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000
FXUS63 KBIS 220508
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1208 AM CDT Sun Apr 22 2018

.UPDATE...
Issued at 1200 AM CDT Sun Apr 22 2018

Currently a weak h500 shortwave is progressing through southern
Canada with an associated dry cold front approaching the ND/MT
border at 05Z. Somewhat gusty southerly winds ahead of the front
with a Northwest wind shift expected to occur with the fronts
passage. Current forecast looks ok.

UPDATE Issued at 929 PM CDT Sat Apr 21 2018

Current very strong post frontal westerly winds across
northeastern and north central Montana as of 02 UTC are not
expected at this time across northwest North Dakota later this
evening as the boundary layer stabilizes, and isallobaric forcing
decreases. However, will continue to monitor trends. Otherwise,
the forecast for tonight is on track and blended to observations
through 02 UTC.

UPDATE Issued at 534 PM CDT Sat Apr 21 2018

Quick update for observed trends through 22 UTC. The CAM suite
through the 21 UTC HRRR iteration suggests the potential for
isolated showers across northwest North Dakota this evening in
association with the cold front currently across eastern Montana.
For now kept the forecast dry as moisture will be a limiting
factor for precipitation.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 156 PM CDT Sat Apr 21 2018

An upper level ridge moves east tonight as a shortwave trough
swings just north of us over Saskatchewan and Manitoba by Sunday
morning. We will transition to quasi-zonal through the afternoon
and evening, as a subtle ridge moves across the west late in
advance of a deepening West coast trough. Widespread highs in the
60s are in the forecast for Sunday afternoon.

.LONG TERM...(Monday through Saturday)
Issued at 156 PM CDT Sat Apr 21 2018

Models are in general agreement regarding the approaching trough.
As the associated upper low tracks across southeastern Montana and
southwestern North Dakota, rain chances will increase Monday
afternoon over the southwest, and eventually into the south
central by the overnight hours. There may be a brief period when
the rain mixes with light snow late, but little to no accumulation
is expected. There will be a tight pressure gradient associated
with this upper level shortwave that will be extending north
northeast from a surface low that will develop over northern
Wyoming before moving near the South Dakota Nebraska border. This
gradient will bring breezy northerly winds to the southwest and
south central Monday afternoon through early Tuesday morning.

Thursday, a dry cold frontal passage will bring a brief cool down,
mainly across the east. By the end of the week a fairly well
deified temperature gradient, from east to west looks plausible,
warmer to the west and cooler to the east. This may be more
pronounced than the Superblend guidance currently has due to the
Bias Corrected grids from the early April Temperatures. This
should sort itself out with time and opted to stick with the
Superblend, which may be cooler, at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1200 AM CDT Sun Apr 22 2018

At midnight (05Z) a dry cold front was approaching the ND/SD
border and will move east through the region overnight. VFR
conditions will prevail through the 06Z TAF forecast.

&&

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

$$

UPDATE...WAA
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...WAA