Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 180537

Area Forecast Discussion
National Weather Service Bismarck ND
1237 AM CDT Thu May 18 2017


Issued at 1234 AM CDT Thu May 18 2017

Inherited forecast remains mainly on track. Temperatures falling
into the 30s across western ND, and will so do so as well central
momentarily. Did increase winds a bit across the James River
Valley where gradient forcing remains robust.

UPDATE Issued at 933 PM CDT Wed May 17 2017

Cloud cover has been a bit reluctant to dissipate this evening,
but latest high-res guidance starts working the clouds out of the
area later this evening and overnight. Current frost headlines
remain in good shape.

UPDATE Issued at 633 PM CDT Wed May 17 2017

No major changes need with this update. Just blended the latest
observations to the going forecast.


.SHORT TERM...(This evening through Thursday)
Issued at 246 PM CDT Wed May 17 2017

Frost Advisory tonight for western and most of central North Dakota.

Forecast highlights in the short term period will be cooler
temperatures with frost tonight, and mainly dry conditions.

Currently, a large scale upper level low was over the Intermountain
West region of Utah/Idaho, with another shortwave low moving
northeastward through the central Plains. A surface low co-located
with the central Plains upper low was associated with showers and
thunderstorms from the central Plains through Minnesota today.
Meanwhile a large surface high pressure system was centered over
central Canada, with its dry northeast wind flow dominating North
Dakota this afternoon.

Tonight the dry high pressure center moves south, with the dry air
with dewpoints in the 30s moving south into North Dakota. Clearing
skies, light northeast/north winds and dry air moving in will allow
temperatures to drop into the low to mid 30s over western and most
of central North Dakota. The James Valley may be able to escape the
frost for tonight, with expected lows in the upper 30s/lower 40s.

Mostly sunny but cool on Thursday, with highs in the mid to upper

.LONG TERM...(Thursday night through Wednesday)
Issued at 246 PM CDT Wed May 17 2017

Thursday night and Friday: The large upper level low is forecast to
be over the 4-corners area, with the upper Mississippi Valley low
now an open wave and moving quickly into the Canadian maritimes. At
the surface, dry high pressure dominates the Northern Plains,
keeping an easterly/northeasterly wind flow across North Dakota,
with mainly clear skies. Another cool night Thursday night/Friday
morning, with morning lows forecast in the low to mid 30s. This will
likely require another frost advisory and/or freeze warning for much
of western and central North Dakota. During the day Friday the
surface high moves east into the Great Lakes area, allowing a
southeasterly wind flow over our area. Meanwhile the 4-corners upper
level low begins its move northeastward into the central Plains.

Friday night and Saturday: The upper low continues its northeastward
progression reaching into eastern North Dakota Friday night and
moving towards Lake Superior Saturday night. Model differences in
today`s runs with discrepancies regarding how far west in North
Dakota the rain showers may reach associated with this system.
However, ensemble means, the NAM, and ECMWF agree on bringing
showers into southwestern and southern ND despite the operational
GFS, which would trend on the dry side for southwestern and central
ND. Thus model consensus favors rain showers Friday night across
southern ND and better chances Saturday in central ND.

Saturday night through Wednesday: 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
Monday/Monday night, bringing chances of showers to our area. This
shortwave then merges with a Hudson Bay low, and begins retrograding
back westward to the Great Lakes. This large low encompasses the
eastern 2/3 of North America, keeping a cool, cyclonic flow over the
Northern Plains with chances of showers off and on through the
remainder of the long term forecast period. High temperatures should
be mainly in the 60s with lows mainly in the 40s for this time


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1233 AM CDT Thu May 18 2017

Gusty north winds at KJMS will slowly subside through Thursday
morning. Otherwise VFR conditions expected through the 06Z TAF
period with a light north to northeast surface flow.


Frost Advisory until 9 AM CDT /8 AM MDT/ this morning for



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