706  
FXUS63 KDVN 212059  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
259 PM CST SAT DEC 21 2024  
   
KEY MESSAGES  
 
- CONFIDENCE IS INCREASING IN A LIGHT ICING EVENT LATE SUNDAY  
NIGHT INTO MONDAY MORNING WITH POTENTIAL IMPACTS TO THE MONDAY  
MORNING COMMUTE.  
 
- WARMING TEMPERATURES WILL BE SEEN THE REMAINDER OF NEXT WEEK  
WITH SEVERAL CHANCES FOR RAIN WITH A LITTLE SNOW.  
 
- THE POTENTIAL IS INCREASING FOR AN ARCTIC OUTBREAK SHORTLY  
AFTER THE START OF THE NEW YEAR FOLLOWED BY COLDER THAN NORMAL  
TEMPERATURES THROUGH MID-JANUARY. REFER TO THE CLIMATE  
SECTION FOR MORE INFORMATION.  
 
 
   
SHORT TERM /THROUGH SUNDAY/  
 
ISSUED AT 255 PM CST SAT DEC 21 2024  
 
QUIET AND COLD CONDITIONS WILL PREVAIL THROUGH SUNSET SUNDAY.  
TEMPERATURES WILL BE A BIT WARMER ON SUNDAY. ATTENTION THEN TURNS TO  
THE APPROACHING CLIPPER SYSTEM.  
 
 
   
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/  
 
ISSUED AT 255 PM CST SAT DEC 21 2024  
 
SUNDAY NIGHT INTO MONDAY  
ASSESSMENT...MEDIUM TO HIGH CONFIDENCE ON A LIGHT ICING EVENT  
 
THE NEXT STORM SYSTEM WILL MOVE QUICKLY THROUGH THE AREA LATE SUNDAY  
NIGHT INTO MONDAY MORNING. FAVORABLE FORCING POINTS TO A QUICK SHOT  
OF PRECIPITATION. ATMOSPHERIC PROFILES SHOW A NARROW LAYER OF  
MOISTURE WITH MUCH DRIER AIR ALOFT. WITH THE LOWEST LAYER OF THE  
ATMOSPHERE AT OR A BIT BELOW FREEZING THE OVERALL SCENARIO LOOKS  
RIPE FOR A DRIZZLE/FREEZING DRIZZLE EVENT MIXED WITH SOME SNOW.  
 
THE AREA MOST FAVORED FOR FREEZING DRIZZLE WILL BE OVER THE SNOW  
FIELD, ROUGHLY NORTH OF A LINE FROM WATERLOO, IA TO KEWANEE, IL.  
SOUTH OF THAT LINE SOME FREEZING DRIZZLE IS POSSIBLE BUT WITH  
TEMPERATURES MARGINALLY WARMER, IT WILL BE SPOTTY IN COVERAGE.  
 
THE TIME FRAME FAVORABLE FOR ANY FREEZING DRIZZLE LOOKS TO BE FROM  
12 AM TO 9 AM ON MONDAY. AMOUNTS LOOK TO BE LESS THAN 0.05 INCHES OF  
GLAZE.  
 
AS TEMPERATURES SLOWLY RISE ON MONDAY, ANY GLAZE THAT OCCURRED  
OVERNIGHT WILL SLOWLY MELT.  
 
MONDAY NIGHT THROUGH SATURDAY  
ASSESSMENT...HIGH CONFIDENCE ON AN ACTIVE WEATHER PATTERN. LOW  
CONFIDENCE ON POTENTIAL IMPACTS.  
 
AFTER A QUIET MONDAY NIGHT AND TUESDAY, AN ACTIVE WEATHER PATTERN  
WILL CONTINUE THE REMAINDER OF THE WEEK WITH SEVERAL CHANCES FOR  
PRECIPITATION.  
 
THE GLOBAL MODELS VARY ON TIMING AND TRACK OF THE SYSTEMS. HOWEVER,  
THE MORE FAVORED TIME PERIODS FOR PRECIPITATION LOOK TO BE TUESDAY  
NIGHT INTO WEDNESDAY AND THURSDAY NIGHT INTO FRIDAY. IN BETWEEN  
THESE TIME FRAMES ADDITIONAL UPPER LEVEL DISTURBANCES ALOFT WILL BE  
MOVING THROUGH THE AREA THAT MAY RESULT IN SPOTTY PRECIPITATION.  
WITH THE WARMING TEMPERATURES, RAIN IS THE FAVORED PRECIPITATION.  
 
WHERE THE SIGNAL IS BETTER FOR PRECIPITATION, THE MODEL CONSENSUS  
HAS A 20-40% CHANCE FOR RAIN TUESDAY NIGHT/WEDNESDAY AND THURSDAY  
NIGHT INTO FRIDAY. THERE IS MAINLY A 15-30% CHANCE FOR RAIN  
WEDNESDAY NIGHT/THURSDAY AND AGAIN FRIDAY NIGHT INTO SATURDAY.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/  
 
ISSUED AT 1125 AM CST SAT DEC 21 2024  
 
VFR CONDITIONS THROUGH 00Z/22 AS HIGH PRESSURE SLOWLY MOVES INTO  
THE EASTERN GREAT LAKES.  
 
