Valparaiso, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

624
FXUS63 KLOT 251751
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1251 PM CDT Sat Apr 25 2026

.KEY MESSAGES...

- Severe thunderstorms Monday with all hazards possible, large
  hail, damaging winds and tornadoes. Heavy rain and localized
  flooding also possible.

- Seasonable and dry conditions this weekend, but cooler temps
  near Lake Michigan.

&&

.DISCUSSION...
Issued at 144 AM CDT Sat Apr 25 2026

A cold front is currently moving across the area with brief
patchy fog possible along the front. Low clouds are widespread
across far eastern WI and much of Lake Michigan and are
spreading southwest into northeast IL currently. Expect this
trend to continue with a cloudy start to the day for at least
northeast IL but these clouds are expected to lift and scatter
by midday. Persistent northeast winds will allow for a large
temp gradient across the area today, with highs in the lower 70s
well inland to only the 50s near Lake Michigan. Low temps
tonight will be in the mid 40s for most locations and then temps
will rebound into the lower/mid 70s for much of the area Sunday,
with another large gradient closer to Lake Michigan Sunday
afternoon, as temps only reach the upper 50s near Lake Michigan.

Primary forecast focus however remains the severe potential for
Monday. Overall, no significant changes. Low pressure will move
from the Plains Sunday to the western Great Lakes region Monday
night, as it slowly deepens. Thunderstorms are expected to
develop across eastern IA/northern MO Monday afternoon and move
east across the local from mid afternoon through late Monday
evening. As previously noted, appears the best chance of any
discrete supercells will be across the southwest cwa (and areas
west and southwest of our area), with an expected evolution
into a squall line and potential QLCS tornado threat. Despite
the fair/good agreement among the models, were still 60+ hours
from the event and additional details/specifics are still to
come.

Heavy rain will possible with these thunderstorms and even with
a possible fast moving line, with precipitable water values into
the 1.5 inch range, there may still be rainfall totals of 1-2
inches. While the usual low-lying/urban flooding would be a
concern with these amounts, if they were to materialize over the
Rock, Fox or Des Plaines River basins, renewed rises would
likely result. While it is far too early for a flood watch, did
coordinate with WPC to include a slight risk for excessive
rainfall, mainly for areas north of I-80, for Monday or day 3.

There may be some wrap around showers Tuesday morning and then
another cold front will move across the area Tuesday night,
shifting winds northeast. Another weak system may move across
the area Thursday bringing a few showers and additional cooler
air. Low temps by the end of next week could be in the mid/upper
30s, thus frost potential will need to be monitored as this time
period approaches. cms

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 1251 PM CDT Sat Apr 25 2026

Key Messages:

- Very low (IFR) CIGs near the lakeshore and at GYY through the
  afternoon.

- The IFR CIGs shift inland through this evening, likely
  impacting the main Chicago terminals by mid to late this
  evening.

- Potential for the low CIGs to build down low enough to lead to
  some fog late tonight into early Sunday morning.

Low cloud cover persists over Lake Michigan and areas as far
inland as 5 to 10 miles. While this will continue to be the case
through the afternoon, we have concerns that this low cloud
cover will spread inland after sunset this evening, potentially
making it into the main Chicago area terminals by 02 or 03Z this
evening. Confidence on the exact timing remains unclear, but
once it does work inland, we are likely to experience very low
CIGS (IFR to LIFR) through the remainder of the night, before
conditions improve mid to late Sunday morning. We may even have
a period late tonight into early Sunday morning in which the
clouds build down to the surface as fog. However, it remains a
bit unclear as to how extensive the fog threat may become. With
all this in mind, we have opted to hit conditions harder in the
TAFs for tonight. Accordingly, we have prevailing IFR CIGS
moving into the main Chicago terminals after 02Z this evening,
and a few hour tempo group early Sunday morning for lower
VSBYs/CIGs.

Conditions will diurnally improve by mid to late Sunday morning,
with VFR conditions expected thereafter. Otherwise, winds will
remain easterly through Sunday.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for the IL
     and IN nearshore waters.

&&

$$

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