569
FXUS63 KBIS 151148
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
648 AM CDT MON JUN 15 2026
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS TODAY, THEN WIDESPREAD
SHOWERS WITH ISOLATED TO SCATTERED THUNDERSTORMS TUESDAY
EVENING THROUGH WEDNESDAY.
- A FEW THUNDERSTORMS COULD BECOME STRONG ALONG AND BETWEEN
HIGHWAYS 85 AND 83 THIS AFTERNOON, AND FROM NORTHWEST TO
SOUTH CENTRAL NORTH DAKOTA TUESDAY EVENING INTO TUESDAY NIGHT.
- TEMPERATURES FAVORED TO REMAIN NEAR TO BELOW NORMAL THROUGH
THE WEEK, WITH HIGHS MOSTLY IN THE 60S WEDNESDAY AND THURSDAY,
AND 70S ALL OTHER DAYS.
- STRONG NORTHWEST WINDS ARE POSSIBLE IN WESTERN AND SOUTH
CENTRAL NORTH DAKOTA ON WEDNESDAY.
UPDATE
ISSUED AT 647 AM CDT MON JUN 15 2026
WIDELY SCATTERED SHOWERS THROUGHOUT NORTHWEST NORTH DAKOTA ARE
PROGRESSING SOUTHEASTWARD QUICKER THAN PREVIOUSLY EXPECTED. POPS
HAVE BEEN UPDATED TO CATCH UP TO THIS TREND. OTHERWISE, THE
FORECAST REMAINS IN GOOD SHAPE.
DISCUSSION
ISSUED AT 513 AM CDT MON JUN 15 2026
CYCLONIC NORTHWEST FLOW PREVAILS OVER THE NORTHERN PLAINS EARLY
THIS MORNING. AN EMBEDDED SHORTWAVE OVER SOUTHEAST SASKATCHEWAN
THAT COINCIDES WITH A WEAK SURFACE/LOW-LEVEL WEST-TO-EAST
ORIENTED COLD FRONT IS PREPARING TO CROSS THE INTERNATIONAL
BORDER. A BROKEN LINE OF WIDELY SCATTERED SHOWERS WITH AN
OCCASIONAL THUNDERSTORM HAS BEEN ASSOCIATED WITH THIS ACTIVITY
THROUGH THE NIGHT, AND HIGH-RESOLUTION MODEL GUIDANCE SUGGESTS
IT WILL CONTINUE INTO NORTH DAKOTA THROUGH THE MORNING. THE
HIGHEST CHANCES FOR RAIN THIS MORNING ARE IN NORTHWEST NORTH
DAKOTA WHERE FORCING MAY BE SUPPLEMENTED BY LEFT EXIT REGION JET
DYNAMICS. THE LEADING EDGE OF DCVA ASSOCIATED WITH THE
SHORTWAVE IS FORECAST TO CLEAR THE STATE BY THE AFTERNOON WHILE
THE WESTERN SIDE OF THE COLD FRONT PUSHES SOUTH MORE QUICKLY
THAN THE EASTERN SIDE. A CONTINUOUS STREAM OF CYCLONIC VORTICITY
IS ANTICIPATED OVER THE REGION THROUGH THE AFTERNOON, WHICH
COMBINED WITH DIURNAL HEATING IS EXPECTED TO RESULT IN SCATTERED
SHOWERS AND THUNDERSTORMS. THERE HAVE BEEN AND CONTINUES TO BE
MIXED SIGNALS ON THE THREAT CEILING FOR STORMS THIS AFTERNOON.
CAPE IS FORECAST TO BE HIGHEST IN CENTRAL AND EASTERN NORTH
DAKOTA AT AROUND 500-1000 J/KG. IN CONTRAST, DEEP LAYER SHEAR IS
FORECAST TO BE MUCH STRONGER OVER WESTERN NORTH DAKOTA AT
AROUND 40-50 KTS (AND UNIDIRECTIONAL), WITH A SHARP CUTOFF TO
ONLY 10-20 KTS CENTRAL AND EAST. IT IS POSSIBLE THAT THERE MAY
BE JUST ENOUGH OVERLAP IN THE HIGHER CAPE AND SHEAR TO ALLOW
STRONGER THUNDERSTORMS TO DEVELOP, WITH A VERY LOW BUT NON- ZERO
PROBABILITY FOR A SEVERE STORM. THIS POTENTIAL CORRIDOR SHOWS
UP IN HREF MAXIMUM UH TRACKS ALONG AND BETWEEN HIGHWAYS 85 AND
83, ALTHOUGH THE MAXIMUM VALUES OF UH THEMSELVES ARE LOWER THAN
WHAT CAMS TYPICALLY SIMULATE FOR A SEVERE THUNDERSTORM.
THEREFORE, A REASONABLE HIGH-END EXPECTATION FOR THE STRONGEST
STORM(S) TODAY WOULD BE HAIL UP TO NICKEL SIZE AND WIND GUSTS TO
AROUND 50 MPH.
