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Area forecast discussion
National Weather Service Great Falls Montana
1155 am MDT Mon Sep 23 2019

..updated aviation discussion...

Update...

Little needing to update this morning. Morning showers will
diminish, although some mountain showers are possible across the
Rocky Mountain front throughout the day today and perhaps into
Tuesday. Some areas of fog are being found in the valleys of SW
Montana this morning, and should diminish later this morning. The rest
of the day looks to be mild with breezy winds. A glancing
disturbance could continue breezy to perhaps windy conditions
tonight into Tuesday, with perhaps a few isolated to scattered
showers also possible. Slightly cooler, although more normal like,
temperatures are also expected for Tuesday. Anglin

&&

Synopsis...

An isolated shower is then possible tonight with a passage of a
weak cold front. Monday then sees near to slightly above normal
temperatures, with dry and breezy conditions. After a few breezy
and near normal temperature days through mid week, a significant
change to much colder and wetter conditions are anticipated late
in the week into the upcoming weekend.

&&

Aviation...
updated 1200 PM MDT Mon Sep 23 2019 (23/18z tafs)

An overall breezy pattern with VFR conditions can be expected
through the forecast period. Today west winds will increase with
some mid to upper level clouds. Breezy winds could linger tonight,
with some lowering of clouds to near MVFR levels. Tuesday then
looks to see VFR conditions with breezy to perhaps windy
conditions. Other than a few mountain showers, little
precipitation is expected in the forecast period, and only a few
scattered showers are possible Tuesday afternoon. Anglin

&&

Previous discussion...
/issued 500 am MDT Mon Sep 23 2019/

Mostly dry cold front moves across the region this morning, with
the most notable aspect of this frontal passage being the gusty
winds it will initiate across the entire region that will persist
for much of the next several days. Temperatures will be slightly
cooler than on Sunday, with that trend continuing through Thursday
under fast west-northwesterly flow aloft. As disturbances and
surface fronts move across the region, winds will increase with
the northern Rocky Mountain front experiencing the strongest winds
at times, especially Monday night into Tuesday. Winds may subside
enough during the overnight hours Tuesday night where some patchy
fog may develop across the area.

Thursday through next Monday...

Forecast models continue to show good agreement that this period
will start off relatively mild and breezy, but the Friday through
Sunday period will be quite cold with the potential for widespread
precipitation. A disturbance will move east across Montana late
Wednesday night into Thursday. This will bring a chance of rain
and High Mountain snow, along with another round of gusty winds
ahead of an approaching cold front from the north. This situation
will need to be monitored for potential high wind highlights.
Temperatures will also cool slightly over those on Wednesday,
falling to around 10 degrees below normal on Thursday. However,
the big weather pattern change will occur Thursday night into
Friday with the passage of the cold front. High pressure behind
this front will shift winds more so out of the north to northeast,
which will drop high temperatures 10 to 15 degrees into the 30s
and 40s on Friday, with steadier cooling into the weekend. While
this is happening, a low pressure trough will dig south over the
Pacific coast states and put Montana under a southwesterly then
southerly flow aloft with a good feed of Pacific moisture. This
will combine with the cooling temperatures and upslope low/mid
level flow to bring widespread rain and snow to the area. There is
some uncertainty regarding precipitation amounts five days away
from the event, but winter weather highlights may be needed.
Overnight lows will fall below freezing for much of the area
Thursday and likely all of the area through the weekend, with some
areas not warming above freezing. This will likely be the first
cold snap of the autumn season with the potential for measurable
snow at lower elevations.

&&

Preliminary point temps/pops...
gtf 71 48 66 41 / 10 10 10 20
ctb 66 45 63 38 / 10 10 10 10
hln 70 47 66 43 / 10 10 10 20
bzn 73 42 68 39 / 0 10 10 20
wey 63 32 61 29 / 10 10 10 10
dln 71 42 66 38 / 0 10 0 0
hvr 74 47 68 39 / 10 20 30 40
lwt 70 46 63 40 / 10 10 20 30

&&

Tfx watches/warnings/advisories...
none.
&&

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