205
FXUS63 KIWX 121032
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
632 AM EDT TUE MAY 12 2026
KEY MESSAGES
- WARMER TODAY AND BECOMING BREEZY IN THE AFTERNOON.
- SHOWERS AND SCATTERED THUNDERSTORMS ARE EXPECTED BY LATE
AFTERNOON AND ESPECIALLY BY EARLY THIS EVENING. WIDESPREAD
SEVERE WEATHER IS NOT EXPECTED BUT A FEW SHOWERS AND STORMS
MAY PRODUCE WIND GUSTS TO 40 TO 50 MPH THIS EVENING.
- COOLER AND WINDY CONDITIONS FOR WEDNESDAY, BUT TEMPERATURES
MODERATE THURSDAY INTO THE WEEKEND WITH HIGH TEMPERATURES INTO
THE LOWER 80S BY SATURDAY AND SUNDAY.
- ADDITIONAL SHOWER AND THUNDERSTORM CHANCES IN STORE FOR THE
UPCOMING WEEKEND.
DISCUSSION
ISSUED AT 335 AM EDT TUE MAY 12 2026
CHANCES OF SHOWERS AND A FEW GUSTY STORMS TONIGHT ALONG WITH
WARMER/BREEZY CONDITIONS CONTINUE TO BE THE MAIN NEAR TERM
FORECAST ITEMS TO ADDRESS.
THE LOCAL AREA REMAINS POSITIONED IN UPPER LEVEL INFLECTION ZONE
THIS MORNING WHICH IS ALLOWING FOR MAINTENANCE OF LOW LEVEL
RIDGE AXIS ACROSS THE AREA WITH A VERY DRY AIRMASS IN PLACE.
EARLY MORNING WATER VAPOR IMAGERY DEPICTS THE NEXT SHORT WAVE OF
INTEREST ACROSS NORTH DAKOTA WHICH WILL SPILL DOWN THE UPPER
RIDGE INTO THE GREAT LAKES REGION TONIGHT. SOME AMPLIFICATION
OF THIS UPPER TROUGH IS EXPECTED TODAY AS A STRONG UPPER JET
STREAK CUTS THROUGH BASE OF THIS TROUGH. SOME WEAK DEEPENING OF
SFC REFLECTION OF THIS SYSTEM IS EXPECTED ACROSS THE WESTERN
GREAT LAKES THIS EVENING, BUT STRONGER UPPER FORCING AND
VORTICITY ADVECTION ACCOMPANYING THE VORT MAX REALLY DOES NOT
LOOK TO AFFECT LOCAL AREA UNTIL AFTER 00Z THIS EVENING. THERE
SHOULD BE A STRENGTHENING ZONE OF ISENTROPIC UPGLIDE WELL AHEAD
OF SFC LOW/COLD FRONT THIS AFTERNOON ACROSS THE SOUTHERN GREAT
LAKES, BUT AN INITIAL VERY DRY SUBCLOUD LAYER WILL LIKELY LIMIT
SENSIBLE WEATHER IMPACTS FOR MOST OF THE AFTERNOON WITH A
POSSIBILITY OF SOME INITIAL VIRGA. A STRENGTHENING OF THE LOW
LEVEL HEIGHT GRADIENT TODAY (PARTICULARLY NW IN TO SW LOWER MI)
SHOULD LEAD TO BREEZY/WINDY CONDITIONS LATER TODAY, BUT LIKELY
DELAYED DUE TO INITIAL STRONG LOW LEVEL INVERSION AND LIMITED
MIXING DEPTHS UNDER INFLUENCE OF WARM ADVECTION. STRONGEST
AFTERNOON GUSTS STILL APPEAR TO BE DISPLACED JUST WEST OF THE
LOCAL AREA INTO CENTRAL/NORTHERN IL, BUT STRENGTHENING SFC
PRESSURE FALLS ACROSS MICHIGAN BY MID-LATE AFTERNOON AND THE
STRONGER GRADIENT COULD ALLOW FOR SOME SOUTH-SOUTHWEST GUSTS TO
30-35 MPH ACROSS THE FAR NORTHWEST. DESPITE LIMITED MIXING
HEIGHTS TODAY, STRENGTH OF WARM ADVECTION WILL ALLOW FOR HIGH
TEMPERATURES CLOSER TO SEASONABLE NORMALS FOR MID MAY.P6SM
