465
FXUS63 KFSD 260442
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1042 PM CST WED DEC 25 2024
KEY MESSAGES
- DENSE FOG CONTINUES ACROSS THE REGION, AND IS EXPECTED TO
CONTINUE INTO AT LEAST THE MORNING HOURS ON THURSDAY. FROST
DEPOSITS MAY LEAD TO SOME SLICK SPOTS ON UNTREATED SURFACES.
- LIGHT DRIZZLE OR SPRINKLES REMAINS EXPECTED ON THURSDAY,
MAINLY ALONG AND EAST OF I-29, WITH A HIGHER RISK (40-60%) FOR
LIGHT RAIN MOVING IN FRIDAY. RAINFALL TOTALS LESS THAN 0.25"
EXPECTED.
- IT REMAINS POSSIBLE THAT WE DEAL WITH FOG/STRATUS THROUGH
FRIDAY, WITH INCREASING CHANCES (GREATER THAN 70%) FOR WARMER
THAN NORMAL TEMPERATURES IN THE 40S BY THE UPCOMING WEEKEND.
MINIMAL POST- HOLIDAY TRAVEL IMPACTS ARE ANTICIPATED THIS
WEEKEND.
DISCUSSION
ISSUED AT 255 PM CST WED DEC 25 2024
MOSTLY OVERCAST SKIES ARE OBSERVED ON SATELLITE THIS AFTERNOON, WITH
SURFACE OBSERVATIONS SHOWING AREAS OF FOG LINGERING WHILE OTHERS
HAVE CLEARED THE FOG FOR THE TIME BEING. STUCK BETWEEN A SURFACE
HIGH PRESSURE TO OUR EAST AND A SURFACE LOW PRESSURE TO THE
WEST/NORTHWEST, SOUTHERLY FLOW IS BRINGING SOME WEAK WARM-AIR
ADVECTION ALONG WITH MILD ISENTROPIC LIFT ACROSS THE REGION. THIS
HAS KEPT THE DREARY CONDITIONS CONTINUING THROUGHOUT THE DAY FOR
MOST, THOUGH SOME STRATUS CLEARING HAS BEEN OBSERVED OVER SOUTH-
CENTRAL SOUTH DAKOTA.
ADDITIONAL FOG AND STRATUS IS EXPECTED INTO THE OVERNIGHT HOURS
GIVEN THE CONTINUED MOIST SURFACE LAYER, STRONG TEMPERATURE
INVERSION, AND SURFACE TEMPERATURES COOLER THAN THE BOUNDARY LAYER.
SIMILAR TO LAST NIGHT, FOG IS MOST LIKELY BETWEEN THE JAMES RIVER
VALLEY AND THE HIGHWAY 71 CORRIDOR, BASICALLY EXCLUDING OUR FAR
WESTERN AND FAR EASTERN COUNTIES. DUE TO THE RISK OF FOG
CREATING VISIBILITIES BELOW 1/4 MILE, WITH PROBABILITIES FOR
VISIBILITIES AT OR BELOW 1/4 MILE RANGING FROM 40 TO 80%, HAVE
EXTENDED/EXPANDED THE CURRENT DENSE FOG ADVISORY TO INCLUDE THE
AFOREMENTIONED AREA THROUGH NOON ON THURSDAY. EXPECT ANOTHER
RATHER MILD OVERNIGHT PERIOD THANKS TO THE STRATUS, WITH MORNING
LOWS IN THE UPPER 20S TO LOWER 30S. HOWEVER AS WE'VE SEEN
TODAY, THIS FOG IS CREATING SOME SLICK PATCHES ESPECIALLY WHEN
TEMPERATURES DIP BELOW FREEZING, SO BE AWARE OF SLICK SPOTS ON
UNTREATED SURFACES OVERNIGHT INTO THE MORNING HOURS.
