Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 220944
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
344 AM MDT Wed Oct 22 2014

.DISCUSSION...
Today through Friday...The upper trough responsible for the recent
precipitation has moved into eastern Montana and as of 3 am there
were only a few lingering showers over north central Montana.
Expect these to end by around 6 am. As for the threat of
fog..there should be enough wind to prevent its formation this
morning with the exception of some of the valleys of southwest
Montana where winds are light. For today an upper ridge will move
into central Montana this afternoon and result in a good deal of
sunshine and no precipitation. For tonight into Thursday night
southwest flow aloft will increase along embedded moisture. Due to
downslope flow any precipitation should be confined to the western
mountains with also a small threat in the southwest valleys by
Thursday night. Snow levels will be relatively high so that
mountain passes should not see any snow.

High Wind situation...With the increasing southwest flow aloft
will have to watch the threat for high winds over the Rocky
Mountain Front this evening into Friday. Models are not in
particularly good agreement on the details of this flow. Models do
not indicate a strong stable layer above the mountains nor a
strong surface pressure gradient both of which would aid in high
wind development. Consequently do not have enough confidence to
issue any high wind highlights but there is enough of a threat
that the situation will need to be watched closely. Blank

Friday Night through Wednesday...Long term models in relatively good
agreement with larger features and timing, but showing some
differences in finer details. Period starts with an upper level high
pressure ridge covering much of the western U.S. with the next in
the series of low pressure troughs approaching from the west. Both
GFS and ECMWF show several small weather systems embedded in the
trough in a disorganized fashion though placement and strength of
these small systems varies between the models. At this time, the
trough is expected to push into central Montana late Saturday
afternoon or Saturday night, and may bring some precipitation,
mainly to the west and southwest mountains. With the current
progressive pattern, the trough moves off to the east fairly
quickly, and the high pressure barely has a chance to start
rebuilding Tuesday before the next area of low pressure sweeps in
Tuesday night. These back to back troughs are expected to bring in
some slightly colder air. Once again, could see some precipitation
with trough passages the middle of next week, but best chances
for this remain over the mountains.

&&

.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.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  60  44  65  44 /   0  10  10  10
CTB  61  40  63  40 /   0  10  10  10
HLN  61  39  66  42 /   0  10  10  20
BZN  56  32  64  38 /  10   0  10  20
WEY  44  23  52  28 /  10   0  10  10
DLN  57  37  62  40 /   0  10  10  20
HVR  63  38  69  41 /  10   0  10  10
LWT  61  39  67  42 /  10  10  10  10

&&

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

$$

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