Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 171719
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1219 PM CDT Sun Sep 17 2017

.UPDATE...
Issued at 1218 PM CDT Sun Sep 17 2017

The stacked low pressure system responsible for the rains the past
few days was over southern Manitoba and western Ontario today. A
surface high pressure system was over eastern South Dakota and
Nebraska. Low clouds and fog from this morning had dissipated, and
cumulus clouds continued to develop with the weak surface heating
and ample low level moisture available from wet soils. Expecting
partly to mostly sunny skies this afternoon, with temperatures
rising through the 50s and into the lower and mid 60s this
afternoon. Current forecast remains on track.

UPDATE Issued at 907 AM CDT Sun Sep 17 2017

Allowed frost advisory to expire at 9 AM and kept mention of
fog through 10 AM. Otherwise no significant changes to the going
forecast.

UPDATE
Issued at 642 AM CDT Sun Sep 17 2017

Fog has developed over portions of western ND the last couple of
hours. Area web cams depict patchy dense fog some locations, along
with a handful of ASOS/AWOS stations at 1/4 of a mile. Will watch
closely and will consider a dense fog advisory in the next hour as
observations have dropped earlier this morning only to quickly
recover.

&&

.SHORT TERM...(Today and tonight)

Issued at 418 AM CDT Sun Sep 17 2017

Forecast highlights in the short term period will be frost/freeze
headlines this morning, then the beginning of a brief warming
trend.

Currently, upper level low pressure over south central Canada
will continue to lift east-northeast with a surface ridge of high
pressure building over the Dakotas. As the winds shifted to
west/southwest low clouds quickly dissipated over the last 2-4
hours across western and central ND, leading to temperatures
dropping well into the 30s. Will let the frost/freeze headlines
continue as is. Could justify easily an expansion of the headlines
but no point at this late hour. Fog also being observed over
portions of the west and this has been maintained in the forecast.

Surface ridge moves east today ahead of an embedded S/WV impulse
moving into southeast MT mid to late afternoon. Mostly sunny to
start the day but will see increasing late day clouds ahead of
this wave mainly south. Subtle area of associated low pressure
will move with the wave and will bring a chance for light showers
to my south central and James River Valley counties this
evening/early Monday morning.

With the transition to more southerly flow temperatures will warm
10-15 degrees from Saturday. Still chilly tonight with lingering
dry air where we could see mid 30s southwest.

.LONG TERM...(Monday through Saturday)

Issued at 418 AM CDT Sun Sep 17 2017

Large area of low pressure developing into the Pacific Northwest
and eventually the Northern Plains will highlight the extended
period.

S/WV ridge will build across the region on Monday as a strong
upper level low develops into the Pacific NW/Northern Rockies. Dry
conditions Monday with temperatures again warming another 10
degrees under a southerly flow pattern.

Monday night into Tuesday the upper low slowly develops east
across the Montana Rockies and southern Canadian Rockies
triggering lee side cyclogenesis across the Northern high plains
of WY/MT. Strong frontal zone moves east into the western Dakotas
Tuesday morning, then across the central Dakotas Tuesday
afternoon as strong embedded waves rotate around the low and lift
northeast through our area. Increasing southerly winds will
transport ample moisture northward into the North Dakota as a low
level jet develops ahead of the system. This setup will favor good
chances for showers and thunderstorms across much of the Northern
Plains. MUCAPE to 2K J/KG and 0-6KM Shear of 40-50KTS will combine
to provide a favorable environment for strong to severe storms.
At this time the favored area for strong to severe convection will
be along to east of Highway 83.

The remainder of the period remains active as both the GFS and
ECMWF depict a long wave trough over the western CONUS through
Saturday maintain southwest flow aloft.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1218 PM CDT Sun Sep 17 2017

VFR conditions are expected through the forecast period with a light
southerly flow, although beginning more westerly at KJMS through 00
UTC Monday. Band of mid clouds and possible showers will lift from
south central into eastern ND 06-12 UTC Monday. Added a scattered
VFR layer at KBIS and broken VFR ceiling with VCSH at KJMS during
this period. Patchy ground fog possible southwest 10-14 UTC Monday,
but at this time best probability looks to remain south of KDIK.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JV
SHORT TERM...NH
LONG TERM...NH
AVIATION...TWH



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