AS HAS BEEN MENTIONED BY PREVIOUS FORECASTERS, THIS PATTERN IS
EXPECTED TO STICK AROUND THROUGH FRIDAY BEFORE A STRONGER WAVE MOVES
ONTO THE NORTHERN PLAINS, LEADING TO THE CONTINUATION OF CLOUDY AND
FOGGY CONDITIONS. IN ADDITION, AREAS ALONG AND EAST OF I-29 MAY SEE
SOME DRIZZLE START TO FORM BY THE LATE MORNING HOURS AS SATURATION
IN THE LOWER LEVELS STARTS TO DEEPEN GIVEN THE CONTINUED POSITIVE
MOISTURE ADVECTION, WITH DRIZZLE REMAINING POSSIBLE INTO FRIDAY
MORNING. THROUGHOUT THE DAY, THE AFOREMENTIONED SURFACE LOW LIFTS
NORTHWARDS WHILE REMAINING OFF TO OUR EAST, FURTHER INCREASING LOW
TO MID-LEVEL MOISTURE RESULTING IN CHANCES FOR RAIN RATHER THAN
DRIZZLE. TEMPERATURES LOOK TO REMAIN WARM ENOUGH THROUGHOUT THE DAY
TO NOT HAVE TO WORRY ABOUT ANY WINTER PRECIPITATION, WITH RAINFALL
AMOUNTS LOOKING TO REMAIN BELOW A QUARTER INCH. HOWEVER, DURING THE
EVENING AND OVERNIGHT HOURS WE'LL HAVE TO WATCH TO SEE IF COLD AIR
IS ABLE TO MOVE IN AND PRODUCE SOME SNOW OR FREEZING RAIN, BUT FOR
NOW HAVE KEPT MENTION OUT OF THE FORECAST GIVEN LOW PROBABILITIES
(<10%).
MOISTURE-STARVED SHORTWAVES MOVE ACROSS THE AREA THE REST OF
SATURDAY AND INTO SUNDAY, WITH AFTERNOON TEMPERATURES IN THE LOWER
TO UPPER 40S EXPECTED, WARMEST ALONG THE SD/NE BORDER. HEADING INTO
MONDAY, A RATHER PROGRESSIVE COLORADO LOW LOOKS TO FORM AND EJECT
ONTO THE PLAINS, BRINGING OUR NEXT ROUND OF PRECIPITATION TO THE
REGION FROM WEST TO EAST, POSSIBLY WITH A WINTRY MIX.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1042 PM CST WED DEC 25 2024
FOG HAS PREDOMINATELY LIFTED ACROSS THE REGION LATE THIS EVENING. A
FEW LOCATIONS SUCH AS KSLB AND KMDS STILL SHOW VISIBILITIES DOWN TO
LIFR THRESHOLDS. OTHERWISE, MOST VISIBILITIES HAVE IMPROVED UP TO
VFR/MVFR/IFR STATUS. CEILINGS ALSO REMAIN AT MVFR/IFR/LIFR LEVELS.
WHILE THIS LATEST TREND LOOKS TO CONTINUE THROUGH THE NIGHT, SHOULD
STILL SEE FOG REDEVELOP ACROSS PARTS OF THE AREA DURING THE
OVERNIGHT HOURS. THIS MAY NOT OCCUR AT KHON, KFSD, AND KSUX THOUGH
SO HAVE LEFT MENTION OF FOG OUT OF ALL TAFS. TRENDS WILL BE CLOSELY
MONITORED THROUGH THE NIGHT. SOUTH/SOUTHEASTERLY WINDS WILL PERSIST
THROUGH THE NIGHT WITH GUSTS UP TO AROUND 20 KNOTS EXPECTED ALONG
HIGHWAY-14.
LIKE WHAT WE HAVE SEEN THE PAST COUPLE OF DAYS, SHOULD SEE ANY
REMAINING FOG LIFT DURING THE MORNING HOURS, LEAVING LOW LEVEL
STRATUS EAST OF THE JAMES RIVER FOR THE AFTERNOON HOURS. COULD SEE
THE STRATUS AGAIN LOWER AND RESULT IN ANOTHER ROUND OF FOG TOWARDS
THE END OF THE TAF PERIOD, BUT CONFIDENCE IS NOT HIGH ENOUGH TO
INCLUDE IN A TAF AT THIS TIME.
FSD WATCHES/WARNINGS/ADVISORIES
SD...DENSE FOG ADVISORY UNTIL NOON CST THURSDAY FOR SDZ039-040-
054>056-061-062-066-067-069>071.
MN...DENSE FOG ADVISORY UNTIL NOON CST THURSDAY FOR MNZ071-080-089-
097-098.
IA...DENSE FOG ADVISORY UNTIL NOON CST THURSDAY FOR IAZ001-002-012-
013-020>022-031-032.
NE...DENSE FOG ADVISORY UNTIL NOON CST THURSDAY FOR NEZ013-014.
DISCUSSION...APT
AVIATION...MEYERS
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