920
FXUS63 KIWX 230022
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
822 PM EDT TUE APR 22 2025
KEY MESSAGES
- WIDELY SCATTERED TO SCATTERED SHOWERS AND STORMS ARE POSSIBLE
TONIGHT INTO WEDNESDAY MORNING, MAINLY NORTH OF US 24 AND
WEST OF INDIANA 15.
- BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS FRIDAY INTO
FRIDAY EVENING. NO SEVERE WEATHER IS EXPECTED AT THIS TIME.
- TEMPERATURES WILL GENERALLY BE ABOVE NORMAL (70S TO LOW 80S)
THROUGH THE PERIOD WITH A BRIEF COOLDOWN (60S) SATURDAY.
DISCUSSION
ISSUED AT 230 PM EDT TUE APR 22 2025
CHALLENGE THROUGH WEDNESDAY MORNING LIES WITH A LOW LEVEL BAROCLINIC
ZONE/THETA-E GRADIENT THAT CURRENTLY EXTENDS FROM SOUTHERN IA EAST
TO N IL AND SOMEWHAT INTO NW INDIANA. KILX AND KDTX 12Z SOUNDINGS
SHOW LOTS OF DRY AIR IN PLACE. A SMALL AREA OF SHOWERS AND STORMS
MOVED ACROSS N IL BUT HAS WEAKENED CONSIDERABLY AS IT ENCOUNTERS THE
DRIER AIRMASS. UPSTREAM SATELLITE AND RADAR DATA SHOWS ADDITIONAL
SMALL AREAS OF SHOWERS AND STORMS THAT WILL TAKE A GENERAL WEST TO
EAST TRACK WITH EACH SUBSEQUENT ONE LIKELY MAKING PROGRESS FURTHER
EAST. MODELS HAVE BEEN CONSISTENT ON ADVECTION OF LOW TO MAYBE MID
50 DEWPOINTS INTO FAR N/NW AREAS BY EARLY EVENING AND THEN EXPANDING
EAST AND SOMEWHAT SOUTH AS EACH SMALL AREA OF PRECIP MESSES WITH THE
GRADIENT LOCATION. LLJ IS BARELY ANYTHING OVERNIGHT (20 KTS AT BEST)
AND IS PARALLEL TO THE THETA-E GRADIENT. CAMS CONTINUE TO REDEVELOP
CLUSTERS OF STORMS IN SE IA/NW IL AND TRACK THEM EAST WITH THE MOST
PRONOUNCED POSSIBLY TAKING SHAPE AFTER 6Z AND MOVING EAST. ELEVATED
INSTABILITY WILL BE IN PLACE WITH STEEPENING LAPSE RATES TO
POTENTIALLY SUPPORT CONTINUATION OF THE PRECIP EAST. EVEN THOUGH
THIS MOVES IN, MODELS STILL SHOW AN OVERALL WEAKENING TREND SO CAN'T
JUSTIFY MORE THAN CHC POPS FOR NOW. EFFECTS OF THE OVERNIGHT PRECIP,
RESTING LOCATION OF THE THETA-E GRADIENT, IMPACTS OF ANY LINGERING
CLOUD COVER AND OTHER MESOSCALE DETAILS WILL DICTATE WHETHER THE
SAME AREAS THAT MAY SEE PRECIP OVERNIGHT COULD SEE ADDITIONAL
SHOWERS/STORMS DEVELOP UPSTREAM AND MOVE IN WED AFTERNOON AND
EVENING. MAJORITY OF CAMS SHOWING THE MOST ACTIVITY THAT DEVELOPS
MAY REMAIN W OR N OF THE AREA. WHILE I SUSPECT EVEN THE SLGT CHC
POPS WED AFTERNOON MAY BE OVERDONE ACROSS THE NORTH I WILL LEAVE
THEM IN PLACE UNTIL WE SEE THE FINAL OUTCOME OF TONIGHT'S PRECIP.
WED AND THURSDAY WILL BE MUCH WARMER WITH HIGHS INTO THE 70S
WEDNESDAY AND SOME 80S THURSDAY BEFORE THE ARRIVAL OF INCREASING
CLOUDS WITH A WEAK SOUTHERN STREAM WAVE. THE BEST DYNAMICS AND
ENERGY WILL REMAIN WELL TO THE WEST OF THE AREA, BUT ARRIVAL OF A
COLD FRONT STILL ENOUGH FORCING AND MOISTURE TO BRING A PERIOD OF
SHOWERS/STORMS POSSIBLY AS EARLY AS FRIDAY MORNING IN THE WEST, WITH
THE BEST CHANCES FRI AFTERNOON INTO EARLY EVENING. HAVE KEPT LIKELY
TO CAT POPS GOING. OVERALL ENVIRONMENT SUPPORTS AT MOST SOME PULSY
THUNDERSTORMS THAT PRODUCE LOCALLY GUSTY WIND AND HEAVY RAIN WITH
OVERALL SEVERE THREAT PRETTY LOW.
A BRIEF COOLDOWN OCCURS SAT INTO SUN BEHIND THE FRONT BEFORE UPPER
LEVEL HEIGHTS RAPIDLY INCREASE AGAIN AS DEEPER LONGWAVE TROUGH OVER
THE WESTERN STATES EDGES SLOWLY EAST INTO NEXT WEEK. SOME ADDITIONAL
WAVES MOVE THROUGH THE FLOW THAT COULD BRING PERIODIC CHANCES FOR
SHOWERS/STORMS BUT NOT ENOUGH CONFIDENCE TO MESS WITH TIMING/POPS AT
THIS POINT.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 814 PM EDT TUE APR 22 2025
A STALLED FRONTAL BOUNDARY AND A WEST-EAST ORIENTED LOW LEVEL
MOISTURE AXIS FROM THE CENTRAL PLAINS INTO NORTHERN ILLINOIS HAS
BEEN THE FOCAL POINT OF SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THIS EVENING. BETTER LOW LEVEL MASS/MOISTURE
CONVERGENCE SHOULD REMAIN ANCHORED WEST OF THE LOCAL AREA, BUT
CANNOT COMPLETELY RULE OUT A FEW ISOLATED SHOWERS WORKING INTO
NORTHWEST INDIANA LATE EVENING/OVERNIGHT. GIVEN CONTINUED LOW
CONFIDENCE, WILL CONTINUE TO KEEP TAFS DRY. A BIT MORE
INSTABILITY WILL BE IN PLACE FOR WEDNESDAY DURING THE AFTERNOON,
BUT A TRIGGER MECHANISM FOR CONVECTION IS NOT CLEAR CUT.
BOUNDARY ACROSS THE REGION THIS EVENING WILL LIFT NORTHWARD BY
WEDNESDAY AFTERNOON AND STRONGER FORCING SHOULD REMAIN DISPLACED
ACROSS THE GREAT LAKES REGION. A LIGHT SOUTHERLY FLOW REGIME
SHOULD PERSIST THROUGH THIS PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...FISHER
AVIATION...MARSILI
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