651
FXUS63 KBIS 280923
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
423 AM CDT SAT JUN 28 2025
KEY MESSAGES
- SCATTERED SHOWERS AND AN OCCASIONAL THUNDERSTORM WILL CONTINUE
ACROSS SOME PARTS OF WESTERN AND CENTRAL NORTH DAKOTA
THROUGHOUT THE DAY TODAY, BUT SEVERE WEATHER IS VERY UNLIKELY.
- HIGHS IN THE 80S TODAY, WITH HUMID CONDITIONS PERSISTING IN
SOUTH CENTRAL AND EASTERN NORTH DAKOTA.
- MUCH QUIETER WEATHER IS EXPECTED SUNDAY INTO TUESDAY, WITH
SLIGHTLY COOLER AND LESS HUMID CONDITIONS.
DISCUSSION
ISSUED AT 422 AM CDT SAT JUN 28 2025
ACTIVE SOUTHWEST FLOW ALOFT REMAINS OVER THE NORTHERN PLAINS EARLY
THIS MORNING. THE REMNANTS OF LAST NIGHT'S SEVERE STORMS ARE NOW
LONG GONE INTO MINNESOTA, BUT SHOWERS AND WEAKER THUNDERSTORMS HAVE
REIGNITED ALONG THE LOW LEVEL JET ALONG THE ND/SD BORDER. A FEW
STRONGER CELLS HAD BEEN EMBEDDED IN THIS ACTIVITY EARLIER IN THE
NIGHT, BUT OBSERVED LIGHTNING ACTIVITY HAS GREATLY DIMINISHED SINCE
3 AM CDT.
A SURFACE TROUGH/FRONTAL BOUNDARY FROM NORTHEAST TO SOUTHWEST NORTH
DAKOTA IS FORECAST TO SLOWLY MEANDER EASTWARD THROUGH TODAY. LITTLE
TEMPERATURE DIFFERENCE IS EXPECTED ON EITHER SIDE OF THE BOUNDARY,
WITH HIGHS EXPECTED TO REACH THE 80S. BUT SOUTHEAST OF THE BOUNDARY
WILL REMAIN QUITE HUMID WITH DEWPOINTS IN THE 60S. CONVERGENCE ALONG
THE SURFACE BOUNDARY LOOKS WEAK, AND DETERMINISTIC GUIDANCE SHOWS
LITTLE TO NO CYCLONIC VORTICITY EMBEDDED IN THE MID TO UPPER LEVEL
FLOW THIS AFTERNOON. THEREFORE, IN SPITE OF AS MUCH AS 2500 J/KG
CAPE AND 40 KTS DEEP LAYER SHEAR SOUTHEAST OF THE SURFACE BOUNDARY,
WE DO NOT EXPECT FORCING TO BE STRONG ENOUGH TO OVERCOME ANOTHER
CAPPING INVERSION THIS AFTERNOON AND EVENING. THE 00Z HREF CONFIRMS
THIS THINKING WITH ONLY A 10 PERCENT NEIGHBORHOOD PROBABILITY OF UH
EXCEEDING 75 M2/S2, WHICH IS ENTIRELY BEING CONTRIBUTED BY THE FV3
CAM THAT HAS A KNOWN HIGH-BIAS FOR INTENSE CONVECTION. WE DO EXPECT
POCKETS OF SHOWERS AND PERHAPS THE OCCASIONAL SUB-SEVERE STORM TO
PERSIST ACROSS THE STATE THIS MORNING, WITH ACTIVITY LIKELY TO WANE
THROUGH THE AFTERNOON AS FORCING STEADILY WEAKENS. THE ONE POSSIBLE
FAILURE MODE FOR A SEVERE STORM-FREE FORECAST FOR TODAY WOULD BE A
REMNANT OUTFLOW BOUNDARY SUPPLYING SUFFICIENT LIFT TO FORCE AIR
PARCELS ABOVE THE LFC, BUT SUCH A BOUNDARY DOES NOT APPEAR TO EXIST
IN OUR FORECAST AREA EARLY THIS MORNING. LATER TONIGHT, A FEW CAMS
BRING CONVECTION ORIGINATING FROM THE BLACK HILLS AND HIGH PLAINS OF
SOUTHEAST MONTANA/NORTHEAST WYOMING INTO FAR SOUTHERN PARTS OF THE
STATE, BUT BY THAT TIME THERE IS NOT EXPECTED TO BE ENOUGH
INSTABILITY/BUOYANCY TO SUPPORT ANY STRONG TO SEVERE CONVECTION.
A MID LEVEL SHORTWAVE IS FORECAST TO DEEPEN OVER SOUTHERN MANITOBA
ON SUNDAY AND DIG INTO THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY.
THIS COULD RESULT IN 1) ISOLATED SHOWERS AND PERHAPS A THUNDERSTORM
ACROSS NORTHERN NORTH DAKOTA SUNDAY AFTERNOON AND EVENING, 2) BREEZY
NORTHWEST WINDS NORTH AND EAST OF THE MISSOURI RIVER SUNDAY AND
MONDAY, AND 3) SLIGHTLY COOLER AND NOT AS HUMID CONDITIONS WITH
HIGHS SUNDAY AND MONDAY CLOSER TO AROUND 75 TO 80. ON MONDAY, THERE
IS TIMING UNCERTAINTY ON THE TRANSITION OF NORTHWEST FLOW ALOFT FROM
CYCLONIC TO ANTICYCLONIC. IF IT STAYS CYCLONIC THROUGH MONDAY
AFTERNOON, WHICH WOULD LIKELY ONLY BE FOR THE EASTERN HALF OF THE
STATE, DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS COULD DEVELOP.
ENSEMBLES PRESENT A VARIETY OF FORECAST OUTCOMES FOR TUESDAY INTO
THE HOLIDAY WEEKEND, BUT THE GENERAL THEME IS FOR NORTHWEST FLOW
ALOFT WITH A WESTERN CONUS RIDGE POSSIBLY SHIFTING INTO THE PLAINS
WEDNESDAY OR THURSDAY, FOLLOWED BY A MORE AMPLIFIED AND CHAOTIC
QUASI-ZONAL FLOW. THE NBM FAVORS HIGHS IN THE 80S FOR TUESDAY AND
BEYOND, BUT COULD SEE A DAY OR TWO IN THE LOWER TO MID 90S DEPENDING
ON THE TIMING AND STRENGTH OF THE THERMAL RIDGE AXIS MOVING OFF THE
ROCKIES. LOW TO MEDIUM CHANCES FOR SHOWERS AND STORMS ARE FOUND
THROUGHOUT THE EXTENDED FORECAST BEGINNING TUESDAY NIGHT. PROSPECTS
FOR SEVERE THUNDERSTORMS NEXT WEEK REMAIN LOW, BUT ARE NON-ZERO.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 422 AM CDT SAT JUN 28 2025
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS WILL REMAIN
POSSIBLE ACROSS WESTERN AND CENTRAL NORTH DAKOTA THROUGH THIS
MORNING, WITH ANY LINGERING ACTIVITY LIKELY DIMINISHING THROUGH
THE AFTERNOON. SEVERE WEATHER IS NO LONGER EXPECTED, BUT BRIEF
DOWNPOURS AND GUSTY WINDS ARE POSSIBLE WITH ANY STORM THAT
DEVELOPS. VFR CONDITIONS ARE OTHERWISE EXPECTED TODAY. WESTERN
AND NORTHERN NORTH DAKOTA WILL SEE WEST TO NORTHWEST WINDS
INCREASE TO 10-20 KTS THIS AFTERNOON, WITH LIGHTER WINDS
ELSEWHERE.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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