096
FXUS63 KLOT 091758
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1258 PM CDT FRI MAY 9 2025
KEY MESSAGES
- GENERALLY ABOVE NORMAL TEMPERATURES ARE IN STORE AWAY FROM THE
LAKE THROUGH NEXT WEEK STARTING ON SATURDAY.
- SHARPLY DROPPING TEMPERATURES ARE EXPECTED SATURDAY AFTERNOON
AND EVENING BEHIND A BACKDOOR COLD FRONT (SIMILAR TO THIS
PAST WEDNESDAY).
- OCCASIONAL SHOWER AND THUNDERSTORM CHANCES ARE FAVORED TO
RETURN NEXT WORK WEEK.
DISCUSSION
ISSUED AT 328 AM CDT FRI MAY 9 2025
THROUGH SATURDAY NIGHT:
THE WORK WEEK WILL CLOSE ON A MORE PLEASANT NOTE TODAY THAN THE
COOL AND BREEZY CONDITIONS EXPERIENCED SINCE WEDNESDAY'S COLD
FRONT PASSAGE. SURFACE HIGH PRESSURE DRAPED ACROSS THE REGION
WILL KEEP DAYTIME WINDS MUCH LIGHTER. NEARLY FULL SUNSHINE AND
DEW POINTS LIKELY TO MIX OUT INTO THE 20S (SOME TEENS POSSIBLE
AT PEAK HEATING!) WILL RESULT IN HIGHS RETURNING TO NEAR
SEASONABLE UPPER 60S TO LOWER 70S WELL INLAND OF LAKE MICHIGAN.
ONSHORE WINDS THROUGH THE DAY WILL LIMIT HIGHS TO THE MID TO
UPPER 50S LAKESIDE, WITH LOWER TO MID 60S A FEW TO SEVERAL MILES
INLAND. TONIGHT WILL BE QUIET AND COOL, BUT SEVERAL DEGREES
MILDER THAN EARLY THIS MORNING.
SATURDAY WILL BE NEARLY A CARBON COPY OF THIS PAST WEDNESDAY'S
WEATHER. A LAKE ENHANCED BACKDOOR COLD FRONT WILL BRING A SHARP
AFTERNOON-EVENING COOLDOWN, ESPECIALLY NEAR THE LAKE (20F+
COOLER WITHIN AN HOUR OR TWO), FOLLOWING HIGHS IN THE 70S TO
AROUND 80F AHEAD OF THE FRONTAL PASSAGE. THERE SHOULD BE ENOUGH
MOISTURE TO SUPPORT SOME SHALLOW CU AS THE FRONT OOZES INLAND,
BUT DEPTHS APPEAR TOO SHALLOW TO SUPPORT ANY SPOTTY SHOWERS WELL
INLAND. EXPECT NORTH-NORTHEAST WINDS TO GUST TO 25-35 MPH
BEHIND THE FRONT, STRONGEST NEAR THE LAKE, MAKING IT FEEL EVEN
COOLER. WINDS WILL QUICKLY EASE SATURDAY NIGHT AFTER A COOL AND
BREEZY EARLY TO MID EVENING PERIOD, WITH OVERNIGHT LOWS IN THE
40S.
CASTRO
SUNDAY THROUGH THURSDAY:
ON SUNDAY (MOTHER'S DAY), AN UPPER-LEVEL RIDGE WILL STRENGTHEN
ACROSS THE GREAT LAKES NORTH OF A CUT-OFF LOW PRESSURE SYSTEM
STALLED NEAR THE GULF COAST. THE NET RESULT WILL BE A BRIEF
"REX" BLOCK, WHICH TYPICALLY LEADS TO A DEARTH OF IMPACTFUL
WEATHER. INDEED, SUNDAY IS SHAPING UP TO BE GORGEOUS WITH HIGHS
IN THE MID 70S TO AROUND 80F, LIGHT WINDS, AND SUNNY SKIES. IN
FACT, FORECAST SOUNDINGS ACROSS OUR AREA DEPICT NO MORE THAN
20KT OF FLOW FROM THE SURFACE TO NEARLY 40KFT ON SUNDAY, AN
UNUSUAL FEAT SHOULD IT VERIFY. SYNOPTIC ONSHORE WINDS AND THEN A
REINFORCING LAKE BREEZE DURING THE AFTERNOON WILL CAP LAKESIDE
TEMPS IN THE 60S AND BRING A MORE MODEST LAKE COOLING FOOTPRINT
INLAND (VS. SATURDAY'S EXPECTED DROP).
