405
FXUS63 KBIS 212132
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
332 PM CST SAT DEC 21 2024
KEY MESSAGES
- PATCHY TO 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.
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 /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1145 AM CST SAT DEC 21 2024
GENERALLY VFR TO MVFR CLOUD COVER WILL REMAIN ACROSS THE
FORECAST AREA TODAY, WITH SOME BRIEF IFR CEILINGS AND PATCHY FOG LINGERING
INTO THE EARLY AFTERNOON HOURS ACROSS THE NORTH CENTRAL. THESE
CONDITIONS COULD IMPACT THE KMOT TAF SITE. LIGHT WINDS AND
MAINLY VFR CONDITIONS ARE THEN EXPECTED THIS EVENING INTO THE
EARLY OVERNIGHT HOURS. LATER TONIGHT THROUGH SUNDAY, CLOUDS WILL
INCREASE ALONG WITH CHANCES FOR PRECIPITATION FROM WEST TO
EAST. THIS COULD BRING MVFR TO IFR CONDITIONS. MIXED
PRECIPITATION OF RAIN, FREEZING RAIN, AND SNOW IS POSSIBLE WITH
THIS NEXT SYSTEM. USED PROB30 GROUPS FOR TAF SITES WITH HIGHER
CONFIDENCE IN SEEING PRECIPITATION DURING THIS TAF FORECAST
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.
DISCUSSION...ANGLIN
AVIATION...ANGLIN
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