938
FXUS63 KIWX 301629
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1229 PM EDT SUN MAR 30 2025
KEY MESSAGES
- 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.
UPDATE
ISSUED AT 1112 AM EDT SUN MAR 30 2025
CONTINUING TO SEE THE SCATTERING OF CLOUDS OVER CENTRAL IL AND
THE INCREASING INSTABILITY MODELED ON MESOANALYSIS AS A RESULT.
AT THE SAME TIME, NOTING LIFTING CIGS OVER THE LAST COUPLE OF
HOURS. THIS IS A SIGN IN FAVOR OF STILL BRINGING STRONG TO
SEVERE THUNDERSTORMS INTO THE AREA. INITIAL CELLS ARE STILL
EXPECTED TO HOLD THE POTENTIAL TO BE CELLULAR WITH MODELS STILL
RETAINING BOUNDARY-PERPENDICULAR FLOW BEFORE CONGEALING INTO A
MORE LINEAR ORIENTATION NOT TOO LONG AFTER THAT. 15Z ACARS
SOUNDING OUT OF STL SHOWS SOME WEAK TURNING IN THE LOW LEVELS
ALONG WITH 100 M2/S2 AND 30 KTS BWD IN THE 0-1 KM LAYER AS WELL
AS A FAIRLY MOIST PROFILE. THIS AIR MASS IS EXPECTED TO BE
ADVECTED THIS WAY, BUT MAY UNDERGO AUGMENTATION TO SOME EXTENT.
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 /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1229 PM EDT SUN MAR 30 2025
MVFR WITH BREEZY SOUTHERLY FLOW AND A FEW SHOWERS IN THE
VICINITY PRE-FRONTAL TO START. COLD FRONT AND LINE(S) OF
CONVECTION ARE THEN ON TARGET TO ROLL THROUGH KSBN AROUND 21Z
AND KFWA ~22Z THIS AFTERNOON. ANY LOCAL SURGES IN THESE LINES
COULD BRING A BRIEF PERIOD OF STRONG TO POTENTIALLY SEVERE WINDS
TO THE TERMINALS. THE OTHER SEVERE HAZARDS ALSO CANNOT BE RULED
OUT. QUICKLY DRY OUT AND POTENTIALLY BECOMING VFR POST-FRONTAL
THEN INTO THIS EVENING BEFORE MVFR CIGS WRAP BACK IN OVERNIGHT
INTO MONDAY MORNING.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 5 AM EDT
TUESDAY FOR LMZ043-046.
UPDATE...ROLLER
DISCUSSION...MARSILI
AVIATION...STEINWEDEL
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