936  
FXUS63 KLOT 191959 CCA  
AFDLOT  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL  
259 PM CDT SUN MAY 19 2019  
   
SHORT TERM
 
 
259 PM CDT  
 
THROUGH TONIGHT...  
 
THROUGH THE LATE AFTERNOON:  
COLD FRONT IS SWEEPING ACROSS THE AREA APPROACHING THE 3PM HOUR.  
DESPITE VEERING WINDS AND DEW POINTS DROPPING BEHIND THE FRONT,  
THERE IS SUFFICIENT FORCING FOR POST FRONTAL SHOWERS PRIMARILY  
SOUTH OF I-80 AFTER SHOWERS OVER NORTHEAST IL EXIT OVER THE LAKE.  
WITH BETTER MOISTURE AND INSTABILITY AXIS QUICKLY SHIFTING  
EASTWARD, THREAT FOR ANY ADDITIONAL ISOLATED STRONG/SEVERE STORMS  
OVER THE NEXT HOUR OR SO WILL BE PRIMARILY OVER NORTHWEST INDIANA  
COUNTIES. MAIN RISK WILL BE GUSTY TO LOCALLY DAMAGING WINDS. THE  
OTHER CONCERN IS THE STRONG WEST-SOUTHWEST WINDS, GUSTING UP TO  
35-40 MPH OVER THE NEXT FEW HOURS. THERE HAVE BEEN A FEW GUSTS  
INTO THE 40-45 MPH RANGE OVER THE PAST HOUR OR SO, BUT PEAK WIND  
GUST SPEEDS SHOULD GRADUALLY SUBSIDE TOWARD SUNSET.  
 
THIS EVENING-OVERNIGHT:  
THERE WILL BE A SECONDARY COLD FRONT/WIND SHIFT TO NORTHWEST ALONG  
WITH FAIRLY STOUT COLD ADVECTION. OUT AHEAD OF THIS, THERE'S A  
PRETTY GOOD SIGNAL ON HIGH-RES/NEAR-TERM GUIDANCE FOR WIDELY  
SCATTERED LIGHT SHOWERS FROM I-80 AND SOUTH, SO CARRIED LOW CHANCE  
CATEGORY POPS FOR THIS. ANY LINGERING SHOWER ACTIVITY SHOULD END  
BY AN HOUR OR TWO AFTER MIDNIGHT. BREEZY WEST-NORTHWEST WINDS AND  
COLD ADVECTION WILL DRIVE TEMPERATURES DOWN INTO THE 40S BY EARLY  
MONDAY, SO QUITE A CHANGE FROM THE PLEASANT READINGS EARLY THIS  
EVENING.  
 
CASTRO  
 

 
   
LONG TERM
 
 
120 PM CDT  
 
MONDAY THROUGH SUNDAY...  
 
THE BREAK FOLLOWING THE CURRENT SYSTEM LOOKS TO BE RELATIVELY  
SHORT LIVED AS ANOTHER POWERFUL SHORTWAVE EMERGES OUT INTO THE  
SOUTHERN PLAINS LATER MONDAY INTO MONDAY NIGHT. THIS CYCLONE IS  
FORECAST TO OCCLUDE WITH A DEEP VERTICALLY STACKED FORECAST TO  
TRACK DUE NORTH ACROSS THE CENTRAL PLAINS TUESDAY INTO TUESDAY  
NIGHT, WITH A FUJIWARA TYPE INTERACTION DEPICTED WITH ANOTHER  
CLOSED LOW DIGGING SOUTHEAST INTO THE INTERMOUNTAIN WEST.  
 
THE WARM CONVEYOR BELT OF THIS SIGNIFICANTLY OCCLUDED SYSTEM IS  
FORECAST TO ARC OUT WELL AHEAD OF THE STORM AND MOVE ACROSS THE  
CWA TUESDAY NIGHT INTO WEDNESDAY MORNING. DESPITE STRONG SHEAR  
PROFILES THAT SHOULD BE IN PLACE, THIS ACTIVITY IS LIKELY TO  
OUTRUN THE BETTER INSTABILITY WITH THE WARM SECTOR LIKELY PINCHED  
OFF TO OUR SOUTH, SO THINKING THE SEVERE THREAT WILL BE MINIMAL  
WITH THIS ACTIVITY TUESDAY NIGHT.  
 
DEEP LONGWAVE TROUGH IS EXPECTED TO REMAIN ANCHORED OVER THE  
WESTERN U.S. THROUGH THE REMAINDER OF THE LONG TERM PERIOD, WITH  
THIS MIDWEEK CYCLONE EXPECTED TO LIFT NORTH TO THE NORTHERN PLAINS  
BEFORE SHEARING EASTWARD AROUND THE PERIPHERY OF AN UNUSUALLY  
STRONG EARLY SEASON SUB-TROPICAL RIDGE FORECAST TO DEVELOP OVER  
THE SOUTHEAST U.S. WE SHOULD BE ON THE PERIPHERY OF THE UPPER  
RIDGE WITH NEARBY BAROCLINIC ZONE PROBABLY FLUCTUATING AROUND THE  
REGION. SHOULD GET INTO THE WARM SECTOR WED INTO THURSDAY WITH A  
PERIOD OF ABOVE AVERAGE TEMPERATURES. TEMPS AND PRECIP CHANCES  
HEADING INTO NEXT WEEKEND WILL HINGE ON THE EXACT PLACEMENT OF  
THIS BOUNDARY, WHICH IS GOING TO BE VERY HARD TO PIN DOWN WITH  
MUCH CERTAINTY THIS FAR OUT.  
 
- IZZI  
 

 
   
AVIATION
 
 
FOR THE 18Z TAFS...  
 
SCATTERED SHRA/ISOLD TSRA WILL CONTINUE ACROSS THE REGION WITH  
MOST LIKELY TIMING AT IMMEDIATE TERMINALS BETWEEN 20-21Z. GUSTY  
SOUTHWEST WINDS LIKELY THIS AFTERNOON WITH HIGHER GUSTS IN STORMS,  
POTENTIALLY BRIEFLY OVER 40KT. COLD FRONT WILL SWEEP ACROSS THE  
TERMINALS THIS AFTERNOON BRING AN END TO THE TSRA THREAT. IN THE  
WAKE OF THE FRONT, TRAILING REGION OF WRAP AROUND CLOUDINESS,  
INCLUDING A LARGE AREA WILL PIVOT INTO THE TERMINAL AREA TONIGHT,  
WITH WINDS GRADUALLY SUBSIDING. LAKE BREEZE WILL LIKELY DEVELOP  
MONDAY AFTERNOON AND MOVE ACROSS THE CHICAGO TERMINALS.  
 
- IZZI  
 

 
   
LOT WATCHES/WARNINGS/ADVISORIES
 
 
IL...NONE.  
IN...NONE.  
LM...GALE WARNING...NEARSHORE WATERS UNTIL 6  
PM SUNDAY.  
 

 
 

 
 
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