506
FXUS63 KABR 182103
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
303 PM CST MON NOV 18 2024
KEY MESSAGES
- UP TO AN INCH OF RAIN IS FORECAST FROM THE JAMES RIVER EAST BY
TUESDAY AFTERNOON.
- COLDER AIR MOVING IN ON TUESDAY WILL RESULT IN A TRANSITION FROM
RAIN TO SNOW TUESDAY NIGHT.
- STRONG WINDS OUT OF THE NORTHWEST WILL EXPAND ACROSS THE AREA
TONIGHT, PEAKING BETWEEN 35 AND 55 THROUGH WEDNESDAY. A WIND
ADVISORY IS IN EFFECT FOR AREAS WEST OF THE JAMES VALLEY.
- LIGHT SNOW ACCUMULATIONS (1" OR LESS) CAN BE EXPECTED NORTHEAST OF
A LINE FROM MOBRIDGE TO MILLER TUESDAY NIGHT/WEDNESDAY, BUT THE BULK
OF SNOW IS EXPECTED OVER THE SISSETON HILLS AND THE WESTERN SIDE OF
THE COTEAU (25 TO 45% CHANCE OF 4+ INCHES)
SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/
ISSUED AT 301 PM CST MON NOV 18 2024
RAIN IS PUSHING NORTH AND WEST INTO SOUTH DAKOTA THIS AFTERNOON.
IT'S LOOKING MORE LIKE AREAS WEST RIVER, ESPECIALLY FROM PIERRE
SOUTH, WILL STAY MOSTLY DRY. ON THE OTHER HAND, AREAS FROM THE JAMES
VALLEY EAST ARE FORECAST TO SEE HALF AN INCH TO OVER AN INCH OF RAIN
THROUGH TUESDAY AFTERNOON.
AS THE SFC LOW MOVES NORTH INTO MINNESOTA TONIGHT, THE PRESSURE
GRADIENT TIGHTENS WITH A 16 MB SPREAD ACROSS SOUTH DAKOTA. COUPLED
WITH SOME STRONG CAA, NORTHWEST WINDS ARE EXPECTED TO INCREASE BY 9Z
ACROSS CENTRAL SD WITH GUSTS OF 40 TO 55 MPH SPREADING EAST THROUGH
THE DAY. THE STRONGEST WINDS WILL REMAIN WEST OF THE JAMES VALLEY
WHERE A WIND ADVISORY HAS BEEN ISSUED THROUGH TUESDAY EVENING.
AS THE LOW CONTINUES NORTH TUESDAY NIGHT, PRECIPITATION MAY BRIEFLY
TAPER OFF TUESDAY EVENING BEFORE WRAPAROUND MOISTURE MOVES BACK IN.
ANY PRECIP TUESDAY NIGHT IS EXPECTED TO BE SNOW.
LONG TERM /WEDNESDAY THROUGH MONDAY/
ISSUED AT 301 PM CST MON NOV 18 2024
THE START OF THE LONG TERM WE WILL HAVE AN UPPER LOW OVERHEAD WITH
SHORTWAVE ENERGY PIVOTING DOWN THE BACKSIDE, INTO NORTHEAST SOUTH
DAKOTA/WESTERN MINNESOTA. THE CORE OF COLDEST AIR HAS MOVED IN AND
LOW LEVEL PROFILES SHOW SHALLOW INSTABILITY. NAM SNOWSQUALL
PARAMETER HIGHLIGHTS THE NORTHEAST OF THE STATE INITIALLY AND THEN
PIVOTS INTO MINNESOTA, WHILE THE CANADIAN AND GFS DO SO FOR A
SIMILAR LOCATION, ALBEIT A FEW HOURS BEFOREHAND. NAM BUFKIT ALSO
INDICATES THAT BESIDES THE LOW LEVEL INSTABILITY, ASCENT (ABOUT 5
MICROBARS) WILL EXISTS IN A MID LEVEL DECK THAT WILL ALSO EXIST
WITHIN THE DENDRITIC GROWTH ZONE. THIS, ENHANCED BY UPSLOPE ACROSS
