281  
FXUS63 KIWX 220933  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
533 AM EDT TUE APR 22 2025  
   
KEY MESSAGES  
 
- INCREASING CLOUDS THIS AFTERNOON AND HIGH TEMPERATURES NEAR  
70.  
 
- SHOWERS AND THUNDERSTORMS THIS EVENING AND OVERNIGHT,  
PRIMARILY NORTHWEST OF US 24.  
 
- VERY WARM WEDNESDAY THROUGH FRIDAY WITH HIGHS IN THE LOW-80S  
THURSDAY FOLLOWED BY SHOWERS AND STORMS FRIDAY.  
 
 
   
DISCUSSION  
 
ISSUED AT 314 AM EDT TUE APR 22 2025  
 
WATER VAPOR THIS MORNING SHOWS AN UPPER-LEVEL LOW LIFTING THROUGH  
MN, WITH A SUBTLE BAROCLINIC ZONE INFERRED TO ITS SOUTH, SPREADING  
THROUGH THE CENTRAL PLAINS. CONVERGENCE IS NOTED IN THE SURFACE  
OBSERVATIONS AND THIS BAROCLINIC ZONE WILL BE THE FORCING MECHANISM  
FOR SHOWERS AND THUNDERSTORMS PRIMARILY NORTHWEST OF US 24 THIS  
EVENING AND OVERNIGHT. GUIDANCE HAS COME NOTABLY FARTHER SOUTH WITH  
RAIN CHANCES SINCE 12 HOURS AGO OWING TO A SEEMINGLY FLATTER, ZONAL  
500-MB PATTERN.  
 
HIGH PRESSURE CURRENTLY OVERHEAD LEAVES BEHIND A STOUT DRY LAYER  
THAT IS FORECAST TO BE CONQUERED AFTER 00Z (8PM EDT) WHEN IMPROVED  
FORCING ARRIVES VIA A MODEST 850-MB JET. INSTABILITY IS GENERALLY  
FORECAST TO BE NEAR 500 J/KG RESULTING IN A NON-ZERO CHANCE FOR  
THUNDER. HOW FAR SOUTH AND EAST SHOWERS AND STORMS PROGRESS IS  
UNCERTAIN. HIGH PRESSURE LINGERS ACROSS NORTHWEST OHIO AND CENTRAL  
INDIANA WHICH WILL CERTAINLY WORK AGAINST WET WEATHER THERE. AN  
OVERALL LACK OF STRONG FORCING PERMITS THIS HIGH TO LOITER RATHER  
THAN EXIT OVER THE EAST COAST. THIS BAROCLINIC ZONE REMAINS INTO  
WEDNESDAY MORNING AS WELL, NECESSITATING SLIGHT CHANCE (20%) POPS.  
 
NOT A WASHOUT TO END THE WEEK BUT THERE ARE SEVERAL CHANCES FOR  
SHOWERS AND THUNDERSTORMS. A SOUTHEAST US RIDGE PUMPS IN ADEQUATE  
GULF MOISTURE WHILE BROAD TROUGHING IN THE WEST SENDS SHORTWAVES  
THROUGH THE FOUR CORNERS AND INTO THE NATION'S HEARTLAND. WET  
WEATHER WILL BE MOST WIDESPREAD FRIDAY AS LOW PRESSURE MOVES  
OVERHEAD. COOLER IN ITS WAKE AS CANADIAN HIGH PRESSURE LIMITS HIGHS  
ON SATURDAY TO THE LOW-TO-MID 60S. THIS IS A NOTABLE CONTRAST TO  
HIGHS WEDNESDAY THROUGH FRIDAY WHICH WILL BE WELL INTO THE 70S TO  
NEAR 80.  
 
BECOMING VERY WARM ONCE MORE IN THE FINAL DAYS OF APRIL WITH MORE  
WET WEATHER AS THE SOUTHEAST US RIDGE AMPLIFIES FURTHER, STEERING  
ADDITIONAL IMPULSES OVERHEAD.  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/  
 
ISSUED AT 529 AM EDT TUE APR 22 2025  
 
TODAY'S WEATHER WILL BE TRANQUIL AND WARM. SKIES WILL REMAIN  
CLEAR DURING THE MORNING AND AFTERNOON HOURS AS HIGH PRESSURE  
BUILDS ACROSS THE MIDWEST AND UPPER GREAT LAKES REGIONS. WINDS  
WILL BECOME LIGHT AND VARIABLE IN THE NEXT FEW HOURS AND PERSIST  
THROUGH THE MORNING. BY THE AFTERNOON, EXPECT LOTS OF SUNSHINE  
AND LIGHT WINDS OUT OF THE SOUTH. CLOUDS WILL INCREASE THIS  
EVENING AFTER SUNSET AS SCATTERED SHOWERS MOVE IN. THE MOST  
FAVORABLE LOCATIONS TO SEE RAIN THIS EVENING WITH BE NORTH OF US  
24 AND WEST OF US 31. KSBN IS MORE LIKELY TO SEE PREVAILING  
SHOWERS AND MVFR CEILINGS/VISIBILITIES TONIGHT, ALTHOUGH IT IS  
NOT OUT OF THE QUESTION THAT KFWA SEES A FEW LIGHT SHOWERS IN  
THE VICINITY. THE HIGHEST CHANCES FOR RAIN AT KSBN COME AT THE  
END OF THE TAF FORECAST PERIOD FROM 06-12Z WEDNESDAY MORNING.  
 
 
   
IWX WATCHES/WARNINGS/ADVISORIES  
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...NONE.  
 
 
 
 
 
DISCUSSION...BROWN  
AVIATION...JOHNSON  
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