Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 181945

Area Forecast Discussion
National Weather Service Bismarck ND
245 PM CDT Wed Apr 18 2018

.SHORT TERM...(This evening through Thursday)
Issued at 150 PM CDT Wed Apr 18 2018

Widespread fog returns tonight and into tomorrow morning.

A surface high pressure system will build into North Dakota
tonight. Light winds combined with a lowering stratus deck will
lead to widespread fog across most of western and central North
Dakota beginning tonight and continuing through tomorrow morning.
The latest CAM model guidance through their 18 UTC iterations
supports fog development during this time, as well as the
forecast NAM and GFS BUFR soundings. It is possible that fog will
linger into the early afternoon hours tomorrow across northwest
North Dakota.

Expect sunshine to break out for most of western and central North
Dakota tomorrow afternoon as much drier air moves into the area,
as suggested by forecast BUFR soundings. This will help warm
southwest and south central North Dakota well into the 50s, while
the far northwest may stay stuck in the upper 40s due to lingering
fog and low stratus. Areas with snowpack still on the ground may
also stay in the 40s, however any leftover snow is continuing to
rapidly melt.

.LONG TERM...(Thursday night through Wednesday)
Issued at 150 PM CDT Wed Apr 18 2018

A pattern change to warmer temperatures and drier weather will
overtake western and central North Dakota this weekend.

A split flow synoptic pattern will prevail Thursday night through
the weekend across the CONUS, with nearly zonal flow aloft over
North Dakota and a large upper-level low over the Central Plains.
This will set the stage for a mainly dry pattern through the
weekend, with very little to no synoptic scale lift expected and
no shortwaves or fronts moving through the region to support

The latest 12 UTC global suite suggests a rather cloudy day on
Friday, leaving temperatures stuck mainly in the 50s across
western and central North Dakota. Clouds decrease significantly
after that with plenty of sunshine expected on Saturday and Sunday
when forecast GFS BUFR soundings suggest low relative humidities
with a well mixed boundary layer up to nearly 700 mb.

As the air aloft mixes down to the surface, compressional warming
will likely lead to high temperatures that are noticeably higher
than what the latest model guidance suggests. The HRRR, RAP, and
the NAM all show model snow depth values that are much too high
compared to observations, which is keeping the forecast
temperatures too low. In addition, bias-corrected model guidance
is too cold as well, likely due to a pattern change. For these
reasons, high temperatures have been manually increased by
several degrees across western and central North Dakota for
Thursday through Sunday over the 12 UTC guidance consensus.

A potent shortwave will swing through North Dakota from the west
on Monday through Tuesday, leading to chances for rain across
southern North Dakota. Conditions look to dry back out for
Wednesday as a ridge tries to build back in.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 111 PM CDT Wed Apr 18 2018

MVFR to VFR cumulus fields will develop across most of western
and central North Dakota this afternoon through sunset. Widespread
IFR/LIFR fog and stratus may re-develop tonight into Thursday
morning across most of western and central North Dakota.




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