611
FXUS63 KFSD 032356
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
656 PM CDT Wed Jul 3 2024

.KEY MESSAGES...

- Scattered thunderstorms are likely along and south of the
  Missouri River and Highway 20 areas later this afternoon and
  evening. Isolated strong storms are possible, with the
  greatest focus south of the Missouri River.

- Scattered rain may continue into July 4th, but coverage
  remains uncertain. A low end severe weather risks develops
  mid- afternoon for portions of SW Minnesota and northern Iowa.

- The holiday weekend remains unsettled with nearly daily risks
  for showers and thunderstorms. Not anticipating any
  widespread heavy rainfall that would impact flood levels at
  this time, but afternoon/evening rain risks may get in the way
  of weekend festivities.

- Cooler than normal temperatures will continue well into next
  week.

&&

.DISCUSSION...
Issued at 207 PM CDT Wed Jul 3 2024

THIS Afternoon: Shortwave energy entering the Plains will
continue to aid in convection development along an ill-defined
surface boundary stretching across northern Nebraska this
afternoon. MLCAPE is only expected to reach up towards 1000-1500
J/KG, with effective shear AOA 25-30 knots. Greatest
development potential will be in north central Nebraska where
EML is weaker. Several clusters of convection will drift
eastward into the evening, potentially merging into one or more
linear clusters as they approach northeastern Nebraska. Again
however, diminishing instability should preclude any widespread
organized severe weather risk, so anticipate the greatest risks
coming from marginal hail and localized higher wind gusts along
or south of the Missouri River and Highway 20.

TONIGHT: Additional convection is likely to develop across the
western Dakotas and Panhandle of Nebraska later this evening as
low- lvl flow backs and deeper 700:500 mb troughing moves into
the Plains. This convection will likely track eastward, but
could also tend to drive southward into a richer low-lvl airmass
across Nebraska after midnight. The end result could be much
more scattered shower development through mid-morning across the
Tri-State area. Temperatures fall into the upper 50s to lower
60s.

4th of July:  Upper troughing will cross the Dakotas on Independence
Day, bringing unsettled weather to much of the Tri-State area.
Initially, scattered showers and very isolated thunderstorms may
move east of I-29 by mid-morning, leaving lowering PoPs into mid-
day.   The passage of the 850mb and then surface front into the
afternoon hours may spark renewed convection over SW Minnesota and
NW Iowa early in the afternoon.  This will generally be a low CAPE
but increased shear environment ahead of the surface boundary,
highly dependent if we could see any breaks in cloud cover
ahead of the advancing front. That said, the primary risks would
be from marginally severe hail, though some enhanced stretching
along the surface boundary could result in funnel development.
Further west, more diurnally driven shower and thunderstorm
activity may develop, though given broad synoptic driving
mechanisms, scattered shower activity could continue into the
overnight hours. I certainly wouldn`t cancel those
evening/sunset plans, but anyone northeast of a line from Huron
to Sioux Falls to Storm Lake will need to be aware of scattered
rain risks, seasonally cool temperatures, and high relative
humidity values continuing through sunset.

FRIDAY:  The upper trough passes east by Friday morning, bringing a
short lived period of mid-lvl ridging for Friday. However,
given the cooler low-lvl temperatures, any surface heating could
result in isolated shower development Friday afternoon.
Temperatures remain below normal.

SATURDAY-SUNDAY:  Rain chances increase on Saturday as yet another
shortwave moves through the Plains Saturday into Saturday evening.
Uncertainty on where the greatest rain risks are focused remains
high, but rain amounts will generally not cause an impact to overall
flooding in the region.  A broad trough building over the Plains
keeps mostly afternoon isolated to scattered convection risks in the
region for Sunday.  Temperatures though remain near to slightly
below normal in most locations.

MONDAY-TUESDAY: Mid-lvl heights begin to rise over the western third
of the CONUS early next week, with a persistent trough sliding
eastward.  Before slightly warmer and drier conditions move into the
central US, there will be a brief transition Monday and Tuesday
where some increased risk for diurnal convection could be possible.
Temperatures remain near to slightly below normal, with some signal
for above normal temperatures by the middle to end of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 656 PM CDT Wed Jul 3 2024

The northern fringes of a line of showers and thunderstorms is
currently passing through portions of the area south of I-90 and
west of the James River Valley, with this activity expected to
diminish as it travels eastwards overnight towards the I-29
corridor. Another round of showers and thunderstorms looks to follow
2-4 hours behind, which is expected to traverse the region from west
to east overnight into the morning hours. Severe weather is not
expected with either round.

Will likely see scattered showers and thunderstorms to some degree
throughout the day on Thursday. While confidence in timing and
placement is low, have kept mention of afternoon thunderstorms as
prob30 groups for KHON and KFSD. Low chances for severe weather east
of I-29 in the afternoon, with large quarter sized hail
possible along with gusts to 60 mph.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...Dux
AVIATION...APT