Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 191439
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
939 AM CDT Fri Apr 19 2019

.UPDATE...
Issued at 938 AM CDT Fri Apr 19 2019

Issued a Red Flag Warning for western ND valid 1 PM CDT to 8 PM
CDT today. Debated back and forth on whether or not to issue,
with relative humidities consistently around 20 percent and the
max model winds from the west around 20 knots, putting us right
on the border of critical fire weather conditions. However, the
GGW morning sounding showed the potential for stronger winds
mixing down, and that potential will move east into western ND
along with the warm front just beginning to move through per WPC
surface analysis. This, along with the Northern Rockies Forecast
Fire Danger class being high to very high in those counties, was
enough to push us to issue the RFW.

.UPDATE...
Issued at 638 AM CDT Fri Apr 19 2019

For the morning update we bumped up sky cover early this morning
west as skies are broken to overcast ahead of the warm front.
expect sky cover to thin as it moves into central ND. For the
afternoon, we blended our current temperatures and dewpoints with
the latest iteration of the Experimental HRRR. This did not lower
minimum RH values in the far west, but did expand the area of mid
20 RH values farther east into central ND. Winds are still around
20 mph this afternoon. As far as fire weather highlights, will
stay with no highlights at this time. If winds behave, we should
be alright, but if we are able to mix down stronger winds aloft,
we may need to revisit fire weather highlights.

&&

.SHORT TERM...(Today and tonight)
Issued at 342 AM CDT Fri Apr 19 2019

Main forecast concerns in the short term period are winds and
temperatures today, and precipitation chances tonight.

Currently, surface low pressure is situated over far eastern
Alberta, with a warm front into eastern Montana. Weak high
pressure remains over central and eastern North Dakota under
mostly clear skies. Mid and high clouds increase over western ND
and eastern MT.

Today, the surface low tracks across Saskatchewan and into western
Manitoba by 00 UTC Saturday. The associated warm front moves into
central North Dakota, and the trailing cold front sags south
into far southern Saskatchewan. This puts western ND into the warm
sector of the surface low with mild temperatures and decent
southwest flow shifting westerly in the afternoon. This raises
some fire weather concerns and those will be discussed more in the
fire weather discussion. We utilized the previous forecast for
high temperatures today, which was just very similar if not just a
bit higher than our given blended guidance. We went on the high
side of guidance for winds this afternoon. So overall a mild day
but breezy to windy this afternoon.

Tonight, the cold front stalls along the International Border and
any precipitation remains mainly north of the border. We will
still carry a slight chance of showers with an isolated
thundershower not out of the question northwest, but in general,
PoPs are a little less than the previous forecast. It looks to be
a mild night with thermal ridging pushing into the area through
the night. We utilized some of the higher guidance available for
lows tonight, with lows in the mid 40s to lower 50s.

.LONG TERM...(Saturday through Thursday)
Issued at 342 AM CDT Fri Apr 19 2019

Main forecast issue in the long term period will be temperatures
and small precipitation chances.

Upper level ridging over the state Saturday morning is flattened
by a northern stream shortwave tracking along the international
border. This wave, combined with energy tracking through the mean
upper ridge over the Northern Rockies, will develop a weak surface
low over the state and then the low and associated cold front that
was lingering along the international border drop into South
Dakota by 00 UTC Sunday. The timing of this is slower than
yesterday and this allows for good heating over the southeast half
of the state on Saturday. Given blended guidance was a good 5-7
degrees warmer than the previous forecast over the southern James
River Valley. This additional warming will produce slightly
unstable conditions here Saturday afternoon. Although atmosphere
is relatively dry, steep lapse rates with energy moving through a
nearly zonal flow could produce a few thunderstorms over the
southern James River Valley Saturday evening. More general shower
activity brushing the southwest Saturday night. Overall, across
the state, precipitation chances will be meager behind the cold
front that drops through the area.

Cooler conditions are expected on Sunday with a stronger shortwave
moving across South dakota. This will bring some shower activity
to the southern tier counties during the day Sunday. Highs will be
in the 60s. Mainly dry conditions are expected through mid week
with slowly moderating temperatures into the 70s by Wednesday. A
cold front may bring some showers by Thursday, with slightly
cooler temperatures.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 638 AM CDT Fri Apr 19 2019

VFR conditions are expected through the forecast period. Light
southerly flow early this morning will become southwest and
increase to around 15 knots. Strongest gradient winds will be over
central ND Friday afternoon along/ahead of a warm front. Gradient
slackens in the west Friday afternoon, but with good mixing,
stronger west winds aloft should be able to mix down making for a
breezy day with winds around 20-30 knots 20-24 UTC, then dropping
rather quickly Friday evening.


&&

.FIRE WEATHER...
Issued at 938 AM CDT Fri Apr 19 2019

Sustained westerly winds 20 to 25 mph with gusts up
to 35 mph combined with minimum relative humdities around 20 percent
and dry fuels, will result in critical fire weather conditions this
afternoon into early evening. Thus, a red flag warning has been issued.
Any fires that ignite will spread rapidly and become difficult to control.

Increasing moisture Friday night and Saturday will keep fire
weather concerns minimal. Drier air will return on Sunday but
temperatures will be cooler, and winds are expected to be at or
below 12 kts.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM CDT /noon MDT/ this afternoon to 8 PM
CDT /7 PM MDT/ this evening for NDZ001-002-009-010-017-018-
031>033-040-041-043-044.

&&

$$

UPDATE...MJ
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...TWH
FIRE WEATHER...MJ


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