147
FXUS63 KIND 210721
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
321 AM EDT SAT JUN 21 2025
KEY MESSAGES
- HEAT ADVISORY IN EFFECT TODAY THROUGH TUESDAY
- HOTTEST CONDITIONS OF THE SEASON THUS FAR THIS WEEKEND INTO NEXT
WEEK, WITH HEAT INDEX VALUES PEAKING FROM 100-105 DEGREES FOR
SEVERAL CONSECUTIVE DAYS
- SLIGHT WEAKENING OF THE RIDGE MID TO LATE NEXT WEEK MAY ALLOW
THUNDERSTORM ACTIVITY TO DROP INTO THE REGION, OFFERING SOME
PROSPECT OF RELIEF FROM THE HOTTEST TEMPERATURES
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 321 AM EDT SAT JUN 21 2025
AS IF ON SCHEDULE FOR THE FIRST FULL DAY OF ASTRONOMICAL SUMMER, THE
HOTTEST STRETCH OF THE YOUNG SEASON THUS FAR BEGINS TODAY, WITH
PLENTIFUL SUNSHINE, INCREASING HUMIDITY, AND HIGHS IN THE LOW 90S AS
UPPER LEVEL RIDGING BEGINS TO STRENGTHEN OVER THE REGION.
THE STRONG INSOLATION TODAY, COMBINED WITH A BIT OF A PRESSURE
GRADIENT IN PLACE, WILL PROMOTE DEEP BOUNDARY LAYER MIXING THIS
AFTERNOON, ON THE ORDER OF 4-7KFT, WHICH WILL ALLOW FOR GUSTY
CONDITIONS AND PROVIDE AT LEAST SLIGHT RELIEF IN THAT MANNER, WITH
WINDS GUSTING AS HIGH AS 25-30 MPH AT TIMES THIS AFTERNOON, BUT
OTHERWISE, DAY ONE OF FAIRLY STIFLING HEAT CAN BE EXPECTED, WITH
PEAK HEAT INDEX VALUES RISING INTO THE UPPER 90S TO LOW 100S ACROSS
THE AREA. HEAT ADVISORY IS ALREADY IN PLACE FOR THE PROLONGED
STRETCH OF HOT CONDITIONS, AND NO CHANGES ARE NECESSARY.
HIGH HUMIDITY WILL KEEP OVERNIGHT LOWS UP TONIGHT, WITH LOW TO MID
70S LIKELY ACROSS THE AREA, OFFERING LITTLE RELIEF FROM THE HEAT
STRESS BUILT UP DURING THE DAY.
LONG TERM (SUNDAY THROUGH FRIDAY)
ISSUED AT 321 AM EDT SAT JUN 21 2025
..PROLONGED HEAT AND HUMIDITY EXPECTED INTO LATE NEXT WEEK
HEAT AND HUMIDITY WILL REMAIN THE NAME OF THE GAME THROUGH MUCH OF
THE COMING WEEK, WITH THE UNCERTAINTY BEING HOW MUCH THE SLIGHT
WEAKENING AND RETROGRESSION OF THE UPPER RIDGE LATER IN THE WEEK MAY
ALLOW AFTERNOON CONVECTION TO DEVELOP, OR RIDGE-RIDING COMPLEXES TO
MOVE INTO THE AREA AND OFFER SOME SLIGHT RELIEF WITH TIME. IT IS
POSSIBLE THAT TRIPLE DIGIT PEAK HEAT INDEX VALUES COULD PERSIST INTO
WEDNESDAY/THURSDAY, AND MAY MERIT EXTENSION TO ALL OR PART OF THE
HEAT ADVISORY, BUT THIS WILL WAIT FOR LATER PACKAGES WHEN SOME OF
THESE DETAILS COME INTO BETTER FOCUS. CENTRAL INDIANA IS LIKELY TO
REMAIN DRY THROUGH AT LEAST MONDAY, AS A LACK OF FORCING FOR ASCENT
COMBINED WITH CAPPING (700 MB TEMPS NEAR 10-12C MUCH OF THE TIME) IS
LIKELY TO KEEP ANY INSTABILITY ALOFT FROM BEING REALIZED.
HIGHS EACH DAY THROUGH AT LEAST THURSDAY LOOK TO REACH THE LOW TO
PERHAPS MID 90S ACROSS MOST OR ALL OF CENTRAL INDIANA, WITH
OVERNIGHT LOWS NO LOWER THAN THE LOW TO MID 70S DUE TO THE HIGH
DEWPOINTS, AGAIN PROLONGING AND EXACERBATING THE CUMULATIVE HEAT
STRESS, PARTICULARLY FOR VULNERABLE POPULATIONS AND THOSE WITHOUT
ACCESS TO ADEQUATE COOLING.
WHILE RECORD TEMPERATURES ARE NOT AT RISK THROUGHOUT THIS STRETCH,
IT IS AGAIN PRUDENT TO EMPHASIZE THE CUMULATIVE NATURE OF HEAT
STRESS, WHICH IS WELL-ILLUSTRATED BY EXPERIMENTAL NWS HEATRISK INDEX
VALUES, WHICH ARE 3-4/MAJOR-EXTREME FOR MULTIPLE COMING DAYS AS A
RESULT OF BOTH THE DAYTIME HEAT AND THE HIGH HUMIDITY/WARM LOW
TEMPERATURES PREVENTING SIGNIFICANT OVERNIGHT RELIEF.
AVIATION (06Z TAF ISSUANCE)
ISSUED AT 117 AM EDT SAT JUN 21 2025
IMPACTS:
- WIND GUSTS UP TO 20-25KT FROM 200-210 DEGREES BETWEEN 15Z AND 00Z
THIS AFTERNOON/EVENING
DISCUSSION:
INCREASING RIDGING ALOFT AND ASSOCIATED SUBSIDENCE WILL PROVIDE
MOSTLY CLEAR SKIES/VFR CONDITIONS THROUGHOUT THE PERIOD. BRIEF
PATCHY FOG NEAR DAYBREAK CANNOT ENTIRELY BE RULED OUT IN FAVORED
LOCATIONS, BUT BREEZES SHOULD STAY UP ENOUGH OVERNIGHT TO PREVENT
THIS AT THE TAF SITES.
THE PRIMARY IMPACT DURING THIS PERIOD WILL BE WIND GUSTS FROM LATE
MORNING INTO THE EARLY EVENING AT ALL SITES, ON THE ORDER OF 20-25KT
AT THEIR PEAK FROM 200-210 DEGREES, OWING TO A WELL-MIXED BOUNDARY
LAYER WITH A DEPTH OF 4-7KFT. THESE GUSTS WILL SUBSIDE IN TYPICAL
DIURNAL FASHION DURING THE EVENING, WITH WINDS TOMORROW NIGHT
REMAINING SOUTHERLY (190-200 DEGREES) AT 7-11KT, AGAIN PREVENTING
ANY SIGNIFICANT FOG.
IND WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM EDT TUESDAY FOR
INZ021-028>031-035>049-051>057-060>065-067>072.
SHORT TERM...NIELD
LONG TERM...NIELD
AVIATION...NIELD
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