446
FXUS63 KBIS 231745
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1145 AM CST MON DEC 23 2024
KEY MESSAGES
- AREAS OF DENSE FOG WILL PERSIST ACROSS MUCH OF NORTHERN AND
CENTRAL NORTH DAKOTA THIS AFTERNOON THROUGH THIS EVENING.
- PATCHY FREEZING DRIZZLE REMAINS POSSIBLE ACROSS CENTRAL NORTH
DAKOTA THIS AFTERNOON.
- ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGHOUT THE WEEK,
ESPECIALLY IN SOUTHWEST NORTH DAKOTA WHERE MOST DAYS WILL
HAVE HIGHS IN THE 40S.
- INCREASING CONFIDENCE IN MUCH COLDER TEMPERATURES TO START THE
NEW YEAR.
UPDATE
ISSUED AT 1145 AM CST MON DEC 23 2024
FOR THIS FORECAST UPDATE, WE HAVE EXTENDED THE DENSE FOG
ADVISORY OVER MUCH OF NORTHERN AND CENTRAL NORTH DAKOTA THROUGH
9 PM CST / 8 PM MST THIS EVENING. VISIBILITIES REMAIN BROADLY
BELOW 1 MILE ACROSS THE NORTH AT THIS TIME, WITH MANY LOCATIONS
DROPPING BELOW 1/4 MILE. SIMILAR CONDITIONS ARE FOUND ACROSS THE
SOUTH CENTRAL, THOUGH A NOTICEABLE GAP IS FOUND GENERALLY ALONG
THE HIGHWAY 3 CORRIDOR. ANY IMPROVEMENT WE MAY SEE THIS
AFTERNOON IS EXPECTED TO BE BOTH BRIEF AND TRANSITORY IN NATURE.
OTHERWISE, NO MAJOR ADJUSTMENTS TO THE FORECAST WERE MADE AT
THIS TIME.
UPDATE
ISSUED AT 945 AM CST MON DEC 23 2024
WIDESPREAD FOG CONTINUES ACROSS NORTHWESTERN AND CENTRAL NORTH
DAKOTA THIS MORNING, WITH VISIBILITIES BROADLY DOWN TO LESS THAN
A MILE ACROSS NORTHWESTERN AND NORTH CENTRAL NORTH DAKOTA AS
WELL AS THE JAMES RIVER VALLEY, WITH QUIET A FEW LOCATIONS
DROPPING DOWN TO <1/4 MILE. MORE MILD VISIBILITY REDUCTIONS HAVE
BEEN FOUND ACROSS SOUTH CENTRAL NORTH DAKOTA THESE PAST FEW
HOURS, ESPECIALLY IN THE COUNTIES ALONG THE MISSOURI RIVER. WE
DID DISCUSS ENDING THE DENSE FOG ADVISORY OVER THESE COUNTIES
THIS MORNING, BUT WITH DAYTIME SATELLITE IMAGERY BECOMING
AVAILABLE IN THE PAST HOUR WE HAVE DECIDED AGAINST IT. A SEGMENT
OF HIGHER CLOUDS TRAWLING ACROSS THIS AREA SEEMS TO HAVE
PREVIOUSLY PREVENTED THE DEVELOPMENT OF THE DENSER FOG, BUT HAS
SINCE BEGUN TO EXIT TO THE SOUTH. WITH VISIBILITIES BEHIND THIS
DECK BEGINNING TO DROP, WE WILL LEAVE THE DENSE FOG ADVISORY AS
IS FOR THIS UPDATE. THUS, NO MAJOR UPDATES TO THE FORECAST WERE
MADE AT THIS TIME, AS IT REMAINS BROADLY ON TRACK.
UPDATE
ISSUED AT 639 AM CST MON DEC 23 2024
THE DENSE FOG ADVISORY HAS ONCE AGAIN BEEN EXPANDED TO THE
SOUTH DAKOTA BORDER. NUMEROUS OBSERVATIONS ACROSS NORTHWEST AND
CENTRAL NORTH DAKOTA ARE REPORTING VISIBILITY UNDER ONE HALF
MILE. DENSE FOG WILL BE THE MAIN FORECAST CHALLENGE AND HAZARD
THROUGHOUT THE DAY.
