368  
FXUS63 KDMX 021738  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
1140 AM CST FRI DEC 2 2016  
   
SHORT TERM
 
/TODAY THROUGH TONIGHT/  
ISSUED AT 412 AM CST FRI DEC 2 2016  
 
WEAK CYCLONIC FLOW CONTINUES TO SUBSIDE AS UPPER SYSTEM MOVES UP  
THE ST. LAWRENCE RIVER VALLEY. STRATUS WILL CONTINUE TO HANG  
TOUGH AS RIDGE AXIS REMAINS JUST WEST OF THE FORECAST AREA FOR  
MUCH OF TODAY. THERE MAY BE A FEW MORE BREAKS IN THE OVERCAST AS  
THE SHALLOW MOIST LAYER CONTINUES TO SHRINK AND SOME PARTIAL  
SUNSHINE IS EXPECTED IN THE SOUTH AND WEST TODAY CLOSEST TO THE  
RIDGE AXIS. TEMPERATURES WILL CLIMB TOWARD THE LOW 40S IN THE  
SOUTH WHERE THE INSOLATION WILL HELP BY AFTERNOON ALTHOUGH LOW 30S  
WILL PERSIST IN THE NORTH UNDER THE THICKER STRATUS AND CLOSE  
PROXIMITY TO THE THERMAL TROF. RIDGE WILL SLIDE ACROSS CENTRAL  
IOWA TONIGHT WITH LIGHT WINDS AND THE CONTINUED SHRINKING OF  
STATUS. TEMPERATURES WILL ALSO BE COOLER TONIGHT AS THE LIGHT  
WINDS AND ADDITIONAL CLEARING SHOULD ENHANCE RADIATIONAL COOLING  
ALLOWING READINGS TO DROP INTO THE 20S OVERNIGHT.  
   
LONG TERM
 
/SATURDAY THROUGH THURSDAY/  
ISSUED AT 412 AM CST FRI DEC 2 2016  
 
LIGHT SNOW ACCUMULATIONS FOR SATURDAY NIGHT AND BIG DROP IN  
TEMPERATURES BY MID-WEEK ARE STILL ON TRACK AND WERE THE MAIN  
FOCUS DURING THE EXTENDED PERIOD. SOME CONTINUITY BEGINNING TO  
SHOW UP BETWEEN THE ECMWF ANY GFS TUESDAY INTO THURSDAY WRT TO  
SNOW POTENTIAL, BUT BOTH DO AGREE ON THE ABNORMALLY COLD  
TEMPERATURES DURING THIS TIME. LEANED SLIGHTLY CLOSER TO THE GFS  
AS IT HAS BEEN THE MOST CONSISTENT WITH ITS RESPECTIVE SOLUTION.  
 
SATURDAY INTO MONDAY...UPPER LEVEL SHORTWAVE QUICKLY EJECTS OUT OF  
THE CENTRAL ROCKIES SATURDAY AND PUSHES INTO WESTERN IOWA BY THE  
LATE AFTERNOON HOURS SATURDAY. SOUNDINGS TAKE A LITTLE TIME  
BECOMING COMPLETELY SATURATED UP TO AROUND 500MB BUT WITH THE  
DECENT FORCING MOVING ACROSS THE STATE BETWEEN 03-12Z SUNDAY, THIS  
SHOULD HELP SATURATE THE SURFACE LAYER TO ALLOW FOR SNOW TO  
DEVELOP OVERNIGHT. SURFACE TEMPERATURES REMAIN NEAR FREEZING OR  
SLIGHTLY WARMER, BUT BELIEVE THERE IS ENOUGH OMEGA WITHIN THE  
DENDRITIC LAYER TO OVERCOME THE MELTING AT THE SURFACE. THUS, THE  
CENTRAL TO SOUTHEAST SHOULD SEE AN INCH OR TWO OF SNOW BY SUNRISE  
SUNDAY AND POTENTIALLY MORE IF THE PRECIPITATION STAYS ALL RAIN.  
THE TIME OF DAY SHOULD ALSO HELP ACCUMULATIONS AS THE BEST FORCING  
AND DEEP MOISTURE OVER THE AREA ARE BETWEEN 06-12Z SUNDAY. NOT  
CONFIDENT IN THE BULLISH NAM INDICATING ADVISORY LEVEL SNOW  
AMOUNTS IN THE SOUTHEAST, PER OTM BUFKIT SOUNDING. HOWEVER, THIS  
LOCATION HASN'T SEEN MUCH WINTER PRECIPITATION YET THIS SEASON AND  
A HEADLINE MIGHT BE NEEDED FOR IMPACTS. SYSTEM QUICKLY MOVES EAST  
AND HAVE CUT BACK ON POPS AFTER 18Z SUNDAY. FINALLY, AT LEAST THE  
WESTERN HALF OF THE STATE SHOULD SEE SOME SUNSHINE SUNDAY  
AFTERNOON. SOME WEAK DOWNSLOPE WINDS DEVELOP SUNDAY AFTERNOON AND  
WITH THE CLEARING SKIES, NUDGED UP MAXIMUM TEMPERATURES ACROSS THE  
WEST.  
 
