150
FXUS63 KIWX 180633
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
233 AM EDT SUN MAY 18 2025
KEY MESSAGES
- COOL AND DRY WEATHER WILL PERSIST THROUGH MONDAY WITH HIGHS IN
THE 60S AND LOW 70S.
- WIDESPREAD RAIN IS EXPECTED TUESDAY INTO WEDNESDAY.
- HIGHS WILL REMAIN BELOW NORMAL FOR THE WEEK.
DISCUSSION
ISSUED AT 233 AM EDT SUN MAY 18 2025
CONDITIONS WILL IMPROVE TODAY AS UPPER LOW CONTINUES TO EXIT EAST.
INCREASING DRY AIR ADVECTION AND SUBSIDENCE WILL YIELD MORE SUN THAN
YESTERDAY. WEAKENING GRADIENT WILL ALSO YIELD LESS WIND BUT LOW
LEVEL FLOW REMAINS N/NW AND COOL TEMPS WILL REMAIN, ESPECIALLY FOR
AREAS NEAR THE LAKE. ANTICIPATE HIGHS AROUND 70F FOR THE SOUTHERN
ZONES WHILE LOCATIONS NEAR LAKE MI HOVER AROUND 60F. CLEAR SKIES
(FOR THE FIRST HALF OF THE NIGHT) AND LIGHT WINDS WILL CAUSE
OVERNIGHT LOWS TO DROP INTO THE LOW/MID 40S FOR MOST.
ATTENTION THEN TURNS TO UPPER LOW CURRENTLY DEVELOPING OVER THE
WESTERN CONUS. THIS UPPER LOW WILL SLOWLY PINWHEEL OVER THE CONUS
AND BRING US RAIN CHANCES MAINLY TUE-WED. MON LOOKS PRIMARILY DRY AT
THIS POINT AS MOST GUIDANCE NOW AGREES STAUNCH GREAT LAKES RIDGE
WILL HOLD FIRM UNTIL TUE AM WITH A STEADY FEED OF COOL/DRY/STABLE
AIR INTO OUR CWA AND BETTER MOISTURE/ASCENT FROM UPPER LOW REMAINING
WELL TO OUR WEST. BEST THETA-E SURGE DOESN'T ARRIVE UNTIL AROUND 12Z
TUE AS UPPER LOW MOVES INTO IOWA. STRONG SOUTHWESTERLY LLJ WILL
EVENTUALLY PUSH INTO OUR AREA DURING THE DAY TUE WITH WIDESPREAD
SHOWERS ANTICIPATED. SURFACE LOW IS SLATED TO TRACK SOUTH OF OUR
AREA SO SBCAPE IS NIL BUT EVEN ELEVATED INSTABILITY IS LACKING DUE
TO POOR LAPSE RATES. STILL CAN'T RULE OUT A FEW EMBEDDED
THUNDERSTORMS BUT NO SEVERE WEATHER IS EXPECTED. SOME POCKETS OF
HEAVIER RAIN ARE POSSIBLE, PARTICULARLY IN OUR SOUTH, ON TUE BUT NOT
ENOUGH TO CAUSE ANY FLOODING CONCERNS. THIS WILL LIKELY BE SEEN AS A
VERY BENEFICIAL RAIN GIVEN OVERALL RELATIVELY DRY CONDITIONS THIS
MONTH. HIGHS TUE-WED WILL REMAIN VERY COOL FOR MID-LATE MAY,
STRUGGLING TO GET ABOVE 60F.
WE TREND BACK TO DRIER CONDITIONS THU-SAT BUT MODELS STILL DIVERGE A
BIT ON HOW THIS UPPER LOW EVOLVES WITH SOME SOLUTIONS SUGGESTING
LIGHT RAIN MAY RETURN AS THIS UPPER LOW MERGES WITH ANOTHER TROUGH
LINGERING OVER EASTERN CANADA. HIGH CONFIDENCE THAT TEMPS WILL
REMAIN ON THE COOL SIDE OF CLIMO THOUGH AS PREDOMINATELY NORTHERLY
FLOW PREVAILS UNTIL CLOSER TO MEMORIAL DAY.
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...AGD
AVIATION...ROLLER
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