998
FXUS63 KFSD 031703
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1103 AM CST MON FEB 3 2025
KEY MESSAGES
- AREAS OF FREEZING DRIZZLE AND FLURRIES HAVE DEVELOPED ACROSS
SOUTHWEST MINNESOTA, PORTIONS OF SOUTHEAST SOUTH DAKOTA AND
NORTHWEST IOWA. HAVE ISSUED A WINTER WEATHER ADVISORY FOR MUCH
OF THE BUFFALO RIDGE/IOWA GREAT LAKES WHERE IMPACTS TO TRAVEL
ARE EXPECTED TO BE GREATER.
- NEAR TO BELOW NORMAL TEMPERATURES IS EXPECTED FOR MUCH OF THE
UPCOMING WEEK.
- TWO CHANCES FOR PRECIPITATION ARE POSSIBLE THIS WEEK. CHANCE
FOR LIGHT FREEZING DRIZZLE AND SNOW ON WEDNESDAY (20-40% CHANCE)
AND ANOTHER CHANCE FOR SNOW ON SATURDAY (40-80% CHANCE).
UPDATE
ISSUED AT 1103 AM CST MON FEB 3 2025
WIDESPREAD STRATUS CONTINUES TO EXPAND SOUTH ACROSS THE AREA THIS
MORNING. WEAK LIFT WITHIN THIS STRATUS LAYER COMBINED WITH LIMITED
MOISTURE IN AN ICE PRODUCING LAYER HAS RESULTED IN REPORTS OF
FREEZING DRIZZLE AS FAR SOUTH AS MITCHELL TO SIOUX FALLS TO SPIRIT
LAKE. BASED ON VISIBLE ICING ON DOT CAMERAS AND EM REPORTS, IT
SEEMS AS THOUGH AREAS ALONG/EAST OF THE BUFFALO RIDGE IN SOUTHWEST
MINNESOTA, AND INTO THE IOWA GREAT LAKES (I.E. HIGHER ELEVATION AND
UPSLOPE ENHANCING THE WEAK LIFT) WILL SEE THE GREATEST IMPACTS TO
TRAVEL FROM THE FREEZING DRIZZLE, SO HAVE ISSUED A WINTER WEATHER
ADVISORY FOR THESE AREAS INTO MID-AFTERNOON.
FARTHER WEST, HAVE NOT YET SEEN SUCH IMPACTS AS WIDESPREAD AS IN
SOUTHWEST MINNESOTA, SO WILL FORGO AN ADVISORY IN SOUTHEAST SOUTH
DAKOTA FOR NOW, BUT WILL CONTINUE TO MONITOR. FORECAST SOUNDINGS
IN THIS AREA ALSO INDICATE COLDER TEMPERATURES WITHIN THE STRATUS
DECK FALLING INTO THE DGZ/ICE-PRODUCING TEMPERATURE RANGE, SO
LOCATIONS ALONG/WEST OF I-29 HAVE A GREATER POTENTIAL OF SEEING
A MIX OF FLURRIES/FREEZING DRIZZLE, OR A WHOLESALE CHANGE TO
SCATTERED FLURRIES BEFORE THIS VERY LIGHT PRECIPITATION WINDS DOWN
THIS AFTERNOON.
DISCUSSION
ISSUED AT 308 AM CST MON FEB 3 2025
LIGHT SNOW CONTINUES TO FALL NORTH OF THE AREA THIS MORNING.
LOCATIONS ALONG HIGHWAY-14 REMAIN DRY ALTHOUGH SOME VERY LIGHT SNOW
IS POSSIBLE INTO THE MID MORNING HOURS. MINOR IF ANY ADDITIONAL SNOW
ACCUMULATIONS IS EXPECTED. THE REST OF TODAY WILL BE MOSTLY CLOUDY
WITH NEAR TO BELOW AVERAGE HIGHS FROM THE UPPER TEENS ALONG HIGHWAY-
14 DOWN TO THE MID 30S ALONG HIGHWAY-20. LOW TEMPERATURES WILL FALL
TO THE SINGLE DIGITS TO LOW TEENS THANKS TO A COLD SURFACE HIGH
SLIDING NORTH OF THE AREA. WINDS WILL BE SLIGHTLY ELEVATED THROUGH
THE NIGHT DUE TO A TIGHTER SURFACE PRESSURE GRADIENT (SPG) IN PLACE.
