983  
FXUS63 KLOT 070818  
AFDLOT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL  
318 AM CDT THU JUL 7 2022  
   
SHORT TERM
 
 
ISSUED AT 317 AM CDT THU JUL 7 2022  
 
THROUGH FRIDAY...  
 
THE SEEMINGLY ENDLESS PARADE OF MCSS AND ASSOCIATED MCVS CONTINUES  
TO RIDE THE PERIPHERY OF THE UPPER RIDGE ACROSS THE CENTRAL AND  
EASTERN U.S. TUESDAY NIGHT'S MCS DID SHOVE THE EFFECTIVE BOUNDARY  
AND PATH OF THE MCS TRAIN SOUTH OF OUR CWA, PROVIDING THE SHORT  
RESPITE FROM THE ACTIVE WEATHER THAT OUR CWA IS CURRENTLY  
EXPERIENCING.  
 
OVER THE NEXT 24 TO 36 HOURS THE EFFECTIVE BOUNDARY WILL BE  
CREEPING SLOWLY NORTHWARD ALLOWING FOR WET WEATHER TO RETURN.  
LOOKING UPSTREAM, MCS WITH WELL DEFINED MCV IS PASSING JUST NORTH  
OF KANSAS CITY AND HEADING IN OUR GENERAL DIRECTION. THE  
ORIENTATION OF THE DOWNSTREAM INSTABILITY/MOIST AXIS AND MID-UPPER  
LEVEL FLOW BOTH FAVOR THIS COMPLEX TURNING EAST AND EAST-SOUTHEAST  
TODAY AS IT APPROACHES AND THEN CROSSES THE MISSISSIPPI RIVER. WE  
WILL SEE MID-HIGH CLOUDINESS INCREASE IN ADVANCE OF THIS FEATURE  
WITH SOME THREAT FOR SOME SHOWERS AND PERHAPS A THUNDERSTORM  
AFFECTING OUR FAR SOUTHWESTERN CWA THIS AFTERNOON.  
 
WATER VAPOR IMAGERY EARLY THIS MORNING SHOWS A WELL DEFINED, MORE  
AMPLIFIED SHORTWAVE TROUGH OVER EASTERN MT AND FAR WESTERN ND  
CRESTING THE UPPER RIDGE AT THIS TIME. THIS FEATURE WILL SHOULD  
PROVIDE THE FOCUS FOR THE NEXT MCS TO DEVELOP TONIGHT OVER THE  
LOWER MISSOURI RIVER VALLEY EAST INTO THE CORN BELT. WILL BE  
INTERESTING TO SEE THE EVOLUTION OF THIS SHORTWAVE AND HOW LIKELY  
TO DEVELOP MCV INTERACTS WITH THE APPROACHING SHORTWAVE TROUGH.  
SOME MODELS ARE DEPICTING A SIGNIFICANTLY WOUND UP VORT WITH A  
MORE WELL DEVELOPED SURFACE REFLECTION (IE FV3 AND ESPECIALLY THE  
NAM). WHILE THAT TYPE OF SOLUTION CAN'T BE RULED OUT, SUSPECT THE  
LIKELY SCENARIO WILL BE A MORE MUTED SURFACE WAVE LIKE DEPICTED BY  
THE ECMWF AND GFS.  
 
EITHER WAY, DOES APPEAR FAIRLY WIDESPREAD AND POTENTIALLY SOAK  
RAIN COULD AFFECT A LARGE PORTION OF OUR CWA LATE TONIGHT INTO  
MAINLY THE FIRST HALF OF FRIDAY. THE SOUTHERN HALF OF THE CWA  
SHOULD SEE THE HEAVIER RAINFALL TOTALS AND ALSO STANDS A BETTER  
CHANCE AS SEEING SOME EMBEDDED CONVECTION OWING TO THEIR CLOSER  
PROXIMITY TO THE INSTABILITY. THE MORE ROBUST SFC BASED  
INSTABILITY AND MEANINGFUL SEVERE THUNDERSTORM THREAT FRIDAY  
SHOULD STAY SOUTH AND SOUTHEAST OF OUR CWA.  
 
IF THE MORE AMPED UP NAM-LIKE SOLUTION WERE TO PAN OUT, THEN  
HEAVIER RAINFALL TOTALS COULD SPREAD FARTHER NORTH INTO THE CWA  
AND AFFECT EVEN THE CHICAGO METRO AREA WITH MORE PRONOUNCED  
DEFORMATION LIKE BAND WITH THE SHORTWAVE. REGARDLESS OF THE  
SOLUTION, FRIDAY LOOKS TO START WET WITH RAIN CHANCES WINDING DOWN  
FROM WEST TO EAST LATE MORNING INTO THE EARLY AFTERNOON.  
INITIALLY RAIN, THEN CLOUD COVER AND STRENGTHENING NORTH TO  
NORTHEAST WINDS DURING PEAK HEATING SHOULD RESULT IN MUCH BELOW  
AVERAGE TEMPS FRIDAY. AREAS NEAR THE LAKE MAY HOLD IN THE UPPER  
60S IN THE AFTERNOON WITH LOW/MID 70S NORTH OF I-80 SHOULD BE  
FAIRLY COMMON FOR HIGH TEMPS.  
 
