207
FXUS63 KIWX 152349
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
749 PM EDT FRI MAY 15 2026
KEY MESSAGES
- VERY WARM THIS WEEKEND WITH HIGHS IN THE LOW 80S.
- SHOWERS AND THUNDERSTORMS AT TIME THIS WEEKEND AND INTO MONDAY
POSE A RISK FOR HEAVY RAINFALL AND INSTANCES OF DAMAGING WIND
GUSTS.
- WET AND STORMY CONDITIONS LINGER INTO THE MIDDLE OF NEXT
WEEK.
UPDATE
ISSUED AT 735 PM EDT FRI MAY 15 2026
SEVERAL THUNDERSTORMS HAVE ALREADY DEVELOPED AND RAPIDLY
INTENSIFIED UPSTREAM ACROSS SW IOWA INTO SE MINNESOTA. MODELS
STILL AGREE ON FURTHER DEVELOPMENT AS THEY MOVE EAST AND THE LLJ
RAMPS UP. WHAT REMAINS UNCERTAIN IS WHAT CONDITION THEY WILL BE
IN BY THE TIME THE REACH OUR WESTERN COUNTIES LATER TONIGHT. NO
MAJOR CHANGES TO FORECAST FOR THE TIME BEING, BUT TRENDS WILL BE
OBSERVED INTO THE OVERNIGHT HOURS.
DISCUSSION
ISSUED AT 152 PM EDT FRI MAY 15 2026
AN ACTIVE FORECAST LIES AHEAD BUT IS ONE MUDDIED BY ELEMENTS OF
UNCERTAINTY. LOW PRESSURE OVER THE MANITOBA/QUEBEC LINE HAS A
COLD FRONT SPREADING THROUGH THE CENTRAL PLAINS THIS AFTERNOON.
THIS COLD FRONT IS THE FOCUS FOR SHOWERS AND THUNDERSTORMS LATER
TODAY WELL TO OUR WEST. THIS ACTIVITY TRACKS EAST OVERNIGHT
ARRIVING TO SOUTHERN LAKE MICHIGAN JUST BEFORE DAYBREAK
SATURDAY. HIGH RESOLUTION GUIDANCE VARIES NOTABLY WITH HOW THIS
PROGRESSES. I HAVE SOME PREFERENCE TO MEMBERS THAT OFFER A
WEAKENING TREND AS THE LINE REACHES SOUTHERN MICHIGAN. THIS
OCCURS AS THE PRIMARY 500-MB JET (75 KTS) IS FOCUSED WELL NORTH
ACROSS THE UP DURING THE EARLY- MORNING HOURS. RISING HEIGHTS
ARE NOTED AT 500MB AS WELL. IN CONTRAST, THERE IS A BLOSSOMING
40-KNOT 850MB JET OVER NORTHERN IL. A NARROW CORRIDOR OF 1,000
J/KG MUCAPE PAIRED WITH 30 KNOTS OF BULK SHEAR YIELDS A NON-ZERO
CHANCE FOR EARLY MORNING ISOLATED SEVERE STORMS, BUT THE LACK
OF UPPER-LEVEL SUPPORT MAY BE THE GREATEST LIMITING FACTOR.
AS THIS AREA OF SHOWERS AND STORMS TRACKS EAST AFTER DAYBREAK
SATURDAY, OR PERHAPS BYPASSES NORTH, THE AFORMENTIONED COLD FRONT IS
NOW STALLED EAST-WEST ACROSS THE FORECAST AREA AND WILL BE THE
FOCUS FOR SCATTERED AFTERNOON THUNDERSTORMS. BOUNDARY- PARALLEL
FLOW INCREASES THE RISK OF TRAINING (BACKBUILDING) THUNDERSTORMS
WHICH CAN RESULT IN INSTANCES OF FLOODING. OUR AIRMASS WILL BE
PLENTY WARM AND HUMID, WITH DEW POINTS IN THE 60S AND PWATS IN
EXCESS OF 1.6"; HIGH CONFIDENCE IN RAIN RATES OF 1" PER HOUR
SATURDAY AFTERNOON. BECAUSE OF LINGERING CLOUD COVER, IT WILL
TAKE TIME FOR INSTABILITY TO REBUILD, STRUGGLING TO REACH 1,000
J/KG PAIRED WITH ABOUT 30 KNOTS OF SHEAR. OVERALL, A MARGINAL
RISK OF ISOLATED DAMAGING WIND GUSTS SATURDAY AFTERNOON, WITH
HEAVY RAINFALL THE GREATER CONCERN.
