421
FXUS63 KBIS 150620
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
120 AM CDT Thu Aug 15 2024

.KEY MESSAGES...

- Isolated showers and thunderstorms are still possible over
  western and central North Dakota tonight, Scattered showers
  and thunderstorms are again possible over central and into
  eastern North Dakota Thursday.

- A few showers and thunderstorms may pass through the area
  Friday night through Saturday night, but overall quieter
  weather is expected Friday into early next week.

- Seasonable temperatures mostly in the upper 70s to mid 80s are
  expected through at least the weekend.

&&

.UPDATE...
Issued at 119 AM CDT Thu Aug 15 2024

Most of the persistent rain has now pivoted into eastern North
Dakota, but is forecast to push back into the Turtle Mountains and
James River Valley on Thursday as the surface low occludes over the
Red River Valley. Fog is beginning to develop along the western
periphery of mid to high clouds associated with the downstream mid
level low. At 1 AM CDT, two separate parts of the state had areas of
dense fog: northern Burke and far northeast Divide Counties, and
Emmons into Logan and McIntosh Counties. Trends will need to be
monitored for a possible Dense Fog Advisory.

UPDATE
Issued at 934 PM CDT Wed Aug 14 2024

The man band of thunderstorms with heavy rain are currently
exiting the James River Valley. We got a report of over 4
inches of rain this evening west of Ellendale in Dickey County.
So these storms continue to be very efficient rainers. To the
west a couple of storms continue to hang on over Dunn county
but activity in the west has dissipated quite a bit since late
this afternoon. We made some updates pare back pops and sky
cover across a good portion of the west and into central ND.

&&

.DISCUSSION...
Issued at 221 PM CDT Wed Aug 14 2024

Longwave trough presently cuts through central Canada and south
through the Dakotas and Minnesota. Associated surface low
pressure is presently located over western South Dakota with
another circulation in southern Saskatchewan, while large surface
high pressure remains over the Great Lakes Region. This
continues to pump very moist air into the state with mixed layer
dewpoints in excess of 60 degrees, and widespread precipitable
water of 1.6 inches or greater over most of the CWA. As a
result, widespread moderate to heavy rain has developed and is
presently impacting much of the state, mainly along and east of
Highway 83.

There were three main factors limiting torrential rain today.
The first is that storms maintained a steady motion, so
residency time over one area hasn`t been excessive. Second,
instability east of Highway 83 has been relatively low overall
leading to more stratiform rain and thundershowers than
organized thunderstorms. Lastly, notable shear today is
virtually non-existent thus preventing more sustained updrafts.
The lack of shear is also what has prevented severe weather.

Thundershowers will continue to gradually end from west to east
through the evening for the western half of the state. Showers
and thundershowers may continue this evening, through tonight,
and into Thursday especially from the James River Valley up
through the Turtle Mountains as aforementioned surface low over
South Dakota wraps up and propagates into northern Minnesota.
Steady rain from these showers and thundershowers may produce
localized areal flooding, or ponding of water, but any further
flash flooding seems unlikely at this time.

Overall, mostly quiet conditions are expected Friday through
Sunday night, though a weak shortwave may bring a few showers
and thunderstorms through the area from west to east Friday
night through Saturday night. The forecast for next week remains
highly uncertain. There is fair agreement in an omega block
setting up. However, exactly where the ridge amplifies over
will determine if there are additional showers and thunderstorms
and just how warm or cool the area becomes. Temperatures will
remain seasonable in the upper 70s to mid 80s for most areas
through the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 119 AM CDT Thu Aug 15 2024

The eastern half of the state will continue to see low ceilings
overnight, mostly IFR but with LIFR possible at times, followed by a
slow improvement to VFR by mid Thursday afternoon. North central
parts of the state could also see a period of MVFR ceilings late
tonight through Thursday morning. Fog is beginning to develop from
northwest to south central North Dakota. KBIS has the highest
probability of visibility restrictions from fog among the major
terminals later tonight into Thursday morning, but confidence in
development there is still not very high. Rain showers are likely to
redevelop over KJMS and surrounding areas on Thursday. Elsewhere,
there are low chances for showers and perhaps a thunderstorm
Thursday afternoon, but most of the western half of the state should
remain dry on Thursday. Northwest winds will increase to around 15
kts Thursday afternoon, with gusts near 25 kts.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Hollan
DISCUSSION...Telken
AVIATION...Hollan