Area Forecast Discussion
Issued by NWS Glasgow, MT

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628
FXUS65 KGGW 210245
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
845 PM MDT Thu Jul 20 2017

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

East winds kicked up this afternoon and flared up fires across the
area. Would have liked to issue a Lake Wind Advisory on this, but
it looks like winds will be falling below criteria in the next
hour or two. Handled this with a social media post.

Otherwise, Water vapor showing moisture stream reaching the CWA
and combined with the upper low moving into Alberta, isolated-
scattered showers/storms look good overnight. Limiting factor will
be the abundant low-level dry air.

Extended Red Flag Warning with an earlier update. TFJ

Previous Discussion...
With a ridge in place temperatures continue warm. With a
boundary/dry line this afternoon across the CWA, expect this
boundary to be the focus for more convection this evening.
Increased pops for tonight. Potential for strong storms has a
Severe Thunderstorm Watch in effect this evening.

Late tonight and Friday a short-wave trough moving across
southwest Canada will push this boundary and a cold front through
eastern Montana. Cold air advection and tighter pressure gradient
will result in stronger northwest winds along with cooler or more
seasonal temperatures. However RHs will remain low, establishing
critical fire weather conditions again. Wind over Fort Peck lake
will also become strong in the afternoon, therefore issued an NPW.

SCT


.LONG TERM...Sat night through Thu...
The latest 12z guidance has not changed much. An upper level ridge
sets up over the area Friday night/Saturday morning, leaving
eastern Montana dry through the weekend. Model consensus still
forecasts an upper low well to the north over Canada Monday night.
Highs mid-week will be a few degrees cooler than over the weekend
and early in the week, but still quite warm. Beyond that, there is
still too much uncertainty to stray too far from model consensus
blends. Hickford

Previous Discussion...The latest 00z model consensus continues to
reflect a gradually building upper level ridge pattern across the
western U.S. and extending into Montana Friday night into the
weekend leading to dry weather conditions and increasingly warmer
temperatures, back to the 90s by Sunday.

An upper level low pressure system tracking well to the north of
the area through Central Alberta/Saskatchewan Sunday night into
early next week may help to flatten the ridge, potentially
lowering high temperatures back to the upper 80s to around 90 by
Tuesday. If the track of this feature occurs as current model
projections suggest, much of any precipitation chances would occur
further north.

The forecast beyond the midweek was trended toward consensus
blends given the usual increasing uncertainty at such larger time
scales. Maliawco


&&

.AVIATION...
VFR conditions.

Isolated showers/storms can be expected overnight and Friday
morning.

The more noticable change will be the wind change, with Northwest
winds gusting to 30 kts Friday afternoon. TFJ

&&

.FIRE WEATHER...

Critical fire weather conditions are expected across the region
this evening and Friday.

The main concern now is the NW winds for Friday. Current Northeast
or East winds this evening will be diminishing noticeably by 10
pm most places. But a front will bring strong NW winds to the SW
zones around midnight tonight then into the eastern zones Friday.
Expect gusts to possibly 40 mph! A Red Flag Warning is in effect
until 9 pm Friday Evening.

Saturday, strong northwest wind and low relative humidity could
again create critical fire weather conditions.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT Friday for MTZ120-122-134>137.

Lake Wind Advisory from noon to 9 PM MDT Friday For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

&&

$$

weather.gov/glasgow



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