Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 140902
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
402 AM CDT Thu Mar 14 2024

.KEY MESSAGES...

- Chances for rain continue today for areas generally southeast of
  the front from from Jackson, MN to Yankton, SD. Highest chances
  (80+%) for a tenth of an inch near Storm Lake and Ida Grove, IA.

- Dry air northwest of the front combined with breezy northerly
  winds and temperatures in the 50s will result in high to very high
  fire danger this afternoon.

- Cooler temperatures and breezy conditions are expected for the
  weekend, with highs at or below seasonal normals Sunday.

- High to very high fire danger expected for Saturday and
  Sunday.

&&

.DISCUSSION...
Issued at 401 AM CDT Thu Mar 14 2024

Early morning satellite imagery shows ample cloud coverage over the
region, mostly due to the anvil clouds from the former MCS that
occurred south of the area. At the surface, temperatures have mostly
been in the lower to upper 40s, though locally a few locations have
started to dip down into the 30s. Throughout the morning hours we
will be watching a surface low slowly move northeastwards into
southern Iowa throughout the morning hours, with weak 700mb
frontogenesis out ahead of the low resulting in weak scattered
showers across portions of northwestern Iowa and eastern Nebraska.
As the low moves closer to the area, the 850-700mb front out ahead
of the low will extend up into portions of the area, but then stalls
out as the low begins to drift more eastwards than northeastwards by
the early afternoon hours. Thus, expect the current showers and
isolated thunderstorms to shift northwards throughout the morning
hours and remain primarily along and southeast of a line from
Jackson, MN and down towards Yankton, SD, where the 850-700mb front
is expected to stall out.

As this front will act to keep vast majority of the available
moisture from reaching northwestwards, any showers that are able to
form and drift into the area will be rather weak. Therefore,
probabilities for a tenth of an inch northwest of the aforementioned
line from Jackson, MN to Yankton, SD fall rather quickly from 25%
down to 0%. By the afternoon hours, dry low-level air will continue
to filter into this region, and combined with the breezy north-
northeasterly winds will result in high to very high fire danger.
Areas along and southeast of the front continue to show decent
chances for light rain given precipitable water values near 0.8" and
moderate frontal forcing, with areas southeast of Storm Lake, IA and
Ida Grove, IA having the highest probabilities. Chances for a tenth
of an inch southeast of the front range from 30 to 80%, dropping
into the 20 to 70% range for a quarter inch, and less than a 40%
chance for seeing half an inch starting from 7am today through 1am
Friday.

By the evening hours, we`ll likely only see a few remaining showers
across eastern northwest IA, with the surface low having shifted
into eastern Iowa. A surface high pressure moves towards the area
from the northwest as the trough axis begins to move through by
Friday morning, resulting in some marginally cooler temperatures.
We`ll likely start the day off on either side of freezing, with
northerly flow through most of the day keeping temperatures in the
lower to mid 50s. Winds will swing to become out of the west-
southwest throughout the evening hours as a strong low pressure
system dives southwards into the great lakes region, with the
attached cold front expected to move through by Saturday morning.

While temperatures behind the front won`t be too bad in the upper
40s to mid 50s on Saturday, the strong surface pressure gradient
(SPG) and cold-air advection (CAA) will create some rather breezy
northwesterly winds. Sustained wind will likely be in the lower to
mid 20s, with gusts into the lower to mid 30s. While relative
humidity values look to be the limiting factor for the moment, with
minimum RH`s expected to be in the mid 20s to mid 30s high to very
high fire danger is expected. Grassland fire danger even had a
couple counties in far southeastern South Dakota climb up into the
extreme category, so that will be something to watch for over the
the next couple shifts. Overnight into Sunday, a surface high
pressure will be moving down towards the region from the north,
bringing with it seasonably cool max temperatures in the 30s and
40s, with breezy northerly winds continuing.

While upper level ridging is expected for the western CONUS on
Monday, the 00Z model runs now show brief upper level ridging before
breaking down the cut-off upper level low over the SW CONUS and
turning it into a shortwave into the southern plains by mid week.
For us, this means we likely won`t have the additional help of upper
level ridging to warm us back up, but surface and low-level flow
continues to remain active bringing us periods of warmer weather.
Look for 40s and 50s on Monday and Tuesday, with 50s and 60s on
Wednesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1035 PM CDT Wed Mar 13 2024

Scattered showers will continue to develop across northeastern
NE and northwestern IA tonight, then continue into Thursday
afternoon. While conditions will primarily be VFR, could see
ceilings lower into the MVFR range over that area by mid to late
morning on Thursday. Northerly winds will increase tonight,
gusting 20 to 25 kts through Thursday evening. Winds then begin
to diminish late Thursday evening.

&&

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

&&

$$

DISCUSSION...APT
AVIATION...JM


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