Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 291607
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1007 AM MDT Mon Sep 29 2014

.UPDATE...

Patchy fog observed this morning appears to be lifting to a broken
low stratus based on surface observations, web cams, and visible
satellite image. Radar depicts a patch of light rain showers
lifting toward the north-northwest through Fergus, Judith Basin,
and eastern Cascade Counties. This activity is associated with an
embedded shortwave rotating through the Great Basin trof. Short
term model guidance supports observed trends for this rain to
dissipate as it moves further north and west. Freshened POPs and
weather to reflect these observations. Meanwhile, surface pressure
falls are noted in southern Alberta and into Glacier county.
Expect this lee surface trof to continue deepening with a
corresponding increase in winds this afternoon. Nutter

&&

.AVIATION...
UPDATED 0450Z.
Widespread low clouds and IFR/LIFR conditions can be expected over
the region through the period. Mountains will be obscured. Light rain
showers will affect areas mainly east of a Havre to Helena line
today. Expect the steady rain to diminish around 00Z Tue...with
scattered showers over much of the region during the overnight
hours. Brusda

&&

.PREV DISCUSSION...
/ISSUED 550 AM MDT Mon Sep 29 2014/
Today through Wednesday...The main message for the first part of the
week is cool and unsettled weather. For early this morning small
temperature-dew point spreads should result in patchy fog. Still do
not have much confidence as to which areas will be favored for
this fog. Otherwise today an upper low over the Great Basin will
move into southwest Montana this afternoon. A weather disturbance
aloft ahead of the upper low will affect eastern Montana.
Therefore the main chances for showers today will be over
southwest Montana and also near and east of a line from Havre to
Great Falls. Then overnight moisture along with the chance for
showers will increase from the west ahead of an upper trough which
will move into the Pacific Northwest. The remnants of this upper
trough then move into the forecast area Tuesday with another upper
trough to follow Tuesday night. The troughs will result in
isolated to scattered showers Tuesday and Tuesday night. The
Tuesday night upper trough will shift into eastern Montana
Wednesday as a temporary upper ridge moves into western Montana.
The ridge will bring increased sunshine and mostly dry conditions
Wednesday afternoon and additionally westerly winds to the east
slopes. Just how strong these westerly winds will be is in
question as the NAM model forecasts near high winds for the Rocky
Mountain Front Wednesday afternoon while the GFS model is much
lighter with wind speeds. For this forecast have gone in between
the two extremes. Blank

Wednesday night through Monday...It will continue to remain a bit
unsettled over the region through Thursday...as an upper level
disturbance moves southward through the region. Even though showers
will accompany this disturbance...the precipitation amounts will be
light...generally less than 0.10 inches and mostly over North
Central MT. The air mass continues to look cold enough that snow
will mix in with the rain in the mountains and over the Plains in
the Cut Bank area. But since any snowfall amounts should be less
than 1/2 inch...any impacts are expected to be minimal/if at all.
After this disturbance moves through...fairly quiet and nice weather
conditions are expected for Friday thru Sunday morning. For Sunday
afternoon and Monday...an unsettled northwesterly flow aloft will
try to set up once again...allowing for weak weather disturbances to
move through the northern portion of the region. Thus there will be
a chance for showers once again...mainly over the northern Rockies
and north of Highway 2 for Sunday afternoon through Monday.
Afternoon temperatures will be in the 50s Thursday...then in the 60s
for Friday through Monday...with a few lower 70s possible on
Saturday. Normal high temperatures for this time of the year are in
the lower to mid 60s. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  65  50  61  41 /  20  30  20  20
CTB  66  44  58  37 /  10  30  50  30
HLN  66  47  61  40 /  20  30  20  20
BZN  62  42  60  34 /  20  30  30  20
WEY  53  32  51  24 /  50  40  60  30
DLN  63  41  58  32 /  30  30  30  20
HVR  64  45  66  42 /  40  20  30  30
LWT  60  45  63  39 /  70  20  20  20

&&

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

$$

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