987  
FXUS63 KDVN 192341  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
541 PM CST THU JAN 19 2017  
   
..AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 330 PM CST THU JAN 19 2017  
 
18Z SURFACE DATA HAS HIGH PRESSURE OVER THE OHIO VALLEY WITH A WEAK  
LOW NEAR KMEM. DEW POINTS WERE IN THE 30S FROM THE GREAT LAKES INTO  
THE CENTRAL PLAINS. DEW POINTS IN THE 40S AND HIGHER RAN FROM THE  
OHIO VALLEY INTO THE SOUTHERN PLAINS TO THE GULF COAST.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 330 PM CST THU JAN 19 2017  
 
A BAND OF LIGHT TO MODERATE RAIN WILL CONTINUE MOVING NORTH THROUGH  
THE AREA THROUGH SUNSET. THE RELATIVELY HEAVIER RAINFALL WILL BE  
ALONG AND EAST OF THE MISSISSIPPI.  
 
AFTER SUNSET, THE QUESTION BECOMES HOW MUCH MORE RAIN WILL DEVELOP  
AS THE UPPER LEVEL DISTURBANCE ROTATES NORTH INTO THE GREAT LAKES.  
GIVEN HOW SATURATED THE ATMOSPHERE IS, IT WILL NOT TAKE MUCH FORCING  
TO GENERATE RAIN.  
 
THE UNSTABLE AIR ALOFT SUGGESTING ISOLATED THUNDERSTORMS IS MORE  
STABLE THAN FORECAST AND THE FORCING IS WEAK. THUS IT NOW APPEARS  
THE THREAT OF ISOLATED THUNDERSTORMS IS NEAR ZERO.  
 
RAIN WILL END FROM SOUTH TO NORTH DURING THE EVENING AND WINDS WILL  
BECOME LIGHT. FOG/DRIZZLE WILL INCREASE IN AREAL COVERAGE DURING THE  
EVENING AND OVERNIGHT HOURS.  
 
GIVEN THE LIGHT WINDS, WET GROUND, AND HIGH MOISTURE CONTENT OF THE  
ATMOSPHERE, A DENSE FOG ADVISORY WILL BE ISSUED FOR MOST OF THE AREA  
TONIGHT INTO FRIDAY MORNING.  
 
PATCHY DRIZZLE AND FOG ARE EXPECTED TO PERSIST INTO FRIDAY AFTERNOON  
DUE TO THE SATURATED ATMOSPHERE AND VERY WEAK LIFT. TEMPERATURES  
TONIGHT/FRIDAY WILL CONTINUE TO AVERAGE ABOVE NORMAL. ..08..  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH NEXT THURSDAY)  
ISSUED AT 330 PM CST THU JAN 19 2017  
 
FRIDAY NIGHT...WITH THE AREA ON THE LEESIDE OF MO RVR WAVE AND  
CONVERGENT SOUTHWESTERLY CYCLONIC FLOW PIVOTING NORTH ACRS THE LOCAL  
AREA, ADDING SUPPORT/LIFT TO WRING OUT SOME PRECIP ESPECIALLY THE  
FIRST HALF OF THE NIGHT/MIDNIGHT. BUT FCST VERTICAL PROFILES/  
SOUNDINGS CONTINUE TO SHOW DRY MID LAYERS ABOVE H85 MB AND THUS  
MAINLY DRIZZLE SOUNDINGS OR A VERY FINE LIGHT RAIN IN SPOTS. ALSO  
WITH ANY LINGERING EASTERLY TO SOUTHEASTERLY COMPONENT TO SFC WINDS,  
SEE AREAS OF FOG CONTINUING WELL INTO THE NIGHT. TEMPS MAY NOT DROP  
OFF THAT MUCH FROM LATE FRI AFTERNOON VALUES OR HOLD STEADY  
OVERNIGHT.  
 
SATURDAY AND SUNDAY...LATEST RUN MEDIUM RANGE MODELS SUGGEST THE DVN  
CWA TO BE STUCK IN THE MIDDLE OF A COMPLEX UPPER AIR PATTERN AND  
MOSTLY IN-BETWEEN WEATHER-MAKING LOWS PIVOTING AROUND EACH OTHER  
THROUGH THE MID CONUS THIS WEEKEND. SATURDAY STILL IN LINE TO BE A  
VERY MILD DAY, AND WITH A FEW BREAKS IN THE OVERCAST FROM TIME TO  
TIME, BOTH THE GFS AND ECMWF SUGGEST MUCH OF THE CWA TO BE WELL UP  
IN THE 50S. INCREASING WEST TO NORTHWEST FLOW TO ADVECT SOMEWHAT  
LOWER THICKNESSES ACRS THE REGION INTO SUNDAY, KNOCKING HIGHS BACK  
INTO THE 40S. WILL HAVE TO KEEP NUISANCE LOW POPS AT TIMES IN THE  
FAR NORTH AND EAST LATE SUNDAY INTO EARLY MONDAY FOR CONSISTENCY/  
MATCH UP PURPOSES.  
 