ANOTHER WARM DAY ANTICIPATE ON MONDAY WITH SURFACE HIGH PRESSURE  
OVERHEAD. TRENDED DRIER MONDAY NIGHT OVER MUCH OF THE FORECAST AREA  
EXCEPT THE FAR NORTHWEST AND SOUTHEAST CORNERS OF THE CWA. THE  
NORTHWEST POPS ARE DUE TO AN APPROACHING COLD AND THE SOUTHEAST  
ARE DUE TO A STRONG UPPER LOW TRACKING ACROSS THE TENNESSEE  
VALLEY WHERE THIS LOCATION MAY GET CLIPPED ON THE NORTHWEST SIDE  
OF THE LOW. HOWEVER, THE TRENDS CONTINUE TO SHIFT THIS SYSTEM  
FURTHER SOUTHEAST AND LIKELY TO MISS THE FORECAST AREA ALTOGETHER  
MONDAY NIGHT.  
 
TUESDAY THROUGH THURSDAY...THE ONLY 6-HOUR CONFIDENT DRY PERIOD  
FORECAST FROM 06Z TUESDAY TO 12Z THURSDAY IS WEDNESDAY 06-12Z TIME  
FRAME AS MUCH UNCERTAINTY REMAINS WITH TIMING AND LOCATION OF NEXT  
SYSTEM. THE GFS REMAINS THE FASTER SOLUTION AND BRINGS A STRONG  
TROUGH INTO THE CENTRAL CONUS AND SURFACE LOW TO IMPACT THE STATE  
DURING THE DAY WEDNESDAY INTO WENDESDAY NIGHT. THE ECMWF IS  
FURTHER SOUTH AND SLOWER WITH TRACK. CURRENTLY, THE TREND OF THE  
EXTENDED MODELS IS TO TRACK THE LOW SOUTH OF THE STATE AND IMPACT  
THE SOUTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY INTO  
WEDNESDAY NIGHT.  
 
HIGH CONFIDENCE IN THE UNSEASONABLY COLD TEMPERATURES TO FILTER INTO  
THE REGION WEDNESDAY AND PERSIST THROUGH THE END OF THE WORK WEEK.  
LOWERED TEMPERATURES WEDNESDAY INTO THURSDAY A 2-4 DEGREES AS 850MB  
TEMPERATURES DROP TO -15 TO -20C AND THE 504-508DAM (1000-500MB)  
THICKNESS LINE CREEPS INTO THE STATE BY THURSDAY. ALSO, STOUT  
NORTHWEST WINDS BY THURSDAY MORNING LOOK TO CAUSE MUCH OF THE  
FORECAST AREA WITH SUB-ZERO WIND CHILL VALUES.  
 

 
   
AVIATION
 
/FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON/  
ISSUED AT 1140 AM CST FRI DEC 2 2016  
 
CEILINGS HANG TOUGH IN IA AND WILL REMAIN LARGELY MVFR WITH PERIODS  
OF HIGHER CIG HEIGHTS BUT AFTER 03Z SHOULD BE SOLIDLY MVFR. BRIEF  
IMPROVEMENT SATURDAY MORNING TO THE END OF THE FORECAST PERIOD AHEAD  
OF THE NEXT SYSTEM. SFC WINDS WILL BE NW THEN SWITCH TO THE SW OR W  
TOWARDS 03/18Z.  
 

 
   
DMX WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
SHORT TERM...COGIL  
LONG TERM...PODRAZIK  
AVIATION...FAB  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab IA Page Main Text Page