372
FXUS63 KBIS 131953
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
253 PM CDT SAT SEP 13 2025
KEY MESSAGES
- SEVERAL ROUNDS OF SCATTERED SHOWERS AND THUNDERSTORMS THROUGH
THE MIDDLE OF NEXT WEEK.
- ISOLATED SEVERE THUNDERSTORMS POSSIBLE THROUGH THIS EVENING,
AND AGAIN SUNDAY AFTERNOON AND EVENING.
- TEMPERATURES FAVORED TO REMAIN NEAR TO ABOVE AVERAGE THROUGH
THE MIDDLE OF NEXT WEEK.
DISCUSSION
ISSUED AT 253 PM CDT SAT SEP 13 2025
A DEEP UPPER TROUGH CONTINUED TO DIG OVER THE ROCKIES THIS
AFTERNOON, WITH SURFACE LOW PRESSURE ANALYZED IN SOUTHWEST NORTH
DAKOTA. A SWATH OF MID-LEVEL WARM AIR ADVECTION ON THE
NORTHEAST SIDE OF THIS LOW HAS SUPPORTED SHOWERS AND
THUNDERSTORMS ACROSS SOUTH CENTRAL AND SOUTHEAST NORTH DAKOTA
EARLY THIS AFTERNOON, WITH ADDITIONAL WEAK CONVECTION ACROSS THE
NORTHWEST. IN BETWEEN THESE TWO AREAS, VERY ISOLATED SHOWERS
HAVE CONTINUALLY DEVELOPED BUT HAVE NOT PERSISTED FOR VERY LONG,
AND LIGHTNING ACTIVITY HAS BEEN OVERALL LOW. AFTERNOON HIGHS
WILL BE IN THE UPPER 60S TO MAINLY MID 70S, WITH WIDESPREAD
CLOUD COVER IN PLACE OVER THE FORECAST AREA.
WE ARE STILL MENTIONING ISOLATED SEVERE THUNDERSTORMS POSSIBLE
THIS AFTERNOON AND EVENING, BUT THINKING THE OVERALL LIKELIHOOD
IS PRETTY LOW. 18Z RAOB AT BISMARCK REVEALS A MODEST CAPPING
INVERSION STILL IN PLACE, WITH ONLY AROUND 500 J/KG OF BUOYANCY
AND AROUND 25 KNOTS OF BULK SHEAR. DETERMINISTIC GUIDANCE HAS
INSTABILITY INCREASING MARGINALLY THIS AFTERNOON BUT SIMILAR
SHEAR, AND WITH HOW MUCH CLOUD COVER HAS BEEN LINGERING AROUND
WITH THE SCATTERED SHOWERS AND THUNDERSTORMS, MUCH ADDITIONAL
DESTABILIZATION SEEMS UNLIKELY. THE LATEST CSU MACHINE LEARNING
OUTPUT HAS REMOVED VIRTUALLY ALL PROBABILITIES OF SEVERE WEATHER
FOR THIS AFTERNOON AND EVENING, WITH ONLY A SMALL AREA OF LOW
CHANCES IN EASTERN MONTANA. THE PRIMARY HAZARD TO BE CONCERNED
WITH FOR ANY THUNDERSTORMS WOULD BE HEAVY RAINFALL AND LOCALIZED
FLOODING POTENTIAL, ESPECIALLY IN ANY AREAS THAT HAVE ALREADY
RECEIVED HEAVY RAIN OVER THE PAST DAY OR TWO. AFTER THE CURRENT
SHOWERS AND THUNDERSTORMS MOVE THROUGH, THERE IS RELATIVELY GOOD
AGREEMENT ON A MODEST BREAK IN PRECIPITATION CHANCES THROUGH
MUCH OF THIS EVENING AND THE OVERNIGHT HOURS, WITH THE EXCEPTION
OF AN ISOLATED SHOWER OR STORM HERE AND THERE.
