Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 162326 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
626 PM CDT Sat Mar 16 2024

.KEY MESSAGES...

- Light snow showers (15-20%) possible east of the Missouri River
  tonight through Sunday morning. No accumulations expected.

- Temperatures bottom out Sunday with highs only in the upper 20s to
  the mid 30s.

- Warm dry southwest winds on Monday will create elevated fire
  danger concerns.

- Mainly dry through Wednesday with above average temperatures.
  Increasing precipitation chances Thu-Sat with near average
  temperatures.

&&

.UPDATE...
Issued at 623 PM CDT Sat Mar 16 2024

See updated aviation discussion below.

&&

.SHORT TERM /THIS EVENING THROUGH SUNDAY NIGHT/...
Issued at 153 PM CDT Sat Mar 16 2024

As of 1PM, skies were overall clear with fair weather cumulus clouds
pushing southeast with sustained winds of 20-30mph with some areas
gusting up to 40mph. As we head into this evening, winds will still
be on the gusty side, as a tighter pressure gradient continues from
the low positioned over Ontario, with forecasted gusts ranging from
30-35kts around 00Z. Once we lose daytime heating/mixing, winds will
diminish a bit overnight, however, CAA of -4 to -9C/12hr and 2 to
4mb/6hr pressure rises continues through the overnight and will help
maintain a "steeper" LLLR, mainly James River Valley and east
(closer to the low). Sustained winds of 10-15kts and gusts of 20-25
kts possible. Sunday afternoon with daytime mixing they do increase
a bit with gusts up to 30kts or so.

With north/northwest flow aloft over the area, a band of mid level
shortwave energy (wrapped around the low) sinks southward over the
central and eastern CWA tonight. This should be just enough lift for
possible light precip as GFS RH does show the air saturating from
850-925mb through Sunday morning with several Rap soundings across
the northeastern CWA showing this moistening of the column along
with omega from ~800mb-sfc. Several of the Cams back this up
indicating some vertical bands of light precip moving in from ND
here and there as this mid level energy continues over the area. So
with I blended in HRRR/RAP/ECAM along with NBM to show this. Any
precip that should fall will be minimal in the form of rain/snow or
snow. Prob of 0.01 per HREF runs between 10-40% with these bands.
Prob of over 0.05" is 20% or less.

This incoming high is bringing colder air with it as
850mb temps at 12Z Sunday are about 10 degrees cooler ranging from -
7 to -15C and 925mb temps -4 to -10C, coldest over northern and
northeastern SD/western MN. Even by Sunday afternoon, 925mb temps
still range in the single digits below zero east of the Mo river.
With this, overnight lows could be tricky for the James River Vally
and east as they should be lower than ensemble forecast, but we will
be dealing with some clouds from this low along with some wind, so
hesitant to go any lower than guidance. Similar to Sunday as temps
seem a little on the warm side so knocked them down a couple of
degrees. We do have a higher sun angle this time of year, so did not
want to drop them too much. Low confidence exists on temps tonight
and Sunday.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 153 PM CDT Sat Mar 16 2024

Still facing the gradual diminishment of western CONUS
ridging/eastern CONUS troffing during the front end of the out
periods. Beyond Wednesday, there remains too much dissonance in the
various (ensemble clusters) model camps regarding care of the upper
flow pattern`s evolution from Thursday onward. At some point between
Thursday and Saturday, models agree that there should be an upper
level trof working west to east across the central/northern plains
region. They just don`t agree on timing/track all that much right
now. Ensemble PoPs continue to paint a general 20 to 50% chance of
precipitation from Thursday through Saturday, with Thursday and
Saturday holding the higher end chances.

Not much has changed in 24 hours regarding temperatures. There is
still quite a bit of (box and whiskers) spread in potential
temperature outcomes next week from Wednesday onward. There is a
subtle cooling trend seen in the ensemble temperature data from
Thursday onward. Looking at 3-hrly probabilities of 2m temperature
being below 34 degrees during those periods containing PoPs, there
continues to be a note-worthy signal for conditions cold enough to
support snow for p-type.

While still under north-northwest flow aloft on Monday, the boundary
layer will take on a southwesterly wind configuration, with warm/dry
air advecting into the CWA. Grassland Fire Danger is already in the
High to Very High category, with a little bit of extreme category
showing up in western Corson County. Similar to what happened on
Friday, stronger mixing/gusting winds should start to materialize by
late Monday afternoon, and moreso across the northern half of the
CWA. Afternoon humidity is forecast to drop to 30 percent or less,
CWA-wide on Monday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 623 PM CDT Sat Mar 16 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail across the area tonight and through
the day Sunday. Northwest winds in the 15 to 30 knot range may
lose their gustiness for a time overnight before increasing again
on Sunday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 8 PM CDT this evening for SDZ004>011-
     016>023-034>037-051.

MN...Red Flag Warning until 8 PM CDT this evening for MNZ039-046.

&&

$$

SHORT TERM...MMM
LONG TERM...Dorn
AVIATION...Parkin


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