Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 270225

Area Forecast Discussion
National Weather Service GLASGOW MT
825 PM MDT Wed Oct 26 2016

.SHORT TERM...for northeast Montana...tonight through Fri...

The ridge over the region will continue to dominate the weather
pattern into Thursday for Northeast Montana. Mid to high level
clouds will keep the temperatures up a few degrees from this
mornings lows at most locations. The cloud cover should reduce the
fog possibilities greatly across the area. Very little updated
this evening with the on going forecast.     Proton

Previous Discussion

Tonight into Thursday morning...There may be some patchy fog in
some of the river valleys along the MT ND border just before
sunrise, however confidence is low for its occurrence. A good
amount of mid to high level moisture is forecast to stream over
the top of the ridge. The upper level high pressure ridge is
forecast to be the strongest on Thursday with the highest heights
with high temperatures running 15 to 20 degrees above normal. Most
likely the nicest day we will have for a number of months. :)

Thursday night into Friday...The upper level high pressure ridge
will undergo some flattening a weakening across NE MT, allowing
for more mid to high clouds to stream across the area long with a
weak weather disturbance that will bring a slight chance of light
showers to portions of Phillips, northern Valley, Roosevelt,
Daniels, and Sheridan counties. The showers are forecast in the
early morning over in Phillips county and then spread east through
the morning into our northeast border region with ND. Max Temps on
Friday will have cooled back to a few degrees above seasonal
values with temperatures running from the upper 40s near the
Canadian border to lower 60s down in Prairie and Wibaux counties.

.LONG TERM...Fri night through Wed...

The long term forecast period is dominated by an unsettled
westerly or southwesterly flow aloft which will introduce a couple
of active weather systems through the region.

The first of these systems will approach northeast Montana from
the southwest Friday night through Saturday morning, being forced
by a short-wave impulse from the central Rocky Mountains. This
wave will weaken as it arrives here, which should keep most of the
accumulating rainfall near and south of highway 200. Fairly good
model agreement here, but the DGEX is the outlier which bring the
precip up and through our central and northern zones. As that
solution is much older and out of the consensus, felt it was best
to trust more the recent consensus over our southern zones.

The next impulse arrives as a larger low pressure trough the
inter-mountain west and the northern Rockies. This could bring
some scattered rain showers to our area.

Also chose to consider some rain/snow mixed precipitation late
Saturday night and late Sunday night given that low temperatures
over our northern zones begin to drop near and below the freezing
mark by then. At this time, do not expect it to amount to much.

Previous long term discussion: The extended forecast period
begins Friday night with a short- wave disturbance developing in
northern Nevada and southern Idaho that will send precipitation
into southern Montana Friday night and Saturday morning. Timing
and location of the disturbance differed in previous model runs
between the EC and the GFS. This was important because there will
be a rather large closed low storm system off the Northwest Coast
feeding moisture into Montana. Previous shifts have blended model
pops. But trimmed back the northern areas due to the undercutting
nature of this more likely wave.

By Saturday the ridge rebounds as the disturbance departs the
area. However, the Pacific trough will be sending significant
amounts of moisture into Northern California and north into Inter-
Mountain West.

Then Sunday with continuing model differences, the trough begins
to move inland. This finally sends moisture across the Divide by
late Sunday. Timing and location will matter less because the
storm system will bring in a wet period Sunday night through
Monday for widespread wetting rains, and possibly a few snow
flakes. Temperatures will drop considerably, highs down into the
40s. The period will not be particularly windy, but brisk winds
with the rain will begin to taper off Monday evening. Overnight
lows will fall down to freezing over most of the area.

Late Monday night through the remainder of the extended period,
however, will see a return to mild but cool conditions.




Synopsis: A large and strong ridge of high pressure now pushing
through the central and northern Rockies will make for very nice
flying weather over the next 24 hours. Some mid level cloudiness
will remain through tonight, but should scattered out to mostly
sunny or partly cloudy skies through Thursday.

Flight conditions: VFR expected throughout. There are some subtle
model hints that KSDY might see some fog through the mid to late
morning hours. Not confident enough to support it in the TAFs
other than a brief mention.

Light and variable winds this evening will increase up to around
7 kts from the SE overnight, then increase up to 12 to 15 kts from
the south through the day Thursday.





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