THE COTEAU WILL BE OUR FOCUS AREA FOR SNOW ACCUMULATIONS. OVERALL
PROBABILITIES FOR 4" HAS DECREASED TO ABOUT 30% (DOWN FROM THE 07Z
4" PROBABILITY OF ABOUT 50%). BLOWING SNOW TOOL CONTINUES TO
ADVERTISE THE POTENTIAL, HOWEVER THIS IS FOCUSED ACROSS THE SISSETON
HILLS AS THAT IS PRIMARILY WHERE ACCUMULATIONS ARE EXPECTED, HOWEVER
WITH NO EXISTING SNOWPACK SUSPECT BLOWING SNOW WILL STRICTLY BE A
FUNCTION OF FALLING SNOW AND WIND. AS FOR WIND SPEEDS, WE WILL
INITIALLY HAVE ABOUT AN 18MB GRADIENT FROM NORTHEAST TO SOUTHWEST
ACROSS THE STATE, WITH PERSISTENT SUBTLE PRESSURE RISES (3MB/6
HOURS). PEAK MIXED WINDS IN NAM BUFKIT ARE AROUND UPPER 30KT TO THE
MID 40KT RANGE, CAPTURED WELL BY THE NBM.
A RIDGE OF HIGH PRESSURE COMES IN BEHIND ON FRIDAY, THOUGH WITH
GRADIENT WINDS LINGERING ACROSS THE FAR EAST/WESTERN MN INTO
THURSDAY. FLOW SHIFTS TO EASTERLY OFF THAT HIGH FOR SATURDAY, SO
LITTLE IN THE WAY OF TEMPERATURE RECOVERY ANTICIPATED. THEN WE START
SEEING UNCERTAINTY AS TO WHETHER WE WILL SEE ANY OR MUCH WARMUP
PRIOR TO THE NEXT COLD AIRMASS WHICH WE ARE PICKING UP IN THE LAST
DAYS OF THE EXTENDED IN THE GEFS WITH THE NBM SHOWING A LOT OF RANGE
PAST MONDAY, BUT WITH EVEN COLDER MEAN/25TH PERCENTILES FOR
HIGHS/LOWS INTO NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1132 AM CST MON NOV 18 2024
TERMINALS KABR,KATY,KPIR,KMBG
CIRRUS HAVE BEGUN TO OVERSPREAD THE REGION FROM THE SOUTH EARLY
THIS AFTERNOON. RAIN SHOWERS AND MVFR TO EVENTUALLY IFR CEILINGS
WILL SPREAD NORTH AND WEST THROUGH EASTERN AND CENTRAL SD THIS
AFTERNOON AND EVENING, INITIALLY IMPACTING WATERTOWN AROUND 21Z
AND ABERDEEN AROUND 00Z. CONDITIONS WILL DETERIORATE THROUGH THE
EVENING VIA MVFR CEILINGS AT PIERRE AND MOBRIDGE, BUT CONFIDENCE
IS LOWER (NEAR OR BELOW 30%) REGARDING WHETHER RAIN WILL EXTEND
THAT FAR WEST. LATER THIS EVENING, EXPECT CEILINGS NEAR OR BELOW
500 FT AT ABERDEEN AND WATERTOWN, CONTINUING OVERNIGHT WITH THE
HEAVIEST RAIN EARLY TUESDAY MORNING.
SOUTHEAST WINDS WILL GUST UP TO 20 KTS THIS AFTERNOON, SWINGING
NORTHWESTERLY LATE THIS EVENING. NORTHWEST WINDS RAMP UP OVERNIGHT
WITH GUSTS OF 30 TO 40+ KTS EXPECTED TUESDAY MORNING AND THROUGH
THE DAYLIGHT HOURS.
ABR WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY FROM 3 AM CST /2 AM MST/ TUESDAY TO MIDNIGHT CST
/11 PM MST/ TUESDAY NIGHT FOR SDZ003>005-009-010-015>017-
033>037-045-048-051.
MN...NONE.
SHORT TERM...WISE
LONG TERM...CONNELLY
AVIATION...BC
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