550
FXUS63 KFSD 261148
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
548 AM CST THU DEC 26 2024
KEY MESSAGES
- AREAS OF DENSE FOG WILL PERSIST ALONG/EAST OF US HIGHWAY 81
THIS MORNING, ESPECIALLY IN HIGHER ELEVATIONS OF THE COTEAU
DES PRAIRIES IN EAST CENTRAL SOUTH DAKOTA, AND IN PORTIONS OF
NORTHWEST IOWA/NORTHEAST NEBRASKA. A DENSE FOG ADVISORY
REMAINS IN PLACE FOR THESE AREAS THROUGH NOON CDT.
- AREAS OF DRIZZLE ARE ALSO EXPECTED WITH THE WIDESPREAD LOW
CLOUDS ALONG AND EAST OF US HIGHWAY 81 TODAY INTO TONIGHT.
NEAR FREEZING TEMPERATURES EARLY THIS MORNING WILL RISE INTO
THE MID-UPPER 30S TODAY, SO IMPACTS FROM POSSIBLE FREEZING
DRIZZLE ARE EXPECTED TO BE MINIMAL.
- SCATTERED LIGHT RAIN SHOWERS/SPRINKLES ARE STILL FORECAST
NEAR AND EAST OF I-29 ON FRIDAY, WITH SEASONABLY MILD HIGH
TEMPERATURES IN THE 40S AND LITTLE TO NO TRAVEL IMPACTS ON TAP
FOR THIS POST-HOLIDAY WEEKEND.
- WILL BE MONITORING POTENTIAL FOR A STRONGER SYSTEM WHICH
COULD IMPACT THE REGION EARLY NEXT WEEK. MODERATE (40-70%)
CONFIDENCE IN PRECIPITATION OCCURRING IN SOME FORM, BUT LOW
(<30%) CONFIDENCE WITH REGARD TO PRECIPITATION TYPE/AMOUNTS
DUE TO VARIATIONS IN POTENTIAL STORM TRACK.
UPDATE
ISSUED AT 535 AM CST THU DEC 26 2024
WEBCAMS ARE STILL SUPPORTING GREATER COVERAGE OF DENSE FOG
ACROSS THE COTEAU IN EAST CENTRAL SOUTH DAKOTA, ALONG THE
HIGHWAY 71 CORRIDOR IN NORTHWEST IOWA AND IN PORTIONS OF
NORTHEAST NEBRASKA, SO WILL LEAVE THE DENSE FOG ADVISORY IN
PLACE FOR THESE AREAS.
HOWEVER, HAVE NOT YET SEEN ANTICIPATED DROP IN VISIBILITY
ACROSS FAR SOUTHEAST SOUTH DAKOTA, MUCH OF NORTHWEST IOWA, AND
SOUTHWEST MINNESOTA AS HAS BEEN INDICATED BY THE MODELS
THROUGHOUT THE NIGHT. THUS HAVE CANCELLED THE ADVISORY FROM
YANKTON TO SIOUX FALLS, INTO SOUTHWEST MINNESOTA AND NORTHWEST
IOWA WEST OF HIGHWAY 71. COULD STILL SEE SOME LOWER VISIBILITY
DEVELOP TOWARD/JUST AFTER SUNRISE, BUT WIDESPREAD DENSE FOG IS
NO LONGER EXPECTED FOR THESE AREAS.
DISCUSSION
ISSUED AT 356 AM CST THU DEC 26 2024
TODAY: EARLY MORNING CHALLENGES HAVE FOCUSED ON FOG AND DRIZZLE AS
ABUNDANT LOW LEVEL MOISTURE PERSISTS IN A BROAD SOUTH-SOUTHEAST FLOW
ACROSS THE REGION. SUBTLE LOW LEVEL LIFT WITHIN/JUST ABOVE THE
STRATUS LAYER PER FORECAST SOUNDINGS HAD RESULTED IN AREAS OF
DRIZZLE/FREEZING DRIZZLE DEVELOPING DURING THE LATE EVENING HOURS,
AND IT SEEMS THIS ALSO HELPED BOOST VISIBILITY FOR A TIME. HAVE BEEN
HESITANT TO DROP THE EXISTING DENSE FOG ADVISORY AS HIGH-RES
GUIDANCE CONTINUES TO SHOW DETERIORATING CONDITIONS AS WE MOVE
THROUGH THE PRE-DAWN HOURS, ESPECIALLY IN THE HIGHER ELEVATIONS OF
THE COTEAU IN EAST-CENTRAL SOUTH DAKOTA AND THE BUFFALO RIDGE IN
SOUTHWEST MINNESOTA. WILL CONTINUE TO MONITOR TRENDS OVER THE NEXT
COUPLE OF HOURS, BUT MAY STILL CANCEL PORTIONS OF THE ADVISORY
BEFORE DAYBREAK IF THIS DETERIORATION DOES NOT MATERIALIZE.
