Crystal Lake, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

903
FXUS63 KDVN 141051
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
551 AM CDT Wed May 14 2025

.KEY MESSAGES...

- There is a 15 to 25 percent chance of showers and storms this
  afternoon into the overnight hours. Brief heavy rain, small
  hail and lighting are the main threats in the strongest
  cells.

- Summer-like temperatures continue through Thursday with near
  record high temperatures possible.

- Severe storms are possible on Thursday but confidence remains
  low that they will occur.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 234 AM CDT Wed May 14 2025

Ridging is forecast to build northward across the area today as
the storm system to our east continues to slowly be reabsorbed
into the Westerlies. High temperatures today will be warmer
with mostly sunny skies and warm advection into the area. High
temperatures today will range from 83 degrees at Dubuque and
Freeport to 87 degrees Fairfield and Memphis Missouri. This will
allow instability to build into the afternoon and a passing
shortwave to our north will once again bring the risk of showers
and storms to the northeast third of area into the early
evening. Heavy downpours, small hail and frequent lightning are
possible.

A negatively tilted trough is forecast to move into the western
High Plains by tonight with strong diffluence ahead of it.
Storms are forecast to develop across the Mid Missouri Valley
tonight and move into western Minnesota where the better forcing
will move. As this occurs, a warm front is forecast to lift
into southern Iowa with a wing of warm advection ahead of it.
This could bring a line of showers and storms to the area
overnight that lifts northward. Lightning and small hail would e
the main threats as the storms look to remain slightly
elevated. Temperatures tonight will be warmer and range from the
lower 60s in far northwest Illinois to the upper 60s in far
southeast Iowa and far northeast Missouri.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 234 AM CDT Wed May 14 2025

Thursday...the entire region will be entrenched in the warm
sector of a developing storm system with the warm front lifting
northward across the area and into southern MN and central WI.
Very warm temperatures aloft (850mb temps around 19C) and high
EFI and shift of tails near 2 from the ECMWF ensemble show the
potential for near to possible record warmth for the area. As
expected, the latest NBM came in warmer for highs (upper 80s/low
90s), but still lower than its 50th percentile values which has
more middle 90s area-wide. If that were to occur, high temp
records would be in jeopardy. I have included these in a climate
section below for reference. Regarding storm potential, there
is high confidence in more than sufficient instability and
moisture for storms, but model soundings and plan views still
continue to show a strong capping inversion in place for much of
the day. A mid level speed max will track across IA late
Thursday afternoon that may allow for CI to develop. If storms
do occur, the latest solutions suggest the northeast half of the
CWA most at risk for storms. All modes of severe weather would
be possible but it appears at this time that large hail is the
main threat. Please continue to monitor the forecast for
Thursday as the track and timing of this storm system may still
change impacting both temperatures and severe weather potential.

Thursdays storm system is forecast to shift to the east on
Friday, with its parent upper level low moving across Minnesota
and into Wisconsin. Recent models runs have expanded the slight
chance coverage across all of eastern Iowa, northwest Illinois
and far northeast Missouri. Adjusted the forecast to have slight
chance of thunderstorms as well as all models except the ECWMF
have CAPE across the area Friday afternoon and evening.
Interestingly,the ECWMF is faster in bringing in cooler
dewpoints on Friday limiting convective potential and leaving
precipitation as showers. Models have been showing stronger
winds on Friday to our east and have blended in stronger winds
across my northwest Illinois counties to account for this
possibility.

Quiet weather is currently forecast for the weekend as high pressure
moves across the area. High temperatures on Saturday and Sunday will
be in the 70s.

Beyond Sunday, models continue to show a series of shortwaves
ejecting into the Plains early next week as 500 MB ridging moves
to the east and southwest flow aloft into the Upper Midwest and
Lower Great Lakes. This is another closed low and models
disagree on its strength at this time, which will impact its
timing and impacts for early next week. This will bring chances
for showers and storms to the region early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 543 AM CDT Wed May 14 2025

High pressure is forecast to build into the area through the day
on Wednesday. Satellite imagery shows fog with visibility
between 2 to 5 miles pushing westward early this morning.
Models are showing a 40 percent chance that MVFR visibilities
will make it to DBQ between 12 and 14 UTC. Placed a tempo group
at KDBQ to account for this. Otherwise VFR conditions will
prevail through the period. Winds are forecast to turn to the
southeast by mid morning with speeds around 10 knots through the
remainder of the period. Isolated showers and storms are
posssible after 00 UTC tonight that will lift northward but
confidence is too low to include them in the TAFs. If showers or
storms did occur, MVFR ceilings and visibilities are possible.

&&

.CLIMATE...
Issued at 219 PM CDT Tue May 13 2025


Record High Temperatures:

May 15:
KBRL: 93 / 1944
KCID: 94 / 1941
KDBQ: 90 / 1944
KMLI: 91 / 1941

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins/Gross
AVIATION...Cousins
CLIMATE...Gross