THIS WILL PUSH WIND CHILLS DOWN TO -15F TO 0F ACROSS THE AREA,
MAKING FOR A COLD MORNING ACROSS THE AREA.
TUESDAY WILL BE A RINSE AND REPEAT OF MONDAY AS 925 MB TEMPERATURES
REMAIN IN THE NEGATIVE TEENS ALOFT. MIXING THESE TEMPERATURES TO THE
SURFACE WILL RESULT IN HIGHS FROM THE TEENS TO UPPER 20S FROM NORTH
TO SOUTH. THE SPG WILL BE RELAXING THROUGHOUT THE DAY AS THE
PREVIOUSLY MENTIONED HIGH DEPARTS TO THE EAST. THIS WILL STILL
RESULT IN COLDER WIND CHILLS THROUGHOUT THE DAY WITH VALUES DOWN TO
THE POSITIVE SINGLE DIGITS TO TEENS. LOW TEMPERATURES WILL FALL TO
THE SINGLE DIGITS AND TEENS OVERNIGHT.
THE NEXT CHANCE FOR PRECIPITATION COMES ON WEDNESDAY AS AN UPPER
WAVE EJECTS FROM THE ROCKY MOUNTAINS AND INTO THE PLAINS. THE EXIT
REGION OF THE UPPER LEVEL JET WILL RESULT IN STRENGTHENING WARM AIR
ADVECTION (WAA) ACROSS THE FORECAST AREA. THIS IS DUE TO THE JETS
INDIRECT THERMAL CIRCULATION BRINGING A RETURN OF BROAD SOUTHERLY
FLOW AT 850 MB. HIGHS AT THIS TIME LOOK TO WARM TO THE MID 20S TO UP
TO ABOUT FREEZING (32F). AT THE SAME TIME, 850 MB TEMPERATURES LOOK
TO WARM TO JUST ABOVE 0C ALOFT, CREATING A WARM NOSE MAINLY FOR
LOCATIONS EAST OF I-29 BUT ESPECIALLY ACROSS NORTHWEST IOWA. WITH
SOUTHERLY FLOW IN PLACE, SOME MOISTURE WILL BE ADVECTED INTO THE
AREA, SETTING THE STAGE FOR MIXED PRECIPITATION. HOWEVER, THE
QUALITY OF MOISTURE DOES APPEAR TO BE LACKING AS SHOWN IN THERMAL
PROFILES. GIVEN A MAINLY DRY DENDRITIC GROWTH ZONE (DGZ) ACROSS
NORTHWEST IOWA, THINK THAT LIGHT FREEZING DRIZZLE WILL BE THE
PREDOMINANT PRECIPITATION TYPE ACROSS IN THIS AREA. COULD SEE
FREEZING DRIZZLE BLEED OVER INTO ADJACENT PARTS OF SOUTHWEST
MINNESOTA AS WELL. HOWEVER, THE DGZ LOOKS TO BE BETTER SATURATED
ACROSS SOUTHWEST MINNESOTA WHERE LIGHT SNOW IS POSSIBLE. THE CHANCES
(~30% CHANCE) FOR LIGHT SNOW WILL EXTEND WEST/NORTHWESTWARD TO
INCLUDE MOST OF I-90 UP TO HIGHWAY-14. IN TERMS OF PRECIPITATION
TYPE, THE NBM SHOWS ABOUT A 30% CHANCE FOR FREEZING RAIN ACROSS
PARTS OF NORTHWEST IOWA. IN TERMS OF AMOUNTS, THE ENSEMBLES ONLY
SHOW A 20-40% CHANCE FOR EXCEEDING A TENTH OF AN INCH OF LIQUID QPF.
IN TERMS OF PRECIPITATION TYPE, THE NBM SUGGESTS A SIMILAR
PROBABILITY OF 20-40% FOR ICE ACCUMULATIONS TO EXCEED A HUNDREDTH OF
AN INCH EAST OF I-29. THESE PROBABILITIES QUICKLY DIMINISH FOR FIVE
HUNDREDTHS AND A TENTH OF AN INCH OF ICE. FOR SNOW, THE PROBABILITY
IS HIGHER, UP TO A 40-60% CHANCE FOR EXCEEDING A TENTH OF AN INCH.