UPDATE
ISSUED AT 455 AM CST MON DEC 23 2024
THIS UPDATE IS MAINLY FOR HEADLINE CHANGES. THE WINTER WEATHER
ADVISORY HAS BEEN CANCELLED. FREEZING RAIN HAS FINALLY DEPARTED
THE STATE, AND ANY LINGERING FREEZING DRIZZLE SHOULD NOT WORSEN
IMPACTS. ADDITIONALLY, THE DENSE FOG ADVISORY HAS BEEN EXPANDED
SOUTH TO INCLUDE AREAS FROM WATFORD CITY TO BISMARCK TO
JAMESTOWN, ALTHOUGH IT MAY TAKE A COUPLE MORE HOURS FOR FOG TO
BECOME MORE PREVALENT IN THESE NEWLY ADDED COUNTIES. ALSO
INCLUDING A MENTION OF FOG DEPOSITING A THIN LAYER OF ICE TO
COVER THE PATCHY FREEZING DRIZZLE THREAT.
DISCUSSION
ISSUED AT 357 AM CST MON DEC 23 2024
A SHORTWAVE TROUGH PIVOTING THROUGH THE RED RIVER VALLEY
CONTINUES TO BRING FREEZING RAIN TO SOUTHEAST NORTH DAKOTA EARLY
THIS MORNING, BUT ACCUMULATING ICE SHOULD BE EXITING THE AREA
BY SUNRISE. IN ITS WAKE, EXCESSIVE LOW LEVEL MOISTURE HAS
MANIFEST AS DENSE FOG AND LIGHT FREEZING DRIZZLE. THE DENSE FOG
HAS MAINLY BE CONFINED ALONG AND NORTH OF A LINE FROM
PLENTYWOOD, MT TO CARRINGTON, WHERE A DENSE FOG ADVISORY REMAINS
IN EFFECT UNTIL NOON. FURTHER SOUTH, THERE ARE STILL OCCASIONAL
REPORTS OF FREEZING DRIZZLE/UNKNOWN PRECIPITATION, SO WILL
LEAVE THE WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 AM CST.
THERE IS HIGH CONFIDENCE THAT LOW STRATUS WILL NOT DISSOLVE
TODAY, LEADING TO A DAMP AND DREARY DAY ACROSS ALL BUT SOUTHWEST
NORTH DAKOTA, WHERE AFTERNOON HIGHS COULD REACH THE 40S. UNDER
THE STRATUS, TEENS AND 20S ARE MORE LIKELY FOR HIGHS TODAY.
WOULD NOT BE SURPRISED TO SEE AREAS OF FOG PERSIST THROUGH THE
AFTERNOON ACROSS THE NORTH, EVEN IF IT CEASES TO BE DENSE. THE
MOST FAVORABLE AREA FOR PATCHY FREEZING DRIZZLE THROUGHOUT THE
DAY IS ALONG AND JUST EAST OF THE HIGHWAY 83 CORRIDOR, WHERE RAP
GUIDANCE SHOWS THE HIGHEST 0-1 KM RH COLLOCATED WITH LOW LEVEL
FRONTOGENESIS.
ANOTHER SHORTWAVE TROUGH IS FORECAST TO CROSS THE STATE FROM
WEST TO EAST TONIGHT THROUGH CHRISTMAS EVE MORNING. LONGER-RANGE
GUIDANCE HAS BEEN AND CONTINUES TO BE INSISTENT ON NO
MEASURABLE PRECIPITATION WITH THIS WAVE, BUT A FEW CAMS ARE NOW
AT LEAST GENERATING SOME REFLECTIVITY, BUT STILL WITH MOSTLY
JUST A TRACE OF QPF. THE CAUSE FOR CONCERN THOUGH IS THAT THERE
IS HIGH CONFIDENCE THAT IF PRECIPITATION REACHES THE SURFACE, IT
WILL FALL AS FREEZING RAIN, AND IT ONLY TAKES TRACE AMOUNTS OF
ICE TO CAUSE IMPACTS. A 20 PERCENT CHANCE OF LIGHT FREEZING RAIN
WAS ADDED TO THE FORECAST THIS EVENING AND TONIGHT, THOUGH IT
MAY NEED TO BE SHIFTED LATER IN TIME INTO TUESDAY MORNING BASED
ON THE MOST RECENT AVAILABLE GUIDANCE. IT SHOULD BE EMPHASIZED
THAT EVEN IF FREEZING RAIN IS OBSERVED FROM THIS SYSTEM, IT WILL
NOT BE NEARLY AS IMPACTFUL AS WHAT OCCURRED FROM YESTERDAY INTO
THIS MORNING.
