Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 270158 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
858 PM CDT Tue Mar 26 2024

.KEY MESSAGES...

- Flurries taper off this evening and winds diminish.

- Opportunity for light precip Thursday night and Friday, generally
20-50%, with potential for freezing rain as well. Amounts look light
(a few hundredths) for the time being.

- Potential for a stronger storm system Saturday night through
Sunday night. Moderate precipitation chances (40-70%) currently,
with mixed rain/snow as precip types.

&&

.UPDATE...
Issued at 854 PM CDT Tue Mar 26 2024

It`s going to be cold tonight; 20 to 30 degrees below normal
cold. Surface high pressure rigde axis is analyzed on the UNR/ABR
cwa border right now. So, light (or no) wind and clear skies over
a relatively fresh snowpack should have low temperatures dropping
to if not below zero in some areas. Going forecast is okay. No
changes planned.

UPDATE Issued at 627 PM CDT Tue Mar 26 2024

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.SHORT TERM /THIS EVENING THROUGH WEDNESDAY NIGHT/...
Issued at 238 PM CDT Tue Mar 26 2024

The departing low, now over the Great Lakes, continues wrapping some
flurries/light snow showers into eastern SD and west central MN this
afternoon. Expect this light activity to taper off by evening. Wind
gusts will also slowly diminish after sunset reducing the blowing
and drifting snow that`s been occurring, primarily in open areas.

High pressure builds in at the surface tonight. Coupled with an
upper trough, caa will push H85 temps down into the negative teens
Celsius resulting in overnight lows in the single digits. Areas
where winds drop off faster and/or have clear skies over fresh
snowpack could potentially see temps bottom out below zero. Some
high clouds may still remain around on Wednesday in the upper
trough, but the day should be dry with lighter winds. Weak waa (and
not as deep of a snowpack) in south central SD may lead to highs in
the 30s there, however northeast SD and west central MN will remain
20 or so degrees below normal with highs in the 20s.

WAA pushes in from southwest to northeast Wed night under a building
ridge. Still expect lows to tank, though, under clear skies.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 238 PM CDT Tue Mar 26 2024

A couple of systems will move into our area for the long term, the
first one Thursday through Friday and the second one (potentially
stronger system) Sunday/Monday. This will bring the potential for
more snow along with the possibility of mixed precipitation.
Starting off on Thursday, Clusters agree well on a ridge moving over
the Northern Plains through the day with a trough/closed low over
the Pacific Ocean. As this ridge pushes east Thursday evening, a
shortwave will move in, associated with this longwave trough, over
the area through Friday. The Clusters show this but a bit of a
difference on the intensity of this wave as Clusters 1/4 (mostly
GEFS) indicate a "deeper" trough compared to the others. Ensembles
agree pretty well on the formation of a weak surface low/trough with
just minor differences in the location of the low as it moves
west to east. With this, the Clusters all indicate show precip
moving in from the west late Thursday into early Friday, and
expanding over the entire forecast through the day before exiting
Friday evening/night.

With this being a fairly quick system, this should keep QPF lower.
Probability of 24hr QPF>0.10" between all the Clusters is about 30%
and under, with this highest from Cluster 3 (67% GEFS) keeping it
along the ND/SD border and Cluster 1(55% GEPS)in north central SD.
Snow look to be light as Prob of 24hr>1" is low between 10-20%,
highest along the ND/SD border. NBM agrees and has less of a chance
for an inch (7% over northeastern SD) as it keeps most of the action
in ND. A warm nose aloft looks apparent early Friday as ENS
sounding for KABR/KMBG does show this layer above freezing with a
shallow surface layer below freezing. EC meteograms hint at this as
well with up to 10% chance of freezing rain/drizzle mainly to the
north of this low (warm front area)from KMBG eastward to K8D3 and
KATY area. NBM WxZR indicates 20-55% chance with the highest over
north central SD. Prob of 24hours>0.01" of ice (per GEFS/GEPS) is 60-
80% mainly over north central SD, and prob over 0.1" is around 20%.
NBM ranges from a trace up to 0.04", highest over north central SD.
So confidence is increasing for this chance of freezing rain.

By the weekend, Clusters agree on this trough out west, deepening
(and becoming positive tilted) off the California coast Sunday with
the axis moving onshore ~Monday. A surface low will form on the lee
side of the Rockies as well with still some differences in timing,
location, and strength of the low. EC meteograms at all ASOS sites
show Ptype as mostly snow to wet snow, changing to a mix, then rain
as temps do warm up towards the afternoons. With the differences in
strength of system, QPF varies a bit as well between the ensembles.
For example,Prob of 24hour QPF>0.10" ending at 7am Monday, ranges
from 30-90% with Cluster 2 (53% GEFS) being the highest percentile
as it is showing a deeper trough/low. Prob of 0.25" ranges from 20-
70% with again, Cluster 2 being the highest. Mean snowfall between
the ensembles are generally 1-3". 25th percentile would mean inch or
less with 90th percentile up to 5-7" as of now. This system is
several days out so low confidence exists on exact QPF amounts.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 627 PM CDT Tue Mar 26 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to prevail over the next 24 hours at
KPIR/KMBG and KABR. Current MVFR conditions will continue to
improve to VFR this evening at KATY. Snow showers/flurries at KATY
should finish up by ~02Z, with just some mainly ground level
blowing/drifting snow expected to persist for a few more hours
after that, until winds begin to subside. High pressure building
into the region will provide for light winds and a sunny/mostly
sunny sky at all four terminals on Wednesday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Dorn
SHORT TERM...Wise
LONG TERM...MMM
AVIATION...Dorn


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