998
FXUS63 KBIS 150644
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
144 AM CDT MON SEP 15 2025
KEY MESSAGES
- DENSE FOG IN NORTHWEST NORTH DAKOTA THROUGH MID MONDAY
MORNING.
- SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH MUCH OF THE
WEEK.
- HIGHS MOSTLY IN THE 70S THROUGH TUESDAY, THEN COOLING INTO
THE 60S BY THE END OF THE WORK WEEK.
UPDATE
ISSUED AT 142 AM CDT MON SEP 15 2025
OBSERVED VISIBILITY FROM CROSBY TO TIOGA HAS CONSISTENTLY BEEN AT
ZERO. THE FOG COULD BRIEFLY LIFT IF A BAND OF RAIN MOVES OVER THE
AREA, BUT OTHERWISE DO NOT SEE ANY INDICATION OF IMPROVEMENT
UNTIL AFTER SUNRISE. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR
THE 4 NORTHWEST COUNTIES UNTIL 10 AM CDT.
LATEST RAP ANALYSIS SHOWS A CLOSED 500 MB LOW OVER HETTINGER,
EMBEDDED IN A NEGATIVELY-TILTED TROUGH WITH A MAJOR AXIS FROM
NORTHEAST MONTANA TO SOUTH CENTRAL SOUTH DAKOTA. BANDS OF SHOWERS
ARE GENERALLY LIFTING NORTH-NORTHWEST ACROSS THE WESTERN THIRD OF
THE STATE AT THE TIME OF THIS WRITING, AND THERE HAS RECENTLY BEEN
ONLY VERY INFREQUENT LIGHTNING OBSERVED IN GRANT COUNTY. THE
BROADER AREA OF RAIN IS EXPECTED TO BEGIN LIFTING TO THE NORTH-
NORTHEAST BY EARLY MONDAY MORNING, FOCUSING ALONG THE HIGHWAY 83
CORRIDOR FROM MINOT TO BISMARCK.
UPDATE
ISSUED AT 936 PM CDT SUN SEP 14 2025
CONDITIONS HAVE TAMED DOWN GREATLY OVER THE AREA AS MOST OF THE
CONVECTION HAS LIFTED INTO MANITOBA/SASKATCHEWAN. SOME SHOWERS
CONTINUE TO LINGER OVER THE AREA, WHICH WILL BE THE TREND
THROUGH THE NIGHT. WITH THAT SAID, CAN NOT RULE OUT A CLAP OR
TWO OF THUNDER, BUT EXPECT ANY STORM TO REMAIN TAME. ONLY
POSSIBLE CONCERN IS IF A HEAVIER SHOWER WERE TO LINGER OVER AN
AREA OF CENTRAL NORTH DAKOTA THAT RECEIVED HEAVY RAIN THIS PAST
AFTERNOON/EVENING. OTHERWISE, ONLY OTHER CONCERN WOULD BE THE
POSSIBILITY OF SOME FOG GIVEN THE MOIST LOWER LEVELS AND LIGHT
WINDS GIVEN THE SURFACE LOW LIFTING IN. HAVE BROAD-BRUSHED
PATCHY FOG IN FOR NOW FOR MOST AREAS AND WILL SEE HOW THIS
EVOLVES GOING INTO THE OVERNIGHT.
UPDATE
ISSUED AT 723 PM CDT SUN SEP 14 2025
THUNDERSTORMS CONTINUE TO LIFT THROUGH CENTRAL NORTH DAKOTA INTO
THE JAMES RIVER VALLEY. CURRENT TORNADIC STORM LIFTING THROUGH
MCHENRY COUNTY CONTINUES TO RUN RIGHT ALONG A GRADIENT OF AROUND
30KTS OF 0-3KM SHEAR, WHICH HAS BEEN THE GENERAL TREND THROUGH
THIS EVENT. A LINE OF STORMS HAS ALSO BLOSSOMED ON THE SOUTHERN
END OF AN AREA OF ELEVATED INSTABILITY, MOVING INTO A MORE
UNSTABLE AIRMASS. SO FAR THE MAIN POSSIBLE THREAT WITH THESE
STORMS WOULD BE WIND, THOUGH BRIEF HEAVY RAIN FELL IN JAMESTOWN
LEADING TO SOME STREET FLOODING. THE EXPECTED GENERAL TREND WITH
THIS WHOLE SYSTEM IS TO CONTINUE TO LIFT NORTHWARD, AND ALSO
EXPECT A DOWNWARD TREND WITH THE LOSS OF DAYTIME HEATING,
ESPECIALLY ON THE EASTERN STORMS.
