Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 220533
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1133PM MDT Tue Oct 21 2014

.UPDATE...
Surface cold front has passed through central and southwest
Montana. Isolated strong wind gusts and occasional lightning
strikes were observed along the leading edge of the cold front.
Pressure rises over the region are allowing wind gusts to settle
down as cooler air moves in. Rain has been steady over the north
central plains, with snow observed on highway passes across the
southwest. This activity will continue to move away to the east
by around 0400 UTC. Shortwave ridging aloft develops quickly by
12Z, and so expect skies to clear quickly by morning. With this
update have freshened POP/QPF and hourly temperature grids to
better match observations this evening. Will need to continue
monitoring for the possibility of patchy dense fog in the morning.
Nutter

&&

.AVIATION...
UPDATED 0533Z.
Radar and surface observations depict an area of stratiform
precipitation remaining over north-central MT at 05z which will
continue to affect KHVR early in the period. This is working its way
to the east and weakening, so should start to see some clearing this
area after 08z. Other terminals already seeing some clearing, and
expect mostly VFR conditions. Exception will be development of some
fog between 10z and 13z, particularly at KBZN and KHLN. This could
bring conditions down to MVFR and possibly IFR during the morning.
00Z KGTF balloon reports freezing level at 072 MSL, so expect icing
from around FL 070 to 180 MSL through 0300 UTC.

&&

.PREV DISCUSSION...
/ISSUED 551 PM MDT Tue Oct 21 2014/
Tuesday through Thursday...Showers will continue to develop
and move through the area as a low pressure system tracks across
the area this afternoon and evening. Most of the precipitation is
expected to move off to the east overnight. Higher elevation
locations especially over the Rocky Mountain Front and Southwest
Montana can expect some light snow accumulations with this system
with the biggest impacts being to area passes with roadways
becoming snow covered and slippery overnight. A weak shortwave
ridge will build into the area behind the system passage and
temperatures should rebound back above seasonal averages by
Wednesday with warm and dry conditions also extending into
Thursday. Suk

Thursday Night through Tuesday...Overall, seasonably mild weather
expected as a progressive pattern steers a series of Pacific low
pressure troughs through the area during the period. High pressure
ridge centered over the Rocky Mountain states at start of period
quickly gives way to Pacific low pressure trough during the weekend.
Models are in relatively close agreement with timing and strength of
system as it moves through with both ECMWF and GFS calling for
temperatures 10 to 15 degrees cooler and areas of rain or snow
showers, mainly over the west and southwest mountains. Downslope
winds will limit precipitation chances over the plains and valleys.
This low pressure trough starts working off to the east on Monday
with high pressure again rebuilding briefly before the next trough
begins pushing in Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  61  44  65 /  70   0  10  10
CTB  36  61  41  63 /  20   0  10  20
HLN  37  62  39  65 /  40  10  10  10
BZN  29  56  31  64 /  70  10  10  10
WEY  24  46  23  52 /  50  10  10  10
DLN  32  56  37  61 /  50   0  10  10
HVR  39  63  39  68 /  60  10   0  10
LWT  38  61  39  67 /  50  10  10  10

&&

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

$$

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