149
FXUS63 KFSD 161854
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
154 PM CDT Thu May 16 2024

.KEY MESSAGES...

- Well above normal temperatures will end the week. Moderate to
high confidence (80-90%) in widespread highs in the 80s on Friday.
Highs in the 80s will likely be limited to parts of northwest IA on
Saturday with the incoming cold front.

- Sunday afternoon into Tuesday starting to look more active with
the potential for some locally heavy rain and severe weather
possible.

&&

.DISCUSSION...
Issued at 153 PM CDT Thu May 16 2024

Model soundings indicate very weak surface based instability later
this afternoon in central SD. If something could develop wind gusts
of 30-40 mph would be possible, but chances of development are very
low. A few stray showers could develop near highway 14 later tonight
as some weak energy moves through northern SD which increases mid
level warm advection, but again chances are very low. Otherwise. a
ridge of high pressure at the surface will drift east tonight with
southerly flow gradually increasing. This should allow for some mild
lows with most locations falling to 50 to 55 overnight. Parts of
northwest IA could slip into the upper 40s as the southerly flow
sets up there latest.

As west southwest flow increases just north of the area very warm
air will build into the region which will set up a hot Friday. Highs
should exceed 80 everywhere and even a chance to touch 90 in central
SD. Instability will increase across the area ahead of this incoming
increasing flow and deepening trough to the west. Overall everywhere
looks pretty capped with some weakness noted in central SD. More
than likely will need to get some development to the west of the
area and have it propagate into central SD in the evening. For now
the severe weather threat looks very isolated with mainly wind to
worry about. Likely just a bit too much dry air to overcome.

Friday night into Saturday a cool front will sweep through the
area. Very mild air will be in place ahead of this front and if just
slow enough lows will mostly be in the 60s east of the James River.
Precipitation chances will be spotty and light. Saturday should be
dry and seasonal with highs in the 70s but gusty northwest winds
behind the front, likely gusting to around 30 mph.

Saturday night into Sunday will see a fairly strong right entrance
region of the upper level jet move across the Northern Plains as a
strengthening southern stream upper level jet moves into the Central
Plains. This upper level energy will bring stronger southwest
flow aloft and a fairly strong mid level wave into the area. The
main questions for severe potential will be the timing of the wave,
with many of the current projections swinging energy into the area
on Sunday morning, with a trailing wave moving through during the
afternoon and evening. The morning wave will be fighting low and mid
level dry air with an EML that is only moderately unstable. This
should support mainly scattered showers and isolated thunderstorms.
Obviously this is far enough out the smaller details are still up in
the air. A look at the soundings suggests the potential for 1000-
1500 J/kg CAPE along with weak to moderate shear late Sunday
afternoon and evening. With some deeper moisture surging in on
Sunday afternoon, then a cold front expected to dive southeast on
Monday we could see some potential for heavy rain and isolated
severe storms both Sunday night and Monday. Some of the latest model
information is slowing things a bit and bringing an increased threat
for rain and thunderstorms behind this front Monday night into
Tuesday, so still some concerns still up in the air during this
time. Regardless a good chance for widespread rainfall and
thunderstorms with some pockets of heavy rain and isolated severe
Sunday night into Tuesday.

Some agreement that the main piece of energy will move through on
Tuesday with temperatures settling back to around normal Tuesday
into Thursday with lower chances for showers and storms Wednesday
and Thursday.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1152 AM CDT Thu May 16 2024

VFR through the period. A very isolated shower will be possible
in central SD late this afternoon and evening which could result
in locally breezy conditions.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08