Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 091131
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
631 AM CDT Thu Jul 9 2020

.SHORT TERM...(Today and Tonight)
Issued at 357 AM CDT Thu Jul 9 2020

Another active morning across the area with MCS to the north and
south of the forecast area with isolated to scattered convection in
between.  Outflow from the various complexes has lowered dew points
along and east of I-29.  Forecast soundings suggest fair substantial
cap lifting from the surface, but much weaker cap exists lifting
aloft.  With lingering boundaries, MCVs and weak cap, could see
additional elevated storms develop mainly across northwest Iowa this
morning. Lifting above the surface severely limits instability, so
do not expect these storms to be severe. 850 HPA temperatures cool
into the upper teens today, so should see highs generally in the 80s
today.

Should be a fairly quiet evening into the overnight tonight as
surface ridge moves into the region.

Increasing southerly winds on Friday will draw moisture back into
the region on Friday.  This will lead to increasing capped
instability across the area.  Fairly strong short wave is expected
to move from the intermountain west into the Dakotas Friday evening,
impacting the region late Friday evening into Saturday morning.  Wind
shear, especially aloft increases as the the wave approaches from
the west.  With stout cap in place, will need to lift from somewhere
above the surface reducing instability some, however, the 1-6 km
bulk shear values are 50-55 knots potentially as high as 60 knots
with both great speed and directional shear.  Agree with SPC`s
assessment that initial storms in western and central South Dakota
will have potential to produce very large hail, but main threat
should transition to wind as storms become more linear.  Have
coordinated adding severe mention in grids from 03-12Z Saturday.

Remainder of the weekend appears to be quieter as northwest flow
aloft develops on the eastern edge of upper level ridge developing
across the west.

Strong upper level trough works into western Canada early next week
leading to an unsettled pattern across the Northern Plains Tuesday
into Thursday.   Temperatures looks to be seasonal to slightly above
normal.

.LONG TERM...(Friday through Wednesday)
Issued at 357 AM CDT Thu Jul 9 2020

Increasing southerly winds on Friday will draw moisture back into
the region on Friday.  This will lead to increasing capped
instability across the area.  Fairly strong short wave is expected
to move from the intermountain west into the Dakotas Friday evening,
impacting the region late Friday evening into Saturday morning.  Wind
shear, especially aloft increases as the the wave approaches from
the west.  With stout cap in place, will need to lift from somewhere
above the surface reducing instability some, however, the 1-6 km
bulk shear values are 50-55 knots potentially as high as 60 knots
with both great speed and directional shear.  Agree with SPC`s
assessment that initial storms in western and central South Dakota
will have potential to produce very large hail, but main threat
should transition to wind as storms become more linear.  Have
coordinated adding severe mention in grids from 03-12Z Saturday.

Remainder of the weekend appears to be quieter as northwest flow
aloft develops on the eastern edge of upper level ridge developing
across the west.

Strong upper level trough works into western Canada early next week
leading to an unsettled pattern across the Northern Plains Tuesday
into Thursday.   Temperatures looks to be seasonal to slightly above
normal.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 625 AM CDT Thu Jul 9 2020

MCV working into western Iowa as of 11Z. This is resulting in
additional showers and thunderstorms across northwest Iowa.
While the ceilings are VFR, heavy rain may temporarily lower
visibility. In addition, Storms could produce gusty winds to 50
mph. Thunderstorms are expected to shift southeast through the
day, and VFR conditions are expected Thursday afternoon into
Thursday night.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...BT
LONG TERM...BT
AVIATION...BT


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