321
FXUS63 KBIS 060708
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
208 AM CDT Mon May 6 2024

.KEY MESSAGES...

- Southeast winds gusting to 50 mph continue over western and
  south central North Dakota into late tonight. Thereafter,
  focus for higher winds Monday shifts east including all of
  central North Dakota including the James River Valley.

- Widespread showers and isolated to scattered thunderstorms
  are expected late tonight through Tuesday, especially in far
  western North Dakota.

- There is a conditional risk of strong thunderstorms Monday
  afternoon, mainly across southern parts of the state.

- Focus for stronger winds shifts to southwest North Dakota for
  Tuesday, after winds shift westerly.

&&

.UPDATE...
Issued at 207 AM CDT Mon May 6 2024

A few showers are beginning to sneak into western North Dakota
as of 100 AM MDT. Meanwhile, some more organized convective
activity is beginning to develop over parts of western and
central South Dakota, moving north. The HRRR has been
consistently advertising what is currently evolving northwest of
Pierre, SD, bringing this activity northward into south central
North Dakota over the next few hours.

UPDATE
Issued at 950 PM CDT Sun May 5 2024

The forecast for tonight remains on track. Showers and
thunderstorms continue to lift north/northeast across the high
plains on eastern Wyoming and Montana. Will see some of this
activity nearing the MT/ND border area later this evening, with
CAMs and NBM still suggesting another area of showers and
perhaps a few thunderstorms developing across South Dakota and
lifting north into western and south central ND overnight.
Models still in great agreement with the formation of a 40-50
knot low level jet, along with lead embedded impulses ejecting
north out of an upper low across the Central Rockies, both of
which would support this development. Opted to keep the wind
advisory as is with this product issuance, despite winds
tapering off some this evening, as the increasing LLJ coupled
with shower activity may mix down some of these stronger winds
tonight.


UPDATE
Issued at 658 PM CDT Sun May 5 2024

Southeast winds remain strong west and south central, with gusts
ranging from 40 to 50 mph. Thus, the wind advisory remains valid
and no changes to headlines with this product issuance.

Mainly a BKN-OVC upper level cloud deck over west and central ND
early this evening. Will see increasing mid level clouds
followed by ceilings lowering as precipitation starts to
develop into the local area later this evening and especially
overnight. Right now all activity is well to our west and
southwest, which should change as the upper low moves over the
Central Rockies and lead impulses start to life north across the
plains as we progress through the night.

&&

.DISCUSSION...
Issued at 221 PM CDT Sun May 5 2024

Current surface analysis places low over the Northern and
Central Rockies, with broad high over the Midwest. This is
resulting in a tight pressure gradient through the Central into
the Northern Plains. Upper level analysis places ridging over
the Northern Plains ahead of low that is now pushing through
Great Basin. Over our neck of the woods, gusty southeast winds
continue in the tight pressure gradient, especially over western
into south central North Dakota. Strongest winds now focused
over southwest North Dakota where some gusts around 50 mph have
been noted.

For tonight, upper low passes over the Rockies with surface low
pushing to the lee side of the Rockies into the plains of
Montana/Eastern Wyoming. In the meantime, a low level jet will
also be intensifying. Gusty southeast winds therefore will
continue through the evening into the overnight given the
gradient and possible enhancement from the jet, but will start
to ease up over western North Dakota after midnight, while
continuing over portions of central North Dakota. In the
meantime, rain shower chances will gradually be on the increase
with the upper low continuing its approach.

On Monday, upper low becomes influenced by a low to the
northwest and becomes negatively tilted as it works into the
Northern Plains, but still remains closed. Chances for
showers/storms will continue to spread across the area, with the
highest chances remaining to the west. There remains some
concern for severe potential over southern portions of the area,
with the potential remaining rather consistent per multiple
runs of the CSU machine learning probabilities. Forcing will be
ample giving the lifting boundary, and 0-6KM deep layer shear
will be more than ample at ~40-60kts, just instability remains
in question. The next issue is winds, with the focus for gusty
southeast winds shifting more into central/eastern North Dakota
with the surface low lifting into the far western
Dakotas/eastern Montana. Pressure gradient remains rather tight,
so expect another round of gusts to 50 mph.

As we get into the overnight into Tuesday, low lifts northeast
well into the Northern Plains and loiters over the region. Still
some question on the exact implications of the dry slot and how
far west it will go. Speaking of Tuesday, northwest winds
become a possible concern over the southwest, but again the
intensity of the winds depend on how far north the surface low
lifts.

Precipitation chances remain through Wednesday and possibly
into Thursday pending the departure of the low from the region.
Seasonably mild temperatures expected.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 207 AM CDT Mon May 6 2024

A strong low pressure system will bring aviation impacts to
western and central North Dakota through the forecast period.
MVFR to IFR ceilings are forecast to build in from southwest to
northeast Monday morning, persisting through the rest of the day
and evening. Periods of showers and isolated to scattered
thunderstorms can also be expected throughout the day Monday and
into Monday night. Southeast winds will remain strong through
the forecast period, increasing to sustained speeds around 20-30
kts with gusts to 35-45 kts Monday afternoon, strongest over
central and eastern North Dakota. Low level wind shear will
impact parts of central North Dakota from KMOT to KBIS until
early Monday morning.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 4 AM CDT /3 AM MDT/ early this morning for
NDZ001-002-009-010-017-018-031>033-040-041-043-044.
Wind Advisory from 6 AM this morning to midnight CDT tonight
for NDZ003>005-011>013-022-023-025-037-048-051.
Wind Advisory until midnight CDT /11 PM MDT/ tonight for
NDZ019>021-034>036-042-045>047-050.

&&

$$

UPDATE...Hollan
DISCUSSION...JJS
AVIATION...Hollan/King/NH