AS THE UPPER TROUGH BASE TILTS FURTHER INTO THE CENTRAL CONUS, A
MORE PRONOUNCED WAVE WITH AN ATTENDANT CLOSED LOW EJECTS NORTH
EARLY SUNDAY MORNING. HIGH-RES GUIDANCE IS CONSISTENT IN
BRINGING IN SHOWERS AND THUNDERSTORMS TO THE ND/SD STATE LINE
AROUND SUNRISE, WHICH IS WHEN BLENDED POPS START TO INCREASE
MORE SIGNIFICANTLY. EXPECT WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH THE DAY AND NIGHT SUNDAY, WITH THE HIGHEST
CHANCES ACROSS CENTRAL NORTH DAKOTA. WE AGAIN HAVE A MENTION OF
ISOLATED SEVERE THUNDERSTORMS, BUT NSSL AND CSU MACHINE LEARNING
GUIDANCE IS EVEN LESS CONVINCED OF TOMORROW COMPARED TO TODAY,
SO OVERALL LOW PROBABILITY OF SEEING ANYTHING STRONG TO SEVERE.
THERE IS A BIT MORE AGREEMENT AMONG ENSEMBLE CLUSTERS REGARDING
THE SYNOPTIC PATTERN TO START THE WORK WEEK, WITH A GENERAL
CONSENSUS OF A LONGWAVE TROUGH BASE EXTENDING FROM THE ROCKIES
TO NORTHWEST MINNESOTA ON MONDAY. ANOTHER WAVE PROPAGATING
THROUGH WILL CONTINUE CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH MONDAY AND MONDAY EVENING, WITH A SHORT-LIVED BREAK
BEFORE ADDITIONAL PRECIPITATION CHANCES CONTINUE THROUGH
MIDWEEK. THERE ARE SOME HINTS THAT AN UPPER RIDGE THAT TRIES TO
BUILD TO OUR WEST WILL GET PINCHED OFF BY A TROUGH DIGGING BACK
IN FROM THE EAST, EVENTUALLY PRODUCING CYCLONIC FLOW ACROSS THE
DAKOTAS FOR THE BACK HALF OF THE WORK WEEK. THE MAIN OUTCOME
FROM THIS WILL BE A COOLING TREND TO GET TEMPERATURES BACK
CLOSER TO NORMAL, WITH HIGHS FROM THURSDAY ONWARD MAINLY IN THE
MID 60S TO LOWER 70S. ON AND OFF PRECIPITATION CHANCES LINGER
BUT ARE LOWER THAN THE CURRENT PATTERN, WITH LESS MOISTURE
PRESENT FROM THE DRIER NORTHWEST FLOW ALOFT.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1246 PM CDT SAT SEP 13 2025
PERIODS OF SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE
THROUGH MOST OF THE TAF PERIOD, WITH POTENTIALLY A BREAK
OVERNIGHT TONIGHT. THE HEAVIEST SHOWERS ARE LIKELY TO PRODUCE
PERIODS OF MVFR TO IFR VISIBILITY REDUCTIONS, AND A FEW OF THE
THUNDERSTORMS COULD BECOME STRONG TO SEVERE, POSSIBLY PRODUCING
HAIL AND ERRATIC, STRONG WIND GUSTS.
GENERALLY LOW VFR TO MVFR CEILINGS THIS AFTERNOON, WITH POCKETS
OF SCATTERED CEILINGS UNDER 1K FEET. VFR CEILINGS ARE MORE
LIKELY AT SOUTHERN TERMINALS THIS EVENING BEFORE MORE WIDESPREAD
MVFR TO POTENTIALLY IFR CEILINGS OVERNIGHT AND INTO SUNDAY
MORNING. ALSO INCREASING CONFIDENCE IN WIDESPREAD PATCHY FOG,
AND DID INCLUDE AT KJMS AND KMOT WITH THIS UPDATE. WINDS ARE
GENERALLY FROM THE EAST TODAY, BECOMING LIGHT AND VARIABLE
OVERNIGHT.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...JONES
AVIATION...JONES
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