shortwave trough that will move through the region this
afternoon and evening. These strong gusty westerly winds will create
gusts of 45 kts to 55 kts over the Rocky Mountain Front and 35 to 45
kts farther east. Behind the weather disturbance expect decreasing
clouds with the exception of the high line where some lingering
showers are expected. Suk

&&

.HYDROLOGY...
Expect increased snow melt Monday through Tuesday as
snow levels range from 7000 to 8000 feet in the north to 8000 to
9000 feet in the south. As for precipitation from Tuesday night
through Thursday afternoon have high confidence that most
locations should see at least a quarter of an inch of
precipitation but some models are showing small areas receiving as
much as 1.5 inches to 2.5 inches during that time frame. Of course
with the model differences confidence in precipitation details is
very low at this point. The threat for flooding will increase with
increased snowmelt followed by increased precipitation. For
Wednesday and Thursday with the cooler temperatures snow levels
should drop to near or below 6500 feet. Blank


&&

.PREV DISCUSSION...
/ISSUED 548 AM MDT Fri Apr 18 2014/
Today through Sunday...An upper trof will move along the
U.S.-Canadian border today bringing scattered showers and cooler
temperatures as an associated cold front pushes across the area.
The surface pressure gradient will tighten and westerly winds will
become gusty by late morning. The strongest winds will occur along
the Rocky Mountain Front and over Glacier and Toole counties. A
high wind warning will remain in place for this area through
tonight. The upper trof moves quickly east and will cross into
northern North Dakota by evening. In it`s wake, high pressure will
build over the Pacific Northwest tonight and move east of the
Continental Divide Saturday. Dry conditions Saturday will also be
accompanied by temperatures reaching the 60s. The ridge,
unfortunately, will be short-lived as a weak upper trof moves
across southern Canada Saturday night/Sunday morning. This feature
lacks any significant moisture and its only effects should be an
increase in clouds and slightly cooler temperatures for Easter
Sunday. Winds will become gusty again Saturday night and into
Sunday though speeds will likely remain below warning criteria.
Temperatures will be near seasonal averages today and climb above
seasonal averages for the weekend.

Sunday night through Friday...Models are in decent agreement into
Tuesday but then significant differences show up. An upper ridge
will result in Sunday night being dry and quite likely Monday as
well. A strong upper trough off the west coast Monday will move into
the west coast states Tuesday with moisture increasing over the area
in the southwest flow aloft. Expect scattered showers to develop
over southwest Montana and spread to central Montana by afternoon.
There will also be a threat of thunderstorms. Precipitation will
increase Tuesday night. Will continue with the inherited forecast
which had chances of precipitation ranging from 70 pct to 100 pct
over a good portion of the forecast area. Models really begin to
diverge by Wednesday. The GFS is dry over most of the forecast area
and in particular over the plains. The ECMWF and GEM models continue
with precipitation over the entire forecast area. On Thursday the
GFS and GEM models have precipitation over the forecast area
associated with an upper low over the Dakotas. On the other hand the
ECMWF has an upper ridge over western Montana with dry conditions
except for possibly the western mountains and southwest Montana. Due
to model differences have stuck close to the inherited chances of
precipitation which show a gradual decrease. Still expect
unseasonably mild temperatures Monday and Tuesday before cooling
sets in the wake of a cold front Tuesday night. Blank

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  31  64  40 /  20  10   0   0
CTB  49  28  61  37 /  20  20   0   0
HLN  57  34  68  39 /  20  10   0   0
BZN  59  29  67  33 /  60  20   0   0
WEY  50  25  55  32 /  60  30   0   0
DLN  59  30  66  35 /  40  20   0   0
HVR  61  31  64  36 /  60  20   0   0
LWT  56  28  62  36 /  40  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING until Midnight MDT tonight Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front...
Toole.

&&

$$


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