 
   
CLIMATE  
 
ISSUED AT 255 PM CST SAT DEC 21 2024  
 
OVERALL THE MJO HAS BEEN ACTIVE SINCE EARLY DECEMBER. NOW  
A LOW FREQUENCY BASE STATE IS CONSTRUCTIVELY INTERFERING THAT IS  
AFFECTING THE PROPAGATION/MAGNITUDE OF THE MJO. THIS SIGNAL IS  
CONSISTENT WITH LA NINA.  
 
THE MJO HAS BEEN IN PHASE 5 FOR THE ABOUT A WEEK WHICH IS  
FAVORABLE FOR WARMER THAN NORMAL TEMPERATURES. THE MJO IS  
FORECAST TO POTENTIALLY AMPLIFY AS IT MOVES TOWARD THE  
INTERNATIONAL DATE LINE IN THE PACIFIC INTO EARLY JANUARY BUT  
CONSTRUCTIVE INTERFERENCE FROM LA NINA MAY SLOW THE EASTWARD  
PROPAGATION. THE MJO IS FORECAST TO MOVE INTO PHASE 6 AND  
EVENTUALLY THROUGH PHASE 7 AND INTO PHASE 8 BY EARLY JANUARY  
AND POSSIBLY INTO PHASE 1 BY MID-JANUARY. WHILE THE CORRELATION  
IS NOT HIGH, PHASES 6 AND 7 CORRELATES TO WARMER THAN NORMAL  
TEMPERATURES WHILE PHASES 8 AND 1 CORRESPONDS TO COLDER THAN  
NORMAL TEMPERATURES. PRECIPITATION WISE, THE CORRELATIONS ARE  
LOWER THAN TEMPERATURES BUT POINT TO DRIER THAN NORMAL  
CONDITIONS.  
 
STRATOSPHERIC WINDS HAVE BEEN QUITE STRONG AROUND THE ARCTIC  
CIRCLE WHICH IS KEEPING THE POLAR VORTEX IN PLACE. HOWEVER, THE  
AVERAGE OF THE GEFS/GEPS ENSEMBLES ALONG WITH THE DETERMINISTIC  
GFS ARE INDICATING THE MEAN ZONAL WIND AT 10 HPA IN THE  
STRATOSPHERE WILL SIGNIFICANTLY WEAKEN LATE NEXT WEEK WHICH WILL  
CONTINUE INTO EARLY JANUARY. AT THE SAME TIME THE 10 HPA  
TEMPERATURES ARE FORECAST TO WARM. HOWEVER, THE AMOUNT OF  
WARMING IS AROUND 5 KELVIN WHICH IS NOT SUPPORTIVE OF A SUDDEN  
STRATOSPHERIC WARMING EVENT.  
 
THE WEAKENING OF THE 10 HPA ZONAL WINDS DOES POINT TO A  
POTENTIAL BREAK DOWN WITH THE POLAR VORTEX FROM THE ARCTIC  
CIRCLE AND AN INTRUSION INTO THE LOWER LATITUDES.  
 
OUTPUT FROM THE GEFS ENSEMBLES SHOW THE MEAN TURNING NEGATIVE  
FOR THE NAO/AO WHILE THE PNA REMAINS SLIGHTLY POSITIVE. THERE  
IS A LARGE SPREAD IN THE ENSEMBLE MEMBERS ON WHAT THE NAO/AO  
WILL DO WHILE PNA SPREAD IS MUCH TIGHTER.  
 
TAKING THIS ALL TOGETHER POINTS TO A POTENTIAL ARCTIC OUTBREAK  
ASSOCIATED WITH A PATTERN CHANGE ALOFT SHORTLY AFTER NEW YEARS.  
THIS PATTERN CHANGE TO A NORTHWEST FLOW POINTS TO COLDER THAN  
NORMAL TEMPERATURES ALONG WITH THE POTENTIAL FOR DRIER THAN  
NORMAL CONDITIONS.  
 
THE CLIMATE PREDICTION CENTER OUTLOOK CORRESPONDS WELL WITH THE  
ABOVE DATA, SIGNALING A 60-70% PROBABILITY OF COLDER THAN  
NORMAL TEMPERATURES THROUGH THE MIDDLE OF JANUARY ALONG WITH A  
55-60% PROBABILITY OF DRIER THAN NORMAL CONDITIONS ACROSS THE  
MIDWEST.  
 
 
   
DVN WATCHES/WARNINGS/ADVISORIES  
 
IA...NONE.  
IL...NONE.  
MO...NONE.  
 
 
 
 
 
SHORT TERM...08  
LONG TERM...08  
AVIATION...08  
CLIMATE...08  
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