572
FXUS63 KIWX 300755
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
355 AM EDT SUN MAR 30 2025
KEY MESSAGES
- MORNING RAIN AND DRIZZLE WILL CONTINUE TO TAPER IN COVERAGE.
- THE POTENTIAL OF STRONG TO SEVERE THUNDERSTORMS REMAINS FOR
THIS AFTERNOON THROUGH THIS EVENING. THE TIME PERIOD OF
CONCERN REMAINS FROM 2 PM EDT THIS AFTERNOON TO 11 PM EDT
TONIGHT. ALL SEVERE WEATHER HAZARDS ARE POSSIBLE INCLUDING
DAMAGING WINDS, LARGE HAIL, AND ISOLATED TORNADOES. THE
GREATEST THREAT OF LARGE HAIL IS EXPECTED TO BE EARLIER IN THE
TIME PERIOD OF CONCERN ACROSS NORTHWEST INDIANA.
- BRIEF SHOT OF COOLER TEMPERATURES MONDAY INTO TUESDAY.
- ANOTHER CHANCE FOR STRONG TO SEVERE THUNDERSTORMS EXISTS ON
WEDNESDAY.
DISCUSSION
ISSUED AT 345 AM EDT SUN MAR 30 2025
AREAS OF RAIN SHOULD CONTINUE TO DIMINISH THROUGH THE MORNING HOURS
AS POCKET OF DEEPER MOISTURE BEGINS TO EXIT NORTHWEST OHIO. GOOD
DEAL OF LINGERING LOW LEVEL MOISTURE AND LIFT FROM BROAD WARM
ADVECTION SHOULD CONTINUE TO SUPPORT POCKETS OF LIGHT
SHOWERS/DRIZZLE FOR NEXT SEVERAL HOURS.
PREVIOUS FORECAST THINKING FROM LAST SEVERAL CYCLES LARGELY REMAINS
INTACT THIS MORNING REGARDING THE SEVERE WEATHER POTENTIAL THIS
AFTERNOON INTO THIS EVENING. A STRONG UPPER LEVEL TROUGH
CONTINUES TO SHARPEN ACROSS THE CENTRAL PLAINS THIS MORNING AS
A 100 KNOT UPPER LEVEL SPEED MAX CUTS THROUGH THE BASE OF THIS
TROUGH ACROSS THE SOUTHERN PLAINS. APPROACH OF THIS MID/UPPER
LEVEL TROUGH AND A MID LEVEL SPEED MAX LIFTING THROUGH
DOWNSTREAM PORTION OF THIS TROUGH SHOULD INTERACT WITH MODERATE
INSTABILITY AXIS AHEAD OF ADVANCING COLD FRONT BOUNDARY FOR
WIDESPREAD SHOWER AND THUNDERSTORM DEVELOPMENT.
THE MAIN ITEMS OF UNCERTAINTY ARE IN REGARDS TO EXACT TIMING GIVEN
TWO DIFFERENT CAMPS IN HIGHER RES GUIDANCE ON WHETHER PRE-FRONTAL
REGION WILL BECOME FAVORED AREA FOR INITIATION, OR A SLIGHTLY SLOWER
EVOLUTION CLOSER TO THE PRIMARY COLD FRONTAL BOUNDARY. THIS
DISCREPANCY APPEARS TO ARISE IN PART FROM SOME DIFFERENCES IN
GUIDANCE HANDLING STRENGTH OF ELEVATED MIXED LAYER ADVANCING INTO
THE AREA TODAY. IF ELEVATED MIXED LAYER IS TOO STRONG, THIS MAY
DISCOURAGE DEVELOPMENT IN PRE-FRONTAL REGION WITH DEVELOPMENT
FOCUSING BACK TOWARD COLD FRONTAL BOUNDARY. UPSTREAM CONVECTION
EARLY THIS MORNING ACROSS THE CORN BELT IS FURTHER COMPLICATING THE
