748
FXUS63 KABR 111426
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
926 AM CDT Fri Jul 11 2025

.KEY MESSAGES...

- A narrow ribbon of near surface smoke will follow a front with
  visibility down to about 2 miles, with a duration of 2-4 hours
  as it tracks through central/north central and northeast SD this
  morning into the early afternoon.

- Marginal risk (level 1 out of 5) for severe storms mainly from
  the James Valley eastward into west central Minnesota this
  afternoon and evening. Hail up to an inch in diameter and wind
  gusts up to 60 mph are possible within the risk area.

- The potential exists for a noticeable cool-down during the
  middle of next week (temperatures 10 to perhaps 15 degrees
  below normal).

&&

.UPDATE...
Issued at 922 AM CDT Fri Jul 11 2025

Just a quick update to put smoke in the TAFS and forecast, as its
come in at 2 miles visibility in Mobridge and Pierre which was a
little lower than what the models were suggesting yesterday.

&&

.SHORT TERM /TODAY THROUGH SATURDAY AFTERNOON/...
Issued at 227 AM CDT Fri Jul 11 2025

A cold front swings through from northwest to southeast today with a
trailing upper trough. There is a marginal risk (1 out of 5) for
severe storms this afternoon with the convection around the front.
The risk area is mainly from the James Valley eastward where CAPE
will be between 2000 and 3000 J/kg. Bulk shear is negligible ahead
of the front, but increases to 30 kts with/just behind the front
around 21z. With those values in mind, shear is the limiting factor
today for severe storms.

Surface high pressure builds in tonight with drier air. The HRRR
shows smoke from Canadian wildfires pushing south into the region
with the upper trough. Will need to monitor for any potential for
visibility reductions as it does show some near-sfc smoke on
Saturday. Upper ridging begins to build in from the west on Saturday
as the trough exits into the Great Lakes. This will help highs
rebound into the 80s from the James Valley west.

&&

.LONG TERM /SATURDAY EVENING THROUGH THURSDAY/...
Issued at 227 AM CDT Fri Jul 11 2025

Clusters agree on a +PNA setup with the Northern Plains in northwest
flow to start out the long term. The top of the ridge does flatten
out as a shortwave moves in off the northern Pacific and over
British Columbia by Sunday. This trough will track southeast,
becoming positive tilted, with the axis from the Pacific Northwest
and northeastward into Canada by Monday evening/Tuesday morning as
the ridge behind it amplifies over the Pacific Ocean. By the middle
of next week, this wave will shift eastward (becoming neutrally
tilted) and passing over the Northern Plains/Canada with a low
amplitude ridge building behind it over the area for the end of the
week. Ensembles diverge a bit on exit of this wave as it shifts
eastward.

Down at the surface, a trough will be over the area Sunday,
extending southward from a low over the Hudson Bay area. With this
incoming wave aloft, a lee low will develop over MT and track
southeast and over western SD Monday evening and over central SD by
Tuesday morning. This low and its cold front will continue
east/southeast with the CWA behind the cold front by Wednesday
morning. This system will bring the return of showers and
thunderstorms Monday evening through Wednesday with the highest NBM
pops of 40-60% Tuesday evening into early Wednesday morning as of
now. Severe threat is a possibility, however, confidence remains low
at this time due to model variability with CSU machine learning
showing a 5% chance. Otherwise, high pressure moves in from the
northwest behind the low and centered over the Northern Plains by
Thursday morning.

Westerly flow (James River and east) to northerly flow will bring in
warmer air from underneath the ridge. 850mb temps will range from 20
to 26C(around average per NAEFS), with surface temps warming in the
upper 80s to the mid/upper 90s. Highest temps both at 850mb and
surface will be over central SD. 25th-75th NBM spread does remain a
bit high ranging between 5-7 degrees. Winds turn southerly ahead of
the low on Monday (at 850mb to surface) with similar 850mb temps as
Sunday, however, the warmer air will spread farther eastward over
the CWA. This will be our warmest day of the week with overall highs
in the 90s to possibly 100 over portions of south central SD.
Uncertainty in exact temps remain high as the spread is up to 13
degrees over the northern half of the state. Highest dewpoints look
to top out in the lower to mid 60s Sunday and Monday, however, as
mentioned in the previous discussion, evapotranspiration is ongoing
which may cause an increase in dewpoints that models have not locked
onto yet. Jumping ahead to behind the low and incoming high, 850mb
temps will range from ~10 to 15C Wednesday and Thursday which is
about 1 standard deviation below normal per NAEFs. Overall highs are
forecasted in the 70s which is about 10-15 degrees below normal. EC
EFI indicates this trend with values of -0.5 to -0.7 and a shift of
tails of zero for TMax on Wednesday and values as low as -0.8 over
the eastern CWA for TMAX on Thursday. Values for TMIN are as low as
-0.7 to -0.8 as lows are forecasted drop into the 50s during this
time. Temps are forecasted to warm up by the end of next week back
into the 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 619 AM CDT Fri Jul 11 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected prevail today. However, showers and
thunderstorms will move through from west to east with a passing
cold front. Vsby may fall in heavier showers.


&&

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

$$

UPDATE...07
SHORT TERM...20
LONG TERM...MMM
AVIATION...20