Hesper, Iowa Weather Forecast Discussion

717
FXUS63 KARX 031846
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
146 PM CDT Fri Oct 3 2025
.KEY MESSAGES...
- Near or record warmth expected Saturday afternoon.
- Potential low end elevated fire weather conditions this
  weekend, primarily west of the Mississippi.
- Rain chances (60-70%) return Sunday afternoon through Tuesday
  morning.
- Frost possible (40%) in central Wisconsin Wednesday or
  Thursday morning.
&&
.DISCUSSION...
Issued at 139 PM CDT Fri Oct 3 2025
Near or record warmth Saturday afternoon
19z WV satellite reveals a stout upper ridge over the central and
southern Plains with an upper low churning eastward over CA. At the
surface, increasing winds aloft over the Rockies have begun to
induce lee troughing while high pressure is present around the
Northeast Corridor, leading to southerly winds across much of the
central CONUS. The end result is an unseasonably warm day with
temperatures reaching into the 80s early this afternoon with high
likely to end up around 15 degrees above normal. However, record
highs for today should be safe as these are mainly in the lower 90s.
Its a different story with respect to records for Saturday as these
are mainly in the mid to upper 80s. While heights aloft do moderate
a bit, tightening surface pressure gradient should lead to a breezy
afternoon with temperatures reaching close to their maximum
potential via robust mixing. Thus, both La Crosse (50-70% per 03.00z
NBM) and Rochester (80-90%) have a good shot at matching or
exceeding previous record highs for October 4th.
Potential elevated fire weather conditions this weekend
The synoptic setup for breezy conditions Saturday described above
should also persist into Sunday. Given the many rain free or nearly
rain free days ahead of this weekend, elevated fire danger may
result. That said, state of the fuels remains in flux with the
lingering summer temperatures resulting in most trees still
retaining green leaves while crops are curing. With this mixed bag
of fuel conditions coupled with afternoon RH values largely
remaining above 30% as the southerly winds, while causing efficient
mixing, also bring in some moisture from the Gulf, current thinking
is that only low-end elevated fire weather conditions, if that, will
be possible. Both days this will be favored - in a relative sense
given low overall danger - in cultivated areas west of the
Mississippi River valley, where 03.12z GFS progged 850mb winds of 35-
40 knots and 35-45 knots will be present during the daytime hours,
leading to 20+ mph sustained winds at the surface.
Rain potential Sunday afternoon through Tuesday morning
03.12z operational guidance suggests western upper low mentioned
above breaks eastward and transitions into a longwave positively
tilted upper trough forcing a cold front southward Sunday night into
Monday. As this front advances, weak disturbances aloft may cool the
mid-levels enough for parcels being forced upward by the front to
become buoyant, leading to showers and perhaps a few thunderstorms.
However, enthusiasm for precip is muted by both the consistent
forward motion of the front and therefore a short residence time
with the main lifting mechanism in our CWA and weak instability to
work with to get the atmosphere to turn over - 03.00z LREF mean
SBCAPE is around 100 J/kg. Thus, while precip is likely (60%-70%),
am not too concerned about hazardously high amounts or, given weak
instability, severe thunderstorms.
Frost potential midweek
In the wake of the longwave upper trough, broad surface high will
build over the Upper Midwest and Great Lakes Tuesday night into
Wednesday night. Depending on timing and location of this feature,
temperatures in central Wisconsin could (40-50% per 03.00z NBM) drop
to or below 36 degrees as skies clear and winds become calm. For
now, still seeing a good amount of variation across guidance so have
stuck with NBM output rather than try to focus on one of these
nights for undercutting blended lows, which is usually a good
bet where excellent radiational cooling conditions are present.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1215 PM CDT Fri Oct 3 2025
VFR conditions expected through the 03.18Z.
Main aviation impact will be increasing south-southwest winds
through Saturday. Strongest winds locally will be seen west of
the Mississippi River Valley in southeast Minnesota and
northeast Iowa with sporadic gusts above 30kts. While slightly
weaker, increased winds will remain through Sunday.
&&
.CLIMATE...
Issued at 144 PM CDT Fri Oct 3 2025
Here are daily record highs/warm lows for Friday and Saturday
with the current forecasted high and lows.
(Record (Year) / Forecast)
October 3 Record Highs:
    La Crosse: 91 (1997)/ 90
    Rochester: 93 (1997)/ 87
October 4 Record Highs:
    La Crosse: 88 (2005)/ 90
    Rochester: 84 (2005)/ 86
October 4 Warm Record Lows:
    La Crosse: 72 (2005)/ 66
    Rochester: 71 (2005)/ 67
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Ferguson
AVIATION...JAR
CLIMATE...Ferguson

NWS ARX Office Area Forecast Discussion