635
FXUS63 KABR 061410 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
910 AM CDT Sun Apr 6 2025

.KEY MESSAGES...

- Temperatures Monday will be 5 to 20 degrees below normal.

- 20-30% chance of light showers Tuesday night through Wednesday
  night. Probability of total moisture exceeding 0.10" is only
  20-30%.

- Temperatures will be on a steady increase through the week,
  peaking next weekend in the 70s, which is 10 to 20 degrees above
  normal.

&&

.UPDATE...
Issued at 904 AM CDT Sun Apr 6 2025

No changes planned to the today period forecast. Monitoring the
approach of a back-dooring cold front up over North Dakota this
morning. While normal diurnal warming is occurring out over
central/south central South Dakota this afternoon, temperatures,
post-frontal, over northeast South Dakota/west central Minnesota
may be steadying out or perhaps beginning to cool a couple
degrees, prior to 7 pm cdt.

&&

.SHORT TERM /TODAY THROUGH MONDAY AFTERNOON/...
Issued at 348 AM CDT Sun Apr 6 2025

The surface weather map showed us in between the main area of high
pressure across CO through NE, and an elongated surface trough over
southern Canada through northern ND. North to northwesterly flow
remains at 500mb, with the main trough over eastern Canada. A
dominant 500mb ridge was set up over the western U.S. Temperatures
today will be nearly 10 degrees above what we experienced yesterday,
topping out in the 50s to low 60s.

A dry cold front will sink from north to south across South Dakota
and western Minnesota from mid afternoon through the evening hours.
Strong cold air advection will slide in behind the cold front,
particularly over eastern SD and western MN. 850mb temperatures over
our northeastern counties will range from around 1C at 18Z today
to -3C by 00Z and -12C by 09Z Monday. The main result will be
increasing winds out of the north tonight, with gusts of 25 to
near 35 mph before diminishing to around 20 mph or less by
daybreak Monday. The strongest winds will be over eastern SD.

Cooler air will remain at the surface. Highs Monday will only be in
the 40s and upper 30s over the Prairie Coteau to west central MN.
These temperatures will be 5 to nearly 20 degrees below normal for
this time of year. With the 500mb ridge nearing from the west and
sliding to eastern MT and the western Dakotas Monday afternoon, a
change is coming.

&&

.LONG TERM /MONDAY EVENING THROUGH SATURDAY/...
Issued at 348 AM CDT Sun Apr 6 2025

Monday night we start out with ridging aloft, with a trough over the
Pacific Northwest. A wave ejects into Montana/southwest Canada late
Tuesday, and east into North Dakota, however past that point
deterministic models diverge on how best to handle the upper waves.
They are, however in better alignment when it comes to the
850mb/near surface pattern, with a surface low/warm front over
Nebraska and then later a dissipating low over northern North
Dakota.  The main question here is how quickly we erode out Mondays
cold air, with Tuesdays weak warm advection on east-southeast winds
resulting in a NBM 25th/75th percentile range in high temperature
between 7-9F for Tuesday. There is a weak, but more well defined
warm tongue out ahead of the aforementioned dissipating low on
Wednesday, with good mixing (west/northwesterlies) and better
agreement within NBM members with respect to highs (only 3-4 degrees
west of the James). Cold advection on the backside of these waves is
also pretty weak, with the GFS deterministic run being the more
aggressive. NBM 25th/75th high temperature range Thursday is still 5
to 10F.

As for moisture, it still appears that the overall weak systems will
only account for a quarter inch or less (only a 10% chance of
exceeding 0.25) of rainfall.

Thereafter we see a fairly significant thermal ridge building in
from the west, in association with a deepening trough across the
western CONUS. Prolonged low level flow ahead of an eventually
developing lee low for the weekend will result in dewpoints slowly
creeping up. NBM mean CAPE has increased into the +500 j/kg range
with the 25th/75th somewhere between 300 to +1000 j/kg. This range
suggest there is still a high level of uncertainty moving forward
with any suggestion of thunder, however if we look at day 7-8
clusters there is good alignment (~80% of members) showing a strong
western CONUS trough in favorable placement to eject into the
Dakotas late in the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 602 AM CDT Sun Apr 6 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period, with non-
diurnal winds increasing late this afternoon and this evening with
gusts of 20-30kts out of the north to northeast.

&&

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

$$

UPDATE...10
SHORT TERM...06
LONG TERM...07
AVIATION...06