425  
FXUS63 KDVN 290445  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
1145 PM CDT SUN MAY 28 2017  
   
..AVIATION UPDATE
 
 
   
UPDATE
 
 
ISSUED AT 617 PM CDT SUN MAY 28 2017  
 
A FEW WEAK SHOWERS AND AN ISOLATED THUNDERSTORM HAVE DEVELOPED  
OVER THE PAST HOUR IN SOUTH CENTRAL IA. THESE WERE AHEAD OF A  
WEAK UPPER LEVEL IMPULSE AND SURFACE TROUGH. AS THE ASSOCIATED  
FORCING APPEARS TO BE MOVING OUT OF AN AXIS OF HIGHER CAPE AND  
THUS BETTER SUPPORT, THESE SHOULD WEAKEN, IF NOT DISSIPATE AS  
THEY ADVANCE EASTWARD INTO SOUTHEAST IA AND FAR NORTHEAST MO EARLY  
THIS EVENING. WILL UPDATE THE FORECAST TO MENTION ISOLATED  
EVENING SHOWERS ALONG AND SOUTH OF THE IA HIGHWAY 34 CORRIDOR.  
 

 
   
SYNOPSIS
 
 
ISSUED AT 356 PM CDT SUN MAY 28 2017  
 
AS FORECAST, THE COLD FRONT EXITED THE CWA EARLY THIS MORNING, WITH  
DRY WEATHER, LOWERING DEWPOINTS, AND HIGHS IN THE MID TO UPPER 70S  
BEHIND IT. THE 10 TO 20 MPH WIND IS ACTUALLY QUITE PLEASANT IN THIS  
TEMPERATURE RANGE, AND AS READINGS COOL OFF THIS EVENING, THE WIND  
WILL ALSO LOWER, THUS, THROUGH SUNSET, IT WILL CONTINUE TO BE AN  
OUTSTANDING DAY.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH MONDAY)  
ISSUED AT 356 PM CDT SUN MAY 28 2017  
 
CLOUDS WILL DECREASE TO CLEAR SKIES AROUND SUNSET TONIGHT, WITH ONLY  
A FEW PATCHES OF MID CLOUDS THROUGH THE NIGHT POSSIBLE IN NORTHWEST  
FLOW. AS THE MIXING DEPTH DECREASES IN THIS PROCESS, WINDS WILL ALSO  
DROP TO UNDER 10 MPH FOR THE REST OF TONIGHT. THE PRESSURE GRADIENT  
WILL KEEP A LIGHT NORTHWEST WIND GOING THROUGH THE NIGHT, AND LOWS  
WILL BE KEPT ABOVE THE CURRENT DEWPOINTS FOR THAT REASON. LOWS OF  
LOWER TO MID 50S ARE SOLIDLY IN THE GUIDANCE BLEND RANGE. MONDAY,  
CONTINUED NORTHWEST FLOW WILL SEND ANOTHER SPOKE OF VORTICITY  
SOUTHWARD, AND THIS MAY ALLOW FOR A SIMILAR UPTICK IN CUMULUS BY  
LATE MORNING, FOLLOWED BY ISOLATED TO SCATTERED SHOWERS. IT SEEMS WE  
WILL BUILD THESE EARLY ENOUGH IN THE DAY TO KEEP THE CHANCES FOR  
THUNDER QUITE LOW, AND HIGHS PROBABLY WILL ONLY TOP OUT IN THE UPPER  
60S NORTH WITH THE EARLY CLOUD ONSET THERE. FARTHER SOUTH, WITH  
MILDER AIR ALOFT, MORE SUN IS EXPECTED, AND HIGHS SHOULD ONCE AGAIN  
REACH THE MID 70S.  
ERVIN  
   
LONG TERM
 
(MONDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 356 PM CDT SUN MAY 28 2017  
 
THE TROF OVER QUEBEC THAT HAS BEEN A MAINSTAY FOR A WHILE WILL  
CONTINUE TO HOLD ON. KEEPING US IN AN ACTIVE WEATHER PATTERN.  
GUIDANCE SUGGESTS THAT THIS WILL CHANGE THE END OF NEXT WEEK AS A  
DEEP TROF MOVES ON SHORE ACROSS THE WESTERN US.  
 