BREEZY NORTHWEST WINDS ARE EXPECTED TO RETURN THIS AFTERNOON,
STRONGEST IN SOUTHWEST NORTH DAKOTA WHERE GUSTS COULD APPROACH
40 MPH. FORECAST HIGHS TODAY ARE IN THE UPPER 60S TO MID 70S.
SHOWERS AND THUNDERSTORMS SHOULD DIMINISH THROUGH THE EVENING,
GIVING WAY TO A QUIET OVERNIGHT PERIOD WITH LOWS IN THE 40S. AN
UPPER LEVEL JET STREAK IS FORECAST TO CURL FROM THE CANADIAN
ROCKIES INTO THE NORTHERN HIGH PLAINS BY TUESDAY MORNING. THE
PLACEMENT OF ITS LEFT EXIT REGION OVER A 700 MB SHORTWAVE AND
LOW LEVEL WARM AIR ADVECTION COULD PRODUCE A BROAD AREA OF LIGHT
RAIN SHOWERS OVER WESTERN AND CENTRAL NORTH DAKOTA TUESDAY
MORNING AND AFTERNOON, WITH LITTLE TO NO CHANCE OF THUNDERSTORMS
UNTIL AT LEAST LATE AFTERNOON. THE NBM SHOWS TUESDAY TO BE THE
WARMEST DAY OF THE WEEK FOR MOST LOCATIONS WITH HIGHS IN THE
LOWER 70S TO LOWER 80S, BUT WONDER IF THIS MAY BE TOO WARM GIVEN
THE EXPECTED INCREASE IN CLOUD COVER AND RAIN CHANCES. IN ANY
CASE, WINDS SHOULD AT LEAST BE MUCH LIGHTER ON TUESDAY.
A POTENT SHORTWAVE IS FORECAST TO EJECT OFF THE CANADIAN
ROCKIES BY TUESDAY EVENING AND DIG INTO THE UPPER MISSISSIPPI
RIVER VALLEY ON WEDNESDAY. SEVERAL CLUSTERS OF SHOWERS AND
THUNDERSTORMS ARE BEING DEPICTED BY CAMS AHEAD OF THE SHORTWAVE
TRAVELING THROUGH THE STATE LATE TUESDAY AFTERNOON THROUGH EARLY
WEDNESDAY MORNING, WITH THE HIGHEST PROBABILITIES FOCUSED FROM
AROUND WILLISTON TO BISMARCK TO JAMESTOWN. THERE IS AN EMERGING
SIGNAL FOR A HIGHLY CONDITIONAL SEVERE THUNDERSTORM THREAT WITH
THIS ACTIVITY, WITH THE TWO KEY CONDITIONS BEING 1) WHETHER, OR
FOR HOW LONG, STORMS WILL REMAIN ROOTED IN THE BOUNDARY LAYER
AND 2) HOW MUCH CAPE AND SHEAR WOULD BE AVAILABLE FOR ELEVATED
CONVECTION. ANY CONVECTION THAT REMAINS ROOTED IN THE BOUNDARY
LAYER TUESDAY EVENING WOULD EXPERIENCE VERY STRONG EFFECTIVE
BULK SHEAR AROUND 50-60 KTS. CAPE IS LESS CERTAIN, WITH
PROJECTIONS RANGING ANYWHERE FROM JUST A FEW HUNDRED TO NEAR
1500 J/KG. THE HIGHEST PROBABILITY FOR A SEVERE STORM WOULD BE
IN NORTHWEST NORTH DAKOTA EARLY TUESDAY EVENING, WITH CHANCES
LOWERING IN SPACE AND TIME. BUT THE 06Z HRRR, WHILE CLEARLY AN
OUTLIER, IS ATTENTION-GRABBING WITH A FEW VERY STRONG UH TRACKS
THROUGH SOUTH CENTRAL NORTH DAKOTA INTO LATE TUESDAY NIGHT. THE
PROBABILITY OF A STORM REALIZING THE AMOUNT OF CAPE AND SHEAR
THAT WOULD BE NEEDED TO PRODUCE STORMS OF THIS MAGNITUDE SEEMS
VERY LOW, ESPECIALLY CONSIDERING BOTH MUCAPE AND EFFECTIVE BULK
SHEAR (USING RAP 2-7 KM SHEAR AS A PROXY) ARE FORECAST TO
DECREASE OVER TIME AND SPACE. WE WILL THEREFORE NOT MESSAGE A
SEVERE POTENTIAL AT THIS TIME, BUT THIS ASPECT OF THE FORECAST
WILL NEED TO BE MONITORED CLOSELY.
THE RISK FOR EVEN JUST GARDEN-VARIETY THUNDERSTORMS IS FORECAST
TO SIGNIFICANTLY LOWER FOR WEDNESDAY AS THE DIGGING SHORTWAVE
BRINGS A MORE STABLE AIR MASS AND WEAKER MID LEVEL WINDS OVER
THE STATE. BUT WIDESPREAD RAIN SHOWERS ARE LIKELY TO CONTINUE
THROUGH AT LEAST THE AFTERNOON. THE FAVORED AXIS FOR HIGHEST QPF
TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON HAS TAKEN A SLIGHT
NORTHWARD SHIFT, WITH 3 OUT OF 4 ENSEMBLE CLUSTERS PLACING IT
FROM NEAR WILLISTON TO FARGO. BUT THRESHOLD PROBABILITIES ALONG
THIS CORRIDOR HAVE ALSO RISEN TO HIGH CHANCES FOR AT LEAST
0.25", MEDIUM CHANCES FOR AT LEAST 0.5", AND LOW CHANCES FOR AT
LEAST 0.75". THE BIGGEST FORECAST CONCERN DURING THE DAY
WEDNESDAY COULD BE FOR STRONG NORTHWEST WINDS. DETERMINISTIC
MODELS SHOW AN INITIAL PUSH OF COLD AIR ADVECTION AND PRESSURE
RISES LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING WITH AROUND
40-50 KTS MIXING POTENTIAL, BUT THE TIME OF DAY SHOULD LIMIT
GUSTS OF THAT MAGNITUDE, AT LEAST TEMPORALLY. A SECONDARY SURGE
THEREOF COULD PASS THROUGH WEDNESDAY AFTERNOON, BUT THIS ONE
CARRIES MUCH HIGHER UNCERTAINTY IN PLACEMENT AND TIMING, AND
MODEL SOUNDINGS SHOW UNCERTAINTY IN THE DEPTH OF THE MIXED
LAYER. REGARDLESS OF MAGNITUDES, PROBABILITIES FOR IMPACTFUL
WINDS ON WEDNESDAY RANGE FROM HIGH IN THE SOUTHWEST TO LOW IN
THE NORTHEAST. THE ECMWF EFI REFLECTS THIS THINKING WITH ITS
WIND GUST VALUES APPROACHING 0.8 AND INCLUSION OF A SHIFT-OF-
TAILS CONTOUR. THE NBM HAS SHOWN A RUN-TO- RUN COOLING TREND BUT
STILL KEEPS HIGHS IN THE MID TO UPPER 60S ON WEDNESDAY. THIS
STILL MAY BE AROUND 5 TO 10 DEGREES TOO WARM FOR ANY AREAS THAT
SEE PERSISTENT CLOUD COVER AND RAIN SHOWERS THROUGHOUT THE DAY,
WHICH COULD BE MUCH OF THE STATE.
A NORTHWEST FLOW PATTERN IS FAVORED TO PREVAIL THROUGH THE END
OF THE WORK WEEK, WITH INCREASING ENSEMBLE SPREAD ON WHETHER
THAT WILL HOLD THROUGH THE WEEKEND OR TRANSITION TO A
PROGRESSIVE AND AMPLIFIED QUASI-ZONAL FLOW. THURSDAY LOOKS TO
REMAIN COOL WITH LINGERING SHOWER CHANCES (20-40 PERCENT) AND
HIGHS STILL IN THE 60S. DESPITE THE INCREASING UNCERTAINTY IN
THE SYNOPTIC PATTERN, NBM MAXIMUM TEMPERATURE SPREADS REMAIN
LOW GIVEN THE FORECAST TIME RANGE AND SHOW A SLIGHT WARM UP
INTO THE 70S THROUGH THE WEEKEND.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 647 AM CDT MON JUN 15 2026
WIDELY SCATTERED SHOWERS WITH AN OCCASIONAL THUNDERSTORM WILL
SPREAD SOUTHEASTWARD ACROSS THE STATE THROUGH THE MORNING. THIS
ACTIVITY IS UNLIKELY TO GREATLY IMPACT AVIATION. THEN THIS
AFTERNOON, SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP, WITH HIGHER PROBABILITIES AND GREATER COVERAGE IN
CENTRAL NORTH DAKOTA COMPARED TO THE WEST. THE STRONGEST STORMS
COULD PRODUCE SMALL HAIL, ERRATIC WIND GUSTS, AND DOWNPOURS
REDUCING VISIBILITY TO MVFR/IFR LEVELS. MVFR CEILINGS COULD ALSO
BE ASSOCIATED WITH SHOWERS AND THUNDERSTORMS, MAINLY FROM KMOT
TO KJMS. SHOWERS AND STORMS SHOULD DIMINISH THROUGH THE EVENING.
VFR CONDITIONS ARE EXPECTED TO PREVAIL OUTSIDE OF AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS. WESTERLY WINDS AROUND 10-15
KTS THIS MORNING WILL TURN TO THE NORTHWEST AND INCREASE TO
15-25 KTS THIS AFTERNOON, THEN BECOME MUCH LIGHTER AND VARIABLE
OVERNIGHT.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...HOLLAN
DISCUSSION...HOLLAN
AVIATION...HOLLAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page