Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 151137
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
637 AM CDT Tue May 15 2018

.UPDATE...
Issued at 630 AM CDT Tue May 15 2018

No significant changes needed for this update. Blended the latest
observations with the going forecast.

&&

.SHORT TERM...(Today and tonight)
Issued at 523 AM CDT Tue May 15 2018

Expected critical fire weather conditions across parts of
northwest and all of north central North Dakota later today
highlights the short term forecast.

A blocking pattern and upper level ridge to our west will slowly
nudge into western North Dakota by tonight. At the surface, high
pressure located to our east over central Minnesota, will bring
southerly flow across the forecast area south of a surface low and
associated cold front draped over the southern Canadian prairies.

Due to a tightening pressure gradient in between the surface high
and low, winds will increase through the afternoon, especially
across the north, where sustained winds near 20 mph and gusts as
high as 35 mph appear likely during the afternoon hours.
Additionally, return flow south of the Canadian front will help
warm all of western and central North Dakota into the upper 70s to
the mid 80s. See the fire weather discussion below for details
regarding the expected critical fire weather conditions parts of
the northwest and all of the north central.

.LONG TERM...(Wednesday through Monday) Issued at 523 AM CDT Tue
May 15 2018

The stalled cold front north of the Canadian border finally
begins to push its way south into and across North Dakota through
the day on Wednesday. As we remain in a southerly return flow
regime, an even warmer day is on tap for Wednesday as highs are
forecast to reach into the mid to upper 80s. Above normal highs
continue to be supported by the 00z NAEFS mean, which advertises
standardized 850 mb temperature anomalies around +2, or in the
90th percentile.

Showers and thunderstorms are likely to develop late Wednesday
afternoon across the southwest and spread into parts of central
North Dakota through the evening and night time hours. SPC has
placed portions of southwestern and south central North Dakota in
a marginal risk for this Day 2 time frame, suggesting the
potential for a couple of strong to severe thunderstorms. While
CAPE values could climb in excess of 1000 J/kg in the south, shear
will remain weak until well after sunset as a low level jet
begins to form over South Dakota and moves towards our border.
This low level jet, in conjunction with an approaching mid-level
shortwave, will help 0-6 km bulk shear values increase to around
30 to 35 knots in the 03z to 12z window Thursday morning over the
south. This shear may help ongoing convection to organize a bit
more.

As this wave moves out on Thursday, a more potent wave is ejected
towards the forecast area from the deepening west coast trough
late afternoon. Uncertainty remains regarding cloud cover
lingering from morning convection and quality of moisture return,
but the 00z and 06z iterations of the NAM and GFS continue to
support a chance of severe weather with strong instability, 30 to
45 knots of deep layer bulk shear, and a deepening surface low
over northwestern South Dakota/associated warm front draped
somewhere over North Dakota. We will continue to monitor this
period closely.

Temperatures are forecast to cool back down into the 60s area
wide.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 630 AM CDT Tue May 15 2018

VFR conditions are expected through the period. Southwest winds
will increase over the north and James River Valley, gusting as
high as 30 to 35 knots during the afternoon hours.

&&

.FIRE WEATHER...
Issued at 523 AM CDT Tue May 15 2018

Issued a Red Flag Warning for north central and much of
northwestern North Dakota for later today.

High temperatures in the low to mid 80s are forecast across most
of the northwestern and all of north central North Dakota later
this afternoon, with minimum relative humidity as low as 17
percent, and southwest winds sustained near 20 mph. When combined
with dry fuels across much of the area, critical fire weather
conditions are expected. While points south and west of the Turtle
Mountains have experienced more green up, forecast winds have
increased and minimum relative humidity values have decreased.
Therefore, decided to upgrade Rolette and Bottineau counties to a
Red Flag Warning and add Pierce, McHenry, Ward, Renville,
Mountrail, and Burke counties.

For the southwest and south central today, highs in the upper 70s
and lower 80s are forecast. Southwest winds of 10-15 mph are
expected, with slightly higher minimum relative humidity values
ranging from 20 to 30 percent.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM this morning to 8 PM CDT this
evening for NDZ002>005-010>013.

&&

$$

UPDATE...ZH
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...ZH
FIRE WEATHER...ZH



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