357
FXUS63 KBIS 231055
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
455 AM CST MON DEC 23 2024
KEY MESSAGES
- PATCHY FREEZING DRIZZLE REMAINS POSSIBLE ACROSS CENTRAL NORTH
DAKOTA THIS MORNING AND AFTERNOON.
- AREAS OF DENSE FOG WILL PERSIST ACROSS NORTHERN AND CENTRAL
NORTH DAKOTA THIS MORNING, AND MAY LAST THROUGH THE AFTERNOON
INTO TONIGHT.
- 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 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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 357 AM CST MON DEC 23 2024
DENSE FOG WITH IFR TO LIFR CEILINGS WILL IMPACT MOST OF
NORTHWEST AND CENTRAL NORTH DAKOTA THROUGH THIS MORNING, WITH
VFR CONDITIONS PREVAILING IN THE SOUTHWEST. PATCHY FREEZING
DRIZZLE WILL ALSO REMAIN POSSIBLE ACROSS CENTRAL NORTH DAKOTA
THROUGHOUT THE DAY. CEILINGS MAY LIFT TO NEAR MVFR LEVELS THIS
AFTERNOON, BUT ARE LIKELY TO SETTLE BACK DOWN TO IFR/LIFR
TONIGHT, WITH DENSE FOG ONCE AGAIN POSSIBLE.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL NOON CST /11 AM MST/ TODAY FOR
NDZ001>005-009>013-017>023-025-035>037.
UPDATE...HOLLAN
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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