320
FXUS63 KBIS 252052
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
352 PM CDT WED JUN 25 2025
KEY MESSAGES
- ISOLATED STRONG TO SEVERE THUNDERSTORMS POSSIBLE LATE THIS
AFTERNOON INTO THIS EVENING WEST CENTRAL AND SOUTHWEST NORTH
DAKOTA.
- ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE IN THE
FAR WEST ON THURSDAY.
- ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE POSSIBLE ON
FRIDAY OVER MOST OF WESTERN AND ALL OF CENTRAL AND EASTERN
NORTH DAKOTA. ALL HAZARDS ARE POSSIBLE.
DISCUSSION
ISSUED AT 202 PM CDT WED JUN 25 2025
SHOWERS HAVE EXITED THE JAMES RIVER VALLEY. ISOLATED SHOWERS AND
A FEW THUNDERSTORMS REMAIN ACROSS THE FAR NORTH AND CONTINUE TO
TRACK OFF TO THE NORTH AND EAST. FARTHER TO THE WEST, SCATTERED
THUNDERSTORMS ARE DEVELOPING OVER NORTHEAST MONTANA IN AN AREA
OF MODERATE INSTABILITY BUT GENERALLY WEAK SHEAR. BETTER SHEAR
IS SITUATED FARTHER EAST, ALONG THE ND/MT BORDER AND INTO
CENTRAL ND. THE MAIN QUESTION FOR LATE THIS AFTERNOON/EVENING IS
WITH A GENERALLY SLOW EASTWARD PROPAGATION, WILL THESE STORMS
CATCH UP WITH THE BETTER SHEAR TO THE EAST. CURRENT SPC
MESOANALYSIS SHOWS THE BETTER EFFECTIVE SHEAR WILL LINGER OVER
THE SOUTHWEST THIS EVENING, WHICH NORTHEAST CONVECTION COULD
CATCH UP TO. ALSO DEVELOPING CONVECTION LATER THIS AFTERNOON
OVER SOUTHEAST MONTANA INTO WESTERN SOUTH DAKOTA AND NE WYOMING
MAY MOVE INTO THIS AREA OF HIGHER BULK SHEAR OVER SOUTHWEST ND.
CONFIDENCE IS RELATIVELY LOW, BUT SHOULD EITHER AREA OF
CONVECTION HOLD TOGETHER LONG ENOUGH, WE COULD SEE A FEW STRONG
TO POSSIBLY SEVERE STORMS IN SOUTHWEST ND. CURRENTLY, IT LOOKS
LIKE THE HIGHEST INSTABILITY REMAINS OVER MONTANA, AND THE
HIGHER SHEAR REMAINS OVER SOUTHWEST ND. CONVECTION THAT
DEVELOPS OVER MONTANA AND HOLDS TOGETHER TO MAKE IT INTO ND
COULD BE CAPABLE OF PRODUCING HAIL TO THE SIZE OF PING PONG
BALLS AND 60 MPH WINDS.
ON THURSDAY AND FRIDAY, WE REMAIN WITHIN A BROAD SOUTHWEST
UPPER FLOW. THURSDAY, A FRONTAL BOUNDARY BECOMES ESTABLISHED
OVER EASTERN MONTANA AND PUSHES INTO WESTERN NORTH DAKOTA, MOST
LIKELY THURSDAY EVENING, BUT POSSIBLY AS EARLY AS THE LATE
AFTERNOON IN THE FAR WEST. WE WILL ONCE AGAIN BECOME MODERATELY
UNSTABLE WITH MLCAPE OF 1000-2000 J/KG BUT ONLY MODEST BULK
SHEAR OF 20 TO 30 KNOTS. ISOLATED THUNDERSTORMS ARE POSSIBLE
ALONG THE SURFACE BOUNDARY THURSDAY AFTERNOON, WHICH CURRENTLY
LOOKS TO BE OVER EASTERN MONTANA. THERE COULD BE SOME DISCRETE
SUPERCELLS INITIALLY, BUT AS CONVECTION MOVES INTO NORTH DAKOTA
THE ATMOSPHERE BECOMES MORE CAPPED. SUPERCELLS WOULD NORMALLY
NECESSITATE LARGER HAIL, BUT WITH THE CURRENT FORECAST POSITION
OF THE BOUNDARY, WILL LIMIT THE HAIL TO QUARTER SIZE, AS WAS
THE CASE WITH THE PREVIOUS SHIFT. CAMS ALSO CURRENTLY DISSIPATE
CONVECTION AS IT PUSHES INTO NORTH DAKOTA. WILL NEED TO MONITOR
HOWEVER.
