000
FXUS63 KBIS 151742
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1242 PM CDT Mon Apr 15 2024

.KEY MESSAGES...

- Multiple rounds of showers and a few thunderstorms are
  possible today through Tuesday. Severe weather is not
  expected.

- Low afternoon humidity and gusty southeast winds will lead to
  near critical fire weather conditions on this afternoon
  across the south.

- Expect cooler temperatures starting on Tuesday and lasting
  into the weekend. The coldest days will be Thursday and Friday
  when highs will mainly range from the upper 30s to mid 40s.

- Some light snow is possible Wednesday night through Thursday
  night, mainly across the north. Little to no accumulation
  expected.

&&

.UPDATE...
Issued at 1242 PM CDT Mon Apr 15 2024

Ceilings have lowered and a thunderstorm developed over Bismarck
late this morning, so we are starting to see some rain reaching
the ground with this second batch of showers, although in many
places where we are seeing radar returns the cloud deck is still
too high. There are some more scattered showers upstream in
central South Dakota but these look even lighter, so not
expecting much activity from these.

Main concern so far today has been isolated strong wind gusts
from the rain showers. Winds aloft aren`t as strong as we would
expect, but somewhat inverted V soundings with a very dry layer
near the surface has allowed for wind gusts as high as 65 mph
across southwest North Dakota. This activity has weakened
slightly over the past hour but we do have a Special Weather
Statement out for counties surrounding the Wind Advisory, to
message potential for occasional wind gusts up to 55 mph through
early afternoon as these showers move through.

UPDATE
Issued at 940 AM CDT Mon Apr 15 2024

Double barrel surface low is analyzed in northeast Wyoming and
northeast Colorado, with radar returns extending to the
northeast across the Dakotas. One area of showers extends
across our eastern counties, moving east, with no lightning
observed with this batch for at least an hour.

Another round of showers with an occasional lightning strike
continues to move north from South Dakota, although cloud decks
are much higher with this round so more likely to be virga, at
least for the immediate future.

After this second round of showers moves through, high-res
guidance is fairly confident on a break in precipitation before
the upper low gets closer and showers and a few thunderstorms
become more widespread late tonight through Tuesday. Updated
POPs with new guidance and following current radar trends,
otherwise going forecast looks good.

UPDATE
Issued at 643 AM CDT Mon Apr 15 2024

Showers and thunderstorms continue across the central and east.
We have updated PoPs to reflect the current radar trends.
Thunderstorms are scattered within these showers. Another round
of showers and thunderstorms are starting to move into the
state from South Dakota, like the other showers, thunder is
scattered within. The forecast remains on track with the showers
becoming a lot more isolated as the dry slow of the low moves
in this afternoon.

&&

.DISCUSSION...
Issued at 400 AM CDT Mon Apr 15 2024

Showers and thunderstorms are developing across southern and
eastern North Dakota early this morning. They are moving east in
the mean flow despite the surface winds being out of the east.
This big upper level low is moving through The Four Corners
region while at the surface, the low is in northeastern
Wyoming. A short ridge is currently moving through the state
which is the reason the showers and thunderstorms are moving
along it. Today the flow will switch to the southwest from the
upper low and trough. CAPE values for this morning and today are
not impressive, looking right around 300 J/kg. So no severe
weather is expected today. The SPC has a marginal risk in South
Dakota, ending at the North Dakota state line, we are just in
general thunder.

After this morning, there will be a lull in the showers until
that ridge fully moves through. We will still carry a slight
chance of PoPs. Highs will be slightly cooler in the lower 70s
and upper 60s. The biggest story for today is the wind. Winds
will gust near 40 mph across the south with the pressure
gradient tightening as the surface low moves out of WY. This
will create near critical fire weather concerns in the south
with relative humidity in the mid 20s. We went with a Wind
Advisory to cover both the winds and the fire danger. This is in
effect from 15z this morning until 04z tonight.

The next round of showers and thunderstorms moves in tonight
with the surface low positioned over eastern South Dakota. The
upper level low will deepen over Nebraska, with a lot of
diffluence over North Dakota allowing for ample lift. CAPE
values again are less than 1000 J/kg so severe weather is not
expected at this time. At 850mb a low level jet will carry Gulf
moisture up to the state. However there will probably be
widespread severe weather between South Dakota and Texas, so
that moisture could get used up before it reaches North Dakota.
Tonight is the highest chances of thunderstorms all week.
Tuesday looks like a washout across the central and east. This
is the day most of our 0.25 to 1.25 inches of rain come from.
The east is in the higher QPF.

Through Wednesday the low moves off through Iowa, while a second
low starts to drop in from Canada. This will bring in cooler
temperatures, along with the chance of snow. The highest snow
chances are in the far northern counties Wednesday through
Thursday night. The rest of the area will be dry and cold.
Overnight lows will be in the 20s with daytime highs in the 30s
and 40s. Winds will be breezy all week as well from the tight
pressure gradients. The flow aloft will be somewhat zonal in
cyclonic flow around the second low. Friday afternoon a slight
ridge could build in from a 3rd low way out west. This could
warm us back into the 50s late next weekend. The following week
looks back to above average temperatures as the 850mb
temperatures warm ahead of this 3rd low. The NBM spreads are
large but look to be between 60 and 70s degrees. A slight chance
of rain is possible with the low on Monday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1242 PM CDT Mon Apr 15 2024

Showers and a few thunderstorms will continue across much of
central North Dakota into this evening, with a break in
precipitation expected. Rain chances increase after 06Z with
rain likely at all terminals Tuesday morning except KXWA. There
is low confidence in where and when we will see a few isolated
thunderstorms through the period. VFR ceilings will persist
until around 12Z, when a broad area of MVFR to IFR ceilings
expand north across the forecast area. Southeast winds will stay
breezy to windy through the night tonight. Rain showers have
been occasionally mixing down wind gusts up to 50 knots. Towards
the end of the TAF period, winds will decrease and begin to turn
northerly at western terminals.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 11 PM CDT /10 PM MDT/ this evening for
NDZ034>036-041-042-044>047-050.

&&

$$

UPDATE...Jones
DISCUSSION...Smith
AVIATION...Jones