380
FXUS63 KABR 130656
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
156 AM CDT SUN SEP 13 2026
KEY MESSAGES
- COOLER THAN NORMAL TEMPERATURES EXPECTED THROUGH WEDNESDAY (HIGHS
IN THE 60S TO LOW 70S) WITH THE EXCEPTION OF A BRIEF WARMUP ON
MONDAY (HIGHS IN THE MID TO UPPER 70S OVER MUCH OF THE FORECAST
AREA). A GRADUAL WARMING TREND WILL BEGIN MID-WEEK AND CONTINUE
THROUGH THE WEEKEND.
- CONFIDENCE IS HIGH ON WIDESPREAD RAIN AND PERHAPS WEAK
THUNDERSTORMS OVERNIGHT TONIGHT THROUGH MONDAY AFTERNOON. HIGHEST
RAINFALL TOTALS ARE EXPECTED ALONG THE US-212 CORRIDOR, WHERE TOTALS
MAY EXCEED ONE INCH (40-60% CHANCE).
- STRONG NORTHWESTERLY WINDS TAKE HOLD BEHIND A COLD FRONT MONDAY
AFTERNOON INTO EVENING. ALONG AND WEST OF THE MISSOURI RIVER, WIND
GUSTS WILL REACH AS HIGH AS 35 TO 45 MILES PER HOUR.
DISCUSSION
ISSUED AT 154 AM CDT SUN SEP 13 2026
MONITORING THE POTENTIAL FOR SOME EARLY MORNING RAIN SHOWERS THIS
MORNING. AREA OF FOCUS IS MAINLY OVER CENTRAL SOUTH DAKOTA, ALTHOUGH
THERE IS SOME SIGNAL IN MODEL GUIDANCE FOR SOME RAIN OVER PARTS OF
NORTHEASTERN SOUTH DAKOTA AND WESTERN MINNESOTA AS WELL. THERE IS A
FAIR DEGREE OF MODEL CONSENSUS FOR THESE SHOWERS TO DEVELOP AND MOVE
OVERHEAD BEGINNING AROUND 08-09Z AND CONTINUING THROUGH SUNRISE AND
INTO THE MORNING HOURS. EXPECTING ONLY LIGHT RAIN OUT OF THESE
SHOWERS, WITH LITTLE ACCUMULATION.
MORE ROBUST CHANCES FOR RAIN ARRIVE SUNDAY NIGHT INTO MONDAY
MORNING. ENSEMBLE MEDIANS FOR PRECIPITATION CONTINUE TO INCREASE,
AND MODELS HAVE TRENDED THE HEAVIEST PRECIPITATION FURTHER SOUTH AS
WELL. THE HEAVIEST RAINFALL IS NOW EXPECTED OVER PARTS OF EASTERN
SOUTH DAKOTA, WITH MEDIANS UP OVER AN INCH IN THAT AREA. NBM
PROBABILITY TO SEE AN INCH OR MORE FOR THE 24 HOURS ENDING MONDAY
EVENING RANGES FROM AROUND 40 TO 60 PERCENT ALONG THE US-212
CORRIDOR. WHILE NO SEVERE WEATHER IS EXPECTED WITH THIS RAIN, THERE
IS SOME HINT TO SOME FLOODING POTENTIAL DUE TO HEAVY RAIN. THE MAIN
DRIVER OF THIS SIGNAL IS A PLUME OF STRONG MOISTURE INTO THE AREA,
AND PWATS SIT AT AROUND 1.5"-1.75" MONDAY MORNING. THIS WOULD BE
WELL OVER 90TH PERCENTILE VALUES FOR THIS TIME OF YEAR BY ABOUT
0.25"-0.5". GIVEN THE WARMTH ABOVE THE SURFACE, THE WARM CLOUD LAYER
IS EXPECTED TO BE SOMEWHERE BETWEEN 11000-12000 FEET, ANOTHER
INGREDIENT IN THE FLOODING FORMULA. WITH FORCING COMING FROM A 50+
KNOT LOW-LEVEL JET, STORM MOTION WILL LIKELY BE FAIRLY QUICK,
MEANING THAT A TRAINING STORM SETUP WILL BE NECESSARY FOR FLOODING