LONG TERM SENSIBLE WEATHER WILL BE A CONTINUATION OF MONDAY WITHOUT  
THE CHANCES FOR PRECIP. THIS IS EXPECTED TO CONTINUE THROUGH AT  
LEAST THURSDAY MORNING, WHEN THE GFS AND GEM SUGGEST A WAVE THROUGH  
THE NORTHWEST FLOW. THIS WAVE WILL HELP TO ADVECT IN DECENT LOW  
LEVEL MOISTURE AND OUR NEXT CHANCE FOR THUNDERSTORMS. GUIDANCE  
SUGGESTS A SUMMERTIME SETUP FOR NOCTURNAL MCS WITH A LLJ AND  
INSTABILITY THURSDAY MORNING THROUGH FRIDAY MORNING. THE TRACK OF  
ANY POTENTIAL MCS WILL LIKELY CHANGE BEFORE THE DAY ACTUALLY COMES.  
THIS IS IMPORTANT TO KEEP IN MIND. IF YOU HAVE SOMETHING TO DO  
WHERE YOU NEED DRY CONDITIONS, GET THEM DONE BEFORE THURSDAY.  
 
INTO THE WEEKEND, THE FLOW BECOMES ZONAL TO SOUTHWEST. THIS WILL  
USHER IN WARMER AND MORE MOIST CONDITIONS AND THE CHANCE FOR SHOWERS  
AND THUNDERSTORMS AGAIN. DIFFERENCES IN MODEL SOLUTIONS LEAD TO LOW  
CONFIDENCE AT THIS TIME. THE GEM AND ECMWF HAVE NW FLOW ACROSS THE  
AREA, WHEREAS THE GFS IS SOUTHWEST WITH A COMPACT WAVE MOVING INTO  
THE AREA.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)  
ISSUED AT 1145 PM CDT SUN MAY 28 2017  
 
CONDITIONS WILL REMAIN VFR OVERNIGHT THROUGH MONDAY. ISOLATED  
SHOWERS OR SPRINKLES WILL BE POSSIBLE WITH WEAK SURFACE FRONTS  
ROTATING THROUGH TONIGHT AND AGAIN MONDAY AFTERNOON. THESE ARE  
EXPECTED TO BE TOO ISOLATED AND LOW IMPACT TO INCLUDE IN THE  
FORECASTS AT THIS TIME. SURFACE WINDS WILL AGAIN INCREASE AND  
BECOME GUSTY FROM MID MORNING THROUGH AFTERNOON, THEN DIMINISH TO  
LESS THAN 10 KNOTS AFTER SUNSET.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 919 PM CDT SUN MAY 28 2017  
 
THE MISSISSIPPI AT BURLINGTON HAS BEEN UPGRADED TO MAJOR CATEGORY  
FLOODING AS FORECAST CONFIDENCE HAS INCREASED THAT LEVELS WILL  
REACH OR EXCEED 18 FEET WEDNESDAY NIGHT OR EARLY THURSDAY MORNING.  
 
OTHERWISE, FLOOD WARNINGS CONTINUE FOR MOST OTHER SITES ALONG THE  
MISSISSIPPI RIVER FOR MINOR TO MODERATE FLOODING. FLOOD WATCHES  
REMAIN IN EFFECT AT BELLEVUE (BLVI4), AND KEOKUK (EOKI4), WHERE  
FORECASTS INDICATE LEVELS REACHING OR JUST EXCEEDING FLOOD STAGE  
THIS WEEK, BUT FORECAST CONFIDENCE IS LOW.  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...NONE.  
IL...NONE.  
MO...NONE.  

 
 

 
 
UPDATE...SHEETS  
SYNOPSIS...ERVIN  
SHORT TERM...ERVIN  
LONG TERM...GIBBS  
AVIATION...SHEETS  
HYDROLOGY...SHEETS  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab IL Page
The Nexlab IA Page
The Nexlab MO Page Main Text Page