PRIOR TO THE ARRIVAL OF THE AFOREMENTIONED SHORTWAVE, ANOTHER
ROUND OF DENSE FOG COULD MATERIALIZE ACROSS CENTRAL AND EASTERN
NORTH DAKOTA TONIGHT. AN EASTWARD PROPAGATING SURFACE TROUGH
SHOULD HELP CLEAR THE FOG FROM WEST TO EAST LATER TONIGHT INTO
THE MORNING, THOUGH THERE IS TIMING UNCERTAINTY IN ITS
PROGRESSION. NEVERTHELESS, THE SURFACE AND UPPER TROUGH SHOULD
CLEAR THE WESTERN TWO THIRDS OF THE STATE BY TUESDAY AFTERNOON,
ALLOWING FOR TEMPERATURES TO WARM INTO THE 40S SOUTHWEST AND 30S
ELSEWHERE. THIS MARKS THE BEGINNING OF A PROLONGED PERIOD WITH
SIMILAR HIGH TEMPERATURES ALL THE WAY INTO THE UPCOMING WEEKEND
AS A QUASI-ZONAL, SPLIT FLOW PATTERN BRINGS MILDER PACIFIC AIR
OVER THE ROCKIES.
THE NBM HAS INTRODUCED A 20 TO 30 PERCENT CHANCE OF
PRECIPITATION TO CENTRAL AND EASTERN NORTH DAKOTA ON FRIDAY AS
DETERMINISTIC GUIDANCE SUGGESTS A MESSY CENTRAL CONUS LONGWAVE
TROUGH WITH NUMEROUS EMBEDDED SHORTWAVES. THIS GENERALLY LINES
UP WITH GLOBAL ENSEMBLE CLUSTER ANALYSIS, ALTHOUGH IT
INTERESTINGLY LEAVES WESTERN NORTH DAKOTA DRY, A SOLUTION WHICH
CURRENTLY ONLY PRESENTS ITSELF IN A SINGULAR, GEFS-DOMINATED,
LOWER-MEMBERSHIP CLUSTER. ALL ENSEMBLE SYSTEMS AND CLUSTERS ONCE
AGAIN SHOW VERY HIGH CONFIDENCE (90 TO 100 PERCENT PROBABILITY)
IN 850 MB TEMPERATURES ABOVE FREEZING. SURFACE TEMPERATURES
COULD ACTUALLY BE ABOVE FREEZING FOR MUCH OF THE DAY FRIDAY
THOUGH, RESULTING IN RAIN AS THE PREDOMINANT FORECAST TYPE FOR
NOW.
AFTER A DRY FORECAST FOR THE WEEKEND, THE NBM RETURNS LOW TO
MEDIUM CHANCES FOR PRECIPITATION (ALL SNOW THIS TIME) FROM THE
WEST ON MONDAY. IT IS ALSO ON MONDAY THAT WE BEGIN TO SEE A
DISTINCT COOLING TREND IN ENSEMBLE GUIDANCE, WITH ALL ENSEMBLE
SYSTEMS SHOWING ANOMALOUSLY COLD 850 MB TEMPERATURES ARRIVING
AROUND NEW YEAR'S DAY.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1145 AM CST MON DEC 23 2024
LOW STRATUS, FOG, AND OCCASIONALLY FREEZING DRIZZLE IS PRESENT
ACROSS MUCH OF WESTERN AND CENTRAL NORTH DAKOTA TODAY,
EXCLUDING THE SOUTHWEST. THESE IFR/LIFR CONDITIONS ARE EXPECTED
TO GENERALLY PERSIST THROUGH THE DAY TODAY, ESPECIALLY ACROSS
CENTRAL NORTH DAKOTA INCLUDING THE TERMINALS OF KMOT, KBIS, AND
KJMS, THOUGH THEY MAY BRIEFLY IMPROVE THIS AFTERNOON. MORE
PATCHY CONDITIONS ARE FOUND IN THE NORTHWEST, SO HAVE LEFT KXWA
WITH PREVAILING VFR CONDITIONS, THOUGH HAVE INCLUDED A TEMPO
GROUP FOR IFR CEILINGS AND VISIBILITY THROUGH THE AFTERNOON.
CONDITIONS ARE EXPECTED TO GENERALLY IMPROVE THROUGH LATE THIS
EVENING AND OVERNIGHT, THOUGH ANOTHER ROUND OF LOW STRATUS AND
FOG IS POSSIBLE TOMORROW MORNING, MOST CONVINCINGLY ACROSS
CENTRAL NORTH DAKOTA. WINDS ARE EXPECTED TO REMAIN GENERALLY
LIGHT AND OUT OF THE SOUTH, BEGINNING TO TURN TO THE SOUTHWEST
BY THE END OF THE 18Z TAF PERIOD.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING FOR
NDZ001>005-009>013-017>023-025-034>037-042-045>048-050-051.
UPDATE...ADAM/HOLLAN
DISCUSSION...HOLLAN
AVIATION...ADAM
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