987
FXUS63 KIWX 242216
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
616 PM EDT TUE MAR 24 2026
KEY MESSAGES
- WARMING TREND TUESDAY THROUGH THURSDAY.
- A STRONG COLD FRONT BRINGS CHANCES (60-90%) FOR SHOWERS AND
STORMS THURSDAY AFTERNOON INTO THURSDAY EVENING. SOME STORMS
COULD BE SEVERE WITH DAMAGING WIND GUSTS, LARGE HAIL, AND
ISOLATED TORNADOES POSSIBLE. THE GREATEST SEVERE WEATHER
THREAT APPEARS TO BE BETWEEN 5PM AND 11PM EDT ON THURSDAY.
SOME LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE.
- COLDER AIR WILL FUNNEL BACK IN ON FRIDAY, WITH GRADUAL MODERATION
NEXT WEEKEND.
DISCUSSION
ISSUED AT 335 PM EDT TUE MAR 24 2026
BROAD MID LEVEL SUBSIDENCE CONTINUES THIS AFTERNOON WITH A DRY
AIRMASS EXPECTED TO PERSIST THROUGH THE FIRST PART OF WEDNESDAY. MID
LEVEL WARM ADVECTION WILL STRENGTHEN TONIGHT WHICH SHOULD RESULT IN
SOME PERIODS OF BROKEN TO OVERCAST MID LEVEL CLOUD COVER INTO
WEDNESDAY. THE NEXT EASTERN PACIFIC DISTURBANCE IS EXPECTED TO MOVE
INLAND ACROSS PACIFIC NORTHWEST ON WEDNESDAY WHICH WILL INDUCE SOME
MID LEVEL HEIGHT RISES ACROSS THE NORTHERN PLAINS AND TRANSITION TO
MORE OF A WESTERLY UPSTREAM LOW-MID LEVEL WIND PROFILE LATE
TONIGHT INTO WEDNESDAY. LEE TROUGHING EAST OF THE ROCKIES WILL
DEVELOP IN THIS PATTERN WITH WESTERLY FLOW REGIME EVENTUALLY
ADVECTING THIS MODIFIED WARMER AIR EASTWARD ACROSS THE MID MS
VALLEY WEDNESDAY NIGHT AND EVENTUALLY TO THE OHIO VALLEY ON
THURSDAY. A LOW LEVEL THETA-E RIDGE ACCOMPANYING THIS EVOLUTION
IS ALSO EXPECTED TO AMPLIFY AND REACH THE WESTERN GREAT
LAKES/OHIO VALLEY WEDNESDAY NIGHT. SOME INCREASE IN ELEVATED
INSTABILITY WITH THIS INITIAL THETA-E ADVECTION COULD PROMOTE
ISOLATED TO SCATTERED SHOWERS AND STORMS LATE WEDNESDAY NIGHT,
PARTICULARLY SOUTH OF I-80 BASED ON CURRENT GUIDANCE PROJECTION
OF WHERE THIS ADVECTIVE FORCING WILL BE MORE PRONOUNCED.
OTHERWISE, THE MODERATING TEMPERATURE TREND WILL CONTINUE INTO
WEDNESDAY WITH HIGHS FROM AROUND 60 NORTHEAST TO THE UPPER 60S
SOUTHWEST.
BY THURSDAY, THE SHORT WAVE INDUCED MID LEVEL RIDGING WILL BECOME
DAMPENED TO A GREATER EXTENT BY A STRONG EASTERN PACIFIC JET
TRACKING ACROSS SOUTHERN CANADA AND BROAD UPPER VORT LOBE ROTATING
ACROSS ONTARIO. THIS SHOULD ALLOW A BROAD LOW LEVEL COLD FRONT TO
SHARPEN FROM THE CENTRAL PLAINS TO THE SOUTHERN GREAT LAKES THURSDAY
AFTERNOON. AN ELEVATED MIXED LAYER IS EXPECTED TO OVERSPREAD
THIS FRONTAL FROM THE ROCKIES DURING THE DAY THURSDAY WHICH WILL
LIKELY CREATE CAPPED CONDITIONS THROUGH EARLY TO MID AFTERNOON.
BY LATE AFTERNOON, POTENTIAL OF CONVECTION SHOULD INCREASE NEAR
THIS FRONTAL BOUNDARY AS LARGE SCALE LIFT/ISENTROPIC FORCING
HELP TO PARTIALLY WEAKEN OR LIFT THE INVERSION HEIGHTS
ASSOCIATED WITH THE EML. SOME UNCERTAINTY REMAINS REGARDING
INITIATION TIME GIVEN INITIAL CAPPING, BUT WOULD EXPECT SOME
ENHANCED LOW LEVEL CONVERGENCE WITH LAKE BREEZE ENHANCED
BOUNDARY NEAR THE FRONT MIGHT REPRESENT SOME OF THE INITIAL
CONVECTION.
