044  
FXUS63 KLOT 162307  
AFDLOT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL  
607 PM CDT MON SEP 16 2024  
   
KEY MESSAGES
 
 
- HOT AND DRY CONDITIONS CONTINUE THIS WEEK.  
 
- LONG-RANGE MODELS ADVERTISE A PATTERN SHIFT DURING THE LAST  
WEEK OF THE MONTH WITH A RETURN OF CHANCES FOR RAIN. TIME  
WILL TELL IF SUCH A PATTERN CHANGE OCCURS.  
 

 
   
DISCUSSION
 
 
ISSUED AT 221 PM CDT MON SEP 16 2024  
 
A STRETCH OF INCREDIBLY QUIET AND DRY CONDITIONS CONTINUES, WITH  
EXPANDING DROUGHT CONDITIONS ACROSS THE AREA.  
 
REGIONAL LOW-LEVEL WATER VAPOR IMAGERY THIS AFTERNOON SHOWS THE  
EXTENT OF AN INCOMING PLUME OF EXCEPTIONALLY DRY LOWER-  
TROPOSPHERIC AIR, WITH BRIGHTNESS TEMPERATURES NEARING 0 C. MODEL  
GUIDANCE INDICATES DEWPOINTS AT 700 MB NEARING -40 C, AND THIS  
APPEARS TO BE CORROBORATED BY RECENT AMDAR SOUNDINGS. THIS WEDGE  
OF DRY AIR IS FORECAST TO LINGER OVERHEAD THROUGH ABOUT THURSDAY  
AS IT WILL BECOME CAUGHT BETWEEN THE TROPICAL CIRCULATION IN THE  
VICINITY OF THE CAROLINAS AND A DIGGING/AMPLIFYING UPPER LOW  
ACROSS THE GREAT BASIN. BASED ON HOW SURFACE DEWPOINTS ARE  
RESPONDING ACROSS NORTHERN INDIANA WITHIN THE CORE OF THE DRIEST  
PART OF THIS AIRMASS, HAVE UNDERCUT BLENDED GUIDANCE DEWPOINTS  
THROUGH THURSDAY AFTERNOON, ALTHOUGH NOT QUITE TO THE VALUES  
ADVERTISED BY THE HRRR/GFS WHICH CONTINUE TO SHOW GENERAL LOW PM  
DEWPOINT BIASES. THANKFULLY, LIGHT WINDS WILL PRECLUDE MORE  
APPRECIABLE FIRE WEATHER CONCERNS. HIGH TEMPERATURES WILL BE A  
DEGREE OR THREE "COOLER" TOMORROW COMPARED TO TODAY AS THICKNESS  
VALUES DECREASE A BIT.  
 
GLOBAL/COARSE-RESOLUTION GUIDANCE REMAINS IN GOOD AGREEMENT  
TOWARDS THE END OF THE WEEK, SUGGESTING THAT INCREASING WEST AND  
SOUTHWESTERLY LOW AND MID-LEVEL FLOW WILL BEGIN TO "FOLD OVER" THE  
HIGHER THETA-E AIRMASS THAT'S BEEN COLLECTING ACROSS IOWA INTO OUR  
AREA DURING THE THURSDAY-FRIDAY TIME FRAME. A MODEST INCREASE IN  
LOW-LEVEL WARM ADVECTION IS FORECAST TO DEVELOP ACROSS EASTERN  
IOWA AND FAR NORTHWEST ILLINOIS THURSDAY NIGHT INTO FRIDAY, AND  
WITH THIS, SOME SIGNAL FOR LIGHT QPF ACROSS OUR I-39 LOCALES IS  
EVIDENT IN TODAY'S 12Z RUNS. THAT SAID, FORECAST SOUNDINGS  
ACROSS OUR AREA SUGGESTS ANY ACTIVITY THAT DOES DEVELOP DURING  
THIS TIME FRAME WILL PROBABLY TEND TO FIZZLE WITH EASTWARD  
EXTENT, AND HAVE CAPPED ANY POPS TO SLIGHT CHANCES ACROSS OUR  
NORTHWEST LOCALES WITH THIS IN MIND.  
 
BEYOND THIS INTO THE WEEKEND AND NEXT WEEK, PROSPECTS FOR  
WIDESPREAD, SOAKING RAINS CONTINUE TO LOOK PRETTY SLIM AS THE  
DEEPEST MOISTURE AND MORE ACTIVE SOUTHWESTERLY FLOW LOOKS TO  
REMAIN JUST TO OUR WEST.  
 
CARLAW  
 

 
   
AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
 
 
ISSUED AT 606 PM CDT MON SEP 16 2024  
 
LIGHT WINDS AND VFR CONDITIONS EXPECTED THROUGH THE 00Z TAF  
PERIOD.  
 
- IZZI  
 

 
   
LOT WATCHES/WARNINGS/ADVISORIES
 
 
IL...NONE.  
IN...NONE.  
LM...NONE.  
 

 
 

 
 
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