Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 290451

1050 PM MDT Sun Sep 28 2014

Updated Aviation Discussion


While a few sprinkles or drizzle is possible this evening, the
main update for tonight was to add patchy fog across the forecast
area. Forecast confidence was low regarding which locations will
receive fog, however With abundant low-level moisture in place,
there will at least be the potential across most areas. Also
lowered pops through Midnight for portions of the plains based on
current radar trends. As additional moisture and a weak upper-
level shortwave move over southwest Montana late tonight and
Monday, have kept chance to likely pops but qpf amounts will be
low. The remainder of the forecast is on track so did not make
any further changes. MLV


An upper level low pressure system currently centered over NV/UT
will lift NE across the ID/WY late tonight through Monday,
maintaining a relatively moist Southeasterly flow aloft over the
region through Monday morning, becoming southwesterly Monday
afternoon and evening. Low clouds and mtn/terrain obscuration will
persist through much of tonight though precipitation will be light
and mainly limited to SW MT. Potential exists for fog at most
terminals tonight as low levels remain very moist, however
confidence in extent and density is low as cloud-cover in mid-levels
will remain intact. Ceilings should improve Monday morning as the
upper level system weakens and some drier begins to entrain into the
flow aloft over the region. Hoenisch


/ISSUED 522 PM MDT Sun Sep 28 2014/

Sunday through Tuesday...Moist and unsettled conditions will
continue through the first part of the week as showers continue to
move into the area with the unseasonably moist flow into the
region. The source for all this instability and moisture continues
to be a slow moving closed low that is making its way across the
Great Basin. Widespread precipitation is not expected through this
timeframe as most of the rainfall should occur as scattered
showers over the next few days. Temperatures should remain
slightly below seasonal values with cloudy conditions throughout
the time period. There will be some breaks in the wet
weather..mainly on Monday as the closed low begins to move off
into the Great Plains,however various shortwaves will move across
the area throughout the period and will bring increased chances to
precipitation. The best example of this will be on Tuesday
Afternoon and Evening, when a disturbance crosses the Rockies
out of Canada and moves over the region bringing some Pacific
Moisture and a Canadian cold front quickly across the region.

Tuesday night through Sunday...An unsettled weather pattern will
continue to reside over the region from Tuesday night through
Thursday. Scattered showers will be possible during this period.
Cooler temperatures are a possibility for Wednesday and Thursday
with a mix of rain/snow possible over the northern plains...mainly
in the vicinity of Cut a surface high quickly sweeps
across northern and central Montana. Snow accumulations expected to
be less than a half inch during any 12 hour period, however could
see some icy areas develop on roads and bridges as temperatures fall
to near freezing during the morning hours. For Friday through Sunday
expect a weak upper level ridge to rebuild over the Northern
Rockies. This will result in warmer air moving back into the region
with afternoon highs in the 60s on Saturday and then mostly mid 60s
to around 70 Sunday. Forecast generally dry for Friday thru
Sunday...but the ECMWF model is starting to hint at a weak upper
level system moving through next Sunday afternoon...producing a few
showers over the northern tier of the region.


GTF  43  66  49  62 /  20  20  20  20
CTB  40  66  44  59 /  20  20  20  20
HLN  42  68  47  62 /  30  20  30  30
BZN  39  64  43  60 /  60  20  40  30
WEY  31  54  31  51 /  90  40  50  50
DLN  39  64  43  59 /  60  40  40  30
HVR  43  64  44  68 /  20  30  20  20
LWT  42  64  45  64 /  60  30  20  20



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