212
FXUS63 KLOT 111705
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1205 PM CDT SUN MAY 11 2025
KEY MESSAGES
- GENERALLY WELL ABOVE NORMAL TEMPERATURES EXPECTED THIS WEEK,
MAINLY AWAY FROM THE LAKESHORE.
- ISOLATED TO SCATTERED SHOWERS AND STORMS EXPECTED MONDAY
THROUGH THURSDAY, THOUGH THERE WILL BE MANY DRY HOURS.
- A THREAT FOR SEVERE WEATHER EXISTS THURSDAY AFTERNOON AND
EVENING, CONTINGENT UPON STORMS DEVELOPING (30-40% CHANCE).
DISCUSSION
ISSUED AT 333 AM CDT SUN MAY 11 2025
QUIESCENT CONDITIONS ARE IN STORE FOR MOTHER'S DAY TODAY AMIDST
CONTINUED BLOCKING PATTERN IN THE UPPER LEVELS AND SURFACE HIGH
PRESSURE ACROSS THE REGION. AMPLE SUNSHINE WILL AID IN
TEMPERATURES WARMING INTO THE MID 70S TO NEAR 80 FOR MUCH OF THE
AREA. HOWEVER, CONTINUED EASTERLY WINDS WILL LEAD TO COOLER
TEMPERATURES IN THE 60S TO MID 70S ACROSS FAR NORTHEAST ILLINOIS
AND FAR NORTHWEST INDIANA (COOLEST ALONG THE LAKESHORE).
A CLOSED UPPER LOW THAT HAS BEEN MEANDERING ACROSS THE LOWER
MISSISSIPPI VALLEY THE PAST FEW DAYS WILL BEGIN TO LIFT NORTH
TOWARD THE REGION TONIGHT INTO MONDAY AS THE UPPER LEVEL
BLOCKING PATTERN BEGINS TO BREAK DOWN. THIS WILL LEAD TO A PLUME
OF LOW-LEVEL MOISTURE LIFTING INTO THE AREA. GUIDANCE HAS
TRENDED SLOWER WITH THE NORTHWARD ADVANCEMENT OF THE HIGHER
DEWPOINTS WHICH WILL LIKELY LIMIT ANY DIURNAL PULSE SHOWERS AND
STORMS TO AREAS MAINLY SOUTH OF I-80 THROUGH THE DAYTIME HOURS.
BY THE EVENING A FEW SHOWERS AND STORMS COULD THEN LIFT ACROSS
THE REST OF THE AREA OVERNIGHT. WARM AND HUMID CONDITIONS WILL
CONTINUE TUESDAY AND WEDNESDAY AS THE UPPER LOW SLOWLY LIFTS
ACROSS THE OHIO VALLEY LEADING TO ADDITIONAL ISOLATED TO
SCATTERED SHOWERS AND STORMS, WITH THE GREATEST COVERAGE
EXPECTED ON TUESDAY. GIVEN WEAK FLOW ALOFT, ANY STORMS WOULD BE
PULSE-LIKE WITH LIGHTNING, BRIEF DOWNPOURS, AND GUSTY WINDS
BEING THE MAIN HAZARDS. LOW-LEVEL INSTABILITY PAIRED WITH AREAS
OF LOW-LEVEL VORTICITY SUGGEST A FEW FUNNEL CLOUDS CAN'T BE
FULLY RULED OUT. HIGHS ARE FORECAST TO WARM INTO THE MID 70S TO
MID 80S INLAND WHILE STILL NOTABLY COOLER NEAR THE LAKE.
THE WESTERN CONUS TROUGH IS FORECAST TO EJECT OFF THE ROCKIES
ON WEDNESDAY WITH LEE CYCLOGENESIS EXPECTED ACROSS THE PLAINS.
THESE FEATURES WILL CONTINUE TO LIFT NORTHEAST TOWARD THE UPPER
MIDWEST INTO THURSDAY. THE MID-UPPER TROUGH MAY EVEN BEGIN TO
TAKE ON A NEGATIVE TILT ON ITS APPROACH WITH A STRONG LOW-LEVEL
MASS RESPONSE HELPING TO FURTHER ADVECT WARM MOIST AIR INTO THE
REGION. IN FACT, THE CURRENT FORECAST HAS HIGHS IN THE UPPER 80S
TO AROUND 90 ON THURSDAY WITH DEWPOINTS IN THE MID 60S. WITH
THIS IN MIND, THURSDAY CONTINUES TO BE THE DAY TO WATCH FOR THE
POTENTIAL FOR SEVERE WEATHER. AS OF THIS WRITING, SPC HAS
NORTHEAST ILLINOIS AND NORTHWEST INDIANA OUTLOOKED FOR A 15%
CHANCE FOR SEVERE WEATHER. OVERALL THERE HASN'T BEEN MUCH CHANGE
IN OUR THINKING WITH THIS UPDATE. CONDITIONS ARE FAVORABLE FOR
SEVERE STORMS: STRONG SHEAR, STEEP MID-LEVEL LAPSE RATES, AMPLE
INSTABILITY, ETC. HOWEVER, QUESTIONS REMAIN AS TO WHETHER STORMS
WILL INITIATE, THOUGH THERE IS MORE MID-UPPER LEVEL FORCING TO
AID IN BREAKING THE CAP COMPARED TO OUR MOST RECENT CONDITIONAL
SEVERE WEATHER DAY IN LATE APRIL. ONE THING OF NOTE IS THAT A
QUICK PERUSAL OF 0Z ECMWF SOUNDINGS ACROSS THE AREA MATCH
SEVERAL ANALOGS FOR SIGNIFICANT HAIL. SOMETHING TO KEEP AN EYE
ON OVER THE NEXT FEW DAYS. STAY TUNED!
FRIDAY THROUGH THE UPCOMING WEEKEND WILL FEATURE A GRADUAL
COOLING TREND WITH PRIMARILY DRY CONDITIONS AS THE
AFOREMENTIONED UPPER TROUGH CLOSES OFF AND SLOWLY DRIFTS ACROSS
ONTARIO.
PETR
AVIATION /18Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 1204 PM CDT SUN MAY 11 2025
THERE ARE NO AVIATION CONCERNS THROUGH THE TAF PERIOD. EASTERLY
WINDS WILL PREVAIL WITH SPEEDS AT OR BELOW 10KT. LOW-END VFR
CIGS MAY DEVELOP TOWARD THE END OF THE 30-HOUR TAF WINDOW AT
ORD/MDW AS LOW-LEVEL MOISTURE INCREASES, THOUGH WILL WITHHOLD
MENTION FOR NOW.
BORCHARDT
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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