516
FXUS63 KIND 221451
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1051 AM EDT SUN JUN 22 2025
KEY MESSAGES
- HEAT ADVISORY IN EFFECT THROUGH FRIDAY
- HOTTEST CONDITIONS OF THE SEASON THUS FAR INTO MUCH OF NEXT WEEK,
WITH HEAT INDEX VALUES AS HIGH AS THE LOW 100S EACH AFTERNOON
- ISOLATED TO SCATTERED THUNDERSTORMS POSSIBLE AT TIMES MID-WEEK
ONWARD
FORECAST UPDATE
ISSUED AT 1049 AM EDT SUN JUN 22 2025
FOCUSING ON THE EXTENDED STRETCH OF HEAT THIS WEEK FOR THIS
MORNING'S UPDATE.
THE STRONG RIDGE OF HIGH PRESSURE RESPONSIBLE FOR THE EARLY SUMMER
HEAT WAVE BECOMES CENTERED OVER THE MID ATLANTIC STATES BY MONDAY,
KEEPING SOUTHERLY FLOW AND WARM AIR ADVECTION OVER THE ENTIRE
REGION. MEDIUM RANGE GUIDANCE CONTINUES TO INDICATE THIS RIDGE AND
ASSOCIATED SURFACE HIGH RETROGRADING BACK OVER THE OHIO VALLEY BY
MIDWEEK, INCREASING CONFIDENCE THAT THIS ANOMALOUS HEAT AND HUMIDITY
WILL PERSIST FOR SEVERAL MORE DAYS. ONE ASPECT OF THE LONG TERM
FORECAST THAT MAY BE THE MOST IMPACTFUL IS THE VERY WARM OVERNIGHT
LOWS WHICH MAY STRUGGLE TO FALL BELOW 75 DEGREES, ESPECIALLY IF
CONVECTION DEVELOPS MIDWEEK, FURTHER ADDING MOISTURE TO THE GROUND
AND POTENTIALLY FURTHER RAISING HUMIDITY LEVELS. WHILE HEAT INDICES
MAY ONLY TOP OUT IN THE 100-106 DEGREE RANGE, THE EXTENDED STRETCH
OF WARM TO HOT OVERNIGHT LOWS AND LACK OF HEAT RELIEF CAN POSE MORE
OF A THREAT TO SENSITIVE/VULNERABLE POPULATIONS. CONFIDENCE IS LOWER
ON HOW WIDESPREAD CONVECTION MAY BE MIDWEEK; HOWEVER WITH THE
SURFACE HIGH AND RIDGING HOLDING STRONG IN THE REGION, A LACK OF
SHEAR AND FORCING AND DRIER FORECAST SOUNDINGS SUGGEST COVERAGE MAY
BE FAIRLY LIMITED WITH ONLY DISCRETE POP UP CELLS. WITH THIS IN
MIND, CONFIDENCE IS HIGHER THAT POTENTIALLY IMPACTFUL HEAT AND
HUMIDITY WILL CONTINUE THROUGH THE END OF THE WEEK, SO WILL GO AHEAD
AND EXTEND THE HEAT ADVISORY THROUGH FRIDAY EVENING FOR ALL OF
CENTRAL INDIANA. WILL UPDATE THE FORECAST AND ADVISORY AS NEEDED
BASED ON CONVECTIVE DEVELOPMENT LATER THIS WEEK.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 310 AM EDT SUN JUN 22 2025
SURFACE ANALYSIS EARLY THIS MORNING SHOWS A VERY STRONG BERMUDA HIGH
PRESSURE SYSTEM IN PLACE. THIS WAS SUPPLYING A VERY WARM AND VERY
HUMID SOUTHERLY FLOW OF AIR TO CENTRAL INDIANA. ALOFT, STRONG
RIDGING WAS IN PLACE DUE TO A DEEP AREA OF HIGH PRESSURE IN PLACE
OVER THE SOUTHEASTERN STATES WITH A STRONG RIDGE AXIS THAT STRETCHED
INTO WESTERN ONTARIO. GOES16 SHOWS CLEAR SKIES ACROSS INDIANA AND
TEMPERATURES WERE STILL IN THE UPPER 70S TO AROUND 80.
LITTLE OVERALL CHANGE IS EXPECTED TODAY AND TONIGHT. THE BERMUDA
HIGH AND RIDGING ALOFT ARE EXPECTED TO MAINTAIN CONTROL OF THE
WEATHER ACROSS THE EASTERN HALF OF THE UNITED STATES INCLUDING
CENTRAL INDIANA. ALL FORCING DYNAMICS WILL BE STEERED WELL NORTH OF
INDIANA, ACROSS CANADA WITHIN THE FLOW ALOFT. FORECAST SOUNDINGS
TODAY AND TONIGHT REMAIN VERY DRY WITH A MID LEVEL INVERSION
SUGGESTED, PREVENTING ANY SIGNIFICANT CU DEVELOPMENT. THUS ANOTHER
SUNNY DAY AND CLEAR NIGHT WILL BE EXPECTED.