HANDLING OF THIS ELEVATED MIXED LAYER, WHICH MAKES IT DIFFICULT TO
HAVE FULL CONFIDENCE EVEN AT THIS SHORT FORECAST DISTANCE ON EXACT
TIMING AND MODE DETAILS. NONETHELESS, IMPACTS IN TERMS OF
SEVERE WEATHER THREATS SHOULD BE SOMEWHAT SIMILAR IN EITHER
SCENARIO AS BACKGROUND DEEP LAYER SHEAR OF 40-50 KNOTS AND
SURFACE BASED CAPES OF 1000-1500 J/KG PROVIDE A CONCERN FOR SOME
SUPERCELL STRUCTURES CAPABLE OF ALL HAZARDS. PRIMARY CONCERNS
STILL APPEAR TO BE DAMAGING WIND GUSTS OF 60 TO 70 MPH AND
ISOLATED TORNADOES GIVEN LOW LCLS AND 0-1 KM SRH VALUES IN THE
100-150 M2/S2 RANGE THIS AFTERNOON. THE TIMEFRAME OF INTEREST
STILL APPEARS TO BE 18Z-02Z TODAY. GIVEN POSSIBILITY OF
SUPERCELL STRUCTURE, LARGE HAIL WOULD BE POSSIBLE, ALTHOUGH
GREATEST RISK OF LARGE HAIL WOULD LIKELY BE EARLIER IN THIS
EVOLUTION DURING THE LATE AFTERNOON HOURS AND ACROSS WESTERN
PORTIONS OF THE FORECAST AREA WHERE SURFACE BASED INSTABILITY IS
MAXIMIZED. SPC HAS EXPANDED PROBS FOR SIGNIFICANT HAIL ACROSS
FAR WESTERN PORTIONS OF THE FORECAST AREA FOR THIS AFTERNOON.
SOME SUBTLE DIFFERENCES IN HANDING OF UPSTREAM TROUGH/MID LEVEL
SPEED MAX APPEAR TO BE UNFOLDING WITH PREFERENCE TO PRIMARY MID
LEVEL JET CORE TO BE DELAYED AND DISPLACED SLIGHTLY FARTHER
NORTHWEST ACROSS THE WESTERN GREAT LAKES DUE TO SOME SLIGHTLY
STRONGER INITIAL DOWNSTREAM RIDGING THIS MORNING. THIS COULD
LOWER POTENTIAL OF TRUE QLCS WITH SLIGHTLY WEAKER LINE NORMAL
SHEAR THAN PREVIOUS INDICATIONS. THIS COULD HOWEVER ALLOW STORMS
TO CONGEAL A BIT MORE QUICKLY, BUT IN A LESS ORGANIZED FASHION
IN TERMS OF A WIDESPREAD SEVERE EVENT. LITTLE CHANGE IN THE
CONVECTIVE OUTLOOK FOR TODAY, WITH AN ENHANCED RISK OF SEVERE
STORMS ACROSS NORTHERN INDIANA/NORTHWEST OHIO AND A SLIGHT RISK
ACROSS SOUTHERN LOWER MICHIGAN. SOME PONDING OF WATER ON ROADS
IN ALSO POSSIBLE, ESPECIALLY IN LIGHT OF SOME AREAS RECEIVING
SOME LOCALLY HEAVIER RAINFALL AMOUNTS THE PAST FEW DAYS. THIS
WOULD LIKELY BE MORE OF THE MINOR FLOOD/FLOOD ADVISORY SCENARIO.
SHOWERS/STORMS EXIT NORTHWEST OHIO LATER THIS EVENING, BUT LAGGING
UPPER TROUGH AND ASSOCIATED COLD CORE ALOFT WOULD ALLOW A FEW
SHOWERS/ISOLATED RUMBLES OF THUNDER TO PERSIST INTO LATE
EVENING/EARLY OVERNIGHT ACROSS NW IN/SW LOWER MI. IT WILL TURN
MUCH COOLER LATER TONIGHT INTO MONDAY WITH DRY CONDITIONS
PERSISTING THROUGH TUESDAY EVENING.