AS FAR AS THE DRIZZLE, HAVE SEEN A MARKED DECREASE IN SHALLOW ECHOES
ON THE KFSD RADAR SINCE OVER THE PAST HOUR INDICATING A DECREASE IN
DRIZZLE COVERAGE, FOR NOW AT LEAST. SOUNDINGS STILL SHOW SOME WEAK
LIFT WITHIN THE STRATUS LAYER AT TIMES THROUGH THE REMAINDER OF
TODAY, SO WILL KEEP DRIZZLE IN THE FORECAST ALONG/EAST OF HIGHWAY 81
WHERE STRATUS IS DEEPEST. HOWEVER, AS HAS BEEN THE CASE THUS FAR,
ACTUAL AMOUNTS ARE NOT EXPECTED TO MEASURE AND WILL STICK WITH VERY
LOW (SUB-15%) POPS THROUGH THE DAY. REGARDING POTENTIAL FOR LIGHT
ICING, WITH TEMPERATURES STEADY TO SLOWLY RISING AND LOW POTENTIAL
FOR MEASURABLE PRECIP, THINK IMPACTS FROM ANY FREEZING DRIZZLE WILL
BE LIMITED TO UNTREATED ROADS/SIDEWALKS OR ELEVATED SURFACES AND DO
NOT PLAN TO ISSUE AN ADVISORY AT THIS TIME.
TONIGHT-FRIDAY: LOW LEVEL MOISTURE PERSISTS ACROSS THE EASTERN CWA
THROUGH TONIGHT WITH LIMITED MID-LEVEL MOISTURE UNTIL LATE TONIGHT
FRIDAY AHEAD OF A MID-UPPER LEVEL WAVE. THE STRATUS WILL BRING A
CONTINUED LOW CHANCE FOR AREAS OF DRIZZLE, THOUGH BY THIS TIME
TEMPERATURES SHOULD RESIDE FIRMLY IN THE MID-UPPER 30S. AS THE WAVE
APPROACHES, THE INCREASE OF MID-LEVEL MOISTURE WILL PROVIDE SOME
POTENTIAL FOR MORE BONAFIDE LIGHT RAIN. TRENDS HAVE BEEN SHIFTING
HIGHER RAINFALL AMOUNTS EAST OF OUR FORECAST AREAS, BUT PORTIONS OF
SOUTHWEST MINNESOTA AND NORTHWEST IOWA COULD STILL SEE RAINFALL UP
TO 0.10" BEFORE ANY RAIN SLIDES EAST OF THE AREA FRIDAY NIGHT.
ALSO OF NOTE WITH THIS WAVE WILL BE A SLIGHT SHIFT TO WESTERLY
WINDS, WHICH SHOULD HELP SCOUR OUR SOME OF THE LOW LEVEL MOISTURE
WHICH HAS BEEN SO PERSISTENT ACROSS THE REGION THIS WEEK. THIS
SHOULD ALLOW FOR A GREATER CHANCE AT MORE PREVALENT SUNSHINE WEST OF
THE JAMES RIVER FRIDAY AFTERNOON.
SATURDAY-SUNDAY: ALTHOUGH LIGHT, WESTERLY LOW LEVEL FLOW DOES BECOME
MORE WIDESPREAD ON SATURDAY AND MODELS ARE IN GOOD AGREEMENT IN
PUSHING THE LOW LEVEL MOISTURE EAST OF OUR AREA, SO THIS WEEKEND
SHOWS GREATER PROMISE OF PARTLY TO MOSTLY SUNNY SKIES. THIS SHOULD
ALSO SUPPORT MORE FAVORABLE MIXING INTO THE WARMER AIR ALOFT, WITH
DAYTIME TEMPERATURES FINALLY WARMING INTO THE 40S OVER MOST OF THE
REGION FOR THE FINAL WEEKEND OF 2024.
