826
FXUS63 KIWX 201724
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
124 PM EDT SUN JUL 20 2025
KEY MESSAGES
- RAIN SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY, WITH TWO
POTENTIAL ROUNDS OF STRONGER STORMS POSSIBLE ALONG AND SOUTH
OF US 30. THE FIRST ROUND FROM 9-2 AM EDT, THE SECOND 2-8 PM
EDT. PRIMARY THREATS WILL BE HEAVY RAIN, LIGHTNING, LOCALIZED
FLOODING, AND GUSTY WINDS UP TO AROUND 50 MPH (MOST LIKELY IN
THE AFTERNOON). CONFIDENCE IN STRONGER STORMS OCCURRING IS
LOW. CHANCES FOR SHOWERS AND STORMS LINGER INTO MONDAY
MORNING.
- THERE IS A MODERATE SWIM RISK FOR THE SOUTHEASTERN LAKE MICHIGAN
BEACHES IN LA PORTE AND SOUTHERN BERRIEN COUNTY FOR TODAY.
- HOT AND HUMID CONDITIONS REMAIN ON TRACK FOR WEDNESDAY AND
THURSDAY WITH HEAT INDICES NEAR OR ABOVE 100 DEGREES.
DISCUSSION
ISSUED AT 345 AM EDT SUN JUL 20 2025
WHILE SIGNALS ARE STRONG IN THE MODELS FOR AT LEAST 2 COMPLEXES
OF STORMS OVER THE NEXT 24 TO 36 HOURS ALONG AND NORTH OF A
QUASI-STATIONARY BOUNDARY, FINER MESOSCALE DETAILS REMAIN
PROBLEMATIC WITH REGARDS TO THE TRACK OF THESE SYSTEMS AND
IMPACTS. OUR FIRST COMPLEX IS RAPIDLY EXPANDING ACROSS SE IOWA
INTO WEST CENTRAL IL. HRRR HAS BEEN FAIRLY CONSISTENT ON THE
EXPANSION OF THIS AREA AS IT TRACKS EAST. WHILE FAIRLY HIGH
CONFIDENCE EXISTS ON IT MOVING INTO EASTERN IL, THE 850-300 MB
FLOW AND LOCATION OF THE THETA-E GRADIENT SUGGEST AT SOME POINT
THE STRONGEST PORTION OF THE COMPLEX WILL BEGIN AN SE TURN IN
THE 12-15Z WINDOW. HAVE MADE SOME MINOR TIMING/POP CHANGES
THROUGH 18Z TO ACCOUNT FOR A SLIGHTLY MORE NORTHWARD TREND ON
THE LIKELY POPS WHILE TRIMMING THE NORTHERN EXTENT OF ANY POPS
AS YOU HEAD INTO MI. WAS TEMPTED TO INCREASE TO CATEGORICAL
ALONG AND SOUTH OF US-24 WHERE GREATEST CHANCE FOR
SHOWERS/STORMS EXISTS, BUT GIVEN NOTED CONCERNS HELD WITH
LIKELY. MAIN CONCERN WILL HEAVY RAIN AS A VERY SOUPY ATMOSPHERE
WILL BE IN PLACE WITH A SWATH OF 0.5-1" OF RAIN IS LIKELY ON THE
US-24 CORRIDOR WITH HIGHER AMOUNTS IN SOME LOCATIONS. NEIGHBORS
TO THE SOUTH HAVE HOISTED FLOOD WATCHES GIVEN RECENT RAINFALL
AND HIGHER LIKIHOOD OF EVEN HEAVIER RAIN AMOUNTS. FOR US, THE
HEAVIEST RAIN THE PAST 24 HOURS FELL WELL NORTH OF THE
ANTICIPATED STORM TRACK TODAY. IN ADDITION, THE COMPLEX SHOULD
REMAIN PROGRESSIVE.
CONFIDENCE DECREASES THIS AFTERNOON AND INTO TONIGHT AS FINAL
TRACK OF THIS COMPLEX WILL GREATLY DETERMINE WHAT, IF ANY,
ADDITIONAL CONVECTION CHANCES EXIST. 06Z HRRR SEEMS TO PAINT A
VERY PLAUSIBLE SCENARIO WITH LITTLE/NO STORMS IN OUR SOUTHERN
AREA FROM MID AFTERNOON INTO EARLY MONDAY IN THE POST MCS
SUBSIDENCE AREA. CONFIDENCE WAS NOT HIGH ENOUGH IN THIS SETUP TO
REMOVE THE LIKELY POPS THROUGH EARLY MONDAY, SO HAVE LEFT THEM
ALONE WITH THE DAY SHIFT IN A BETTER POSITION TO SEE HOW THE
TRENDS LOOK.
UPPER LEVEL RIDGING WILL BEGIN TO INCREASE LATE MONDAY INTO MID
WEEK, FINALLY ENDING THE TRAIN OF CONVECTIVE SYSTEMS, BUT ALSO
USHERING IN A RETURN TO HOT AND HUMID CONDITIONS. NO CHANGES
MADE TO LATER PERIODS AS SIGNALS REMAINING CONSISTENT ON
WEDNESDAY AND THURSDAY BEING THE WARMEST DAYS (HIGHS NEAR OR
ABOVE 90) AND HEAT INDICES NEAR OR ABOVE 100 DEGREES (HIGHEST
THURSDAY). BY NEXT WEEKEND, THE HEAT DOME WILL LIKELY HAVE
SHIFTED EAST ENOUGH TO END THE HEAT IMPACTS AND ALSO BEGIN TO
ALLOW AT LEASE SOME CHANCES FOR SHOWERS AND STORMS TO RETURN.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 119 PM EDT SUN JUL 20 2025
A SLOW MOVING FRONTAL BOUNDARY IS CURRENTLY JUST NORTH OF THE US
30 CORRIDOR. NORTH OF THE FRONT, WINDS HAVE ALREADY SHIFTED FROM
THE WEST TO THE NORTH AT KSBN. EXPECT A SIMILAR WIND SHIFT TO
OCCUR THIS EVENING AT KFWA ONCE THE FRONT MAKES IT THROUGH
(BETWEEN 21Z TO 00Z TONIGHT). SCATTERED LIGHT TO MODERATE RAIN
CONTINUES TO PUSH THROUGH THE AREA, WITH POTENTIAL FOR SOME
REDEVELOPMENT LATER TODAY MAINLY SOUTH OF US 24. HAVE KEPT IN A
TEMPO GROUP FOR THUNDER AT KFWA FOR A FEW HOURS THIS EVENING IN
CASE SCATTERED STORMS DO DEVELOP. CEILINGS SHOULD REMAIN ON
THE LOW END OF VFR, DOWN TO MVFR IN ANY STORMS. OTHERWISE,
EXPECT LIGHT WINDS THIS EVENING AND INTO THE OVERNIGHT FROM THE
NORTH. WITH A DRIER AIRMASS ADVECTING IN FROM THE NORTH,
LINGERING MOISTURE NEAR THE GROUND AND CLEARING SKIES OVERNIGHT
COULD LEAD TO SOME RADIATION FOG DEVELOPING BY EARLY MONDAY
MORNING. MUCH LIKE THIS MORNING, FOG WILL LIKELY BE PATCHY.
DURING THE DAY MONDAY, DRY AND PLEASANT WEATHER IS EXPECTED.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...FISHER
DISCUSSION...FISHER
AVIATION...JOHNSON
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