- IZZI  
 

 
   
LONG TERM
 
 
ISSUED AT 316 AM CDT THU JUL 7 2022  
 
FRIDAY NIGHT THROUGH WEDNESDAY...  
 
THE REMNANTS OF SHOWERS ASSOCIATED WITH A WEAK SURFACE FRONT/UPPER  
WAVE WILL BE MOVING EAST-SOUTHEAST OUT OF OUR FORECAST AREA FRIDAY  
NIGHT, WITH NORTHEASTERLY WINDS AS HIGH PRESSURE MOVES IN. COOLER,  
DRIER AIR WILL MOVE IN OVER THE WEEKEND, WITH BELOW SEASONAL  
TEMPERATURES, ESPECIALLY ON SATURDAY WHEN MOST HIGH TEMPERATURES  
WILL BE AT OR BELOW 80. THIS WILL BE ESPECIALLY TRUE ALONG THE LAKE  
MICHIGAN SHORE, WHERE TEMPERATURES WILL STAY IN THE LOWER 70S. THE  
SURFACE RIDGE AXIS WILL MOVE SOUTH OF OUR REGION SUNDAY AFTERNOON,  
SHIFTING WINDS TO THE SOUTHEAST, WHICH WILL TEND TO KEEP ONLY THE  
ILLINOIS SHORE COOLER IN THE MID 70S VS. LOWER 80S INLAND. A WEAK  
FRONT MOVES THROUGH THE REGION ON MONDAY, WITH A CHANCE OF SHOWERS  
AND POSSIBLE STORMS MONDAY INTO MONDAY NIGHT. AHEAD OF THIS FRONT  
DEWPOINTS WILL CLIMB INTO THE UPPER 60S TO LOWER 70S, SO MONDAY MAY  
FEEL A LITTLE MUGGY. NORTHWESTERLY WINDS BEHIND THE FRONT SHOULD  
BRING IN SLIGHTLY DRIER (LOWER 60S DEWPOINTS) AND COOLER AIR (HIGHS  
IN THE MID TO LOW 80S) BEHIND THE FRONT. AN UPPER WAVE OR TWO MAY  
MOVE OVERHEAD TOWARDS THE MIDDLE OF THE WEEK, BRINGING CHANCES FOR  
SHOWERS, BUT THIS FAR OUT CONFIDENCE IN THE EXACT TRACK OF THESE  
WAVES IS LOW.  
 
BKL  
 

 
   
AVIATION
 
 
FOR THE 06Z TAFS...  
 
AVIATION WEATHER CONCERNS FOR 06Z TAFS:  
 
* MVFR TO IFR CEILINGS ARE OVER OR IN THE VICINITY OF THE TERMINALS,  
AND COULD DROP CEILINGS, OR VISIBILITIES IN EASTERN SITES, BELOW  
VFR.  
* CHANCE FOR SHOWERS, POSSIBLE STORMS, LATE THURSDAY INTO FRIDAY  
MORNING.  
 
HIGH PRESSURE REMAINS OVER OUR AREA WITH NORTHEASTERLY FLOW.  
OCCASIONAL MVFR TO IFR CEILINGS MAY MOVE OVER THE TERMINALS FROM OFF  
OF LAKE MICHIGAN, BUT THESE LOWER CIGS ARE SHORT-LIVED, WITH THE  
EXCEPTION OF GARY (GYY), WHICH HAS BEEN IFR FOR THE PAST FEW HOURS.  
IN ADDITION TO LOW CIGS, GYY'S VISIBILITIES HAVE BEEN DOWN TO 3  
MILES THIS EVENING. GYY WILL CONTINUE TO SEE THESE LOWER CIGS AND  
VIS UNTIL LATER THIS MORNING. THE THREAT OF LOWER CIGS SHOULD END  
SHORTLY AFTER SUNRISE THIS MORNING. AFTERWARDS VFR CONDITIONS WILL  
PREVAIL TODAY AT LEAST UNTIL THE MID-AFTERNOON. A WAVE WILL APPROACH  
FROM THE WEST THIS AFTERNOON, BRINGING A CHANCE FOR SHOWERS IN THE  
LATE AFTERNOON FOR ROCKFORD, AND IN THE EARLY EVENING FOR THE OTHER  
SITES. CONFIDENCE ON THIS OCCURRING AND TIMING OF SHOWERS IS LOW,  
WITH BETTER CHANCES FOR PRECIPITATION FURTHER SOUTH, SO I'VE KEPT  
THE PROB30 INDICATING THIS POSSIBILITY. THERE IS NO MENTION OF  
THUNDERSTORMS AT THIS TIME, BUT THEY CANNOT BE RULED OUT, ALTHOUGH  
THE TIMING AND DYNAMICS FOR STORM ACTIVITY IS NOT GREAT. THEREFORE  
THERE IS NO MENTION IN PRESENT TAFS.  
 
BKL  
 

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

 
 

 
 
VISIT US AT WEATHER.GOV/CHICAGO  
 
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:  
WWW.FACEBOOK.COM/NWSCHICAGO  
WWW.TWITTER.COM/NWSCHICAGO  
WWW.YOUTUBE.COM/NWSCHICAGO  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab IL Page
The Nexlab IN Page Main Text Page