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 201424
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
824 AM MDT Sun Apr 20 2014

.UPDATE...

After a cold front moved across the area last night, dry, mild and
breezy conditions are expected today for most of the area. The
only exception is in the higher elevations of the Rocky Mountain
Front where a few showers are possible through midday. Made a few
tweaks to sky cover this morning, otherwise no other changes were
made. MLV

&&

.AVIATION...
UPDATED 1135Z.
VFR conditions will prevail for the next 24 hours. A few showers
over Blaine County and far northern Fergus County should move east
of those counties by 8 am mdt. Also scattered showers over the Rocky
Mountain Front should mostly end by noon.  The main weather issue
today will be gusty west to northwest winds. Have at least average
confidence in forecast winds at the taf sites. Do be aware that
there could be isolated gusts to 45 knots through noon. Winds will
gradually diminish late this afternoon through overnight. Blank

&&

.HYDROLOGY...
Expect increased snow melt Monday through Tuesday as snow levels
rise to between 8500 and 9500 feet by Tuesday. With better agreement
amongst the models regarding precipitation details it now looks like
most lower elevations will receive from 0.4 inch to 0.7 inch
precipitation with mountains receiving from 0.7 inch to a little
over an inch with the bulk of the precipitation falling Tuesday
afternoon and Tuesday night. The convective nature of precipitation
Tuesday evening could result in localized heavier amounts than those
listed above. The threat for flooding will increase early next week
with increased snowmelt followed by widespread precipitation Tuesday
afternoon and night. For Wednesday and Thursday, cooler temperatures
and lower snow levels should reduce runoff from snowmelt at higher
elevations. Blank

&&

.PREV DISCUSSION...
/ISSUED 535 AM MDT Sun Apr 20 2014/

Today through Tuesday...A Pacific cold front associated with a
shortwave trough moving east along the US/Canadian border will
clear eastern portions of the forecast area early this morning.
Main impact from this feature will be gusty winds, especially over
areas along the Rocky Mtn Front and east along the MT/AB border.
Wind gusts so far have peaked around 40kts and confidence is
somewhat low that gusts in excess of 50 kts will be any more than
isolated in the High Wind Warning area, but with the wind maximum
at around 6000ft present through the morning period will keep the
highlight going. Aside from a few isolated showers along the
Continental Divide as well as the Hill/Blaine county areas early
this morning, dry conditions will prevail with broken cloud-cover
early this morning clearing from west to east behind the shortwave
trough. Upper level ridging moves east over the region tonight
through Monday for continued dry conditions with temperatures
warming from near seasonal averages today to around 10 degrees
above seasonal averages on Monday. Winds will also diminish
tonight and remain relatively light from the east to southeast
through Monday and Monday night. On Tuesday, A deep upper level
trough moves into the interior western US with an inverted trough
of low pressure at the surface strengthening over central MT
Tuesday afternoon as the initial shortwave and upper level Jet
energy associated with the upper level trough move into the region
from the SW. Expect showers to develop and become widespread
Tuesday afternoon with marginal instability allowing for the
development of a few weak thunderstorms as well late Tuesday
afternoon. Hoenisch

Tuesday night through Sunday...The main message during the period is
models have gotten into better agreement with the midweek system in
comparison to a day ago. The latest ECMWF run is much stronger with
the system than previous runs and is more like what the GFS has been
advertising as far as strength goes. On the other hand the GFS is
farther north with the system and is more like the ECMWF in this
regard. Models forecast a weather disturbance aloft to lift
northeast through the area Tuesday night as a surface cold front
moves east. As has been advertised this period should see the
greatest precipitation. An upper low will develop over southeast
Alberta or southwest Saskatchewan by late Wednesday though the GFS
is a little farther south. The westerly flow aloft and at the
surface on the south side of the upper low will lead to downslope
effects and have lowered chances of precipitation for some areas as
well as precipitation amounts. Then for Wednesday night the
circulation on the back side of the upper low should spread
precipitation south into north central and central Montana and have
increased the chances of precipitation for those areas.
Precipitation should then diminish as an upper ridge moves into
central Montana Thursday night. Thereafter southwest flow aloft will
develop and moisture will increase. Due to model differences with
regard to precipitation details did not go real high with the
chances of precipitation but did raise inherited values a little.
Blank

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  60  34  68  45 /   0   0   0   0
CTB  57  30  66  39 /   0   0   0  10
HLN  61  37  69  44 /   0   0   0  10
BZN  63  32  70  40 /   0   0   0  20
WEY  56  30  61  35 /  10   0   0  30
DLN  62  34  68  41 /   0   0   0  10
HVR  65  31  70  40 /  10   0   0   0
LWT  58  32  66  40 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING until 6 PM MDT this evening Eastern Glacier...
Liberty...Northern Rocky Mountain Front...Southern Rocky
Mountain Front...Toole.

&&

$$


weather.gov/greatfalls
www.twitter.com/NWSGreatFalls
www.facebook.com/US.NationalWeatherService.GreatFalls.gov





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