Winthrop, Iowa Weather Forecast Discussion

065
FXUS63 KDVN 042346
AFDDVN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
646 PM CDT Thu Sep 4 2025
.KEY MESSAGES...
- A quick-moving cold front will bring a brief chance of rain showers
  late this evening into the overnight hours, mainly along and
  north of Highway 30.
- Gusty west to northwest winds will develop behind the front,
  with potential for 30+ mph gusts before slowly weakening
  after sunrise Friday.
- Cooler than average temperatures will persist through the
  weekend before a significant warm up begins for the work week
  next week.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 202 PM CDT Thu Sep 4 2025
Forecast remains on track for a quick-moving mid-level shortwave and
an attendant surface cold front to sweep across the northern
portions of our region late this evening through the overnight
hours, leading to a brief chance (30-60%) of light showers. Signals
from the deterministic and ensemble guidance for thunderstorm
chances shows very weak instability (less than 100 J/kg of MUCAPE)
and the 04.12z HREF ensemble probability of lightning are less than
10%, so we have pulled any mention of thunder from the forecast.
Rainfall amounts also appear minimal as the WPC ensemble exceedance
probabilities of a tenth of an inch only show 18% (74% for at least
0.01"). The bigger story with this system will be a period of strong
west to northwest winds behind the front as cold air advection
increases, enhancing momentum transport to the surface. HREF
exceedance probabilities of 35 mph gusts are currently around 60-
80%, so it will be quite breezy overnight. These same exceedance
probabilities look to lessen significantly after sunrise Friday
morning, so expect winds to gradually weaken as we go through the
morning hours. Temperatures should fall to near 50 north to the
upper 50s south tonight.
The remainder of the day Friday will continue to be cooler than
average and breezy, with highs only in the lower 60s north to the
upper 60s south. There might be also be a slight chance of very
light showers (20%) across the southern portions of the CWA along an
850-700 mb layer FGEN band along a baroclinic zone, which several of
the CAMs are showing. Similar to tonight, lightning doesn`t appear
likely with this activity. HREF ensemble soundings show quite a bit
of dry air below the 800 mb level, which should make it difficult to
generate measurable rainfall with this band. Thus, we have capped
our chances of precipitation at 20%.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 202 PM CDT Thu Sep 4 2025
Overall, a drier and cooler stretch of weather is expected Friday
night through Monday. The main focus for the long-term period will
be on a few chilly nights, especially Friday night through Sunday
night. The latest ECMWF EFI/Shift of Tails indicates values of -0.7
to -0.9 for low temperatures each night in our area, which supports
a decent signal for some chilly mornings from the ECMWF ensemble
guidance. Overnight lows are forecast to fall to the lower to middle
40s each night, which will feel more like early October than early
September! It doesn`t appear likely that we would break any record
lows, although some record cool high temperatures will be in play
for Friday. See our Climate section below for the records list.
Temperatures look to rebound for Monday through Wednesday as
southerly flow returns, with highs back into the 70s, and even some
lower to middle 80s by Wednesday. A few systems could move through
our region by Tuesday and Wednesday, but differences among the
guidance make it difficult to pin down coverage and timing details.
Something to keep an eye on for now.
Despite a few mid-level shortwaves passing through over the weekend,
dry conditions should prevail given a lack of moisture through the
column to generate precipitation.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 635 PM CDT Thu Sep 4 2025
A fast moving storm system is forecast to move across eastern
Iowa TAF sites tonight. The frontal boundary is forecast to move
through all TAF sites between 03 and 09 UTC with winds switching
from the south to west. Winds are forecast to be gusty during a
small window during the frontal passage with gusts up to 25
knots. Once the front passes, low level wind shear is forecast
to develop after 03 UTC between 1000 and 1500 ft with speeds
increase to 40 to 45 knots in this layer from the southwest.
LLWS is forecast to diminish after 09 UTC. There is a small
window for LLWS at KBRL and it was left out of the TAFs for now.
Northwest winds are forecast to strengthen after 12 UTC Friday
with sustained speeds of 10 to 15 knots and gusts up to 25 knots
especially during the morning hours. There is also a small
window for showers at KCID and KDBQ with the highest confidence
at KDBQ where a tempo group was added. VFR conditions are
forecast to prevail through the period in except in any showers
that develop near KCID and KDBQ this evening.
&&
.CLIMATE...
Issued at 620 PM CDT Mon Sep 1 2025
RECORD COOL HIGH TEMPERATURES:
              September 4      September 5
Moline        61 in 1874       61 in 1876
Dubuque       58 in 1994       61 in 1920
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Cousins
CLIMATE...NWS

NWS DVN Office Area Forecast Discussion