Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 250256

Area Forecast Discussion
National Weather Service Bismarck ND
956 PM CDT Wed May 24 2017

Issued at 945 PM CDT Wed May 24 2017

Update to blend in observed radar trends with the going forecast.
Thunderstorm threat is mostly focused to the southwest along a
nose of steeper mid-level lapse rates. Otherwise no major changes
to the forecast.

UPDATE Issued at 810 PM CDT Wed May 24 2017

Updated to expire Wind Advisory with surface winds diminishing to
below advisory criteria on recent observations.

UPDATE Issued at 703 PM CDT Wed May 24 2017

We increased PoPs along and west of the Highway 83 corridor with
this update to reflect the eastward-propagating line of showers
moving across western ND early this evening. The vast majority of
convection-allowing model guidance, including recent HRRR cycles,
is not as aggressive with the areal coverage of precipitation as
radar imagery suggests. An exception was the 18 UTC 3 km NAM, so
we weighted the evening precipitation forecast strongly to that
simulation. We maintained a chance of thunderstorms in the west
and south central too in respect to mid-level lapse rates near
7 C/km, though CAPE for parcels lifted above a dry boundary layer
is meager outside of far southwest ND early this evening.


.SHORT TERM...(This evening through Thursday)
Issued at 257 PM CDT Wed May 24 2017

Gusty southerly winds ahead of the surface trough and associated
cold front will continue through the afternoon, although they may
diminish far west as the center of the trough moves over. The
short term CAM models have been more excited about thunderstorms
even though the cape is barely there. Shear is plentiful and with
the current lightning in eastern Montana, will include a few
hours of thunderstorms west and then trail off thunder to just
the southwest this evening.

Without good instability cant seem to get too excited about rain
potential over the next 24 hours. Current consensus is between a
tenth of an inch and up to a quarter of an inch west and north.

By Thursday the trough will be east and the chances for
precipitation remain just along the northern boarder. Used the
highest guidance for wind speeds Thursday which gave a reasonably
breezy but not windy day with west to northwest winds. Highs
Thursday will range from the lower 60s southwest to lower 70s
James River Valley. Current greenup will again keep fire danger
below the high level even with the gusty winds.

.LONG TERM...(Thursday night through Wednesday)
Issued at 257 PM CDT Wed May 24 2017

The weekend is shaping up to be on the cool side with scattered
showers. The best chance for showers still looks like Saturday.
Global Models see a sharply curved shortwave trough rotating
around the upper low which may produce enhanced vertical motion
fields Saturday. Following this, the upper low circulates around
Ontario funneling several more shortwave troughs through the
Northern Plains in what could be a modestly active northwest flow
regime. This pattern often produces an active thunderstorm
pattern in early June. While the Forecast Blend guidance is
generally dry see some potential next week. However due to
uncertainty left the extended after Monday dry but something to


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 945 PM CDT Wed May 24 2017

A band of showers will move across western ND this evening, and
through central ND between about 04 and 09 UTC. There`s also a
small chance of thunderstorms with this shower activity, but we
refrained from including even a VCTS in the 00 UTC TAFs since
confidence is low in their occurrence at any of the terminals.
Otherwise, gusty south winds will diminish this evening. Winds
will become westerly by Thursday afternoon and increase once more
with gusts to 30 kt behind a cold front.




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