MONDAY THROUGH NEXT THURSDAY...AFTER A BOUT OF EARLY WEEK RIDGING  
WITH CONTINUED ABOVE NORMAL TEMPS, EYES WILL FOCUS ON THE NEXT MAIN  
WAVE ROLLING OUT ACRS THE MIDWEST TUE INTO WED. MANY DETAILS ON HOW  
FAR NORTH OR SOUTH THIS LOW PROPAGATES STILL TO BE WORKED OUT UNTIL  
THEN, AS WELL AS RESULTANT THERMAL PROFILES FOR PRECIP TYPES AND  
AMOUNTS. ..12..  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 537 PM CST THU JAN 19 2017  
 
GENERALLY IFR/LIFR/MVFR CONDITIONS TO PREVAIL THE NEXT 24 HOURS DUE  
TO MOIST SOUTHEAST FLOW AND PASSING UPPER DISTURBANCES PRODUCING PERIODS  
OF LIGHT RAIN AND DRIZZLE. EPISODES OF VLIFR CONDITIONS LIKELY LATE  
EVENING INTO MID MORNING HOURS AT ALL TERMINALS AT OR BELOW AIRPORT  
FLIGHT MINIMUMS.  
 

 
   
HYDROLOGY
 
 
ISSUED AT 330 PM CST THU JAN 19 2017  
 
ROCK RIVER: FLOOD WARNINGS FOR MODERATE FLOODING CONTINUE AT JOSLIN  
AND MOLINE. AT MOLINE, THE RIVER MAY BE NEAR CREST NOW JUST UNDER  
THE MAJOR FLOOD STAGE. THERE IS STILL SOME UNCERTAINTY IN ROUTED  
WATER FLOW TOWARD THIS SITE FROM THE GREEN RIVER, MAKING FOR ONGOING  
CONCERNS THAT THIS LOCATION MAY STILL RISE ABOVE THE MAJOR FLOOD  
STAGE. ALSO, MORE RAINFALL TODAY AND TONIGHT, ALONG WITH ICE  
MOVEMENT IN THE RIVER MAY CAUSE RAPID FLUCTUATIONS IN THE STAGE AT  
THIS LOCATION.  
 
MISSISSIPPI RIVER: THE LATEST RIVER STAGE TRENDS INDICATE THAT RIVER  
LEVELS CONTINUE TO RISE SLOWLY AT BOTH SITES(GLADSTONE AND  
BURLINGTON) THAT ARE IN MODERATE AND MAJOR FLOOD RESPECTIVELY.  
INCREASED FLOW FROM RUNOFF FROM RECENT RAINFALL AS WELL AS NEW  
RAINFALL TONIGHT, AND THE ONGOING ICE JAM DOWNSTREAM OF BURLINGTON,  
WILL LIKELY LEAD TO AT LEAST MINOR ADDITIONAL RISES ON THE  
MISSISSIPPI IN THESE AREAS THROUGH FRIDAY NIGHT. THE WATCH FOR THE  
EVENTUAL EROSION OF THE ICE JAM CONTINUES, AND ONCE THE ICE JAM  
GIVES WAY, EXPECT THE LEVELS IN THE RIVER AROUND THE AFFECTED SITES  
IN FLOOD TO DROP NOTICEABLY.  
 
OTHER SITES: RECENT AND FORECAST RAINFALL/RUN-OFF, COMBINED WITH ICE  
ACTION IS ALSO PRODUCING RISES TO OR NEAR THE FLOOD STAGE AT SOME  
SITES ON THE IOWA RIVER IN IOWA. ON THE LOWER GREEN RIVER IN IL, AN  
AREAL FLOOD WARNING CONTINUES FOR NOW WHILE AREA OFFICIALS MONITOR  
FLOODING IMPACTS ALONG THIS STRETCH OF RIVER AND ASSOCIATED HIGH  
WATER ENHANCEMENT/FLOODING ON PORTIONS OF THE HENNEPIN CANAL...BUT  
SOME RECENT THOUGHTS ARE THAT IT MAY BE ALLOWED TO EXPIRE THIS  
AFTERNOON.  
 
WITH THE ONGOING MILD WEATHER AND MORE RAINFALL FORECAST, AREA  
RIVERS IN GENERAL WILL STILL HAVE TO BE WATCHED INTO THE START OF  
THE WEEKEND FOR MORE ICE ACTION AND JAMS POSSIBLY PRODUCING  
ADDITIONAL FLOODING. ..12..  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...DENSE FOG ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY FOR  
BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-JACKSON-  
JOHNSON-JONES-LINN-LOUISA-MUSCATINE-SCOTT.  
 
DENSE FOG ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST FRIDAY  
FOR DES MOINES-HENRY IA-IOWA-JEFFERSON-KEOKUK-LEE-VAN BUREN-  
WASHINGTON.  
 
IL...DENSE FOG ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST FRIDAY FOR  
HENRY IL-MERCER-ROCK ISLAND.  
 
DENSE FOG ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST FRIDAY  
FOR HANCOCK-HENDERSON-MCDONOUGH-WARREN.  
 
MO...DENSE FOG ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST FRIDAY  
FOR CLARK-SCOTLAND.  
 

 
 

 
 
SYNOPSIS...08  
SHORT TERM...08  
LONG TERM...12  
AVIATION...NICHOLS  
HYDROLOGY...12  
 
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