Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 252335

Area Forecast Discussion
National Weather Service Great Falls MT
533 PM MDT Tue Oct 25 2016



Tonight through Thursday...Moisture ahead of a shortwave trough will
bring scattered showers to the mountains of Western and Southwest
Montana through tonight. A few light showers may also move across
North Central Montana after midnight, but breezy westerly downslope
winds will hinder significant rainfall. An upper level high pressure
ridge will then build back into the area on Wednesday in the wake of
the shortwave. The resulting moist westerly flow aloft will keep
shower activity over Northwest Montana to the Continental Divide,
while continued gusty westerly winds along the Rocky Mountain Front
keep the plains dry. The ridge will then shift east into the Great
Plains Wednesday night into Thursday, but the resulting southwest
flow aloft and increasing southwest downslope winds will keep
precipitation along and west of the Continental Divide. Wind gusts
on Thursday will mostly be in the 25 to 35 mph range over North
Central Montana, but 40 to 55 mph gusts are possible closer to the
Rocky Mountain Front. Light measurable snow will be possible, but
mainly above 8000 feet. Temperatures will cool a few degrees over
today in the wake of the shortwave, but the downsloping winds will
warm temperatures to about 10 degrees above normal on Thursday.
Overnight lows will remain mild and mostly in the mid 30s to lower
40s.  Coulston

Thursday Night through Tuesday...

AFTERNOON UPDATE: A few minor changes needed for the long term
today. Morning models have the late week system progressing a little
faster...placing rain in the sw Friday morning...spreading northeast
through the day. Rain then lingers through the evening into the
overnight hours. Increased pops during this period to include likely
across many areas. Models also painting higher QPF than previously
indicated...with 0.20 to 0.50 inches possible from Great Falls to
Lewistown and south...with the higher amounts coming across the
south. Brief ridging looks to diminish showers
Saturday...however...GFS indicating a weak wave may bring a few
scattered showers Saturday evening into Sunday. Sunday night through
Halloween is still seeing model differences. GFS and Euro now
indicating more of a weak progressive wave. Either solution still
indicates rain possible for Sunday night into
Halloween...however...the coverage and amount of rain is only at mid
confidence. Models are also indicating rain showers could diminish
by trick or treat time Monday evening. Those with Halloween plans
should keep an eye on the latest forecasts. Please see previous
discussion for further break down of the weather pattern details.

PREVIOUS FORECAST DISCUSSION: A shortwave system ejects from the
Eastern Pacific low and crosses the Great Basin Thursday night.
Timing variations persist among model solutions, but all bring
widespread precipitation through western and central MT sometime on
Friday. One to two-tenths of an inch of rainfall may be possible on
Friday, with higher totals in the mountains. Snow levels of 6500 ft
msl or higher would preclude any impacts for travel over mountain
passes. This system exits quickly with mild and generally drier
conditions for Saturday. The next wave moves through Oregon on
Sunday, and spreads precipitation through our region from the
southwest Sunday night into Monday. As this system passes through,
the flow aloft transitions to a more unsettled zonal pattern.
Temperatures remain above average through the period. PN


.AVIATION...Updated 2330Z.

Moist southwest flow aloft will continue over Central and Southwest
Montana through Wednesday. A weak disturbance aloft will keep
isolated showers mainly over the western mountains. Elsewhere,
mostly dry conditions will continue through Wednesday. VFR
conditions will prevail through the next 24 hours.


GTF  42  63  47  65 /  10  10  10  10
CTB  37  57  40  59 /  10  10  10  10
HLN  41  65  42  64 /  10  10  10  10
BZN  41  65  42  66 /  10  10  10   0
WEY  34  53  29  57 /  20  10  10  10
DLN  39  64  39  63 /  10  10  10  10
HVR  40  59  41  63 /  10  10  10  10
LWT  42  63  44  67 /  10  10  10  10



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