133  
FXUS63 KBIS 220006  
AFDBIS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BISMARCK ND  
606 PM CST SAT DEC 21 2024  
   
KEY MESSAGES  
 
- AREAS OF FOG POSSIBLE TONIGHT INTO SUNDAY MORNING.  
 
- FREEZING RAIN EXPECTED ACROSS NORTHWESTERN NORTH DAKOTA ON  
SUNDAY, WITH A WINTRY MIX OF RAIN, FREEZING RAIN, AND SNOW  
POSSIBLE ELSEWHERE.  
 
- A WARMING TREND IS EXPECTED THIS WEEKEND THROUGH EARLY NEXT  
WEEK ACROSS WESTERN NORTH DAKOTA, WITH ABOVE NORMAL  
TEMPERATURES FAVORED STATEWIDE FROM CHRISTMAS EVE THROUGH THE  
END OF THE WEEK.  
 
 
   
UPDATE  
 
ISSUED AT 546 PM CST SAT DEC 21 2024  
 
MOSTLY CLEAR SKIES ACROSS WESTERN AND CENTRAL ND EARLY THIS  
EVENING. THE EXCEPTION BEING LOW STRATUS AND FOG REMAINING  
AROUND THE TURTLE MOUNTAINS IN BOTTINEAU AND ROLETTE COUNTIES.  
WITH SOME REDUCED VISIBILITIES REPORTED EARLY THIS EVENING AT  
BOTTINEAU AND ROLLA, ADDED A MENTION OF PATCHY FOG. OTHERWISE NO  
CHANGES NEED ED TO THE GOING FORECAST.  
 
 
   
DISCUSSION  
 
ISSUED AT 332 PM CST SAT DEC 21 2024  
 
WESTERLY FLOW PATTERN ALOFT WILL CONTINUE THROUGH TONIGHT, WHILE  
A SURFACE HIGH PRESSURE TO OUR NORTH MAINTAINS LIGHT WINDS  
ACROSS THE REGION. OVERALL LOOK FOR MAINLY DRY CONDITIONS  
THROUGH TONIGHT, WITH LOWS IN THE SINGLE DIGITS TO THE NORTH AND  
WARMING INTO THE 20S ACROSS THE SOUTHWEST. SOME LINGERING CLOUD  
COVER WILL ALSO BE FOUND IN THE NORTH AND EAST THROUGH THIS  
EVENING, WITH INCREASING CLOUDS FROM AN APPROACHING CLIPPER  
SYSTEM FOUND LATER TONIGHT. BEFORE THIS SYSTEM ARRIVES, LIGHT  
WINDS AND INCREASED TEMPERATURES WILL BRING THE POTENTIAL FOR  
PATCHY TO AREAS OF FOG TO MUCH OF THE CWA TONIGHT. HI-RES MODELS  
INDICATE THERE COULD BE SOME DENSE FOG AT TIMES TONIGHT PERHAPS  
LINGERING INTO SUNDAY MORNING.  
 
CLIPPER SYSTEM THEN MOVES ACROSS THE STATE SUNDAY MORNING  
THROUGH THE DAY, EXITING SUNDAY EVENING. ENSEMBLES AND  
DETERMINISTIC FORECAST DATA CONSISTENT ON THIS WAVE TAKING MORE  
OF SOUTHWESTERN ND TRACK, ALTHOUGH MODELS INDICATING SOME DECENT  
QG CONVERGENCE ALONG AND NORTH OF THE MISSOURI RIVER. THERE IS  
LIMITED FRONTOGENESIS FORECAST WITH THIS WAVE, THUS LIMITING THE  
BANDING POTENTIAL. THE MAIN CONCERN WITH THIS WAVE WILL BE THE  
FREEZING RAIN POTENTIAL GIVEN THE WARM AIR ALOFT ALREADY IN  
PLACE DURING PASSAGE OF THIS WAVE. FORECAST SOUNDINGS SHOWING  
ANYTHING FROM BRIEF FREEZING FOLLOWED BY SNOW, TO FREEZING  
DRIZZLE OR FREEZING RAIN, TO DRY AIR LIMITING FREEZING RAIN  
UNTIL SATURATION WHEN MAINLY SNOW WOULD TAKE OVER. THUS A WIDE  
RANGE OF UNCERTAINTY REMAINS WITH THIS SYSTEM WHEN IT COMES TO  
PTYPES. THERE IS SOME INCREASING CONFIDENCE THOUGH FOR FREEZING  
RAIN INITIALLY IN THE NORTHWEST STARTING SUNDAY MORNING. 70% OF  
THE CLUSTERS SHOWING LIGHT ICE ACCUMULATION IN THESE AREAS.  
GIVEN THIS SLIGHTLY INCREASED CONFIDENCE AND THE POTENTIAL  
IMPACTS TO HOLIDAY TRAVELERS, WENT WITH A WINTER WEATHER  
ADVISORY FOR NORTHWESTERN NORTH DAKOTA. THE NBM CHANCES FOR  
ACCUMULATING ICE ARE SIMILAR TO CENTRAL AREAS OF NORTH DAKOTA,  
MAINLY ALONG THE HIGHWAY 83 CORRIDOR, ALTHOUGH THERE IS LESS  
CERTAINTY ON FREEZING RAIN VERSUS THE CHANGE OVER TO SNOW IN  
THESE AREAS. THUS LEFT THEM OUT OF THE ADVISORY FOR NOW, AND  
WILL HAVE TO BE MONITORED. MOST OTHER AREAS THAT SEE  
PRECIPITATION WITH THIS WAVE COULD STILL SEE A WINTRY MIX, WITH  
MAINLY RAIN EXPECTED IN THE FAR SOUTHWEST TO SOUTH CENTRAL. THE  
CHANCE FOR A TENTH OF AN INCH OR MORE OF ICE ACCUMULATIONS FROM  
FREEZING RAIN SUNDAY STILL REMAINS BELOW 10% FOR ALL AREAS.  
SNOWFALL WITH THIS SYSTEM ALSO LOOKS TO REMAIN ON THE LIGHT SIDE  
WITH THE CHANCE FOR AN INCH OR MORE ALSO LESS THAN 15%.  
OTHERWISE LOOK FOR CONTINUED MILD TEMPERATURES IN THE WEST  
SUNDAY WITH HIGHS IN THE 30S TO LOWER 40S, WITH 20S ACROSS THE  
EAST. SNOW AND FREEZING RAIN WILL COME TO AN END ACROSS CENTRAL  
AND EASTERN PORTIONS SUNDAY EVENING. LIGHT WINDS AND MILD  
TEMPERATURES COULD PERHAPS PROVIDE SOME FOG SUNDAY NIGHT INTO  
MONDAY MORNING, DEPENDING IF CLOUDS CAN CLEAR OR NOT BEHIND THE  
CLIPPER SYSTEM.  
 