THIS FRONT IS KICKED POLEWARD SATURDAY NIGHT AS THE WARM SECTOR
AMPLIFIES IN RESPONSE TO A TROUGH DIGGING IN OVER THE FOUR CORNER
REGION. INCREASING CONFIDENCE IN A MAINLY-DRY SUNDAY AS SHOWERS AND
STORMS BECOME FOCUSED ELSEWHERE IN THE MIDWEST AND UPPER GREAT
LAKES, BUT WILL HOLD ON TO NBM POPULATED 20-30% POPS. MONDAY
STILL APPEARS TO BE THE "BEST" DAY OVERALL FOR SEVERE
THUNDERSTORMS, BUT TIMING REMAINS UNCERTAIN. A PREFRONTAL
SHORTWAVE COULD BE THE FOCUS FOR AFTERNOON STORMS, WELL AHEAD OF
THE COLD FRONT THAT MOVES THROUGH OVERNIGHT. IN THE AFTERNOON,
STEEP LOW-LEVEL LAPSE RATES PRESENT A DAMAGING WIND GUST CONCERN
FROM THUNDERSTORMS WHILE A UNIDIRECTIONAL WIND PROFILE, ALONG
WITH ELEVATED CLOUD BASES, LIMITS THE OVERALL TORNADO CONCERN.
BOUNDARY-PARALLEL FLOW WILL CONTINUE TO POSE A RISK FOR HEAVY
RAINFALL IN THIS WARM, HUMID ENVIRONMENT.
THE COLD FRONT SLOWLY MOVES THROUGH TUESDAY AND WEDNESDAY, ITS
EASTWARD PROGRESS SLOWED BY STRONG SUBTROPICAL HIGH PRESSURE. THUS,
A RAINY AND STORMY START TO THE WEEK THAT LINGERS INTO AT LEAST
WEDNESDAY BEFORE HIGH PRESSURE PUSHES IN FOR THE LATE-WEEK
PERIOD.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 735 PM EDT FRI MAY 15 2026
SEVERAL THUNDERSTORMS ALREADY DEVELOPING ACROSS SOUTHWESTERN IA
INTO SOUTHEAST MN WITH SOME PRODUCING LARGE HAIL. AS THEY MOVE
EAST, THE INDIVIDUAL CELLS SHOULD CONGEAL INTO A LINE OF STORMS
AND MOVE ACROSS IA/IL, REACHING KSBN NEAR/AFTER 9Z. MUCH
UNCERTAINTY REMAINS AS TO THE STRENGTH/COVERAGE OF THESE STORMS
AS THEY OUTRUN THE BEST SUPPORT. HAVE LEFT THE TEMPO THUNDER AT
KSBN AND PROB30 AT KFWA LATER TO HANDLE WHAT MAY BE LEFT OVER.
EVEN MORE UNCERTAINTY EXISTS WITH EVOLUTION OF ADDITIONAL
SHOWERS AND STORMS NEAR THE STALLING FRONTAL BOUNDARY. CAMS HAVE
THEIR OWN IDEAS, CAUSING CONCERNS ON EXACT IMPACTS. GREATEST
CHANCES WILL BE AT KFWA, BUT FOR NOW REMOVED THE PREDOMINATE
THUNDER MENTION AND OPTED FOR PROB30 IN THE AFTERNOON. COULD
NEED TO GO BACK TO PREDOMINATE OR TONE DOWN EVEN MORE DEPENDING
ON TRENDS LATE TONIGHT INTO SATURDAY MORNING.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...FISHER
DISCUSSION...BROWN
AVIATION...FISHER
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