Hampshire, Illinois Weather Forecast Discussion

061
FXUS63 KLOT 080519
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1219 AM CDT Mon Sep 8 2025
.KEY MESSAGES...
- A gradual warming trend to average or above temperatures mid-
  late week.
&&
.DISCUSSION...
Issued at 219 PM CDT Sun Sep 7 2025
GOES-19 water vapor imagery shows the long wave trough slowly
moving east of northern Illinois this afternoon. Winds remain
mostly out of the northwest, with the exception being a lake
breeze developing, as seen on radar, switching nearshore winds
to the east-northeast. Drier air will continue to filter in and
as the sun sets, the cumulus field should dissipate for clearer
skies overnight. Temperatures will drop to the low 40s and
potentially upper 30s in isolated areas and upper 40s to around
50 closer to Lake Michigan. With winds becoming light to calm
overnight and skies clearing, patchy fog cannot be ruled out
Monday morning. However, given how dry the air mass is expected
to be, fog should be mostly confined to known low, sheltered
rural areas like forest preserves. Lastly, recent high-res
models have been suggesting that there is a weak mid-level wave
embedded in the northwest flow that will develop over northern
Iowa overnight with a slug of moisture along with warm air
advection associated with it. While showers may develop there
tonight, most models have these showers moving into southern
Wisconsin by day break. And even if they made it into Winnebago
County, they would be moving toward a drier air mass and
forcing should be weak enough that no formal mention of even
sprinkles was put in the forecast.
As the surface high slowly moves eastward, winds will become
more southerly advecting in a warmer air mass. Temperatures are
expected to increase into the low 70s by Monday afternoon. As
weak surface ridging and southerly winds remains through mid
week, temperatures will slowly increase each day with low to
mid 80s possible by Wednesday.
A pair of upper level waves, one over southern Iowa/northern
Missouri the other across the upper Midwest, will move east
through the early part of the week. However, latest model runs
are showing a trend toward a drier air mass locally and better
forcing displaced to Wisconsin. So, it was no surprise that the
latest NBM pulled mentionable PoPs out of our forecast area.
There is still a chance that later runs bring PoPs back down
into the CWA for areas close to the state line, but for now the
forecast is trending drier.
Behind the passage of those waves, upper level ridging grows
over the Southern Plains and spreads eastward. Despite low-
level easterly flow, subsidence associated with the building
upper ridge will maintain warmer temperatures in the 80s with
upper 70s along the lake. There is still some uncertainty with
how warm temperatures will get over the weekend. The GEFS
continues to have a stronger ridge closer to the forecast area
which could keep drier and warmer conditions. However, the Euro
continues to suggest an upper level trough coming down from
Canada could flatten that ridge and potentially have have some
shower chances Saturday into Sunday (which would impact max
temps). The blend did bring in PoPs into Wisconsin Saturday
night, but kept northern Illinois dry and capped max afternoon
temps in the upper 80s which seemed reasonable at this distance.
DK
&&
.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 1219 AM CDT Mon Sep 8 2025
VFR conditions are expected through the period, though MIFG
cannot be ruled out for DPA/GYY/RFD early this morning. S winds
around 5 knots at ORD/MDW will shift SSW by sunrise, partly in
response to a strong land breeze developing offshore. Outlying
locations will remain calm through sunrise. SSW winds up to
around 10 knots are then expected today. A weak lake breeze will
likely wash out east of ORD/MDW early this evening, but a
broader SSE/SE wind shift will still occur by mid-evening and
persist well into the early morning hours on Tuesday.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion