188
FXUS63 KBIS 270000
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
700 PM CDT FRI JUN 26 2026
KEY MESSAGES
- LOW TO MEDIUM CHANCES FOR THUNDERSTORMS TONIGHT. A FEW STORMS
COULD BECOME STRONG, MAINLY IN SOUTHWEST NORTH DAKOTA.
- NUMEROUS SEVERE THUNDERSTORMS ARE POSSIBLE LATE SATURDAY
AFTERNOON THROUGH SATURDAY NIGHT. EXPECTED HAZARDS INCLUDE
HAIL UP TO 2 INCHES IN DIAMETER AND DAMAGING WINDS UP TO 70
MPH, WITH A TORNADO POSSIBLE.
- ADDITIONAL ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE
POSSIBLE SUNDAY THROUGH MONDAY.
- NEAR TO ABOVE NORMAL TEMPERATURES ARE FAVORED THIS WEEKEND
THROUGH THE MIDDLE OF NEXT WEEK, WARMING TO WELL ABOVE NORMAL
HEADING INTO THE FORTH OF JULY HOLIDAY WEEKEND.
UPDATE
ISSUED AT 700 PM CDT FRI JUN 26 2026
LOW LEVEL STRATUS PERSISTS ACROSS MUCH OF WESTERN AND CENTRAL
NORTH DAKOTA AT THE TIME OF THIS EARLY EVENING UPDATE, THOUGH
SOME CLEARING CAN BE FOUND ACROSS THE FAR SOUTHWEST. UPSTREAM IN
NORTHEASTERN WYOMING SHOWERS AND THUNDERSTORMS HAVE BEGUN TO
DEVELOPING OVER THE TERRAIN IN THE BLACK HILLS, AND ARE EXPECTED
TO LIFT TOWARD SOUTHEASTERN NORTH DAKOTA THROUGH THE LATE
EVENING INTO THE EARLY OVERNIGHT PERIOD. ISOLATED STRONG TO
MARGINALLY SEVERE STORMS WILL BE POSSIBLE (LOW CHANCE) AS THEY
MOVE INTO THE SOUTHWEST, THOUGH THE WINDOW FOR THIS WILL BE
BRIEF. SHOWERS AND GENERAL THUNDERSTORMS WILL CONTINUE TO MOVE
TO THE NORTH AND EAST OVERNIGHT. HAVE MADE SOME MINOR
ADJUSTMENTS TO THE SKY COVER WITH THE FORECAST, THOUGH OTHERWISE
THE FORECAST REMAINS IN GOOD SHAPE AT THIS TIME.
DISCUSSION
ISSUED AT 346 PM CDT FRI JUN 26 2026
A WEAK MID LEVEL SHORTWAVE IS LIFTING NORTHEASTWARD THROUGH THE
EASTERN HALF OF THE STATE THIS AFTERNOON. ISOLATED TO WIDELY
SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE THROUGH THE
AFTERNOON FROM THE TURTLE MOUNTAINS THROUGH THE JAMES RIVER
VALLEY. CAPE AND SHEAR ARE NOT FORECAST TO BECOME SUFFICIENT TO
SUPPORT STRONGER CONVECTION.
AN UPPER LEVEL RIDGE IS FORECAST TO MOVE OVER WESTERN NORTH
DAKOTA TONIGHT, BUT IT COULD BE UNDERCUT BY MID LEVEL SOUTHWEST
FLOW WITH EMBEDDED SHORTWAVE ENERGY. ONE TO SEVERAL CLUSTERS OF
THUNDERSTORMS ARE LIKELY TO DEVELOP NEAR THE MOUNTAINS OF
CENTRAL MONTANA THIS EVENING AND QUICKLY MOVE EASTWARD TOWARD
WESTERN NORTH DAKOTA BY AROUND MIDNIGHT. SOME CAMS MAINTAIN
STRONGER CONVECTION IN SOUTHWEST NORTH DAKOTA LATE TONIGHT AS
BOTH MUCAPE AND EFFECTIVE BULK SHEAR INCREASE IN RESPONSE TO A
STRENGTHENING LOW LEVEL JET. THE INTENSITY OF CONVECTION WILL
ULTIMATELY BE DICTATED BY THE CAPE/SHEAR PARAMETER SPACE OF THE
ELEVATED INFLOW LAYER, WHICH MAY NOT NECESSARILY BE THE MOST
UNSTABLE LAYER. NEVERTHELESS, THERE IS A LOW PROBABILITY FOR A
MARGINALLY SEVERE THUNDERSTORM IN SOUTHWEST NORTH DAKOTA LATE
TONIGHT, WITH NO GREATER THAN BASELINE HAZARDS EXPECTED (QUARTER
SIZE HAIL AND/OR 60 MPH WIND GUSTS). SCATTERED SHOWERS AND
THUNDERSTORMS MAY CONTINUE TO PROPAGATE NORTHEASTWARD THROUGH
THE NIGHT INTO SATURDAY MORNING AS THE LOW LEVEL JET SLIDES
EASTWARD.
PERSISTENT SOUTHERLY FLOW AHEAD OF A LEE SURFACE TROUGH WILL
PROMOTE STRONG MOISTURE TRANSPORT ON SATURDAY, BUT MID LEVEL
CAPPING IS LIKELY TO PREVENT SURFACE-BASED CONVECTION PRIOR TO
LATE AFTERNOON. SURFACE WINDS COULD APPROACH ADVISORY CRITERIA
ACROSS ALL BUT FAR WESTERN NORTH DAKOTA SATURDAY AFTERNOON, WITH
SUSTAINED SPEEDS AROUND 20 TO 30 MPH AND GUSTS TO NEAR 45 MPH.
IT WILL ALSO BE WARMER AND MORE HUMID FOR MOST AREAS, WITH
DEWPOINTS IN THE 60S AND HIGHS AROUND 90 IN THE SOUTHWEST, THE
MID TO UPPER 70S FAR NORTH, AND 80S IN BETWEEN.
BY LATE SATURDAY AFTERNOON, THE LEE SURFACE TROUGH IS FORECAST
TO LIE ALONG THE ND/MT BORDER, WITH A POTENTIAL TRIPLE POINT
AXIS SOMEWHERE BETWEEN GLENDIVE AND WILLISTON. MID LEVEL HEIGHT
FALLS SHOULD BE SPREADING INTO WESTERN NORTH DAKOTA AT THIS
TIME, AND AN UPPER LEVEL JET STREAK IS ALSO FORECAST TO BE
POINTED TOWARD THE BLACK HILLS, PLACING ITS LEFT EXIT REGION
OVER THE LEE SURFACE TROUGH. ALL THIS COMBINED WITH STRONG
DIURNAL HEATING SHOULD SUFFICIENTLY ERODE CAPPING TO INITIATE
CONVECTION IN WESTERN NORTH DAKOTA BETWEEN 5 AND 7 PM CDT. SHEAR
VECTOR ORIENTATION TO SURFACE BOUNDARIES TENDS TO FAVOR AN
INITIAL DISCRETE MODE BOTH ALONG THE WEST-TO-EAST WARM FRONT
ACROSS NORTHERN NORTH DAKOTA AND ALONG THE NORTH-TO-SOUTH LEE
TROUGH, ALTHOUGH DEEP-LAYER MEAN WIND VECTORS ARE MORE PARALLEL
TO THE LEE TROUGH WHICH COULD ANCHOR UPDRAFTS TO THAT BOUNDARY
AND CAUSE QUICKER UPSCALE GROWTH. FOR ANY DISCRETE STORMS, 3000
J/KG CAPE AND 0-6 KM SHEAR INCREASING TO 40-50 KTS THROUGH EARLY
EVENING WILL SUPPORT VERY LARGE HAIL. BECAUSE OF THE POTENTIAL
FOR MID LEVEL DRY AIR ENTRAINMENT AND STRONGER LOW LEVEL
SHEAR/SR INFLOW, WE HAVE LIMITED OUR MOST LIKELY MAXIMUM HAIL
SIZE FORECAST TO 2 INCHES IN DIAMETER FOR NOW. THERE IS AT LEAST
SOME RISK FOR A TORNADO, ESPECIALLY IN NORTHWEST NORTH DAKOTA
WHERE A MORE DUE EASTERLY LOW-LEVEL/SURFACE FLOW IS FORECAST.
