120
FXUS63 KIWX 171746
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
146 PM EDT SAT MAY 17 2025
KEY MESSAGES
- TODAY WILL BE COOL, CLOUDY, AND BREEZY WITH HIGHS IN THE MID
60S.
- SUNSHINE RETURNS ON SUNDAY BUT COOL TEMPERATURES REMAIN.
- WIDESPREAD RAIN IS EXPECTED TUESDAY AND WEDNESDAY.
DISCUSSION
ISSUED AT 246 AM EDT SAT MAY 17 2025
POSTFRONTAL CAA NOW WELL UNDERWAY WITH 850MB TEMPS DROPPING INTO THE
LOW SINGLE DIGITS IN THE WAKE OF SLOWLY DEPARTING MID/UPPER LOW.
PERSISTENT LOW LEVEL CYCLONIC FLOW COULD SUPPORT A FEW SPRINKLES IN
OUR N/NE ZONES AT TIMES TODAY BUT EXPECT ONLY TRACE AMOUNTS WITH
MOST OF OUR AREA REMAINING ENTIRELY DRY. BIGGEST SENSIBLE WEATHER
IMPACT TODAY WILL BE AMPLE CLOUDS DUE TO RESIDUAL BOUNDARY LAYER
MOISTURE IN CAA REGIME AS WELL AS SOME GUSTY WINDS. DESPITE EXPECTED
CLOUD COVER, STILL EXPECT DECENT MIXING WITH MOMENTUM TRANSFER FROM
FORECAST SOUNDINGS SUGGESTING FREQUENT 30-35MPH GUSTS. CALENDAR-DAY
HIGHS LIKELY ALREADY REACHED WITH AFTERNOON TEMPS PROBABLY TOPPING
OUT IN THE MID 60S...ROUGHLY 5-10 DEGREES BELOW NORMAL. OVERALL NOT
A GREAT WEATHER DAY. SUNDAY WILL BE MUCH BETTER WITH LESS CLOUDS,
LESS WIND AND HIGHS A FEW DEGREES WARMER AWAY FROM THE LAKE.
A LARGE UPPER LOW IS EXPECTED TO DEVELOP OVER THE ROCKIES LATE THIS
WEEKEND AND EVENTUALLY EJECT EASTWARD DURING THE MIDDLE OF NEXT WEEK.
THERE REMAIN SOME IMPORTANT TRACK DETAILS TO WORK OUT GIVEN A FAIRLY
COMPLICATED INTERACTION WITH PERSISTENT QUEBEC TROUGH/UPPER LOW. NO
MAJOR CHANGES TO NBM INITIALIZATION WHICH WAS IN LINE WITH PREVIOUS
FORECAST IN SHOWING HIGH POP'S MAINLY TUE INTO WED. A FEW EMBEDDED
THUNDERSTORMS REMAIN POSSIBLE BUT THE RISK OF SEVERE WEATHER IS LOW
GIVEN LIMITED INSTABILITY NORTH OF LOW TRACK. EXACT RAINFALL AMOUNTS
HIGHLY UNCERTAIN AT THIS RANGE BUT NOT EXPECTED TO CAUSE ANY
FLOODING GIVEN RECENT (MAINLY) DRY CONDITIONS. THIS PATTERN WILL
ALSO SUPPORT HIGHS WELL BELOW NORMAL (LOW/MID 60S) FOR MUCH OF NEXT
WEEK.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 140 PM EDT SAT MAY 17 2025
COLD ADVECTION VFR STRATOCU WILL LINGER AT TERMINALS THIS
EVENING, WITH SOME POTENTIAL SCATTERING AT KFWA LATER THIS
EVENING. POST-FRONTAL INVERSION/SUBSIDENCE AND SHALLOW LOW
LEVEL MOISTURE MAY ALLOW THESE LOW CLOUDS TO LINGER THROUGH MUCH
OF THE PERIOD, ALTHOUGH SOME SUBTLE MID LEVEL HEIGHT RISES ON
SUNDAY MAY RESULT IN MORE OF SCATTERED TO BROKEN NATURE OF THESE
LOW CLOUDS. MIXING TODAY HAS BEEN ENHANCED BY THIS COLD
ADVECTION WITH GUSTS AS HIGH AS 35 KNOTS REPORTED. THESE GUSTS
SHOULD DIMINISH EARLY EVENING, ALTHOUGH SOME GUSTS TO 15 TO 20
KNOTS MAY PERSIST THROUGH THE EARLY EVENING HOURS AS LAPSE
RATES ARE SLOW TO WEAKEN. INCOMING LOW LEVEL RIDGE AXIS TONIGHT
INTO SUNDAY WILL RESULT IN WEAKER WEST-NORTHWEST WINDS FOR
SUNDAY, GENERALLY 10-15G15-20KT RANGE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043-
046.
DISCUSSION...AGD
AVIATION...MARSILI
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