GIVEN OUR VERY WARM AND HUMID AIR MASS, HIGHS SHOULD RUN A TIC
HIGHER TODAY, WITH SOME LOCATIONS REACHING THE MID 90S. THIS WILL
ALLOW HEAT INDEX VALUES TO REACH THE LOW 100S, ALONG WITH A HIGH
WBGT RISK. LOWS AGAIN WILL ONLY FALL TO THE MIDDLE AND UPPER 70S.
OVERALL, ONGOING HEAT ADVISORY REMAINS IN GOOD SHAPE.
LONG TERM (MONDAY THROUGH SATURDAY)
ISSUED AT 310 AM EDT SUN JUN 22 2025
..PROLONGED HEAT AND HUMIDITY EXPECTED INTO NEXT WEEKEND
EXPECTATIONS FOR MUCH OF THIS WEEK REMAIN ROUGHLY THE SAME AS THEY
HAVE BEEN FOR SEVERAL DAYS. A STRONG UPPER LEVEL RIDGE WILL REMAIN
THE PREDOMINANT FEATURE ACROSS THE AREA, CENTERED EAST/SOUTHEAST OF
THE REGION, PRODUCING MULTIPLE CONSECUTIVE DAYS OF HEAT AND HUMIDITY.
WILL CONTINUE TO CARRY A DRY FORECAST FOR MONDAY, THOUGH WOULD NOT
BE SHOCKED TO SEE A FEW POP UP SHOWERS/STORMS NEAR PEAK HEATING, AS
FORECAST SOUNDINGS SHOW THE CAPPING/SUBSIDENCE INVERSION TO BE
WEAKER MONDAY AND BEYOND, THOUGH THE COLUMN DOES REMAIN LARGELY
SUBSIDENT WITH NO FEATURE TO PROVIDE LARGE SCALE FORCING FOR ASCENT.
AS FOR TUESDAY AND BEYOND, THE RIDGE WEAKENS SLIGHTLY AND SLIDES
BACK SOUTHWESTWARD A BIT, WHICH MAY ALLOW FOR BOTH CONVECTIVE
DEVELOPMENT NEAR AND JUST AFTER PEAK HEATING, AND/OR FOR THE OUTSIDE
POTENTIAL THAT CONVECTION SPARKED UPSTREAM ON THE PERIPHERY OF THE
RIDGE TO SINK INTO THE REGION ON ANY EXTANT INSTABILITY GRADIENTS.
OPPRESSIVE HEAT AND HUMIDITY WILL CONTINUE AT LEAST INTO MID WEEK
AND MAY CONTINUE BEYOND INTO THE WEEKEND, THOUGH UNCERTAINTY ON
TEMPERATURES (AND THUS HEAT INDEX VALUES) INCREASES WITH TIME AS
CONVECTIVE POTENTIAL IS REINTRODUCED INTO THE SCENARIO. NONETHELESS,
HIGH TEMPERATURES WILL LIKELY REMAIN AT LEAST IN THE UPPER 80S IF
NOT LOW TO EVEN MID 90S AT TIMES, WITH PEAK AFTERNOON HEAT INDEX
VALUES AROUND 100 OR SLIGHTLY HIGHER AT TIMES. WILL LEAVE HEAT
ADVISORY AS IS FOR NOW.
LOOKING OUT IN THE LONGER RANGE, IT DOES NOT APPEAR THAT SIGNIFICANT
HEAT RELIEF WILL ARRIVE MUCH BEFORE EARLY TO MID PORTIONS OF NEXT
WEEK, WHEN GUIDANCE SHOWS A MORE SUBSTANTIAL LOW PRESSURE SYSTEM
POTENTIALLY BRINGING A COLD FRONTAL PASSAGE TO THE AREA.
AVIATION (12Z TAF ISSUANCE)
ISSUED AT 610 AM EDT SUN JUN 22 2025
IMPACTS:
- NONE; VFR CONDITIONS EXPECTED THIS TAF PERIOD.
DISCUSSION:
NO CHANGES TO PREVIOUS FORECAST. ONGOING VFR CONDITIONS WILL ARE
EXPECTED. STRONG HIGH PRESSURE AT THE SURFACE OVER THE SOUTHEASTERN
UNITED STATES WILL CONTINUE TO ALLOW FOR VERY WARM AND HUMID
TROPICAL AIR TO REMAIN ACROSS THE TAF SITES. STRONG RIDGING WILL BE
FOUND ALOFT. FORECAST SOUNDINGS SHOW A DRY COLUMN THROUGH THE PERIOD
AND CONVECTIVE TEMPERATURES WILL NOT BE REACHED. THUS VFR WITH
UNLIMITED CEILINGS.
IND WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 8 PM EDT TUESDAY FOR INZ021-028>031-035>049-
051>057-060>065-067>072.
UPDATE...CM
SHORT TERM...PUMA
LONG TERM...NIELD
AVIATION...PUMA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page