315 
FXUS63 KBIS 020005
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
705 PM CDT Tue May 1 2018

.UPDATE...

Issued at 700 PM CDT Tue May 1 2018

Tweaked sky cover grids based on latest satellite imagery and
trends, along with latest high res guidance. 

Some light showers will be possible across the southern James
River Valley this evening as an area of rain continues northeast
across central SD. Surface high pressure ridge draped across the
Northern Plains will act to keep the precipitation mainly to our
south. 

Mid level S/WV moving east/southeast out of Alberta/Saskatchewan
will bring some light rain to the northwest overnight, then across
western and central ND on Wednesday. 

Overall updates were minor for this forecast issuance. 


&&

.SHORT TERM...(This evening through Wednesday)
Issued at 132 PM CDT Tue May 1 2018

A few stray light rainshowers ending later this afternoon with 
decreasing cloud cover overnight.

A weak shortwave continues moving northeast through central North
Dakota this evening, bringing with it a slight chance of a light
rainshowers. Current satellite and surface weather observations
show low stratus across western and central North Dakota as of
18z, with some minor clearing beginning to take place across the
northwest. Skies will continue to clear a bit across the north 
tonight, before thicker cloud cover returns tomorrow morning ahead
of another shortwave.

Another round of spotty light rainshowers will move across 
central North Dakota tomorrow afternoon as a second shortwave 
moves through, ending during the evening. Cloud cover will also 
decrease later tomorrow afternoon and evening from west to east as
a surface high pressure begins building in from eastern Montana.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 132 PM CDT Tue May 1 2018

A relatively quiet weather pattern dominates the long term
forecast with seasonable to above average temperatures. Near
critical fire weather conditions expected across northwest and
north central North Dakota on Thursday as breezy post-frontal
northwest winds sustained at 15-20 kts are collocated with
relative humidities between 20 and 30 percent.

The 12z iteration of the ECMWF and GFS show a split flow synoptic
pattern with northwest flow aloft for the Northern Plains through
the weekend. A few weak shortwaves will swing through western and
central North Dakota, bringing chances for scattered rainshowers 
from time to time. Instability looks to be lacking, with little to
no CAPE associated with these shortwave passages. Therefore,
chances for thunderstorms look to be slim with light rainshowers
being the more likely outcome.

With no significant ridges or troughs moving through North Dakota
through the weekend, near normal temperatures are expected to
slightly above average.

The ECMWF shows an upper level low moving into western North
Dakota Monday night into Tuesday, bringing with it enough
instability, moisture, and lift for showers and thunderstorms. The
GFS disagrees on the timing and intensity of this upper level low,
so will continue to monitor the threat of thunderstorms early next
week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)

Issued at 700 PM CDT Tue May 1 2018

Any lingering MVFR stratus clouds will slowly erode this evening
improving to VFR. An increase in mid level clouds and some light
rain chances are expected from west to east late tonight into the
day Wednesday as a frontal boundary moves through the region. 
Conditions should remain VFR. 


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...NH
SHORT TERM...TK
LONG TERM...TK
AVIATION...NH