HOWEVER, THESE PROBABILITIES ALSO DIMINISH FOR RECEIVING AN INCH OR
MORE. THE GENERALLY LACKING SATURATION AND PROBABILITIES SUPPORT THE
NOTION THAT THIS WILL BE A LIGHT PRECIPITATION EVENT. COULD SEE
GUSTY WINDS WEDNESDAY NIGHT THOUGH AS THE PRECIPITATION PUSHES
EASTWARDS AND A SHOT OF COLD AIR ADVECTION (CAA) IS DELIVERED ACROSS
THE FORECAST AREA. MEDIUM RANGE GUIDANCE SHOWS WINDS OF 40 TO UP TO
60 KNOTS AT 850MB. HOWEVER, QUESTIONS REMAIN AS TO HOW HIGH MIXING
WILL BE ABLE TO REACH UP TO. OTHERWISE, TEMPERATURES WILL FALL TO
THE SINGLE DIGITS AND TEENS OVERNIGHT.
THURSDAY AND FRIDAY LOOK QUIET WITH HIGHS MODERATING TO THE 20S,
30S, AND POTENTIALLY UP TO 40F ON FRIDAY. HOWEVER, ANOTHER UPPER
LEVEL WAVE WILL PUSH INTO THE NORTHERN PLAINS LATE FRIDAY THROUGH
SATURDAY. THERE IS UNCERTAINTY REGARDING HOW THIS WAVE WILL EVOLVE
AMONGST THE DETERMINIST MODELS. CHANCES FOR PRECIPITATION LOOK
DECENTLY HIGH AT THIS TIME WITH THE ENSEMBLES SHOWING A BROAD 40-80%
CHANCE FOR EXCEEDING A TENTH OF AN INCH OF LIQUID PRECIPITATION.
HOWEVER, THE HIGHEST PROBABILITIES LIE NORTH OF THE FORECAST AREA.
HAVE STUCK WITH MODEL BLENDED POPS AT THIS TIME BUT WILL KEEP AN EYE
ON THIS SYSTEMS POTENTIAL OVER THE COMING DAYS. HIGH TEMPERATURES
LOOK TO REMAIN IN THE UPPER 20S TO UPPER 30S WITH LOWS FALLING TO
THE SINGLE DIGITS AND TEENS.
NO BREAK IN THE NEAR SEASONAL TEMPERATURES FOR SUNDAY AND MONDAY AS
HIGHS REMAIN IN THE TEENS, 20S, AND LOW 30S WITH LOWS FALLING TO THE
SINGLE DIGITS AND TEENS. COULD SEE LOWS FALL TO BELOW 0F MONDAY
NIGHT BUT THIS IS QUITE UNCERTAIN AT THIS TIME.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1103 AM CST MON FEB 3 2025
MVFR-IFR STRATUS WILL PERSIST ACROSS MUCH OF THE AREA THROUGH
SUNSET, THOUGH GRADUAL IMPROVEMENT IS FORECAST FROM WEST TO EAST
WITH PORTIONS OF SOUTHWEST MINNESOTA/NORTHWEST IOWA SEEING
POTENTIAL FOR IFR CEILINGS PERSIST THE LONGEST.
ALONG WITH THE MVFR-IFR CEILINGS WILL BE AREAS OF MVFR-IFR
VISIBILITY IN EITHER -FZDZ OR FLURRIES. AS WITH THE LOWER STRATUS,
LOWER VISIBILITY AND POTENTIAL FOR FREEZING DRIZZLE WILL PERSIST
LONGEST ACROSS SOUTHWEST MN AND INTO THE IOWA GREAT LAKES DUE TO
HIGHER ELEVATION AND A WEAK UPSLOPE NORTH-NORTHEAST FLOW.
OVERALL, IMPROVING CONDITIONS ARE EXPECTED AFTER 04/00Z-02Z WITH
VFR CONDITIONS EXPECTED TO PREVAIL FOR THE LATTER HALF OF THE TAF
PERIOD.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR
MNZ071-072-080-081-089-090-097.
IA...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR
IAZ002-003.
NE...NONE.
UPDATE...JH
DISCUSSION...MEYERS
AVIATION...JH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page