TO DEVELOP. PERHAPS THE GREATEST LIMITATION IS A LACK OF INSTABILITY
IN THE AREA. MUCAPE VALUES STRUGGLE TO HIT EVEN 500 J/KG, SO THERE
IS MUCH TO BE DESIRED. ALL THIS TO SAY THAT WHILE FLOODING CAN'T
QUITE BE RULED OUT, IT DOES APPEAR TO BE SOMEWHAT OF AN EDGE CASE
WITH OTHERWISE BENIGN RAINFALL. LATEST FLASH FLOOD GUIDANCE VALUES
STILL EXCEED NBM 90TH PERCENTILE VALUES, SO IN ALL LIKELIHOOD
WHATEVER RAIN FALLS, THE GROUND WILL BE ABLE TO HANDLE. IT SHOULD
ALSO BE NOTED THAT WHILE THERE IS CURRENTLY A FOCUS ON THE US-212
CORRIDOR, THE RECENT SHIFT SOUTHWARD SHOULD BE A REMINDER THAT
FURTHER SHIFTS OF THE AXIS OF HEAVIEST RAINFALL WILL STILL BE
POSSIBLE DESPITE A LIMITED TIME FRAME BEFORE THE PRECIPITATION
ARRIVES.
BEHIND THE RAIN MONDAY MORNING, A COLD FRONT WILL PASS THROUGH THE
FORECAST AREA MONDAY AFTERNOON. AS THE FRONT PASSES, WINDS WILL TURN
FROM SOUTHERLY OUT AHEAD TO NORTHWESTERLY BEHIND. THESE
NORTHWESTERLY WINDS WILL INCREASE TO 20 TO 30 MILES PER HOUR,
PARTICULARLY ALONG AND WEST OF THE MISSOURI RIVER. GUSTS MAY EXCEED
WIND ADVISORY CRITERIA AT TIMES, ALTHOUGH THE LATEST NBM GUIDANCE
KEEPS THOSE CHANCES (~20-50%, INCREASING MOVING NORTHWEST) OVER
CORSON AND DEWEY COUNTIES. WHILE NO PRODUCT WILL BE ISSUED ON THIS
SHIFT, A HEADLINE MAY BE NEEDED WITH FUTURE FORECAST PACKAGES,
ESPECIALLY WITH THE NBM'S TENDENCY TO UNDERFORECAST WIND SPEEDS
UNDER A COLD AIR ADVECTION REGIME.
TEMPERATURES TUESDAY WILL RETURN TO SLIGHTLY BELOW NORMAL (HIGHS IN
THE MID TO UPPER 60S) AFTER A BRIEF WARMUP TO NEAR-NORMAL ON MONDAY.
MID-WEEK, A WEAK UPPER-LEVEL RIDGE BEGINS TO BUILD OVERHEAD. THIS
WILL LEAD TO A GRADUAL WARMING TREND THROUGH THE END OF THE WEEK.
EXPECT MULTIPLE SHORTWAVES TO MAKE THEIR WAY INTO THE REGION AND
BRING ADDITIONAL CHANCES FOR RAIN TO THE FORECAST AREA.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1235 AM CDT SUN SEP 13 2026
TERMINALS KABR,KATY,KPIR,KMBG
VFR CONDITIONS ARE FORECAST WITH MID/UPPER LEVEL CIGS. EXPECTING
A COUPLE AREAS OF LIGHT RAIN TO MATERIALIZE BETWEEN NOW AND 15Z.
HAVE STARTED INTRODUCING SOME PROB30 GROUPS (PRETTY LOW
CONFIDENCE IN WHERE/WHEN SOMETHING DEVELOPS) FOR THIS,
CONSIDERING PRECIPITATION IS SUPPOSED TO START DEVELOPING WITHIN
THE NEXT 3 TO 6 HOURS. WINDS OUT OF THE NORTHWEST (KABR/KATY)
CONTINUE TO WEAKEN AND WILL BRIEFLY BE LIGHT/VARIABLE BEFORE
BECOMING PREDOMINANTLY SOUTHEASTERLY, LIKE KMBG/KPIR.
ABR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
DISCUSSION...BC
AVIATION...10
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