Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231742
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1140 AM MDT Thu Oct 23 2014

AVIATION SECTION UPDATED

.UPDATE...
Current forecast is on track...with just a few minor adjustments.
Have increased pops in the St Mary and East Glacier Park region as
precip has spread out just a bit from the mountains.
Otherwise...just small little adjustments to temps/sky grids.

In terms of high winds for tonight...mid level winds continue to
be near 65 knots per the NAM model over the Rocky Mountain
Front...but mixing it down to the surface continues to be a
problem. We will look at this further for the afternoon package.
Brusda

&&

.AVIATION...
UPDATED 1730Z.
Extensive plume of Pacific moisture and southwest flow aloft ahead
of an approaching upper-level trof will keep widespread mid-level
ceilings (generally above 8000-10000 feet) across central and
southwest MT through tonight.  Most terminals will not see
precipitation, but did put in a mention of VCSH at KBZN/KHLN after
02Z as forecast models showing a few showers over higher terrain
near those locations as a surface cold front passes through the
region.  Breezy to gusty winds will continue through early evening;
widespread gusts of 25-35 kts likely.
Waranauskas

&&

.PREV DISCUSSION...
/ISSUED 600 AM MDT Thu Oct 23 2014/
Today through Saturday...There will be a strong moist southwest
flow aloft today and tonight which will bring precipitation to the
western mountains. A weather disturbance aloft will zip across
southern Canada tonight. The associated cold front will spread
south tonight and should bring scattered showers to the mountains of
southwest and central Montana with a slight chance of showers for
the southwest valleys. Downslope should keep the plains dry. Snow
levels over the western mountains will drop to near 6000 feet by
late tonight but by then precipitation will have diminished so any
significant snow should be confined to the higher mountains. Friday
afternoon an area of lift will develop over southwest Montana and
this lift will spread north Friday night. Moisture associated with
this lift will be primarily aloft with low levels remaining
on the dry side. Hence will keep the main threat for precipitation
confined to the mountains. Early Saturday an upper ridge will be
over western Montana and this ridge will shift into eastern
Montana during the afternoon. Meanwhile a deep upper trough will
be approaching the west coast. The main moisture with the upper
trough will stay to the west of Montana so expect a dry day.

As for the high wind watch tonight and Friday morning for the
Rocky Mountain Front..although winds will be strong aloft today
and tonight do not see a real good mechanism for bringing them to
the surface. In particular do not see an inversion above mountain
top level and the cold front tonight does not look very strong. In
addition models continue to be quite different on just how strong
winds aloft will be. Consequently confidence is not high enough to
turn the high wind watch to a warning but on the other hand
confidence that winds will not reach high wind criteria is not
high enough to drop the watch. Will have day shift take another
look. Blank

Saturday Night through Thursday...Models continue in good agreement
advertising another upper level low pressure trough moving in
Saturday night and Sunday while at the same time surface high
pressure over central Canada pushes some cooler air south into
Montana. Best chances for precipitation appear to be limited to the
west and southwest mountains, and temperatures will drop about 10
degrees Monday. As trough exits to the east Tuesday, weak high
pressure will build over the area, however, it appears several
smaller systems embedded in the flow will be working their way
through keeping skies mostly cloudy with cooler temperatures and
periods of gusty winds through the remainder of the period. Chances
of precipitation remain low. Next low pressure trough then expected
to move through late next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  63  44  58  40 /  10  10  10  10
CTB  62  40  56  35 /  10  10  10  20
HLN  65  43  59  39 /  10  20  20  20
BZN  64  38  59  33 /  10  20  20  20
WEY  51  31  51  27 /  10  20  20  10
DLN  61  40  59  37 /  20  20  20  10
HVR  68  42  61  35 /  10  10   0  10
LWT  66  42  59  39 /  10  10  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH from 6 PM MDT this evening through Friday
morning Northern Rocky Mountain Front...Southern Rocky Mountain
Front.

&&

$$

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