Area Forecast Discussion
Issued by NWS Bismarck, ND

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091
FXUS63 KBIS 240524
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1224 AM CDT Wed May 24 2017

.UPDATE...
Issued at 1219 AM CDT Wed May 24 2017

No major changes required for this update.

UPDATE Issued at 942 PM CDT Tue May 23 2017

Did expand the Frost Advisory into the James River Valley for
tonight. Upper level RAP relative humidity fields through the 01
UTC iteration suggest cirrus will be thinnest across the James
River Valley with light winds in the weakening surface ridge axis.
However, did cancel the advisory for Hettinger, Adams, Stark and
Dunn counties where greater cirrus and increasing return flow
will prevent frost formation.

UPDATE Issued at 634 PM CDT Tue May 23 2017

Little change with this update other than to blend to observed
trends through 23 UTC. Will continue to evaluate guidance through
the evening as an expansion of the Frost Advisory into the James
River Valley tonight may be needed.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 241 PM CDT Tue May 23 2017

A few highlights in the short term period: A frost advisory for
portions of southwest and south central ND tonight into early
Wednesday morning; Clouds and winds will continue to diminish
over the James River Valley west to the Missouri Valley this
afternoon/evening. The gusty winds from earlier today, near 40 MPH
over south central North Dakota were related to the strong
temperature/pressure differences between the cloud and rain
cooled air southeast and the clearing skies/subsidence to the
west.

For tonight have trended the minimum temperatures down by using
the lowest of all guidance for low temperatures tonight. This
would have worked out well last night as well as temperatures
were 5 to 7 degrees cooler across the southwest than the ensemble
guidance was. Issued the frost advisory for late tonight and early
tomorrow for these adjusted temperatures.

For Wednesday, skies will be mostly sunny through most of the day
until an advancing shortwave and associated cold front move to
eastern Montana. This will bring some late afternoon clouds and a
chance for showers and a few thunderstorms to the far west.
However CAPE is pretty modest so expected fairly widely scattered
non severe thunderstorms. Return flow from the South and warm
advection should warm temperatures into the upper 60s to lower
70s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 241 PM CDT Tue May 23 2017

The cold front will be the focus for showers and isolated
thunderstorms along a narrow band of instability Wednesday
night. By Thursday the showers will be departing to the east and
cooler temperatures into the 60s to around 70 seam reasonable.
Not getting a lot of cold advection from this shortwave trough
that initially tracks across the southern Prairie Provinces of
Canada. But then the GFS dumbbells this upper low across the
Northern Plains through the weekend keeping an extended period of
scattered showers and cool temperatures through Memorial day
weekend, especially Sunday. The ECMWF is a bit warmer and dryer
through Sunday then brings a cold front through Monday. So with
this disagreement between global models will keep the Superblend
guidance for the weekend which gives moderate chances of showers
and slightly cooler temperatures through the Memorial Day weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1219 AM CDT Wed May 24 2017

Gusty southerly winds will develop today. Showers will move from
west to east across the area from late this afternoon into this
evening. Localized MVFR cigs will be possible in the heavier
showers. Otherwise...VFR conditions expected.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 9 AM CDT /8 AM MDT/ this morning for
NDZ019>023-025-034>037-042-045>048-050-051.

&&

$$

UPDATE...AJ
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...JJS



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