Area Forecast Discussion
Issued by NWS Great Falls, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KTFX 240131
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
731 PM MDT Tue Sep 23 2014

.UPDATE...

Increased PoPs/QPF across Hill, Chouteau, Fergus and Blaine counties
through midnight as scattered showers and isolated thunderstorms
move over the area. These showers have been gradually diminishing
over the last few hours and should end by midnight. In addition,
there are a few showers approaching the Continental Divide so have
kept a slight chance pops in the higher terrain along the divide
through midnight. Precipitation amounts with these showers will be
less than one-tenth of an inch. Brief gusty winds of 20 to 30 mph
are also possible. The remainder of the forecast is on track so
made no further changes. MLV

&&

.AVIATION...
UPDATED 2345Z.
A line of showers and isolated thunderstorm continues to move
eastward through the region...and will affect areas mainly east of a
line from Cut Bank...to Great Falls to Bozeman. Most of the precip
should diminish between 03z and 06z Wed. Mainly VFR conditions are
expected overnight...and through the day on Wednesday.
However...surface winds will increase quite a bit over much of North
Central MT during the afternoon hours. Brusda

&&

.FIRE WEATHER...Winds across the Northern Rockies will
strengthen through the night and become strong and gusty Wednesday
afternoon. Relative humidities will drop below 20 percent along
the slopes of the Rockies and adjacent plains. Grasslands and
fields in the region have become very dry. Due to the combination
of winds, humidities and dry fuels, a Fire Weather Watch has been
issued for Wednesday afternoon and evening.

&&

.PREV DISCUSSION...
/ISSUED 545 PM MDT Tue Sep 23 2014/

Tonight through Thursday...A deep trof is over the Eastern Pacific
and southwest flow ahead of this system is bringing moisture towards
Central Montana. Mid-level winds will strengthen during the night
and overnight lows remain quite moderate in some locations. Warm
conditions will continue as the air mass will be quite warm and near
record max temps are expected Wednesday. Conditions will become
slightly unstable Wednesday afternoon across the southern half of
the CWA but without the moisture needed for development. In the
upper levels, a jet will move across the Pacific Northwest and
across the Northern Rockies Wednesday. Strong gusty winds will
develop across the Northern Rockies and adjacent plains. With some
dry conditions existing across the northwest, a fire weather watch
has been issued for Wednesday afternoon and evening for that area.
The low pressure trof over the Eastern Pacific remains nearly
stationary and Central Montana will continue to be influenced by
upper level high pressure. The air mass will remain dry, stable, and
warm through Thursday, and near record max temps are again possible
Thursday. Zelzer

Thursday Night through Tuesday...Medium range models are in good
agreement with the general unsettled pattern through this period
with a significant cool down. However, there are some minor
placement differences with regards to precipitation throughout the
period, so have gone with a continued compromise solution.

The deep upper level trough of low pressure, with its axis off the
Pacific coast, will continue to move onshore through Saturday. The
resulting moist and unstable southerly flow aloft will bring an
increasing chance of showers and thunderstorms to the area. The
trough will become more negatively tilted Saturday night through
Sunday night, which will bring a more southeasterly flow to the area
that will tap into some moisture from the Gulf of Mexico. Diffluence
aloft will also increase in this flow configuration, which will add
lift to the system. A cold front in Canada will also move south
nudging into north central Montana Friday night into Saturday,
shifting winds to a more upsloping northerly direction. With this
combination of moisture, lift, and upslope, chance of showers will
increase into the likely category for much of the area. Mention of
thunderstorms also appropriate for the southern and eastern portions
of the area. Temperatures in the 70s to lower 80s on Friday will
generally fall into the mid 50s to 60s on Saturday. The trough will
begin moving off to the east out of the area Monday into Tuesday,
and although models differ on the exact details during this period,
they do agree on keeping temperatures cooler and weather unsettled
with a chance of showers and a lesser chance of thunderstorms. Highs
will generally stay in the mid 50s to mid 60s and lows will fall
into the mid 30s and 40s. Mountain locations will likely receive at
least a light rain/snow at times through the weekend and into the
early part of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  89  54  88 /  10   0   0   0
CTB  48  87  44  82 /  10   0   0   0
HLN  53  89  52  87 /  10   0   0   0
BZN  49  85  47  85 /  10   0   0   0
WEY  37  74  35  75 /  10   0   0   0
DLN  51  83  48  82 /  10   0   0   0
HVR  52  91  52  89 /  20   0   0   0
LWT  53  89  54  90 /  20   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH from Wednesday afternoon through Wednesday
evening Eastern Glacier...Eastern Pondera...Liberty...Northern
Rocky Mountain Front...Toole.

&&

$$

weather.gov/greatfalls
www.twitter.com/NWSGreatFalls
www.facebook.com/NWSGreatFalls




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.