Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 152025

Area Forecast Discussion
National Weather Service Bismarck ND
325 PM CDT Sun Oct 15 2017

.SHORT TERM...(This evening through Monday)
Issued at 325 PM CDT Sun Oct 15 2017

Upper level shortwave was off to our east, moving into the Great
Lakes area, with upper level ridging building over western North
America. The surface frontal boundary was also east of our area
moving through the Red River Valley, with a surface high pressure
ridge axis over the Plains.

Tonight the surface high ridge axis moves east as an approaching
warm front moves east across the Front Range towards the western
border of the Dakotas. Look for mainly clear skies with overnight
lows in the 30s as northwesterly winds decrease and become
southwesterly tonight.

On Monday the broad upper level ridge expands across central North
America, and a surface warm front moves east across the Dakotas.
Looking at highs in the 60s with breezy westerly winds of 15 to 20

.LONG TERM...(Monday night through Sunday)
Issued at 325 PM CDT Sun Oct 15 2017

Upper ridge over the western United States meanders towards the
east bringing dry conditions and a warming trend this week with
above average temperatures in the 60s and 70s. There are fire
weather concerns for Tuesday with very dry and warm conditions
expected - strength of surface winds will be the fly in the ointment.

Strong warming over the western half of the US is on tap for Tuesday
with the strengthening of the western ridge ahead of a strong, fast-
moving shortwave in the flow progged to move quickly eastward across
the Canadian Rockies. Ensemble means of global models depict 90th
percentile H850 temperatures building into North Dakota. The
operational GFS is advertising H850 temps of +14C to +18C across
North Dakota with decent westerly H850 winds of 25-35 knots. The
operational NAM is similar with H850 temps of +14C to +17C with H850
winds of 25-35 knots. There is a decent surface pressure gradient
with general 3-hr pressure falls of 3 mb across the region. Raised
winds a tad from consensus models, but there are times in warm
advection cases that the stronger winds off the surface do not reach
the surface. Will wait for the next couple of model runs to see if
this pattern remains consistent from run to model run.

The fast-moving Canadian shortwave moves across central Canada to
Hudson Bay. This will be accompanied by a surface cold front that
is forecast to reach northwestern ND around midnight Tuesday night,
and sweep southeast across the state by daybreak Wednesday morning.
Gusty northwest winds will usher in cooler air (highs in the mid 50s
to mid 60s). Operational models are depicting 3-hr pressure rises of
3-6mb behind the front, but the blended model consensus suggests
this will not occur. Raised winds just a tad late Tue night through
Wed morning.

The cool air will be replaced quickly by strong warming again for
the end of the work week. Strong ridging ahead of a strong longwave
trough moving into the west coast will allow unusually warm air to
build again into our area. Latest ensemble statistics hint at
another very warm day on Friday.

Saturday/Sunday: The west coast longwave trough moves east crossing
the Northern Plains. Models suggest a northern low and southern low
developing along the trough, with ND between the two. Consensus
models are only suggesting very low chance of rain scenarios for
next weekend with seasonal temperatures.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1215 PM CDT Sun Oct 15 2017

The western edge of the mid level cloud cover was approaching the
Turtle Mountains and had reached the James Valley. A mostly clear
and breezy afternoon with northwest winds gusting to 25-30 knots
expected. Breezy again Monday with westerly winds increasing during
the later periods of Monday morning to set up another breezy
afternoon on Monday. VFR conditions for all TAFS for the 18z TAF




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