Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 190239

Area Forecast Discussion
National Weather Service Bismarck ND
939 PM CDT Thu May 18 2017

Issued at 937 PM CDT Thu May 18 2017

Only change needed for mid-evening update was to adjust cloud
cover up a bit towards the north to address high clouds.
Otherwise, going forecast is on track.

UPDATE Issued at 648 PM CDT Thu May 18 2017

Only change for early evening update was to increase cloud cover a
bit over far southern locations based on latest satellite trends.
Otherwise, going forecast is in good shape.


.SHORT TERM...(This evening through Friday)
Issued at 242 PM CDT Thu May 18 2017

Forecast highlights in the short term period will be continued cool
and dry weather, with a frost advisory to be issued for tonight
across all of western and central North Dakota.

Currently, a large upper level low was over the 4-corners area, with
an associated surface low over the southern Plains where a severe
weather outbreak was underway. Surface high pressure dominated the
Northern Plains with its center over southern Saskatchewan/Manitoba
and a dry northeasterly wind flow dominated North Dakota.

Tonight the cool high pressure system moves east into southeastern
Manitoba with winds across ND becoming easterly and winds of 5 to 10
mph are expected. Dewpoints were mainly in the 20s to lower 30s
across the state. We are expecting widespread frost across western
and central ND, with some freezing temperatures possible as well. A
frost advisory is in effect.

On Friday the 4-corners upper level low begins lifting northeastward
into the central Plains, and the cool Canadian surface high
continues moving towards the Hudson Bay/Great Lakes area. This will
allow winds to become southeasterly, and expecting increasing clouds
from the south to move into southern ND, with a slight chance of
afternoon showers across the southern tier of counties. Highs should
range from around 60 north to the low to mid 50s south.

.LONG TERM...(Friday night through Thursday)
Issued at 242 PM CDT Thu May 18 2017

Patchy frost in the southwest Friday night/Saturday morning...and in
the southwest and south central Saturday night/Sunday morning.

Friday night through Saturday night: The upper low continues its
northeastward progression reaching the Dakotas Friday night and
moving into northern Minnesota Saturday night. The GFS and ECMWF, as
well as ensemble means and the NAM agree that the northern fringe of
showers associated with this system may affect far southern counties
in North Dakota late Friday night, with better chances Saturday in
eastern and south central ND. Today`s models were a bit slower
bringing the chance of precip into the state, and indicate a
lingering chance of showers Saturday night over mainly the James
Valley and in eastern ND.

Sunday and Monday: Following the exiting upper level low, the mean
upper flow becomes northwesterly across North Dakota, with a narrow,
meridional ridge over the west coast of North America. The models
are indicating a significant shortwave low moving south across
central Canada and moving through the Dakotas Sunday night-Monday
night, bringing chances of showers to our area.

Tuesday through Thursday: The models begin to diverge after Monday.
The GFS builds a ridge over the Rockies, keeping a cool northerly
flow over ND through Thursday. the ECMWF develops a shortwave ridge
over the Rockies and into the western Plains in response to a
significant upper level shortwave low diving southeast out of the
Canadian Rockies. Model consensus keeps temperatures fairly seasonal
with highs in the 60s to lower 70s with lows in the 40s, with only
off and on low chances of showers.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 648 PM CDT Thu May 18 2017

VFR conditions through the forecast period.


Frost Advisory from 1 AM CDT /midnight MDT/ to 9 AM CDT /8 AM
MDT/ Friday for NDZ001>005-009>013-017>023-025-031>037-040>048-



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