214
FXUS63 KFSD 082306
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
606 PM CDT Mon Jul 8 2024

.KEY MESSAGES...

-  Risks for isolated showers and thunderstorms continue
   through Wednesday. Most of this activity will be daylight
   driven, and should remain below severe limits.

-  Wildfire smoke aloft will continue to stream southeast over
   the upcoming days. By Wednesday morning, there will be some
   potential for surface smoke and AQI impacts.

-  Convection risks may increase Thursday night into Friday
   ahead of building short duration heat wave. Severe weather
   risks remain uncertain.

-  Temperatures begin to rise by the end of the week and through
   next weekend. Confidence is high in widespread moderate heat
   risk levels with potential for major levels. Most dangerous
   conditions focused on Sunday and advisory conditions may be
   met.

&&

.DISCUSSION...
Issued at 205 PM CDT Mon Jul 8 2024

THIS Afternoon:  Isolated convection trying to develop along two
weak surface convergent lines.  One along the edge of the Buffalo
Ridge and a second on a slowly southeast advancing surface trough
just on the eastern edge of the CWA.  This activity is expected to
remain isolated and non-severe in nature.    Further west, a very
visible plume of smoke stretches from north to south across the
eastern Dakotas into northern Nebraska.

TONIGHT:  Mostly clear skies are anticipated tonight, but both
HRRR/RAP projections pull smoke slightly east and southeast into
Tuesday morning.  Have increased sky cover to hint at the hazy
skies.  Temperatures fall into the upper 50s to lower 60s, and as we
saw Monday morning, wouldn`t rule out valley fog with the light and
variable surface winds.

TUESDAY: Another warm day with variable winds expected for Tuesday.
Once convective temperatures are reached by late to early morning we
should again to see scattered convection develop.  While severe
storms aren`t likely, it`s not impossible to see a storm or two
capable of smaller hail and gusty winds given MLCAPE approaching
1000 J/KG.  While the majority of this convection will dissipate
towards evening, a stronger shortwave will dip southward along the
Red River valley into western Minnesota overnight. This wave may
keep scattered showers or even a thunderstorm or two going into
daybreak Wednesday. Elevated smoke is also expected to continue
through the region.

WEDNESDAY:  The aforementioned shortwave trough tracks into
southeast Minnesota by mid-day Wednesday, creating an additional
risk for isolated to scattered convection within the dPVA corridor
ahead of the wave. This may end up in portions of Northwest Iowa and
southern Minnesota and far eastern South Dakota.  While the severe
risk again appears low, given increasing mid-lvl lapse rates,
and potential for boundary layer updraft stretching, would need
to be at least aware of the potential for small hail or brief
landspouts. Additionally, wildfire smoke from Alberta/BC fires
will continue to sink southward, with the new north flow very
favorable for spreading a thicker plume of smoke into the Tri-
State area. Some model guidance is suggesting that subsidence
behind the shortwave and behind a weak cold front may pull some
smoke to the surface Wednesday. Will need to monitor this time
period for possible air quality issues into Thursday.

THURSDAY-FRIDAY:  Warm advection begins to return to the Plains as
mid-lvl heights grow over the western third of the CONUS.   There
will likely be a marked increase of mid-lvl clouds, especially by
Friday, but also temperatures rising above normal.  Some elevated
convection risks may develop late Friday evening into Saturday
morning.

SATURDAY-MONDAY:  Biggest story through the upcoming weekend will be
rising temperatures and potential for heat related headlines.  Broad
low-lvl warm advection increases Saturday, as a surface warm front
surges into the Northern Plains and Great Lakes.  The development of
more favorable southerly winds will push high temperatures into
the upper 80s to 90s on Saturday. A surface front moving into
the eastern Dakotas and an increasing SPG will induce a stronger
southwesterly wind Sunday, pushing the nose of an 925:850
thermal ridge towards the Tri-State area. The end result will be
high temperatures in the 90s in most locations. Ensemble
probabilities have risen towards a greater than 70% probability
of at least 90 degree temperatures Sunday afternoon. Have pushed
temperatures a bit closer to the 75th percentile. The rise in
dew points and resultant humidity values Sunday into Monday may
push heat index values towards the 100 degree mark in the MO
river valley Saturday, and over a much larger area on Sunday. In
fact, feel the NBM may be a bit low-biased for the time of the
year given the approach of peak evapotranspiration rates which
may push dewpoints even higher. Corresponding NWS heat risk
products suggest advisories should be considered in many areas
Sunday.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 600 PM CDT Mon Jul 8 2024

VFR conditions will continue for the duration of the TAF period.
Taking a look across the area, mostly clear conditions continue
with a few areas of wild fire smoke overhead. While this smoke
won`t likely reach the surface during the TAF period, will
become somewhat more noticeable aloft by Tuesday morning.
Otherwise, light and variable winds will likely continue for the
duration of the TAF period.

&&

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

&&

$$

DISCUSSION...Dux
AVIATION...Gumbs