CLOSER TO 23Z-00Z, UPPER LEVEL FORCING SHOULD INCREASE FROM UPSTREAM
SHORT WAVE ALONG WITH SOME BETTER PRE-FRONTAL MOISTURE TRANSPORT
BUILDING INTO FAR NORTHERN INDIANA AND SOUTHERN LOWER MICHIGAN FROM
NORTHERN ILLINOIS. DESPITE THIS PERIOD OF STRONGER LOW LEVEL
MOISTURE TRANSPORT, LOW LEVEL DEW POINTS WILL BE LESS THAN IDEAL
TO REALIZE ANY INSTABILITY OF NOTE, ESPECIALLY IN LIGHT OF
WARMISH MID LEVEL THERMAL PROFILES. STRONGLY FORCED NATURE OF
THIS SYSTEM SHOULD ALLOW FOR RAIN SHOWERS TO EXPAND IN COVERAGE
IN PRE-FRONTAL FORCING ZONE ACROSS NORTHERN IN/SOUTHERN LOWER
MI/FAR NORTHWEST OHIO THIS EVENING WITH A FEW ISOLATED STORMS
NOT OUT OF THE QUESTION. SUBCLOUD LAYER WILL LIKELY BE QUITE
DRY INTO EARLY EVENING, SO RAIN SHOWER ACTIVITY COULD LOCALLY
ENHANCE DOWNDRAFTS FOR SOME ISOLATED 40+ MPH WIND GUSTS NOT OUT
OF THE QUESTION. SOME ADDITIONAL DEVELOPMENT IS POSSIBLE ALONG
ACTUAL SFC COLD FRONT MID-LATE EVENING ACROSS NW PORTIONS OF THE
AREA, WHICH WILL LIKELY BE ACCOMPANIED BY VERY NARROW ZONE OF
SOME WEAK MLCAPES ON THE ORDER OF 200-400 J/KG. THIS SHOULD ALSO
BE AT THE LEADING EDGE OF SOME BETTER MID LEVEL LAPSE RATES DUE
TO DIFFERENTIAL TEMP ADVECTION (COOLING MID LEVEL PROFILES)
WITH THE UPPER TROUGH APPROACH. A FEW CELLS ALONG COLD FRONT
COULD PRODUCE SOME 40+ MPH WIND GUSTS AND SOME SMALL HAIL, BUT
POTENTIAL OF SFC BASED DEVELOPMENT LOOKS QUITE LIMITED. WHILE
CANNOT COMPLETELY RULE OUT A ROGUE 60 MPH GUST, THE POTENTIAL OF
SEVERE CONTINUES TO LOOK QUITE MARGINAL WITH THIS SETUP.
WEDNESDAY STILL LOOKS TO FEATURE WINDY/COOLER CONDITIONS AS THE
UPPER TROUGH TAKES ITS TIME PROGRESSING ACROSS THE GREAT LAKES
REGION AS AN ADDITIONAL UPSTREAM SPEED MAX DIGS THROUGH BASE OF THE
UPPER TROUGH ACROSS NORTHERN PORTIONS OF THE OHIO VALLEY. GIVEN
CYCLONIC FLOW AND SOME SIGNS OF SOME LOW LEVEL MOISTURE WRAPPING
BACK CYCLONICALLY INTO FAR NE IN/SC LOWER MI/FAR NW OHIO, CANNOT
RULE OUT A FEW RESIDUAL LIGHT SHOWERS/SPRINKLES DURING THE DAY
WITH SOME WEAK/SHALLOW INSTABILITY.
MERIDIONAL FLOW IN AMPLIFIED FLOW PATTERN WILL KEEP DRY AIR IN PLACE
ACROSS THE REGION ON THURSDAY, WITH JUST LIMITED WARMING OF
TEMPERATURES. THE NEXT EASTERN PACIFIC TROUGH SKIRTING ACROSS SW
CANADA WILL ALLOW FOR SOME PROGRESSION OF THIS PATTERN AND
RETURN WARM/MOIST ADVECTION BY LATER THURSDAY NIGHT INTO EARLY
FRIDAY. SOME ELEVATED MOISTURE RETURN COULD ALLOW FOR SHOWERS OR
PERHAPS ISOLATED STORMS BY FRIDAY, BUT POTENTIAL OF SFC BASED
CONVECTION MAY BE CONFINED TO AREAS SOUTH/SOUTHWEST OF THE LOCAL
AREA.
