266
FXUS63 KFSD 080824
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
324 AM CDT Mon Jul 8 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms possible this afternoon
  into the evening, especially areas east of I-29. While the
  threat for severe weather is very low, small hail and a brief
  funnel cloud is possible.

- Isolated afternoon into early evening showers/storms continue
  through Wednesday. Severe weather is not expected.

- Temperatures for the first half of the week will be on the
  cool side of average for this time of year. However, a big
  warm up is on the way by the weekend along with an increase in
  humidity.

&&

.DISCUSSION...
Issued at 320 AM CDT Mon Jul 8 2024

Areas of patchy, dense fog are possible this morning along and east
of I-29. This will burn off quickly after sunrise. Mostly sunny
skies for today, warming into the upper 70s to low 80s. With
dewpoints in the low 60s, conditions may feel a bit muggier than
we`ve experienced recently.

Later this afternoon, there is a chance for some very isolated
showers and thunderstorms. Precipitable water values of 1+
inches, and long skinny CAPE indicate these showers may be
capable of producing brief, heavy downpours. As these showers
will be spotty in nature, most areas will not see any rain, but
those that do could see a few hundredths. Under any of the
stronger storms a half inch may be possible. Though we have some
mild instability in the form of a 500- 1000 J/kg of MLCAPE,
strong forcing and bulk shear are lacking this afternoon, and so
we are not expecting severe weather. However, water vapor
imagery corroborates model guidance of an area of increased
vorticity on the backside of the low pressure system that is
slowly moving off to the northeast. In addition, the
non-supercell tornado parameter increases to 1-2 along and east
of I-29, especially over western Minnesota. This indicates that
there is a possibility for some brief funnels this afternoon in
that area. These should not touch the ground, but can be
alarming when witnessed. Tonight, northwesterly winds will
become light and variable, bringing another chance for some
patchy fog Tuesday morning. Lows will be in the low 60s.

TUESDAY-WEDNESDAY: The slow eastward progression of the upper low
spinning over the Great Lakes will keep enough energy in place for
low end chances of showers and thunderstorms during the afternoon
and early evening hours both days. The area most likely to see
showers is east of I-29. Temperatures will begin to warm into the
mid 80s for highs, and dewpoints will increase into the mid 60s by
Wednesday.

THURSDAY AND BEYOND: As mentioned in the previous discussion, an
upper ridge begins to build in Thursday and through the weekend. 500
mb heights rise as a large high pressure sets up over the
intermountain west. As the high pressure builds in we will see highs
increase a couple degrees every day until we get into the upper 80s
and mid 90s by Sunday. Dew points also gradually increase into
the upper 60s as southerly winds at the surface bring northward
moist air from the Gulf. By Saturday and Sunday, areas of
northwestern Iowa will see dew points in the low 70s. This will
result in heat indices approaching the mid 90s. People with
sensitivities may need to plan ahead for the hot and muggy
conditions this upcoming weekend.

This period will remain mostly dry, though there are several weak
mid-level waves that may bring isolated shots of rain. Overall any
precipitation that does fall will be minimal.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1025 PM CDT Sun Jul 7 2024

VFR conditions will continue for the duration of the TAF period.
Taking a look across the area, any lingering showers will
gradually continue to dissipate over the next hour or so.
Otherwise, quieter conditions will return as lighter winds
continue for the duration of the period. Lastly, lingering low
level moisture could lead to some patchy areas of fog mostly
along the Missouri River Valley tonight. However, confidence in
occurrence is low at this time.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...Gumbs