CONSENSUS OF CAM SOLUTIONS INDICATES A PRONOUNCED INSTABILITY
GRADIENT ACROSS NORTHERN INDIANA BY THURSDAY EVENING WHICH WILL
LIKELY BE A FOCAL POINT FOR CONVECTIVE INITIATION AS BETTER POOLED
LOW LEVEL MOISTURE BY EVENING HELPS TO OVERCOME ANY LINGERING WEAK
CIN. IT DOES APPEAR THAT COMBINATION OF TEMPS IN MID 70S TO LOWER
80S AND DEW POINTS FROM UPPER 50S TO MID 60S SHOULD SUPPORT MLCAPES
OF 1000-1500 J/KG WITH A GOOD DEAL OF DEEP LAYER SHEAR. THE LOW
LEVEL KINEMATIC FIELDS ARE STILL SOMEWHAT UNCERTAIN,
SPECIFICALLY JUST HOW WELL MIXED THE WARM SECTOR WILL BE WHICH
WILL AFFECT THE POTENTIAL HAZARDS OF WIND VS TORNADO POTENTIAL.
LARGE HAIL WILL ALSO BE POSSIBLE GIVEN THE PRESENCE OF THE EML,
AND IF SUPERCELL STRUCTURES DEVELOP, THIS COULD SUPPORT SOME
HIGHER END LARGE HAIL IN EXCESS OF 1.50" IN DIAMETER. THE CURRENT
EXPECTATION IS THAT A MESSY MIXED-MODE OF CONVECTION WOULD BE
POSSIBLE WITH SOME SMALL COMPONENT OF BACKGROUND SHEAR NORMAL TO
THE BOUNDARY, SOME INITIAL DISCRETE DEVELOPMENT IS EXPECTED. BY
LATER IN THE EVENING, EXPECTING THIS TO QUICKLY GROW UPSCALE TO
MORE OF A LINEAR MODE GIVEN STRONG FRONTAL FORCING AND MAJORITY
OF SHEAR PARALLEL TO THE BOUNDARY. THE GREATEST SEVERE THREAT
STILL APPEARS TO BE IN THE 21Z-03Z PERIOD. ADDITIONAL STORMS ARE
POSSIBLE AFTER 02 OR 03Z BUT MIGHT TREND MORE ELEVATED GIVEN
EXPECTED SOUTHWARD PROGRESSION OF COLD FRONT. THESE STORMS LATE
IN THE EVENT COULD STILL POSE SOME RISK OF HAIL THROUGH LATE
EVENING.
THE OTHER POTENTIAL HAZARD THURSDAY NIGHT IS HEAVY RAIN/FLOODING.
LOW LEVEL MOISTURE AXIS SHOULD BE MORE EFFICIENTLY POOLED BY
THURSDAY EVENING ACROSS THE AREA, WITH STRONG MOISTURE CONVERGENCE
ALONG AND JUST BEHIND THE SFC FRONT. THIS COULD YIELD A BAND OF 1-2"
RAINFALL AMOUNTS ACROSS SOUTHERN HALF/SOUTHEAST HALF OF THE AREA,
WITH A POTENTIAL OF LOCALLY HIGHER AMOUNTS IN STRONGER CONVECTIVE
ELEMENTS.
A TREND BACK TO COOLER/BLUSTERY CONDITIONS IS IN STORE FOR FRIDAY
BEHIND THE FRONT WITH MODERATION BACK TO THE UPPER 50S TO AROUND 60
BY THE END OF THE WEEKEND. FLOW WILL DEAMPLIFY ONCE AGAIN BY EARLY
NEXT WEEK WHICH WILL BE SUPPORTIVE OF CONTINUED MODERATION IN TEMPS.
THE ACTIVE EASTERN PACIFIC PATTERN WILL CONTINUE ACROSS SOUTHERN
CANADA WHICH WILL MAKE LOCAL AREA PRONE TO ADDITIONAL STRONGER
SYNOPTIC COLD FRONTS BY THE MIDDLE OF NEXT WEEK WITH ADDITIONAL
SHOWER AND THUNDERSTORM CHANCES.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 614 PM EDT TUE MAR 24 2026
THE SURFACE HIGH PRESSURE SYSTEM THAT HAS BEEN WELL EAST OF THE
AREA OFF THE EAST COAST WILL CONTINUE TO MOVE AWAY FROM THE
REGION AND BECOME ABSORBED IN THE SUBTROPICAL RIDGE. FARTHER
WEST, LOW PRESSURE HAS BEEN DEVELOPING ACROSS THE ROCKIES AND
INTO THE HIGH PLAINS. THE PRESSURE GRADIENT BETWEEN THESE 2
SYSTEMS HAS BEEN CAUSING SOUTH WINDS OVER NORTHERN INDIANA. SOME
WIND GUSTS MAY RANGE FROM 15 TO 20 KNOTS WEDNESDAY AFTERNOON.
THIS SCENARIO WILL REMAIN IN PLACE THROUGH THE TAF PERIOD.
TEMPERATURE/DEW POINT SPREADS WERE HOVERING AROUND 25 DEGREES
AND WITH LITTLE INITIAL MOISTURE ADVECTIVE, NOT MUCH CHANCE FOR
FOG TONIGHT. HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL
THROUGH THE ENTIRE TAF PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...SKIPPER
AVIATION...MARSILI
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