THERE'S SOME VARIANCE IN HOW QUICKLY THE TEMPORARY "REX BLOCK"
WILL BREAK DOWN EARLY NEXT WEEK. THIS WILL AFFECT WHETHER
SHOWER AND SOME THUNDERSTORM CHANCES RETURN AS EARLY AS LATE
MONDAY AFTERNOON AND EVENING, PARTICULARLY SOUTH OF I-80. THE
CURRENT OFFICIAL FORECAST SIDES WITH THE DRIER GUIDANCE FOR NOW.
HIGH TEMPS LOOK TO BE SUMMER-LIKE IN THE LOWER 80S, EXCEPT ONLY
IN THE UPPER 60S TO AROUND 70F NEAR/ALONG THE IL SHORE.
TUESDAY INTO WEDNESDAY, DEVELOPING UPPER-LEVEL TROUGHING IN THE
NORTHWESTERN UNITED STATES WILL ENCOURAGE THE CUT-OFF LOW
PRESSURE SYSTEM ALONG THE GULF COAST TO LIFT EAST-NORTHEASTWARD
TOWARD THE GREAT LAKES. INCREASING LOW-LEVEL MOISTURE AND
CONTINUED WARM TEMPERATURES WILL HENCE ENCOURAGE DAILY DIURNAL
INSTABILITY, TOGETHER SUPPORTING A RETURN OF CHANCES FOR SHOWERS
AND THUNDERSTORMS. TUESDAY IS CURRENTLY "FAVORED" TO HAVE THE
HIGHEST COVERAGE OF SHOWERS AND STORMS (POPS IN THE 30 TO 50%
RANGE). WEAK FLOW ALOFT, MINIMAL CAPPING BUT WITH SKINNY CAPE
DUE TO MID-LEVEL LAPSE RATES OF 5.5-6.5C/KM, AND MODEST FORCING
SHOULD RESULT IN ISOLATED TO WIDELY SCATTERED PULSE TYPE
CONVECTION, QUICKLY DISSIPATING PRIOR TO SUNSET.
ENSEMBLE MODEL GUIDANCE ADVERTISES A CONTINUATION OF MUCH
ABOVE-AVERAGE TEMPERATURES IN THE 80S (ASIDE FROM LAKESIDE
COOLING) AS WELL AS ELEVATED HUMIDITY LEVELS THROUGH THE REST OF
NEXT WEEK. WITH THE PACIFIC TROUGH EVENTUALLY EJECTING EASTWARD
THROUGH THE CENTRAL US, THERE MAY BE A WINDOW OR TWO FOR STRONG
TO SEVERE STORMS IN THE BROAD MIDWEST REGION AT SOME POINT LATE
NEXT WEEK. THURSDAY AFTERNOON AND EVENING COULD BE A "TIME TO
WATCH" LOCALLY FOR AN ORGANIZED CONVECTIVE THREAT, THOUGH
THERE'S PLENTY OF TIME FOR CHANGES IN KEY SYNOPTIC PIECES AND
MESOSCALE DETAILS.
CASTRO/BORCHARDT
AVIATION /18Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 1258 PM CDT FRI MAY 9 2025
VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD, WITH ONLY SOME
PASSING CIRRUS THROUGH AT LEAST TONIGHT. NE WINDS 5 TO 10 KNOTS
WILL GRADUALLY VEER SE THIS EVENING AND SW OVERNIGHT AS A
SURFACE RIDGE CROSSES THE AREA. A BACKDOOR COLD FRONT WILL THEN
SURGE ACROSS NORTHEAST ILLINOIS LATE SATURDAY MORNING, WITH NE
WINDS GUSTING TO AROUND 25 KNOTS THROUGH THE AFTERNOON.
KLUBER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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