Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 200509

Area Forecast Discussion
National Weather Service Bismarck ND
1209 AM CDT SAT AUG 20 2016

Issued at 1205 AM CDT Sat Aug 20 2016

Showers continue to linger over the southern James River Valley
into portions of south central North Dakota. Some additional
showers will be possible over eastern portions of the area later
tonight with the next weak wave moving through. Will also keep
mention of fog in over central locations where some clearing may
lead to development. Will keep a close eye on this over the next
few hours.

UPDATE Issued at 946 PM CDT Fri Aug 19 2016

Current temperatures look reasonable so left them alone.
Forecast min temperatures are a little lower than latest blend of
short term guidance but not enough confidence to nudge
temperatures only a couple degrees. Clearing skies west should
allow for some good cooling over the next several hours, but
upstream clouds will move into the area after midnight. Will let
overnight shift adjust if needed.

Another concern was potential for low clouds and fog early
Saturday morning. Mesoscale models are hinting and some lower
stratus from Minot and Bismarck east to Jamestown. Clearing skies
and light winds in the west could allow for some patchy for
formation also, especially southwest and south central where
heavier rain amounts during the day Friday will add moisture to
the lowest levels of the atmosphere. Looking at the BUFKIT
forecast soundings and MOS guidance there does not seem to be a
strong signal for fog, but with mesoscale models continuing to
hint at the possibility, and recent rainfall and decent
radiational cooling will throw in a mention of patchy fog for
mainly central ND. Afore mentioned increasing clouds may inhibit
radiational cooling in the west. Mostly cloudy skies will likely
remain in the east so think best potential remains over central
ND. Made some minor adjustments to sky cover and pops based on
latest satellite and radar imagery. Updated text products will be
out shortly.

UPDATE Issued at 616 PM CDT Fri Aug 19 2016

Areas of rain continue to slowly dissipate as they track northeast
across south central ND. Elsewhere convective showers and a few
thunderstorms have developed over the north, central and southwest
where more insolation was realized. This activity is moving
southeast and is also expected to slowly diminish as we move
through the evening. Added some isolated evening thunder and
adjusted pops based on latest radar. Will visit lows and possible
fog with the next update.


.SHORT TERM...(This evening through Saturday)
Issued at 321 PM CDT Fri Aug 19 2016

Currently...surface high pressure was centered over western/central
MT. Latest satellite pic indicate the base of the upper level trough
extending southwestward across Manitoba, the northwest corner of ND,
and into northern WY. The area of light to moderate rain ahead of
the upper trough continued across southwest/south central ND into
western SD.

The latest iterations of the operational and experimental HRRR
depict the area of light rain ending over southwestern ND late this
afternoon/early evening, but continuing in south central ND near the
Missouri Valley for much of the evening hours. Farther east towards
the James River Valley, the models indicate light rain beginning
there late this afternoon, and continuing tonight as the main area
of precipitation moves southeastward. Models are indicating that
although the main base of the upper level trough should be into the
Red River Valley by Saturday morning, a trailing upper level impulse
in the northwest flow will move southeast across ND. Kept chances of
rain showers in the James River Valley Saturday into the afternoon.

Lows tonight should range from 45 to 55, with highs Saturday from
the mid 60s in the James Valley to the lower 70s west.

.LONG TERM...(Saturday night through Friday)
Issued at 321 PM CDT Fri Aug 19 2016

After lingering precipitation exits the James River Valley Saturday
afternoon, the large surface high will have moved southeastward
towards Iowa/Missouri. At upper levels, a northwest flow regime will
be in place across the Dakotas, with the base of the upper level
trough well to the east into the Great Lakes area. This will allow
clearing skies over North Dakota, and with the cool air in place
this should bring another night with low temperatures in the 40s.

The upper level western ridge builds quickly into the western Plains
Sunday and Monday, bringing a warming trend late this weekend into
early next week. Highs Sunday mid 70s to lower 80s, with Monday
highs mid 80s to lower 90s. Meanwhile an upper low moves into the
western British Columbia coast Sunday, moving eastward across the
Rockies Monday, reaching the northern US and Canadian prairies
Monday night/Tuesday. The GFS is a bit faster bringing an attendant
cold front east across our area Monday night, with the ECMWF
depicting a frontal passage on Tuesday. This will bring the next
chances for showers and thunderstorms to our area. The model
consensus guidance is suggesting the next chances begin Tuesday, but
chances are small with the best forcing in Canada.

After the cold front and upper level trough passage, cooler
conditions will return to our area by mid-week, with highs in the
70s and lows in the 40s and 50s.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1205 AM CDT Sat Aug 20 2016

Main concern will be the development of mvfr cigs/vsbys at KBIS/KJMS
between 09z-12z Saturday and continuing until 18z Saturday.
Patchy fog briefly reducing vsbys to mvfr range appears more likely
at KJMS and possibly at KBIS as well. Utilized a vcfg at KBIS and
reduced vsbys to mvfr at KJMS where confidence is slightly higher.
Rest of the terminals will have cigs hovering in the low vfr range,
at or above 3500ft agl until 18z-21z Saturday, then gradual clearing
taking place through the rest of the period.


.BIS Watches/Warnings/Advisories...


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