BY FRIDAY, IT LOOKS LIKE MODERATE TO POSSIBLY STRONG
INSTABILITY IS FORECAST TO DEVELOP ACROSS MUCH OF WESTERN AND
CENTRAL NORTH DAKOTA WITH SUFFICIENT DEEP LAYER SHEAR FOR
SUPERCELLS TO DEVELOP AS MID-LEVEL FLOW STRENGTHENS. AT THIS
TIME IT LOOKS LIKE VERY LARGE HAIL AND DAMAGING WINDS WOULD BE
THE MAIN THREAT. A TORNADO OR TWO CAN NOT BE RULED OUT HOWEVER.
ON SATURDAY THE SEVERE POTENTIAL MAY LINGER OVER SOUTH CENTRAL
AND INTO EASTERN NORTH DAKOTA, WITH ANOTHER DAY OF STRONG
INSTABILITY AND STRONG SHEAR. THE EVENTUAL LOCATION OF THE
SURFACE BOUNDARY WILL PLAY A BIG PART IN THE AMOUNT AND
INTENSITY OF THUNDERSTORM ACTIVITY OVER OUR FORECAST AREA, WITH
A BETTER SEVERE POTENTIAL PROBABLY FARTHER TO OUR SOUTH AND
EAST, BUT STAY TUNED AS THIS MAY CHANGE.
DRIER AND COOLER CONDITIONS RETURN LATE IN THE WEEKEND AND INTO
EARLY NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1143 AM CDT WED JUN 25 2025
CURRENTLY, SHOWER ACTIVITY IS EXITING KXWA, KMOT AND KJMS. WE
MAY BE ABLE TO START THE 18Z TAF PERIOD OUT WITH NO SHOWER OR
THUNDERSTORM ACTIVITY, OR IF NOT IT SHOULD BE SHORT LIVED.
LATER TODAY, SHOWER AND THUNDERSTORM ACTIVITY IS FORECAST TO
DEVELOP AROUND THE ND/MT BORDER AND MOVE EASTWARD TOWARDS
CENTRAL ND BEFORE DISSIPATING LATER THIS EVENING. CONFIDENCE IN
ANY ONE LOCATION IS PRETTY LOW SO WILL MOST LIKELY GO WITH A
PROB30 FOR WESTERN TAF SITES FOR NOW AND ADJUST AS THINGS
DEVELOP THIS AFTERNOON.
LATER TONIGHT, WIDESPREAD MVFR-IFR AND POSSIBLY LIFR CEILINGS
ARE EXPECTED TO DEVELOP OVER SOUTH CENTRAL INTO SOUTHEAST NORTH
DAKOTA, AND SPREAD WEST AND NORTH TO COVER MUCH OF WESTERN AND
CENTRAL ND BY THURSDAY MORNING. AT THIS TIME THE CONFIDENCE IS
HIGHER FOR LOW CEILINGS THAN FOG, ALTHOUGH WE DO EXPECT THERE
WILL BE SOME FOG, ESPECIALLY ALONG THE WESTERN FRINGES OF WHERE
THE STRATUS SETS UP. AS FOR THE STRATUS THE NBM 1D VIEWER
SUGGESTS OVER AN 80 PERCENT PROBABILITY OF MVFR CEILINGS TONIGHT
WITH AROUND A 55 PERCENT PROBABILITY OF IFR CEILINGS AND AROUND
A 25 TO 30 PERCENT PROBABILITY OF LIFR CEILINGS AT BISMARCK
WITHIN THE 1AM TO 7AM TIMEFRAME. PROBABILITIES ARE SIMILAR OR
HIGHER AT KJMS BUT LESS FOR KDIK KXWA AND KMOT. LOW STRATUS AND
FOG SHOULD BEGIN TO DISSIPATE LATER IN THE MORNING ON THURSDAY.
EXPECT SURFACE FLOW TO REMAIN EAST TO SOUTHEAST THROUGH THE
PERIOD AT 5-15 MPH.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...TWH
AVIATION...TWH
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