SUNDAY NIGHT-MONDAY NIGHT: FOCUS WILL SHIFT TO A STRONGER MID-UPPER
LEVEL TROUGH AND ASSOCIATED SURFACE LOW EJECTING OUT OF THE ROCKIES
SUNDAY NIGHT, AND MOVING ACROSS THE PLAINS MONDAY-MONDAY NIGHT. THIS
SYSTEM LOOKS TO BE FAIRLY PROGRESSIVE, BUT UNCERTAINTY IN TRACK IS
HIGH DUE TO A WIDE VARIANCE IN MODEL SOLUTIONS. CLUSTERS SUPPORT THE
SLIGHT NORTH-SOUTH DIFFERENCES SEEN IN THE DETERMINISTIC MODELS, BUT
MOST CLUSTERS SHOW AT LEAST MODERATE (40-70%) PROBABILITIES FOR AT
LEAST 0.10" LIQUID-EQUIVALENT OCCURRING SOMEWHERE IN OUR FORECAST
AREA LATE SUNDAY NIGHT INTO MONDAY NIGHT. THE BIGGER QUESTION WITH
THE TRACK WILL BE WITH THE THERMAL PROFILES AND RESULTING PRECIP
TYPE, THOUGH MOST FAVOR AN INITIAL RAIN/FREEZING RAIN POTENTIAL LATE
SUNDAY NIGHT INTO MONDAY, SWITCHING TO SNOW AS THE COLDER AIR POURS
IN LATER MONDAY-MONDAY NIGHT. TOO MUCH UNCERTAINTY TO DETERMINE
AMOUNTS FOR ANY SPECIFIC TYPE, BUT THIS WILL BE A PERIOD WORTH
WATCHING IF YOU HAVE TRAVEL PLANS EARLY NEXT WEEK.
TUESDAY-WEDNESDAY: THE TRANSITION TO 2025 WILL SEE TEMPERATURES
SETTLE BACK CLOSER TO SEASONAL NORMALS. PRECIPITATION CHANCES ARE
LOW, THOUGH CANNOT RULE OUT SOME LIGHT SNOW AT TIMES AS WEAK WAVES
SLIDE THROUGH THE PREVAILING NORTHWEST FLOW ALOFT.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 535 AM CST THU DEC 26 2024
IFR-LIFR CEILINGS WILL REMAIN THE RULE FOR MOST AREAS ALONG AND
EAST OF US HIGHWAY 81 THROUGHOUT THIS TAF PERIOD, INCLUDING KFSD
AND KSUX AIRFIELDS. LOW STRATUS MAY OCCASIONALLY BE ACCOMPANIED
BY MVFR-IFR VISIBILITY IN FOG OR PERIODS OF DRIZZLE AND MAY HAVE
TO WATCH FOR LIGHT ICING IN HIGHER ELEVATIONS NORTH OF I-90
WHERE 11Z TEMPERATURES ARE AT/JUST BELOW FREEZING. LOCATIONS
ALONG AND SOUTH OF I-90 HAVE SUFFICIENTLY WARMED ABOVE FREEZING
AND ICING IS NOT EXPECTED.
WEST OF HIGHWAY 81, THE JAMES RIVER VALLEY AREAS (KHON-KMHE) ARE
STARTING OFF THE PERIOD NEAR THE EDGE OF IFR STRATUS WITH
MODERATE (50-70%) CONFIDENCE OF CLEARING FOR KHON BY MIDDAY.
ANY CLEARING WOULD BE SHORT-LIVED THOUGH, AS THE STRATUS IS
EXPECTED TO WORK BACK INTO THE JAMES RIVER VALLEY AFTER SUNSET
TONIGHT.
FSD WATCHES/WARNINGS/ADVISORIES
SD...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR SDZ039-040-054>056-
061.
MN...NONE.
IA...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR IAZ003-014-022-032.
NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ013-014.
UPDATE...JH
DISCUSSION...JH
AVIATION...JH
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