Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 220619
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1219 AM CST Wed Nov 22 2017

.UPDATE...
Issued at 1218 AM CST Wed Nov 22 2017

The surface arctic high pressure dome was centered over eastern
SD/NE with its axis extending northward across eastern ND.
Temperatures in the vicinity of this axis of ND were mainly in the
single digits above zero. Farther west, southerly winds developed
Tuesday evening, and temperatures there have been steady or rising
the past few hours. As of 11 pm cst temperatures were mainly in the
teens across the western quarter of the state, with lower 20s in the
Bowman area of the far southwest corner of ND. High clouds had
entered western ND and were approaching the highway 83 corridor at
midnight. The warm advection above the surface layer is well
underway.

The short term high res models indicate light snow chances beginning
around 3 am cst in western Divide and Williams counties in the
northwest corner of the state, and expanding eastward mainly along
and north of highway 2 before sunrise. Temperature profiles suggest
this precip should be mainly in the form of light snow, with chances
of sleet beginning in western Divide/Williams counties before
sunrise. After sunrise the precipitation type becomes more of the
freezing rain/sleet variety from west to east with time...as in the
ongoing forecast. Updates to follow as precipitation develops.


UPDATE Issued at 952 PM CST Tue Nov 21 2017

Another round of lowering temperatures, this time moreso across
the central. Although not as drastic as the previous cut.
Temperatures have steadied west and were rising where mid and high
clouds have begun to increase. Other than adjusting temperatures
a little, no significant changes. Did take a look at pops late
tonight. Latest consensus blend of short term models still bring
slight chance pops into the northwest 9-12 UTC. This is handled
well with the current forecast.

UPDATE Issued at 723 PM CST Tue Nov 21 2017

As expected, temperatures are dropping fast across western and
central ND. However, clouds and strong warm advection are quickly
approaching the west. Have used a blend of short range guidance as
a start this evening, as they seemed to have a reasonable handle
on temperatures dropping central, but increasing west. this gives
some temperatures around zero northwest and north central
(although mid clouds moving into the far northwest should
eliminate additional temperature falls there) and single digits
most everywhere but the far southwest where teens will be the
rule.

UPDATE Issued at 540 PM CST Tue Nov 21 2017

Surface High pressure was situated over western and central early
this evening with mainly clear skies and light or diminishing
winds. The surface high will slide southeast tonight. Main issue
this evening will be how far temperatures drop under good
radiational cooling conditions, before a return flow sets up and
temperatures begin to rise in the west after midnight. Will take
another look at temperatures later this evening. Otherwise no
changes other than some minor tweaks to lower cloud cover and
updating latest sensible weather elements.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 141 PM CST Tue Nov 21 2017

A wintry mix far northwest and north central Wednesday morning
highlights the short term forecast.

Cold surface high pressure across the Northern Plains this
afternoon will propagate into the Central and Southern Plains
tonight. A surface warm front will propagate into the Missouri River
Valley between 12-15 UTC Wednesday morning, with an elevated warm
layer aloft with the slope of the warm front extending further
east into north central North Dakota and the James River Valley. A
clipper will propagate along the low level baroclinic zone from
northwest to southeast across the state through the day. The 12
UTC global guidance is further north with this clipper compared to
yesterday. Thus, the potential for a wintry mix of freezing rain,
sleet and snow has also shifted north compared to yesterday, now
across extreme northwest North Dakota and through the north central
along and north of US Highway 2. While QPF amounts are light, even
a small amount of freezing rain will impact travel.

The aforementioned baroclinic zone will lead to a large spread in
forecast highs for Wednesday, only in the 20s across the Turtle
Mountains, to the 50s southwest and south central. Brisk northwest
winds with gusts around 30s kts are forecast across southwest
North Dakota in the wake of the clipper.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 141 PM CST Tue Nov 21 2017

Record highs possible on Thanksgiving, and a very windy
Friday highlight the extended forecast.

The 00 UTC NAEFS 850 mb mean temperatures climb to their 99th
percentiles across much of western North Dakota on Thanksgiving.
With favorable southwesterly winds, the top edge of the 12 UTC
suite forecast envelope for highs is possible across western and
portions of central North Dakota. As southwest winds and greater
mixing will be late to arrive across the James River Valley
through the Turtle Mountains, a large spread in temperatures is
once again expected on Thanksgiving. Highs perhaps around 70 are
forecast southwest, with perhaps only the 40s and 50s for the
James River Valley and Turtle Mountains.

Location....Forecast High...November 23.....Thanksgiving All Time

Dickinson........70...........63 in 1984........65 in 1998
Williston........64...........56 in 2011........56 in 2002
Bismarck.........60...........62 in 2011........62 in 2002
Minot............57...........55 in 1942........57 in 2011

In a setup similar to Monday, Friday looks to be very windy in
the wake of a strong cold front extending from a clipper system
across Manitoba into Ontario. Strong gradient winds with 45-55 kts
to mix in the 800-850mb layer, with steep low level lapse rates
and cold air advection behind the front support the potential for
strong winds across western and central North Dakota on Friday.
This will have to be closely monitored for a possible High Wind
Watch.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1218 AM CST Wed Nov 22 2017

Light winds and VFR conditions late tonight. A warm front will lift
into the area and bring some VFR ceilings (6000ft) from Williston to
Minot through around 10 UTC. Wednesday low pressure will track
from northwest into southeast ND. Early Wednesday (13-17z)low
level winds shear develops over western ND with 40-50kt winds
around 2000 feet and light south to southwest winds at the
surface. VFR clouds and light precipitation then spread across
KISN and KMOT. Currently only mention of VCSH at KMOT with
precipitation mainly north of these TAF sites. Surface winds shift
from south to west to northwest at all taf sites during the day
with the passage of the low and associated surface front.

&&

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

$$

UPDATE...JV
SHORT TERM...PA
LONG TERM...PA
AVIATION...TWH


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