LOOKING AHEAD, THERE IS GROWING CONCERN FOR ANOTHER ROUND OF SEVERE
THUNDERSTORMS ON WEDNESDAY. A STRONG EASTERN PACIFIC TROUGH WILL
ALLOW FOR YET ANOTHER DEEP CYCLONE TO FORM ACROSS CENTRAL
PLAINS/CORN BELT EARLY WEDNESDAY. CONFIDENCE IN HIGH THAT KINEMATICS
WITH THIS SYSTEM WILL BE VERY STRONG AND MAIN FORECAST ITEM OF
UNCERTAINTY DEALS WITH NORTHWARD EXTENT OF PRIMARY MLCAPE AXIS.
GIVEN BACKGROUND SYNOPTIC FIELDS, INSTABILITY MAGNITUDES WILL
NOT HAVE TO BE THAT STRONG TO RESULT IN A POTENTIAL OUTBREAK OF
SEVERE WEATHER FOR THE MID MS VALLEY, SOUTHERN GREAT LAKES, AND
OHIO RIVER VALLEY WITH ALL MODES OF SEVERE WEATHER POSSIBLE.
MORE ON THIS EVENT WILL BE FORTHCOMING IN THE DAYS AHEAD.
OTHERWISE, AFTER BELOW NORMAL TEMPS EARLY WEEK, SHARP WARM/MOIST
ADVECTION WILL TAKE TEMPS/DEW POINTS ABOVE CLIMO NORMALS
HEADING INTO WEDNESDAY. FRONTAL BOUNDARY ASSOCIATED WITH THIS
SYSTEM MAY TEND TO STALL ACROSS THE OHIO RIVER VALLEY LATE WORK
WEEK WHICH WILL MAKE LOCAL AREA PRONE TO ADDITIONAL ROUNDS OF
SHOWERS AND POSSIBLY SOME THUNDER WITH ANY ADDITIONAL FRONTAL
WAVES.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 146 AM EDT SUN MAR 30 2025
STRONG LOW LEVEL ADVECTION OF MOISTURE CONTINUES AT BOTH SITES
WITH STRATUS AND MAYBE SOME PATCHY DRIZZLE OR LIGHT SHOWERS
EXPECTED TO DOMINATE THROUGH 15 TO 17Z BEFORE STRONG MIXING
ARRIVES AHEAD OF A PRE-FRONTAL TROUGH. ANTICIPATE IFR CONDITIONS
AT KSBN (SOME POTENTIAL FOR BRIEF PERIODS OF LIFR) AND KFWA ON
THE MVFR/IFR LINE.
FOCUS THEM SHIFTS TO SHOWER/STORM CHANCES ALONG EITHER THE PRE-
FRONTAL TROUGH OR THE MAIN COLD FRONT. MODEL CAMPS REMAIN SPLIT
AND EACH RUN OF THE HI-RES MODELS SEEMS TO BRING A NEW SCENARIO
LEADING TO OVERALL LOW CONFIDENCE. STORMS (STRONG-SEVERE) COULD
DEVELOP AT KSBN AS EARLY AS 19Z OR AS LATE AS 23Z SO HAVE OPTED
TO KEEP THE PREVIOUS TIMING IN PLACE FOR NOW. INTRODUCED THUNDER
AT KFWA CLOSER TO 00Z MON. TOYED WITH THE IDEA OF A TEMPO, BUT
GIVEN THE LOW CONFIDENCE FELT A MORE BROADBRUSHED 3 HOUR WINDOW
SEEMED THE BEST WAY TO HANDLE. WHILE NOT REFLECTED IN THE
FORECAST, WIND GUSTS OVER 50 KTS AND HAIL AS WELL AS LOWER
CIGS/VSBY ARE ALL ON THE TABLE. LATER FORECASTS WILL NEED TO
FINE TUNE THINGS FURTHER.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM MONDAY TO 5 AM EDT TUESDAY FOR
LMZ043-046.
DISCUSSION...MARSILI
AVIATION...FISHER
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