765  
FXUS63 KABR 240304  
AFDABR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ABERDEEN SD  
904 PM CST TUE JAN 23 2018  
   
UPDATE
 
 
ISSUED AT 903 PM CST TUE JAN 23 2018  
 
HAVE SLOWED DOWN THE ONSET OF FOG, AND SHIFTED IT FARTHER EAST, GIVEN  
THE SLOW MOVEMENT OF THE UPSTREAM LOW CLOUDS AND FOG AND MODEL  
GUIDANCE. OTHERWISE, FEW ADDITIONAL CHANGES WERE NEEDED TO THE  
ONGOING FORECAST.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH WEDNESDAY AFTERNOON)  
ISSUED AT 317 PM CST TUE JAN 23 2018  
 
THE FORECAST CHALLENGE TONIGHT INTO WEDNESDAY WILL BE WHETHER OR NOT  
FOG AND/OR LOW STRATUS FORMS OVER THE CWA FOR A THIRD CONSECUTIVE  
NIGHT, AND ITS IMPACTS ON TEMPERATURE.  
 
CURRENTLY, TEMPERATURES ARE HOLDING IN THE 20S ACROSS THE EASTERN  
THIRD OF THE CWA, WHERE LOW STRATUS CLOUDS AND PATCHES OF FOG  
PERSIST. THE SUN IS SHINING THROUGH SOME HIGH CLOUDS ACROSS THE  
WESTERN TWO-THIRDS OF THE CWA, WHERE TEMPERATURES ARE WARMING INTO  
THE 30S AND 40S.  
 
THE HIGH CLOUDS ARE ASSOCIATED WITH AN UPPER LEVEL WAVE WORKING  
THROUGH THE REGION. ONCE THAT WAVE/CLOUDINESS MOVES SOUTHEAST OF THE  
REGION, ANOTHER CLEAR SKY NIGHT ON LIGHT (ALBEIT WESTERLY COMPONENT)  
WINDS WILL BE IN PLAY. AND, THERE WILL PROBABLY BE ADEQUATE LOW  
LEVEL MOISTURE STILL AROUND TONIGHT IN THE NOCTURNAL BOUNDARY LAYER  
TO AIDE IN MORE FOG OR LOW STRATUS DEVELOPMENT, ESPECIALLY WITHIN  
AND BETWEEN THE MISSOURI AND JAMES RIVER VALLEYS AND UP ON THE  
PRAIRIE COTEAU. EAST OF THE COTEAU MAY END UP BEING MORE STRATUS  
THAN FOG. SINCE THERE IS SUPPORT FROM THE RAP IN BUFKIT, ALONG WITH  
SEVERAL OTHER NUMERICAL GUIDANCE DATA SETS, OPTED TO STICK WITH FOG  
MENTION IN THE WEATHER GRIDS FOR TONIGHT INTO THE FIRST HALF OF THE  
DAY WEDNESDAY. SIMILAR TO LAST NIGHT, TEMPERATURES SHOULD NOT DROP  
OFF MUCH MORE THAN PERHAPS 5 TO 10 DEGREES UNDERNEATH CLOUDY AREAS  
TONIGHT. CLEAR AREAS MAY BE ABLE TO DROP CLOSER TO 15 TO 20 DEGREES  
BEFORE STABILIZING IN FOG/STRATUS ENVIRONMENT, WITH A SLOW  
TEMPERATURE REBOUND EXPECTED ON WEDNESDAY, IF FOG/STRATUS TONIGHT  
PANS OUT.  
   
LONG TERM
 
(WEDNESDAY EVENING THROUGH TUESDAY)  
ISSUED AT 317 PM CST TUE JAN 23 2018  
 
WHEN THE PERIOD OPENS WEDNESDAY NIGHT, A LARGE UPPER LEVEL RIDGE OF  
HIGH PRESSURE IS BEGINNING TO BUILD INTO THE REGION. BY FRIDAY  
MORNING, THE UPPER RIDGE HAS SHIFTED EAST AND IS BEING REPLACED BY A  
LARGE/BROAD UPPER LEVEL TROUGH OF LOW PRESSURE. BY SUNDAY MORNING,  
WE'RE RIGHT BACK WHERE WE STARTED WHEN THE PERIOD OPENED, WITH  
ANOTHER UPPER LEVEL RIDGE TRYING TO BUILD INTO THE REGION FROM THE  
WEST. HOWEVER, THE 12Z GSM DETERMINISTIC SOLUTIONS ALL AGREE TODAY  
ON THIS NEXT UPPER LEVEL RIDGE BEING SUPPRESSED WHILE IT WORKS INTO  
THE MIDDLE OF THE COUNTRY AND FOR A BRIEF PERIOD HEADING INTO DAY 7,  
THERE COULD ACTUALLY BE NEARLY ZONAL FLOW OVER THE REGION.  
 
IN THIS CONTINUED PROGRESSIVE PATTERN OF RIDGE/TROF/NEARLY ZONAL  
FLOW, THE FORECAST IS STILL BASICALLY A DRY FORECAST. THE WARMING  
TREND STILL SHOWS UP IN THE DETERMINISTIC LOW LEVEL THERMAL PROGS AS  
WELL AS ENSEMBLE GUIDANCE THROUGH FRIDAY. THE ONSET OF THE BROAD  
LONGWAVE UPPER TROF STILL PROGS A COLD FRONTAL PASSAGE THROUGH THE  
CWA LATE IN THE WEEK, WITH TEMPERATURES COOLING BACK DOWN TO NEAR,  
OR PERHAPS JUST BELOW, CLIMO NORMAL FOR THE WEEKEND. THE SUPPRESSED  
RIDGE/NEARLY ZONAL FLOW SET-UP FOR EARLY NEXT WEEK POTENTIALLY  
USHERS A QUICK TURN AROUND BACK INTO SOME WELL ABOVE CLIMO NORMAL  
TEMPERATURES BY TUESDAY.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)  
ISSUED AT 534 PM CST TUE JAN 23 2018  
 
CONFIDENCE IS GROWING THAT ABR WILL JOIN ATY IN THE IFR CATEGORY  
BY AROUND 06Z TONIGHT AS ADDITIONAL LOW LEVEL MOISTURE SINKS SOUTH  
FROM ND. MBG WILL BE ON THE WESTERN EDGE OF THIS LOW CLOUD/FOG  
FIELD, AND AM LESS CONFIDENT THAT IT WILL OCCUR. TOOK OUT MUCH OF  
THE FOG POTENTIAL AT PIR FOR NOW, BUT IT MAY BE ABLE TO SLIP IN  
AROUND 09Z WEDNESDAY. WINDS SHOULD BE AROUND OR BELOW 10KTS  
THROUGH THE PERIOD.  
 

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

 
 

 
 
UPDATE...KF  
SHORT TERM...DORN  
LONG TERM...DORN  
AVIATION...KF  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SD Page
The Nexlab MN Page Main Text Page