Byron, Minnesota Weather Forecast Discussion

361
FXUS63 KARX 301057
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
557 AM CDT Tue Sep 30 2025
.KEY MESSAGES...
- Dry conditions and above normal temperatures to continue
  through Friday.
- Low rain chances (20-35%) return to the forecast starting
  Saturday and continue into early next week.
&&
.DISCUSSION...
Issued at 255 AM CDT Tue Sep 30 2025
Today - Friday: Dry and Mild
A relatively benign work week is expected across the Upper Midwest
with upper level ridging dominating the pattern. Temperatures are
expected to be on a general upward trend through the week (apart
from Wednesday when ample high cloud cover will hamper peak
diurnal heating). One of the large drivers in the warming trend
will be the upper ridge keeping a dome of anomalously warm 850
mb temperatures over the Northern Plains and Upper Midwest. In
conjunction, a strong surface high is expected to build across
the east coast creating a substantial return flow sector across
the central CONUS by mid to late week. This will allow warmer
temperatures to penetrate further north and create abnormally
warm conditions for early October. There is high confidence in
this outcome with cluster analysis supporting the upper level
ridge generally holding firm until the weekend when more
differences begin to appear. Temperatures by the end of the week
will climb into the mid 80s with Friday seeing temperatures
push into the upper 80s. There are even some non-zero
probabilities of seeing highs hit 90 degrees across portions of
northeast Iowa and the Mississippi River Valley on Friday. With
these probabilities in mind, it`s not hard to guess that the EC
ensembles EFI and SOT are high across the area Thursday through
Saturday. This indicates that a significant amount of EC
ensemble members have shifted temperatures above climatology
and, in many cases, well above climatology. Record highs don`t
look to be under threat Friday (93 at RST, 91 at LSE) but
temperatures will still be well above normal and essentially
summer-like.
This heat and extended dry period will lead to some increase in
fire weather concerns. Overall, winds look to remain too low to
create any critical fire weather conditions but warm temperatures,
low RHs, and fall vegetation continuing to dry out will serve
to increase the availability of fuels across the region. The
area of highest concern in our area would be West Central
Wisconsin where soils and vegetation look to be the driest.
Saturday - Early Next Week: Rain Chances Return
As the surface high holds firm across the eastern seaboard, the
upper level ridge will gradually start to phase east by this
weekend. At the same time, an upper trough is expected to move
into the Pacific Northwest. Cluster analysis highlights some
significant differences in the timing and amplitude of said
trough but it is expected to gradually move into the Rockies.
This will put our area in southwest flow aloft, allowing for
shortwaves to ripple across the Upper Midwest. This, along with
an approaching frontal boundary from the west, look to set off
some low rain chances starting early Saturday morning. Though
there remains plenty of uncertainty as to how the upper trough
will evolve, the general consensus for now is that our area will
remain in southwest flow aloft into early next week. This will
allow for continued low rain chances from Saturday onwards.
Have largely stuck with the NBM for rain chances as low
confidence in any large scale forcing and shortwaves not being well
resolved at this timeframe precludes any significant
alterations. A cold front looks to finally move through the
area on Monday, bringing our much needed reprieve from the warm
temperatures. Highs Saturday and Sunday are still expected to be
in the upper 70s to low 80s for much of the area before cooling
back into the mid and upper 60s post-frontally by Tuesday.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 557 AM CDT Tue Sep 30 2025
Some patchy fog will continue for areas east of the Mississippi
River into the mid morning. High level clouds, between 20kft and
25kft, will be in the region through the TAF period. Light
southeast winds expected around 10 mph through the day then
becoming light and variable for the overnight.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Barendse
AVIATION...Cecava

NWS ARX Office Area Forecast Discussion