535
FXUS63 KIWX 131022
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
622 AM EDT MON JUL 13 2020
SYNOPSIS
ISSUED AT 327 AM EDT MON JUL 13 2020
AVERAGE TO SLIGHTLY BELOW AVERAGE TEMPERATURES WITH LOWER HUMIDITY ARE
IN PLACE FOR TODAY AND TUESDAY WITH JUST A MIX OF SUN AND CLOUDS.
HIGH TEMPERATURES AS WELL AS CHANCES FOR SHOWERS AND
THUNDERSTORMS INCREASE FOR WEDNESDAY AS A LOW PRESSURE SYSTEM
APPROACHES. REMAINING WARM AND UNSETTLED LATE WEEK.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 327 AM EDT MON JUL 13 2020
MID LEVEL RIDGE AXIS SLIDES EAST ARRIVING LATE TONIGHT. THIS
ALLOWS THE LOW LEVEL JET TO STAY WEAK DURING THE PERIOD. SO, WHILE
THERE IS SOME WEAK LOW LEVEL INSTABILITY AND LAPSE RATES UP TO
850 MB, WINDS SHOULD STAY LIGHT AND AM EXPECTING JUST A MIX OF SUN
AND CLOUDS AROUND DURING THE DAY AS WEAK SHORTWAVES MOVE THROUGH
IN THE NORTHWEST FLOW.
HIGH TEMPERATURES TODAY SHOULD BE CLOSE TO SUNDAY'S WITH 850 MB
TEMPS FAIRLY CLOSE TO, IF NOT SLIGHTLY COOLER THAN, SUNDAY'S. THIS
SHOULD PUT US IN THE LOW 80S FOR HIGHS. THEN FOR MONDAY NIGHT,
MINIMAL CLOUDINESS, DRIER DEW POINTS AND LIGHT WINDS SHOULD HELP US
FALL BACK TOWARDS THE LOW 60S, EXCEPT UPPER 50S WEST OF US-31.
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 327 AM EDT MON JUL 13 2020
THE LONG TERM IS CHARACTERIZED BY A TRANSITION FROM A TROUGH EAST,
RIDGE WEST PATTERN TO A TROUGH WEST, RIDGE EAST PATTERN. THE PATTERN
TRANSITION OCCURS AS A WAVE (OUR NEXT PRECIP CHANCE) APPROACHES THE
AREA WEDNESDAY. SOME MODEL DISAGREEMENT STILL EXISTS WITH THE TRACK
THAT THIS WAVE TAKES TO GET TOWARDS THE AREA SO SOME MODELS HAVE THE
PRECIPITATION STARTING BEFORE 18Z. WOULD RATHER SIDE WITH THE EC AND
LET THE DIURNAL FORCING OF THE AFTERNOON AND THE WAVE GET CLOSER TO
THE AREA TO HELP GET PRECIP GOING ACROSS OUR NORTH. AS SUCH, WILL
LEAVE THE 15-20 POPS IN FOR AREAS WEST OF US-31 AND NEAR THE LAKE
FOR WED, BUT THE BETTER CHANCE FOR POPS IS DEFINITELY IN THE
AFTERNOON, ESPECIALLY WITH THE THETA-E BOUNDARY STILL DEPICTED ALONG
THE IL/IN BORDER AT 18Z. THUNDERSTORM POTENTIAL IS THERE FOR LATER
WEDNESDAY DEPENDING ON ITS TIMING WITH SBCAPE BEING MODELED TO RISE
ABOVE 1500 J/KG. SOME SHEAR IS AROUND, BUT IT'S RATHER MARGINAL AT
BETWEEN 20-30 KTS AND COULD BE BOUNDARY PARALLEL, WHICH COULD LEAD
TO SOME TRAINING OF CELLS AND PERHAPS EVEN SOME SLOW-MOVING ONES
ESPECIALLY WITH THE INCREASED MOISTURE. GUSTY WINDS ARE ALSO
POSSIBLE WITH THIS EVENT.
ANYWAYS, BACK TO TUESDAY, THE AFOREMENTIONED UPPER RIDGE AXIS IS
STILL ACROSS THE AREA ALLOWING ANOTHER DAY OF QUIET WEATHER.
HOWEVER, SIMILAR MIXING HEIGHTS TO TODAY, BUT WARMER 850 MB
TEMPERATURES ALLOW FOR A WARMER DAY, MORE LIKE THE MID 80S AS
OPPOSED TO LOW 80S FOR HIGHS. THE AREA COULD START TO FEEL A SLIGHT
INCREASE IN HUMIDITY BY THE END OF THE DAY, ESPECIALLY AREAS WEST OF
US-31, BUT THE BETTER CHANCE FOR NOTICEABLY INCREASED HUMIDITY
OCCURS WEDNESDAY.
THE PRECIP CHANCE FOR WEDNESDAY WAS DISCUSSED ABOVE, BUT TEMPERATURE-
WISE, WEDNESDAY LIKELY SEES MANY AREAS REACHING THE UPPER 80S, BUT
COULD SEE A FEW AREAS REACH 90 DEGREES WITH THE INCREASED WARMTH,
ESPECIALLY IF THE HIGHER DEW POINT AIR (~70F) WAITS UNTIL LATER DAY
LIKE THE EC DEPICTS.
THEN, IT APPEARS THE THETA-E BOUNDARY ACTUALLY LINGERS NEARBY FOR
THURSDAY AND FRIDAY SO WILL HOLD ONTO THE BLENDED POPS THERE,
WHICH ARE ACCOMPANIED BY THUNDER. THE POTENTIAL FOR SPOTS THAT
REACH 90 DEGREE TEMPS RETURN FOR FRIDAY AND THE WEEKEND.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 620 AM EDT MON JUL 13 2020
HIGH PRESSURE SETTLES IN TO PROMOTE VFR CONDITIONS WITH MOSTLY
CLEAR SKIES. LIGHT NORTHERLY WINDS THIS MORNING INCREASE TO 5-10 KTS
DURING THE DAY. FAIR WEATHER CUMULUS MAY DOT THE AREA IN THE
AFTERNOON.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
SYNOPSIS...ROLLER
SHORT TERM...ROLLER
LONG TERM...ROLLER
AVIATION...COBB
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