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Area forecast discussion
National Weather Service Bismarck ND
924 PM CST Thu Nov 21 2019

Update...
issued at 922 PM CST Thu Nov 21 2019

Added some patchy fog northwest, over the snow cover, where the
satellite nighttime microphysics channel is suggesting some light
fog is forming.

Update issued at 620 PM CST Thu Nov 21 2019

The challenge tonight will be temperatures, especially over snow
covered areas north. A few remnants of clouds remain across the
northwest, but these will diminish shortly in the low level warm
advection. Will trend low temperatures down a few degrees north,
otherwise current forecast looks OK.

&&

Short term...(this evening through friday)
issued at 233 PM CST Thu Nov 21 2019

The short term forecast period is highlighted by the beginning of
a warming trend, especially for areas in southern North Dakota.

Aloft, a mid level trough was moving over the upper Mississippi
Valley into the Great Lakes region. Strong height rises in the
wake of the trough with a surface high over North Dakota was
responsible for mostly clear skies and light winds this afternoon.

A brief ridge will move over the northern plains tonight with
a modest open wave trough upstream over the northern rockies.
Surface pressure falls ahead of this oncoming trough will bring
warm west/southwesterly low level winds through the day Friday
with sustained winds of 15-20 mph likely. This return flow
developing overnight may keep temperatures from dropping too
quickly, though single digits may be possible in some areas of
fresh snow. High temperatures on Friday approach 50 in the
southwest while snow covered areas of the north stay generally in
the 30s.

Long term...(friday night through thursday)
issued at 233 PM CST Thu Nov 21 2019

The long term forecast period is highlighted by warming
temperatures through the weekend with breezy conditions,
especially Sunday. There exists some potential for accumulating
snow mid to late next week, however uncertainty is very high at
this point.

This weekend, the upper level mean flow becomes northwesterly with
several embedded waves and weak frontal passages occurring Friday
night and Saturday night. Favorable timing for westerly warm air
advection ahead of each front will keep temperatures warm Saturday
and Sunday with the warmest temperatures in the southwest where
highs may reach the low 50s both days. The snow covered north
remains the coolest with highs in the 30s. Temperatures could be
warmest on Sunday, just ahead of a frontal passage associated with
a stronger mid level wave and upper level jet. The overlap of
strong 850mb winds and the cold air advection regime will be
greatest in the southwest Sunday afternoon. Naefs guidance has
850mb winds Sunday at or at least the 90th percentile for
climatology in the western portion of the state. This lends to
some confidence that northwest surface winds in the west could
approach advisory criteria with 20-30 mph sustained winds
possible. Some light snow with the frontal passage will also be
possible though accumulations will likely be low given the
northerly and dry moisture source of the trough.

A cooling trend develops early next week with a broad longwave
trough setting up over much of the Continental U.S.. high temperatures Monday
look to be mainly in the 30s with highs in the 20s and 30s
Tuesday and Wednesday. Persistent cyclonic flow aloft keep slight
chances for snow featured in the forecast Monday through
Wednesday.

For late next week, ensemble guidance shows a synoptic tendency
towards a western Continental U.S. Trough and southwest flow over the
central-northern plains. This pattern could favor higher chances
for precipitation including accumulating snow.....From the
southern High Plains through somewhere between the Great Lakes
region and possibly the northern plains. Run to run and model to
model variability in the track, timing, and strength of any
organized cyclones during this time period has been very high and
will continue to be so until lead time decreases substantially.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 620 PM CST Thu Nov 21 2019

Large high pressure over the region will maintain VFR conditions
tonight and Friday.



&&

Bis watches/warnings/advisories...
none.
&&

$$

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