870
FXUS63 KLOT 200830
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
330 AM CDT SUN APR 20 2025
KEY MESSAGES
- BREEZY AND COOL TODAY WITH SHOWERS AT TIMES.
- WIDESPREAD SHOWERS WITH EMBEDDED THUNDERSTORMS TONIGHT. A FEW
STRONGER STORMS WITH LOCALLY GUSTY WINDS POSSIBLE ESPECIALLY
SOUTH OF I-80.
- WINDY CONDITIONS ON MONDAY WITH WEST-SOUTHWEST GUSTS IN THE
35-45 MPH RANGE.
- WELL ABOVE NORMAL TEMPERATURES EXPECTED INLAND OF THE LAKE
FOR THE REST OF THE UPCOMING WEEK AFTER A COOL MONDAY.
DISCUSSION
ISSUED AT 330 AM CDT SUN APR 20 2025
THROUGH MONDAY:
(COMING SOON)
MONDAY NIGHT THROUGH SATURDAY:
IN THE WAKE OF TODAY/MONDAY'S SYSTEM, PATTERN ACROSS THE CONUS
WILL TRANSITION TO MOSTLY ZONAL FLOW FOR THE REMAINDER OF THE
UPCOMING WORK WEEK. A STRONGER THAN USUAL BERMUDA HIGH AND LEE
TROUGHING WILL RESULT IN PERSISTENT AND BROAD SOUTHERLY FLOW OFF
THE GULF, PULLING MOIST AIR NORTH ACROSS MUCH OF THE CENTRAL AND
EASTERN PORTIONS OF THE COUNTRY.
GUIDANCE IS IN SURPRISINGLY GOOD AGREEMENT BRINGING A LOW
AMPLITUDE WAVE RIPPLING THROUGH THE ZONAL FLOW ACROSS THE
MIDWEST AND WESTERN GREAT LAKES LATER TUESDAY AND TUESDAY NIGHT.
THE HEIGHT FALLS WITH THIS WAVES WILL ENCOURAGE A MODEST
SOUTHERLY LOW LEVEL JET TO DEVELOP AND STREGNTHEN THETA-A
ADVECTION TUESDAY NIGHT. THE SHOULD RESULT IN A PERIOD OF
SHOWERS AND THUNDERSTORMS TUESDAY NIGHT, ESPECIALLY NORTH OF
I-80 AS IT LOOKS NOW.
ANOTHER, MORE PRONOUNCED NORTHERN STREAM SHORTWAVE TROUGH WILL
PASS MOSTLY NORTH OF THE AREA LATER IN THE WEEK. COLD FRONT
TRAILING FROM THE ACCOMPANYING SFC LOW SHOULD MOVE ACROSS THE
AREA LATE THURSDAY/EARLY FRIDAY TIME FRAME, BRINGING WITH IT
ANOTHER OPPORTUNITY FOR SOME SHOWERS AND STORMS.
AFTER SEASONABLY COOL TEMPS MONDAY, LOOK FOR A WARMING TREND TO
SOLIDLY ABOVE AVERAGE TEMPERATURES TUESDAY THROUGH THURSDAY. AS
IS SO OFTEN THE CASE THIS TIME OF YEAR, LAKE BREEZES EACH
AFTERNOON SHOULD KEEP TEMPS NOTABLY COOLER NEAR THE LAKE. A
RETURN TO MORE SEASONABLE TEMPERATURES IS EXPECTED JUST IN TIME
FOR THE WEEKEND IN THE WAKE OF THE LATE WEEK COLD FRONT.
- IZZI
AVIATION /06Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 1249 AM CDT SUN APR 20 2025
- WDLY SCTD -SHRA EXPECTED FROM LATE THIS MORNING THROUGH EARLY
EVENING, GREATEST COVERAGE EXPECTED AT RFD
- PERIOD OF SHOWERS EXPECTED LATE THIS EVENING INTO OVERNIGHT
HOURS TONIGHT INTO MONDAY MORNING
VFR CONDITIONS ARE EXPECTED THROUGH MOST OF DAYTIME HOURS TODAY,
THOUGH SOME WDLY SCTD -SHRA ARE EXPECTED FROM MID MORNING
THROUGH THE EARLY EVENING HOURS. GREATEST COVERAGE OF SHOWERS
WILL BE WEST OF THE CHICAGO AREA, CLOSER TO RFD, WITH SOME
VIRGA AND SPRINKLES/VERY LIGHT SHOWERS MORE LIKELY AT THE
IMMEDIATE CHICAGO TERMINALS. A MORE FORMIDABLE BAND OF SHOWERS
WILL SWEEP ACROSS THE REGION LATE THIS EVENING INTO THE PRE-DAWN
HOURS MONDAY.
LIGHT/VARIABLE OR LIGHT EASTERLY WINDS WILL BEGIN TO INCREASE
FROM THE THE EAST TOWARD SUNRISE THIS MORNING, THEN CONTINUE TO
INCREASE WITH AT LEAST SOME OCNL GUSTINESS DEVELOPING BY MID
MORNING. EASTERLY WINDS WILL STRENGTHEN FURTHER LATER THIS
AFTERNOON INTO THIS EVENING WITH OCNL GUSTS TO AROUND 30 KT
POSSIBLE.
- IZZI
MARINE
ISSUED AT 326 PM CDT SAT APR 19 2025
HAVE ISSUED A GALE WATCH FOR THE ILLINOIS AND NORTHWEST INDIANA
NEARSHORE WATERS FROM MONDAY MORNING THROUGH EARLY MONDAY
EVENING.
LOW PRESSURE AT OR JUST UNDER 1000 MB WILL TRACK FROM
IOWA SUNDAY NIGHT TO NORTHERN LOWER MICHIGAN MONDAY AFTERNOON
AND ACROSS LAKE HURON MONDAY EVENING. BREEZY EAST-SOUTHEAST
WINDS SUNDAY NIGHT MAY RESULT IN HAZARDOUS WAVES FOR SMALL CRAFT
ALONG THE ILLINOIS NEARSHORE. THEN IN THE WAKE OF THE SYSTEM ON
MONDAY, WINDS WILL QUICKLY SHIFT TO SOUTHWEST AND THEN WEST
WHILE RAPIDLY INCREASING DUE TO A TIGHT PRESSURE GRADIENT. WHILE
THE TOP END MAGNITUDE OF THE SPEEDS/GUSTS VARIES AMONGST THE
GUIDANCE FOR MONDAY, IN GENERAL FELT THE SIGNAL WAS STRONG
ENOUGH TO ISSUE A GALE WATCH GIVEN EXPECTED MONDAY MORNING
ONSET. FOR NOW, THE FORECAST WILL INDICATE GALE SPEEDS/GUSTS TO
AROUND 35 KT BUT THE MORE BULLISH GUIDANCE SUGGESTS GALES UP TO
40 KT OR EVEN A BIT HIGHER ARE POSSIBLE. INCREASING STABILITY
OFFSHORE WILL LIKELY LIMIT THE GALES TO THE FIRST 2-3 MILES OF
THE NEARSHORE. WESTERLY WINDS WILL STEADILY EASE MONDAY EVENING.
CASTRO
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 AM CDT MONDAY
FOR THE IL AND IN NEARSHORE WATERS.
GALE WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE
IL AND IN NEARSHORE WATERS.
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