DISCUSSION
ISSUED AT 231 PM CDT SUN SEP 14 2025
SURFACE LOW NOW LIFTING NORTHWARD, CENTERED BETWEEN PIERRE AND
MOBRIDGE, SD, WITH WARM FRONT WRAPPING INTO THE NORTH SIDE OF
THE LOW. BROAD AREA OF SHOWERS AND STORMS HAVE DEVELOPED OVER
SOUTH CENTRAL INTO SOUTHWEST NORTH DAKOTA. IN THIS VICINITY,
MORE LOW-LEVEL SRH RICH AIR IN THE VICINITY OF THE WARM FRONT
WILL BRING A TORNADIC THREAT. THIS HAS BEEN CONFIRMED BY
MULTIPLE TORNADOES THAT HAVE ALREADY OCCURRED OVER FAR SOUTH
CENTRAL NORTH DAKOTA. THERE ALSO IS A LIMITED LARGE HAIL/WIND
THREAT. ANOTHER GREAT CONCERN GIVEN THE MOISTURE RICH
ENVIRONMENT IS HEAVY RAIN, THUS THE POTENTIAL FOR FLOODING. THE
THREAT FOR THE SEVERE WEATHER CONTINUES INTO THIS EVENING BEFORE
DISSIPATING.
SYSTEM WILL MEANDER NORTH THROUGH THE NIGHT. MODELS STILL SHOW
A BIT OF TIMING UNCERTAINTY WITH THE DEPARTURE OF THE LOW INTO
CANADA ON MONDAY, NOW GENERALLY SOMETIME IN THE AFTERNOON/EARLY
EVENING. THIS KEEPS HIGH CHANCES FOR SHOWERS BUT COMPARATIVELY
LOWER CHANCES FOR THUNDERSTORMS IN THE FORECAST ON MONDAY,
DECREASING FROM SOUTH TO NORTH IN THE AFTERNOON THROUGH THE
EVENING. NOT LONG AFTER THE DEPARTURE OF THE LOW LATE MONDAY,
ANOTHER WAVE DEEPENING OVER THE NORTHERN ROCKIES WILL BEGIN
SENDING DCVA INTO THE REGION ON TUESDAY, WHICH KEEPS A 20 TO 40
PERCENT CHANCE OF RAIN IN THE FORECAST. GUIDANCE THEN SHOWS
ANOTHER SHORTWAVE DIGGING DOWN FROM CANADA ON WEDNESDAY. THIS
WAVE IS LIKELY TO BRING A COOLER AIR MASS INTO THE REGION, WHICH
MAY HOLD THROUGH THE END OF THE WEEK AS THE WAVE INTERACTS WITH
THE OTHER AFOREMENTIONED WAVE AND MEANDERS AROUND THE UPPER
MIDWEST. THE NBM MAINTAINS A 30 PERCENT CHANCE OF RAIN ON
WEDNESDAY, FOLLOWED BY ONLY A 20 PERCENT CHANCE THURSDAY THROUGH
SATURDAY.
FOR MONDAY AND TUESDAY, HIGH TEMPERATURES ARE MOSTLY EXPECTED
TO BE IN THE 70S, THOUGH PARTS OF SOUTHWEST AND SOUTH CENTRAL
NORTH DAKOTA COULD STAY IN THE MID TO UPPER 60S SHOULD IT RAIN
MOST OF THE DAY. ENSEMBLES THEN SHOW A DISTINCT COOL DOWN FOR
THE SECOND HALF OF THE WEEK, WITH HIGHS MOSTLY IN THE 60S
THURSDAY THROUGH SATURDAY. FORECAST LOWS TONIGHT REMAIN CLOSER
TO SUMMERTIME VALUES OF MID 50S TO LOWER 60S, THEN GRADUALLY
COOL TO AROUND 45 TO 50 FOR THE SECOND HALF OF THE WEEK.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 142 AM CDT MON SEP 15 2025
SHOWERS WITH AN OCCASIONAL THUNDERSTORM WILL CONTINUE ACROSS THE
WESTERN HALF OF NORTH DAKOTA OVERNIGHT, SLOWLY LIFTING NORTH-
NORTHEAST THROUGH MONDAY AFTERNOON. RAIN COULD REDUCE VISIBILITY AS
LOW AS IFR LEVELS AT TIMES. DENSE FOG AND LIFR CEILINGS HAVE
DEVELOPED IN NORTHWEST NORTH DAKOTA. THESE CONDITIONS MAY REACH KXWA
EARLY MONDAY MORNING. MVFR TO IFR CEILINGS ARE EXPECTED ACROSS
CENTRAL NORTH DAKOTA OVERNIGHT. THE LOW CEILINGS MAY SWING TOWARD
KJMS MONDAY MORNING BEFORE LIFTING NORTHWARD MONDAY AFTERNOON.
CENTRAL NORTH DAKOTA WILL SEE SOUTHWESTERLY WINDS INCREASE TO
AROUND 10-15 KTS MONDAY AFTERNOON, WITH NORTHWESTERLY WINDS
AROUND 10 KTS FARTHER WEST.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR NDZ001-002-
009-010.
UPDATE...HOLLAN/JJS
DISCUSSION...ANGLIN/HOLLAN/JJS
AVIATION...HOLLAN
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