Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 211433
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
933 AM CDT Fri Apr 21 2017

.UPDATE...
Issued at 933 AM CDT Fri Apr 21 2017

Based on the GOES16 visible imagery loop and HRRR visibility
field, have decided to extend the Dense Fog Advisory most areas
until 17z/Noon CDT Friday. Exceptions to this were counties in
the James River Valley and in the far north central where the
majority of the counties were clear, and not expecting any further
advection or fog development. Updates forthcoming.

UPDATE Issued at 835 AM CDT Fri Apr 21 2017

Based on webcam trends through 13 UTC and the 12 UTC RAP/HRRR,
extended the dense fog advisory through 10 am CDT.

UPDATE Issued at 628 AM CDT Fri Apr 21 2017

Dense fog has spread through much of the area per latest
observations and spotter reports. The only exception so far is
far northwest North Dakota and portions of the far southern James
River Valley. Latest HRRR seems to have a rather good grasp on
this and keeps the fog in place through the early morning eroding
it out around mid-morning. A dense fog advisory was issued a
little over an hour ago when the fog started to really set in, and
will expire at 900 am cdt.

&&

.SHORT TERM...(Today and tonight)
Issued at 305 AM CDT Fri Apr 21 2017

Current surface analysis places trough stretching along the
eastern edge of the Rockies, while high settles through the
eastern plains into the upper Midwest. Upper level analysis places
modest ridge over the northern plains, with trough dipping through
the Rockies. Over our region, areas of fog have developed and
continue to spread through random portions of the area.

For today...areas of fog will continue through early morning,
diminishing late morning. Otherwise, a pleasant day is expected
with mild temperatures while modest upper ridge remains over the
region. Mainly quiet weather continues tonight, though a wave
passing to the north may allow some light showers to sneak into
northern portions of the area as it pushes upper level level high
to the south while a cold front approaches the area.

.LONG TERM...(Saturday through Thursday)
Issued at 305 AM CDT Fri Apr 21 2017

Aforementioned cold front settles into far northern portions of
the area on Saturday, then starts to back into northeastern
portions of the area overnight Saturday into Sunday. This will
bring cooler temperatures to these areas along with shower chances
along and north of the boundary. To the south, milder temperatures
expected.

Sunday night into Monday, an aggressive short wave trough
approaches the region while a surface low deepens near the Black
Hills and pushes easterly. This will bring increasing
precipitation chances to the area. Most precipitation that does
develop will be rain, but can not rule out some snow developing
over northern locations. Chances diminish Monday night.

Models then start to differ for the remainder of the week with
where to place the next upper low over the region. With that said,
will continue to places some precipiation chances in the forecast
given the generally unsettled pattern.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 835 AM CDT Fri Apr 21 2017

Widespread LIFR conditions in fog expected to remain over most
locations through mid-morning. Once the fog erodes, VFR conditions
will prevail.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until noon CDT /11 AM MDT/ today for NDZ004-
005-010>013-017>023-025-031>035-040>045.

&&

$$

UPDATE...KS
SHORT TERM...JJS
LONG TERM...JJS
AVIATION...AYD



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