HERE, THE HREF ADVERTISES 0-1 KM SRH INCREASING OVER 100 M^2/S^2
BY EARLY EVENING, WITH STP IN THE 1-2 RANGE. THERE COULD ALSO
BE A NARROW WINDOW IN BOTH TIME AND SPACE FOR A TORNADO THREAT
TO EXTEND SOUTHWARD ALONG THE LEE TROUGH IF STORMS ARE ABLE TO
REMAIN DISCRETE. THE HREF SHOWS THIS POTENTIAL TO BE ALONG AND
WEST OF HIGHWAY 83 FROM AROUND 8 TO 10 PM CDT. BUT LATEST CAM
GUIDANCE DOES TEND TO FAVOR A QUICKER TRANSITION TO A CLUSTER OR
LINEAR MODE ON ACCOUNT OF INCREASING SYNOPTIC SCALE FORCING AND
COLD POOL CONGLOMERATION AS CONVECTION SPREADS INTO CENTRAL
NORTH DAKOTA HEADING INTO THE OVERNIGHT HOURS. ONCE THIS OCCURS,
THE DOMINANT HAZARD WILL TRANSITION TO DAMAGING WINDS, WHICH
COULD BE WIDESPREAD AND SIGNIFICANT. MOST, IF NOT ALL REQUISITE
INGREDIENTS FOR +80 MPH WINDS APPEAR TO BE IN PLACE. THERE IS
STILL JUST ENOUGH FORECAST UNCERTAINTY IN FINER-SCALE DETAILS TO
LIMIT THE MOST LIKELY MAXIMUM WIND GUST POTENTIAL TO 70 MPH IN
OUR MESSAGING, BUT AN INCREASE TO 80 MPH MAY BE NEEDED WITH
FUTURE FORECAST UPDATES. WHILE THE TORNADO THREAT WOULD BE
RELATIVELY LOWER WITH A QLCS THAN WITH DISCRETE SUPERCELLS, IT
WOULD STILL BE GREATER THAN ZERO.
AFTER THE SEVERE THREAT ENDS LATE SATURDAY NIGHT (OR PERHAPS
EARLY SUNDAY MORNING) THERE IS UNCERTAINTY IN A CONDITIONAL
SEVERE THREAT ON SUNDAY WHICH COULD BE HEAVILY INFLUENCED BY HOW
THE POST-MCS ENVIRONMENT EVOLVES. THERE IS HIGH CONFIDENCE IN
STRONG DEEP LAYER SHEAR ON SUNDAY, BUT LOWER CONFIDENCE IN
FORCING, THE WESTWARD EXTENT OF MOISTURE/BUOYANCY, AND CIN. THIS
CONDITIONAL SEVERE THREAT NOW APPEARS TO EXTEND THROUGH SUNDAY
NIGHT AND INTO MONDAY AS AN UPPER LEVEL LOW DEEPENS BETWEEN THE
NORTHERN ROCKIES AND NORTHERN PLAINS, BUT THERE IS SOME ENSEMBLE
SPREAD IN ITS EVOLUTION. BEYOND MONDAY, ENSEMBLES BROADLY FAVOR
A SOUTHWEST FLOW PATTERN PREVAILING THROUGH THE END OF NEXT
WEEK, WITH TEMPERATURES TRENDING ABOVE NORMAL. AFTER A BREAK ON
TUESDAY, DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS, SOME
STRONG TO SEVERE, RESUME FOR THE SECOND HALF OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 700 PM CDT FRI JUN 26 2026
LOW VFR TO MVFR CEILINGS CAN BE FOUND AT ALL TERMINALS TO BEGIN
THE 00Z TAF PERIOD, THOUGH ARE EXPECTED TO IMPROVE TO MAINLY VFR
BY THE EARLY EVENING. LATE THIS EVENING AND OVERNIGHT, SHOWERS
AND THUNDERSTORMS ARE EXPECTED TO MOVE FROM SOUTHWEST TO
NORTHEAST, PROMOTING ANOTHER PERIOD OF LOWERED CEILINGS AT ALL
TERMINALS. MVFR TO IFR CEILINGS ARE ANTICIPATED AT OUR WESTERN
TERMINALS OF KXWA AND KDIK, AND AT OUR NORTHERN TERMINAL OF
KMOT, WHILE MAINLY MVFR CEILINGS ARE EXPECTED FOR THE SOUTH
CENTRAL TERMINALS OF KBIS AND KJMS. WHERE THUNDERSTORMS DO
DEVELOP, MVFR TO IFR CEILINGS CAN BE ANTICIPATED ALONG WITH
GUSTY AND ERRATIC WINDS. SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO GENERALLY DIMINISH BY THE EARLY OVERNIGHT PERIOD ACROSS THE
WEST, WHILE SOME SCATTERED SHOWERS AND ISOLATED THUNDER WILL
REMAIN POSSIBLE ACROSS PORTIONS OF CENTRAL NORTH DAKOTA THROUGH
THE MID MORNING. GUSTY SOUTHEAST WINDS ARE EXPECTED TO PERSIST
ACROSS MUCH OF THE FORECAST AREA THROUGH THIS EVENING AND
OVERNIGHT, STRENGTHENING THROUGH LATE SATURDAY MORNING AND
AFTERNOON. LLWS IS POSSIBLE OVER PORTIONS OF THE FAR SOUTHWEST
TONIGHT THROUGH EARLY SATURDAY MORNING, INCLUDING AT KDIK.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...ADAM
DISCUSSION...HOLLAN
AVIATION...ADAM
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