478
FXUS63 KBIS 111012
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
512 AM CDT Thu Jul 11 2024

.KEY MESSAGES...

- Thunderstorms (20 to 40%) west and central this afternoon and
  tonight could produce damaging winds up to 60 mph in far
  western North Dakota.

- Hot and humid conditions are expected Thursday through
  Sunday, with highs mostly in the upper 80s to upper 90s.

- Severe weather threat continues Friday through Sunday morning
  for much of North Dakota. Severe wind gusts and large hail are
  possible.

&&

.DISCUSSION...
Issued at 458 AM CDT Thu Jul 11 2024

Today temperatures are forecast to climb into the upper 80s to
lower 90s. The upper level ridge has flattened out resulting
in zonal flow aloft. A weak impulse continues to move across
eastern Montana this morning, showers could make it into the
northwest this morning but this impulse should die out. A
stronger impulse associated with a shortwave trough will
traverse through the jet stream this afternoon and evening
bringing forth a chance for thunderstorms (20 to 40%). Some of
these storms could be severe as forecast model soundings have
DCAPE 1500 j/kg. This could support severe thunderstorms with
damaging wind gusts up to 60 mph for very far western North
Dakota. Storms will push into central North Dakota later tonight
with the severe weather risk decreasing as instability
decreases.

Zonal flow aloft will continue the severe weather threat as
thunderstorms could form along another impulse passing through
the region Friday. Another round of severe weather is possible
Friday afternoon as mid level lapse rates of 9 C/km exceeding
700 mb and 1500 to 2500 j/kg of MLCAPE. Bulk shear around 35 to
45 kts will help in organization of storms. Organized high based
storms out west could result in severe wind gusts and large
hail. Storms will likely become linear in nature by the evening
hours moving across the north central. CAMs only go out through
the early evening hours for Friday so much could change in the
mean time. The main areas of concern are the north central and
the western half of the state.

Saturday, another shot of severe weather is possible as another
impulse moves through the main stream of the jet stream. Ample
instability and high dewpoints will help enhance the severe
weather risk. Saturday`s threat is more of an evening/overnight
threat. Deterministic models have an MCS moving though the
northwest to the southeast by Sunday morning. There is an SPC
Day 3 Outlook highlighting all of North Dakota in a marginal
risk with the central and eastern half of the state in a slight
risk where the potential MCS could track. The main threat looks
to be wind at this time, but large hail shouldn`t be ruled out.

Friday the upper level ridge will shift the low level thermal
ridge across western South Dakota orientated southeast to
northwest intersecting southwest North Dakota. This will last
through Saturday resulting in widespread temperatures in the 90s
with a chance for 100 in the southwest. Dew points in the 60s
and temperatures in the 90s will lead to hot and humid
conditions across the state.

The upper level ridge will persist through next week out west. The
question for our region is how much will the ridge dampen early next
week opening the door for more shortwaves and slightly cooler
temperatures as a back door cold front could enter the region.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1228 AM CDT Thu Jul 11 2024

VFR conditions will continue across the region for the next 24
hours. Southerly winds will pick up this afternoon around 15 to
20 kts. Thunderstorms are possible this afternoon and evening
out west. There is some uncertainty on location and timing of
storms, therefore TSRA was not added to the current TAF for
KXWA and KDIK.

&&

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

&&

$$

DISCUSSION...Johnson
AVIATION...Johnson