310
FXUS63 KABR 281737 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1137 AM CST Fri Feb 28 2025

.KEY MESSAGES...

- Strong northwesterly wind gusts of 40 to 55 mph from mid morning
  into this afternoon. This will lead to a Very High or Extreme
  Grassland Fire Danger, which means that conditions are favorable
  for fires to quickly spread or get out of control.

- Near normal temperatures on Saturday will give way to another
  period of above normal temperatures on Sunday and Monday.

- There is a 30-40% chance of rain on Monday night and Tuesday. It
  may be cold enough for snow to mix in as the precipitation comes
  to an end from west to east Tuesday.

&&

.UPDATE...
Issued at 1123 AM CST Fri Feb 28 2025

See the updated aviation discussion below.

UPDATE Issued at 1102 AM CST Fri Feb 28 2025

Wind gusts are living up to expectations this morning, with 40-50
mph reports widespread across northeast South Dakota and west
central Minnesota. Models continue to depict a peak in winds by
early/mid afternoon before starting to decrease later this
afternoon and evening. The wind advisory and red flag warning will
continue as planned. Also monitoring precip on obs. So far light
snow is just east of our forecast counties but will maintain the
slight chance mention in the forecast.

UPDATE Issued at 534 AM CST Fri Feb 28 2025

Updated for the 12Z Aviation discussion below.

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 257 AM CST Fri Feb 28 2025

A pretty warm morning across SD, with temperatures in the 40s as of
2am, as we`re in the warm sector of a 987mb low located near the
Lake of the Woods. The first of two cold fronts associated with this
low is moving southeast across southern ND at this time and seeing
temperatures falling slightly behind it (along with a little more
gusty winds than we`re seeing). Otherwise, some mid-high clouds
streaming southeast across the area from MT under the northwest flow
aloft and associated with a strong 500mb jet streak (80-90kts) in
central ND.

Expect that surface low to quickly slide southeast through the Great
Lakes region today. That quick movement will lead to a tight
pressure gradient over the area today, but weaken fairly quickly
this afternoon and evening as Canadian high pressure builds in to
southern Manitoba. The main story for today will be the winds, aided
by the cold air advection and the strong winds above the surface
(KABR VWP picking up 40-50kts a few kft above the surface). First
push of low level cold air advection starts over the next few hours,
but does look like that surge will struggle to steepen the low level
lapse rates, largely limiting the amount of mixing that occurs and
keeps the winds in check during the first part of this morning and
as diurnal mixing starts to develop. The main period to watch for
the winds will be from mid morning through early afternoon. This is
when both diurnal mixing increases enough to tap into the strong
winds aloft (45-50kts at 850mb) and over the northeast half of SD
and into west-central MN, the secondary push of cold air advection
arrives with the secondary cold front. Expect a strong surge to the
winds during that first 1-3 hours behind the cold front, with winds
easily gusting into wind advisory level (45-55mph). Do have some
concern that we`ll need a brief high wind warning for gusts to 60
mph over the northeast CWA during that initial push (NBM probs of
max gusts over 48kts is 40-70% along the Coteau). Thinking that the
current wind advisory will handle things for now and will highlight
brief periods of those stronger winds in the text product.

In addition to the winds with the secondary cold front, global
models and CAMs continue to point to some light precipitation along
the front in northeast part of the CWA during the late morning and
into the early afternoon. Existing forecast had a pretty good handle
on the timing of it moving through and have continued to fine tune
the timing as it slides into northeast SD and west-central MN before
diminishing as it continues farther south and runs into drier air.
Would expect an initial brief period of rain before switching to
snow due to the amount of cold air aloft and the low wet bulb zero
heights (starting around 1kft and quickly falling behind the front).
With the strong winds, any snow showers could lead to quickly
reduced visibilities and with the steep low level lapse rates, we
even get 30-60 J/kg of sfc based CAPE, which could help aid
localized heavier snow showers. Overall, the snow squall potential
is low (parameter is weaker and smaller coverage than a couple days
ago) and the the narrow area of coverage will likely limit the
impacts. Also want to mention that behind the front the temps will
be falling to and below freezing by evening, so any wet roads could
become slick.

Finally for today are the fire weather concerns. With dry conditions
in place with the above normal temperatures and lack of snow cover,
do have very high Grassland Fire Danger across northern SD. As for
traditional Red Flag criteria, we`re not hitting the 20-25% RH
needed, but we can relax that to 30-40% with the expected high
winds. With the brief warm up and then falling temps behind the
secondary cold front over the northeast part of the CWA, RH values
look to stay at or above 50% in that area and will highlight the
fire concerns in both the wind advisory and our external messaging.
But over the south central, RH values do look to fall into the mid-
upper 30s this afternoon with warmer temperatures. While the winds
are not quite as strong in that area, do feel that the there`s
enough to warrant a Red Flag over south central SD and coordinated
that issuance with the neighboring offices.

Behind today`s active weather, expect quiet and cooler conditions
for tonight and Saturday, as we remain under northwesterly flow
aloft with a highly amplified ridge to our west (US/Canadian
Rockies) and a trough over the Great Lakes and Ohio River Valley.
This will allow the previously mentioned Canadian high to drop
southeast through eastern ND tonight and settle into
central/southern MN on Saturday. The drier air associated with the
high will eat away at the low stratus that moves in behind the
secondary cold front (both over northeast SD and also into western
ND). Thus, will have the partly-mostly cloudy conditions diminish
through the rest of the period (holding on the longest over central
SD). As for temperatures, expect much cooler conditions on Saturday
(highs in the 30s to mid 40s), but that`s pretty close to normal for
this time of the year.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 257 AM CST Fri Feb 28 2025

Temperatures look to continue to rebound Sunday and Monday as sfc
high pressure slides to the southeast allowing for warmer air to
return to the region along with an upper level ridge. A weak system
will pass to the south of the region so not much expected weather
wise.

However, things look to be a bit more unsettled Tuesday and
Wednesday as a system ejects from the rockies and enters the
northern plains. It appears a band of rain/snow will set up
somewhere in eastern SD Tuesday but moisture looks somewhat limited.
NBM pops look ok for now. The system will exit fairly quickly as it
organizes southeast of the area. Cooler temps will return as well
during this period, but will remain above normal through the entire
period.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1123 AM CST Fri Feb 28 2025

Terminals KABR,KATY,KPIR,KMBG

Strong northwest winds will be the primary concern at all TAF
sites today. 30-40 KTS gusts will be frequent across the region.
An MVFR cloud deck is also dropping southwest but should not last
more than a few hours at any TAF site. Winds will gradually
diminish later this afternoon and evening.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 6 PM CST /5 PM MST/ this evening for
     SDZ003>011-015>023-033>037-045-048-051.

     Red Flag Warning until 6 PM CST /5 PM MST/ this evening for
     SDZ033>037-045-048-051.

MN...Wind Advisory until 6 PM CST this evening for MNZ039-046.

&&

$$

UPDATE...Serr
SHORT TERM...SRF
LONG TERM...Scarlett
AVIATION...Serr