UPPER LEVEL FLOW PATTERN IS EXPECTED TO LOSE SOME AMPLITUDE BY THE
WEEKEND WITH LARGER SCALE UPPER TROUGH EXPECTED TO OVERSPREAD
WESTERN CONUS. PREDICTABILITY IN THE EVOLUTION OF THIS ADDITIONAL
PACIFIC ENERGY IS ON THE LOW SIDE WITH A WIDE SPREAD IN
DETERMINISTIC/ENSEMBLE SOLUTIONS REGARDING PROGRESSION OF NORTHERN
STREAM SHORT WAVES AND EXTENT OF TROUGHING LINGERING BACK
ACROSS THE ROCKIES/FOUR CORNERS. THE OVERALL PATTERN THIS
WEEKEND INTO EARLY NEXT WEEK DOES APPEAR TO BE ONE WITH A
POTENTIAL OF BETTER DESTABILIZATION AND PERIODS OF HIGHER
SHOWER/STORM CHANCES, BUT RESOLVING THESE CHANCES IN 6-HOUR
PERIODS REMAINS DIFFICULT. OF GREATER FORECAST CONFIDENCE IS THE
TREND TO ABOVE NORMAL TEMPERATURES AT LEAST THROUGH THE WEEKEND
WITH HIGH TEMPS IN THE LOW TO MID 80S LOOKING LIKELY FOR
SATURDAY AND SUNDAY.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 630 AM EDT TUE MAY 12 2026
A LOW LEVEL RIDGE AXIS WILL DEPART TO THE EAST THIS MORNING
ALLOWING LIGHT SOUTHEASTERLY RETURN FLOW TO DEVELOP SHORTLY
AFTER 12Z. A STRONG SHORT WAVE TROUGH ACROSS EASTERN
ND/NORTHERN MN WILL BE THE FEATURE TO MONITOR FOR NORTHERN IN
WEATHER HEADING INTO TONIGHT. AN UPPER JET STREAK DIGGING
THROUGH THE BASE OF THIS TROUGH THIS MORNING WILL ALLOW FOR
AMPLIFICATION OF THIS UPPER TROUGH ACROSS THE GREAT LAKES REGION
INTO THIS EVENING. ISENTROPIC UPGLIDE ACROSS THE MID/UPPER MS
VALLEY THIS MORNING WILL SHIFT ACROSS THE SOUTHERN GREAT LAKES
THIS AFTERNOON WHICH COULD ALLOW FOR SOME ISOLATED-SCATTERED
SHOWER ACTIVITY AFTER 21Z. HOWEVER, AN INITIALLY DRY SUBCLOUD
LAYER COULD LIMIT THIS POTENTIAL UNTIL AFTER 00Z WHEN MID/UPPER
LEVEL FORCING BEGINS TO STRENGTHEN FROM THE AFOREMENTIONED
UPSTREAM TROUGH. SOME INCREASE IN LOW LEVEL MOISTURE
TRANSPORT/INCREASED SOUTHWESTERLY LOW LEVEL FLOW SHOULD ALLOW
SHOWERS TO BECOME MORE WIDESPREAD THIS EVENING GIVEN STRONGLY
FORCED NATURE OF THIS SYSTEM. ADDITIONAL SCATTERED SHOWERS ARE
EXPECTED TO DEVELOP ALONG THE ASSOCIATED COLD FRONT,
PARTICULARLY ACROSS KSBN VICINITY LATER THIS EVENING WHERE A
NARROW WEAK INSTABILITY AXIS SHOULD BE MAXIMIZED (~200-400 J/KG
MLCAPE). WHILE AN ISOLATED THUNDERSTORM IS POSSIBLE AT BOTH
TERMINALS THIS EVENING/EARLY OVERNIGHT, WILL CONTINUE TO OMIT
MENTION WITH THE 12Z TAFS DUE TO LIMITED INSTABILITY MAGNITUDES
AND LOW CONFIDENCE. HAVE ALSO MAINTAINED PRIMARILY VFR
CONDITIONS, BUT BRIEF MVFR CONDITIONS ARE POSSIBLE TONIGHT IN
ASSOCIATION WITH RAIN SHOWERS.
OTHERWISE, EVOLUTION OF DEPARTING RIDGE AXIS AND SOME DEEPENING
OF UPPER MS VALLEY SFC LOW SHOULD ALLOW FOR STRENGTHENING
GRADIENT TODAY, ALTHOUGH AXIS OF STRONGER SOUTHWESTERLY FLOW
SHOULD RESIDE ACROSS NORTHERN ILLINOIS DURING THE AFTERNOON.
WILL MAINTAIN STRONGEST WINDS ACROSS KSBN VICINITY WITH SOME
GUSTS TO 25+ KNOTS DURING THE MID-LATE AFTERNOON HOURS.
ONE OTHER ITEM THAT MAY NEED TO BE CONSIDERED IS INCLUSION OF
LLWS CONDITIONS THIS EVENING. SOME DECOUPLING COMBINED WITH
AXIS OF STRONGER LOW LEVEL FLOW SHIFTING EAST COULD PROMOTE SOME
MARGINAL LLWS CONDITIONS IN THE 00Z-05Z TIMEFRAME BUT
CONFIDENCE IN MEETING CRITERIA IS LOW AT THIS TIME.
IWX WATCHES/WARNINGS/ADVISORIES
IN...FROST ADVISORY UNTIL 8 AM EDT /7 AM CDT/ THIS MORNING FOR
INZ005>009-012-014-017-018-103-104-116-203-204-216.
OH...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR OHZ001-002-004-
005-015-016.
MI...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ078>081-177-
277.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 11 PM EDT
WEDNESDAY FOR LMZ043-046.
DISCUSSION...MARSILI
AVIATION...MARSILI
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