THE HOLIDAY WEEK THEN LOOKS TO BE MAINLY DRY AND MILD ACROSS  
MUCH OF THE CWA. WE SEE THIS PATTERN OF TRANSIENT RIDGE  
FOLLOWED BY WEAK SHORTWAVE TROUGH FOLLOWED BY ANOTHER BRIEF  
RIDGE THIS COMING WEEK, WITH THE WESTERLY FLOW ALOFT PROVIDING  
MILD TEMPERATURES. MONDAY MAY STILL BE SLIGHTLY BELOW NORMAL  
ACROSS EASTERN AREAS. WIDESPREAD HIGH TEMPERATURES IN THE 30S TO  
LOWER 40S ARE THEN EXPECTED TUESDAY THROUGH THE END OF THE  
WEEK, WITH MILD LOWS IN THE MID TEENS TO MID 20S. THIS COULD END  
BEING A MILD CHRISTMAS FOR MANY GIVEN AVERAGE HIGH TEMPERATURES  
ARE GENERALLY IN THE MID 20S WHILE AVERAGE LOW TEMPERATURES ARE  
GENERALLY IN THE MID SINGLE DIGITS. CHANCES FOR PRECIPITATION  
ARE FAIRLY LIMITED AT LEAST THROUGH CHRISTMAS DAY. LATER NEXT  
WEEK CLUSTERS INDICATE A RETURN TO A BROAD TROUGHING PATTERN,  
ALTHOUGH THEY ALSO INDICATE THIS COULD BE A SPLIT WAVE PATTERN,  
LIMITED PRECIPITATION CHANCES. EVEN SO, NBM STILL SHOWING UP TO  
10% CHANCES FOR ACCUMULATING SNOW IN A 24 HOUR PERIOD TO END THE  
HOLIDAY WEEK INTO THE THE UPCOMING WEEKEND. ALTHOUGH NOT LARGE  
AT THIS TIME, PERHAPS STILL WORTH MONITORING GOING FORWARD.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z MONDAY/  
 
ISSUED AT 546 PM CST SAT DEC 21 2024  
 
VFR CONDITIONS TO BEGIN THE 00Z TAF PERIOD ACROSS ALL BUT THE  
FAR NORTH CENTRAL WHERE LOW CLOUDS REMAIN. THROUGH THE LATE  
EVENING AND OVERNIGHT HOURS STRATUS AND FOG ARE FORECAST TO  
EXPAND ACROSS NORTHERN NORTH DAKOTA AND THEN SPREAD SOUTH,  
POSSIBLY IMPACTING ALL TAF SITES BY SUNDAY MORNING. KDIK WOULD  
BE THE TAF SITE MOST LIKELY TO REMAIN OUT OF THE FOG AND IFR-  
LIFR CEILINGS AND VISIBILITIES. ON SUNDAY, BEGINNING AROUND 15  
UTC IN THE NORTHWEST, MIXED PRECIPITATION WILL MOVE INTO  
NORTHWEST NORTH DAKOTA, TRACKING SOUTHEAST THROUGH THE REMAINDER  
OF THE DAY. KXWA WOULD BE THE MOST LIKELY TAF SITE TO RECEIVE  
FZRA SUNDAY, BUT A BRIEF PERIOD CAN'T BE RULED OUT AT ANY TAF  
SITE. VARIABLE SURFACE WINDS GENERALLY UNDER 10KTS THROUGH THE  
TAF PERIOD.  
 
 
   
BIS WATCHES/WARNINGS/ADVISORIES  
 
WINTER WEATHER ADVISORY FROM 6 AM CST /5 AM MST/ TO 6 PM CST  
/5 PM MST/ SUNDAY FOR NDZ001-002-009-010-017-018-031-032.  
 
 
 
 
 
UPDATE...TWH  
DISCUSSION...ANGLIN  
AVIATION...TWH  
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