137
FXUS63 KBIS 191806
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
106 PM CDT Thu Sep 19 2024

.KEY MESSAGES...

- It will be windy through this evening with sustained west
  winds up to 30 mph at times. Gusts to 50 mph will be possible
  across the west, southwest, and far south central.

- Expect medium to high chances (40 to 70 percent) for rain
  showers today, mainly across the north. Isolated thunderstorms
  (20 percent chance) will be possible in the north as well.

- A cooling trend is forecast for the end of the week, with
  highs in the 60s by the weekend.

&&

.UPDATE...
Issued at 105 PM CDT Thu Sep 19 2024

Main update is for the ongoing Wind Advisory. Strong sustained
winds with gust approaching 45 MPH are starting to be reported
from Beach to Dickinson, and in the Williston area. Given at
least sustained criteria is expected to continue through this
afternoon have expanded the Wind Advisory northward. Will
maintain the same end time, although perhaps extension for some
counties will be needed. Otherwise the forecast remains on
track. Showers continue to be found across the north and may
expand southward today. Cooler temperatures will also be found
today.

UPDATE
Issued at 1007 AM CDT Thu Sep 19 2024

Limited updates needed this morning. Showers associated with a
wrapped upper level low continue to be found mainly in the
north. This trend looks to continue through the day, although
isolated showers could extend southward through this afternoon.
There still looks to be just enough instability for a few
thunderstorms in the north today, mainly along and north of US
Highway 2. The threat for severe weather is low. Otherwise,
continue to monitor breezy to windy conditions for today.
Current Wind Advisory remains valid. Much of western North
Dakota may also get close to advisory criteria today. 12Z HREF
Ensemble data is starting to come in, and max values are right
on the cusp of criteria. For now will continue to monitor and
leave the advisory as is.

UPDATE
Issued at 622 AM CDT Thu Sep 19 2024

The stacked low is now approaching the southern
Saskatchewan/Manitoba border as showers are rotating into the
northwest part of the state out of northeastern Montana and the
southern Canadian Prairies. Chances for rain will increase
through the morning across the northwest, shifting into the
north central by late morning or early afternoon. There may be
enough instability floating around for some thunder after 15z or
so. No major changes were needed for this update.

&&

.DISCUSSION...
Issued at 330 AM CDT Thu Sep 19 2024

A stacked low is currently centered over the southeastern corner
of Saskatchewan and will slowly creep east northeast into
Manitoba by later this afternoon. While most of the large scale
forcing will remain north of the International border, there
should be enough lift to maintain medium to high chances (40 to
70 percent) of wrap around rain showers across much of the
northwest and north central. While instability will be weak, RAP
forecast soundings suggest the potential for 100 to 500 J/kg
MUCAPE through much of the afternoon across the north. Thus a
few thunderstorms are also possible (20 percent chance north).

A tight pressure gradient and steepening lapse rates will lead
to more breezy/windy conditions through the late afternoon
hours. The strongest winds (out of the west or west northwest)
should be across the south, with sustained values up to 30 mph
and gusts to 50 mph. We did expand the Wind Advisory east a
tier, and it now includes Sioux and Grant counties. A few other
areas across the west could flirt with advisory criteria at
times through the morning and afternoon.

Precipitation should move out to the northeast by this evening
and winds will continue to decrease, giving way to a mostly
clear sky overnight. Lows will drop into the lower 40s to the
lower 50s. With light winds and a clear sky overhead, a few
upper 30s may not be out of the question across portions of the
west.

A low amplitude ridge axis will cross the state on Friday, which
should help to briefly bump up temperatures. NBM highs are
forecast to range from the lower 70s to the lower 80s. A
reinforcing cold front will then cross the state Friday night
into Saturday morning as the next trough moves through. These
features will bring the next low chance (20 to 30 percent) of
rain showers (maybe a thunderstorm or two) to the area Friday
evening through Saturday morning. Lows Saturday morning will
range from the lower 40s to the lower 50s. Saturday should be
rather blustery behind the cold front with breezy northwest
winds and highs only in the 60s. We will see some clouds hanging
around through the first part of the day on Saturday, but
surface high pressure will start to nudge in from the west late
afternoon and into the evening, which should lead to diminishing
clouds.

As winds calm and the sky clears Saturday night, it may become
rather chilly, especially across portions of the west where we
will likely dip into the mid to upper 30s. Expect lows in the
low to mid 40s mainly east of the Missouri River. Thus, some
frost is certainly looking like a possibility across the west
Sunday morning. However, if we trend more towards the NBM 25th
percentile, lows at or below freezing are not out of the
question across the southwest.

Low amplitude progressive flow will be the pattern driver into
the middle of next week with highs expected to mainly be in the
lower 60s to lower 70s and only low chances of showers (15
percent) Monday night into Tuesday. Lows should mainly be in the
40s.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 105 PM CDT Thu Sep 19 2024

VFR to MVFR cloud cover will remain across most sites through
this afternoon. A few showers or isolated thunderstorms are
possible this afternoon as well, mainly along and north of US
Highway 2 (KXWA to KMOT to KRUG and north). Confidence was only
high enough to include VCSH at the KMOT TAF at this time. Strong
westerly winds are also expected through this afternoon.
Showers, gusty winds, and lower ceilings look to diminish this
evening into the early overnight hours. VFR conditions will then
prevail into Friday morning. Many sites will see westerly winds
become southwest to south tonight into Friday.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 4 PM CDT /3 PM MDT/ this afternoon for
NDZ009-017-018-031>033-040>045.

&&

$$

UPDATE...Anglin
DISCUSSION...ZH
AVIATION...Anglin