609  
FXUS63 KABR 121125 AAA  
AFDABR  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE ABERDEEN SD  
525 AM CST TUE DEC 12 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 359 AM CST TUE DEC 12 2017  
 
THE RIDGE OF HIGH PRESSURE AT THE SFC IS EXITING TO OUR SOUTH EARLY  
THIS MORNING, WITH OUR ATTENTION MOVING TO THE WAVE MOVING ACROSS  
BRITISH COLUMBIA. WHILE THE OVERALL 500MB PATTERN OF 500MB TROUGH  
EAST, AND RIDE OVER THE FAR WESTERN STATES REMAINS, THIS TROUGH WILL  
SINK ACROSS SOUTHERN SASKATCHEWAN EARLY THIS EVENING, AND AND OVER  
THE EASTERN DAKOTAS OVERNIGHT. TAKING A LOOK AT THE SFC PATTERN,  
WARMER AIR LOOKS TO BE THE RULE TODAY. EXPECT HIGHS IN THE 50S TO  
NEAR 60F WEST TO THE UPPER 30S EAST AS A WEAK TROUGH SLOWLY PUSHING  
INTO THE DAKOTAS. THIS WILL BE IN ADVANCE OF THE SFC LOW THAT WILL  
BE SET UP ACROSS SOUTHERN MANITOBA BY 00Z WEDNESDAY. TEMPERATURES  
WILL BE TRICKY TONIGHT, HOVERING NEAR FREEZING, WITH THE POTENTIAL  
TO BE A FEW DEGREES ABOVE FREEZING FOR MUCH OF THE NIGHT. ROAD  
SURFACES MAY BE COOLER, LEADING TO AN ISSUE OF LIGHT MIXED  
PRECIPITATION THAT COULD ACCUMULATE ACROSS FROZEN SURFACES. ANY  
PRECIPITATION THAT DOES FALL PRIOR TO 12Z WEDNESDAY SHOULD BE LIGHT.  
THE MAIN CHANGE IS AN INCREASE TO THE WINDS TONIGHT AS THE SFC LOW  
SHIFTS INTO MN AFTER 06Z. WINDY CONDITIONS WILL BE THE RULE WITH  
WINDS OUT OF THE NORTHWEST GUSTING 35 TO NEAR 45 MPH, ESPECIALLY  
OVER AND WEST OF THE JAMES RIVER VALLEY. INCLUDED THE MENTION OF  
LIGHT ICING, AND INCREASING WINDS IN THE HWO.  
   
LONG TERM
 
(WEDNESDAY NIGHT THROUGH MONDAY)  
ISSUED AT 359 AM CST TUE DEC 12 2017  
 
THE HIGHLY MERIDIONAL PATTERN ACROSS THE CONUS IS EXPECTED TO  
CONTINUE, BUT WITH SOME MODIFICATION. THE LATEST MODELS ARE HINTING  
AT DE-AMPLIFICATION, ALONG WITH A RETROGRESSION OF THE LONG WAVE OVER  
THE CONTINENT. THESE CHANGES COULD EVENTUALLY LEAD TO A COOLER  
FORECAST OVERALL, BUT THAT ISN'T LIKELY TO OCCUR UNTIL A WEEK OR SO  
FROM NOW.  
 
THE MAIN SYSTEMS TO AFFECT THE FORECAST AREA DURING THE PERIOD WILL  
BE ON WEDNESDAY, THURSDAY, AND SOME WEAKER ENERGY FOR THE WEEKEND.  
EACH SYSTEM LOOKS TO PROVIDE AT BEST ONLY LIGHT AMOUNTS OF PCPN. THE  
WEDNESDAY SYSTEM MAY HAVE THE POTENTIAL TO PRODUCE A MIX OF TYPES,  
AT LEAST EARLY ON WEDNESDAY. HOWEVER, CONFIDENCE IN LL THERMAL  
PROGS IS LOW AND WE MIGHT END UP BEING WARMER THAN CURRENTLY  
FORECAST AS MIXING A HEAD OF SOUTHEASTWARD MOVING CLIPPER WILL BE  
GOOD. THIS WILL MEAN THE DIFFERENCE BETWEEN RAIN/SNOW AND SOME  
FREEZING RAIN. THAT SAID MOST OF THE PCPN ON WEDNESDAY IS EXPECTED  
OVER THE NORTHEAST CWA, AND MAINLY IN THE MORNING.  
 
THE SYSTEM FOR THURSDAY SHOULD DELIVER MOSTLY SNOW AS CRITICAL  
THICKNESS AND SOUNDINGS POINT TO THAT PCPN TYPE BEING PREDOMINANT.  
ONCE AGAIN PCPN AMOUNTS ARE EXPECTED TO BE LIGHT. TEMPERATURES  
OVERALL WILL FAVOR NEAR TO ABOVE NORMAL FOR THE PERIOD AS THE AREA  
CONTINUES TO BASK UNDER A RELATIVELY MILD AIRMASS.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)  
ISSUED AT 522 AM CST TUE DEC 12 2017  
 
A BATCH OF MVFR CIGS OVER KABR/KATY WILL GRADUALLY DISSIPATE THIS  
MORNING, LEAVING VFR CONDITIONS REGION-WIDE FOR THE REST OF THE  
DAY. GUSTY WINDS WILL INVADE THE AREA LATE TONIGHT.  
 

 
   
ABR WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
MN...NONE.  

 
 

 
 
SHORT TERM...KF  
LONG TERM...TDK  
AVIATION...TDK  
 
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