202
FXUS63 KIWX 180527
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
127 AM EDT SUN MAY 18 2025
KEY MESSAGES
- WINDY THIS AFTERNOON WITH WEST WINDS GUSTING NEAR 35 MPH AT
TIMES.
- REMAINING COOL THROUGH NEXT WEEK.
- PERIODS OF RAIN EXPECTED TUESDAY INTO WEDNESDAY.
DISCUSSION
ISSUED AT 219 PM EDT SAT MAY 17 2025
RAW CONDITIONS WILL PERSIST THIS AFTERNOON THANKS TO GUSTY WEST
WINDS, MOSTLY CLOUDY SKIES AND STEADY TEMPS IN THE MID 50S TO MID
60S. THIS IS OCCURRING UNDER COOL/CYCLONIC NORTHWEST FLOW ON THE
SOUTHWEST FRINGE OF AN EXITING LOW PRESSURE SYSTEM. THIS SYSTEM
WILL GRADUALLY BEGIN TO LOSE ITS INFLUENCE LOCALLY TONIGHT INTO
SUNDAY WHILE TRACKING TRACKING TOWARD NEW ENGLAND AND FAR SOUTHERN
QUEBEC. THE RESULT WILL BE A LESS WINDY SUNDAY AND A TREND TOWARD
MOSTLY SUNNY SKIES FROM SW TO NE BY THE AFTERNOON HOURS AS LARGE
SCALE SUBSIDENCE AND DRYING OVERSPREADS.
MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH A LARGE LOW
PRESSURE SYSTEM EMERGING OVER THE CENTRAL PLAINS MONDAY, THEN SLOWLY
TRACKING EAST INTO THE MID MS/NORTHERN OH VALLEYS TUESDAY INTO
WEDNESDAY. MONDAY SHOULD BE MAINLY DRY THANKS TO DRY LOW LEVEL ENE
FLOW ON THE SOUTHERN FRINGE OF HIGH PRESSURE. RAIN IS THEN
EXPECTED TO OVERSPREAD THE AREA FROM SW TO NE LATE MONDAY
NIGHT INTO TUESDAY AS DEEPER MOISTURE ADVECTS INTO A TIGHTENING
FRONTAL SLOPE. INSTABILITY APPEARS LIMITED DUE TO NEARLY MOIST
ADIABATIC LAPSE RATES NORTH OF THE SFC BOUNDARY IN CENTRAL
IL/IN. HOWEVER, COULD SEE LOCALLY HEAVY RAIN AND EMBEDDED
THUNDER GIVEN THE FORCING AND MOISTURE QUALITY (PRECIPITABLE
WATER VALUES NEAR 1.25 INCHES). COVERAGE AND INTENSITY OF THE
RAIN SHOWER ACTIVITY MAY TREND TO DIMINISH NEAR THE LOW PRESSURE
CENTER A BIT THEN INTO WEDNESDAY AS DEEPER MOISTURE EXITS EAST.
DRIER AIR DOES EVENTUALLY FILTER IN TOWARD THE END OF THE WEEK
IN WAKE OF THIS SYSTEM WITH BELOW NORMAL TEMPERATURES HOLDING IN
RESPONSE TO NEGATIVE HEIGHT ANOMALIES MERGING OVER THE NORTHEAST
AND SOUTHEAST CANADA.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 126 AM EDT SUN MAY 18 2025
A SHORTWAVE DIVES SOUTHWARD FROM TAF START INTO SUNDAY MORNING
AND HAS A CHANCE TO BRING SOME MVFR CIGS WITH IT TOWARDS SBN
FROM LATE TONIGHT INTO EARLY SUNDAY MORNING. MOISTURE IS MUCH
LOWER IN THE TIME HEIGHT SECTIONS WHEN COMPARED TO YESTERDAY AND
THE SOURCE REGION HAS THE MVFR CIGS TO ADVECT SOUTHWARD WITH IT
SO THIS ADDS ADDITIONAL CONFIDENCE TO THE SCENARIO. AS SUCH,
WILL ADD A TEMPO GROUP TO HANDLE THIS CHANCE. WIND-WISE, OUR
WEST NORTHWEST WINDS VEER TOWARDS NORTHERLY BY THE END OF THE
END OF THE FORECAST PERIOD. WINDS ARE EXPECTED TO BE LIGHTER
THAN YESTERDAY, BUT A PERIOD OF 20 KT WIND GUSTS WILL BE
POSSIBLE THIS AFTERNOON AS MIXING OCCURS IN THE PEAK HEATING
PERIOD AND THE GRADIENT TAKES ITS TIME TO SLOWLY RELAX FROM TWO
DAYS AGO.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...ANDERSEN
AVIATION...ROLLER
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