428
FXUS63 KBIS 281149
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
649 AM CDT MON JUL 28 2025
KEY MESSAGES
- SCATTERED TO NUMEROUS SEVERE THUNDERSTORMS ARE LIKELY ACROSS
SOUTHERN NORTH DAKOTA THIS MORNING AND AFTERNOON. A
SIGNIFICANT DAMAGING WIND THREAT COULD DEVELOP ALONG AND
SOUTH OF I-94, WITH GUSTS AS HIGH AS 80 MPH.
- ISOLATED SEVERE THUNDERSTORMS ARE ALSO POSSIBLE ACROSS
NORTHERN NORTH DAKOTA THIS MORNING AND AFTERNOON. EXPECTED
HAZARDS INCLUDE HAIL AS LARGE AS PING PONG BALLS AND WIND
GUSTS UP TO 70 MPH.
- BELOW AVERAGE TEMPERATURES ARE EXPECTED THIS WEEK, WITH HIGHS
MAINLY IN THE 70S AND LOWS MAINLY IN THE 50S.
UPDATE
ISSUED AT 649 AM CDT MON JUL 28 2025
SHOWERS AND THUNDERSTORMS HAVE ENTERED WESTERN NORTH DAKOTA
EARLY THIS MORNING, WITH A FEW SEVERE THUNDERSTORMS ALREADY
IMPACTING FAR WEST CENTRAL ND. THE EXPECTATION REMAINS THAT
STORMS WILL INCREASE IN INTENSITY THIS MORNING THROUGH THE
AFTERNOON HOURS, WITH THE POTENTIAL FOR A SIGNIFICANT DAMAGING
WIND THREAT TO DEVELOP ALONG AND SOUTH OF I94.
DISCUSSION
ISSUED AT 437 AM CDT MON JUL 28 2025
SEVERAL INGREDIENTS ARE FORECAST TO BE IN PLACE THIS MORNING AND
AFTERNOON THAT COULD ALLOW A BOW ECHO/DERECHO TO ORIGINATE IN
SOUTHWEST OR SOUTH CENTRAL NORTH DAKOTA. HOWEVER, THERE IS STILL
SOME FORECAST UNCERTAINTY IN CONVECTIVE EVOLUTION AND PLACEMENT OF
THE HIGHEST END SEVERE STORM IMPACTS.
SCATTERED SHOWERS AND THUNDERSTORMS ARE ONGOING ACROSS NORTHEAST
MONTANA EARLY THIS MORNING. THESE ARE LIKELY TIED TO MID LEVEL
IMPULSES EJECTING NORTHEASTWARD OFF THE NORTHERN ROCKIES IN A
SOUTHWEST FLOW ALOFT REGIME. ALSO IN PLAY IS AN UPPER LEVEL JET
STREAK ACROSS SOUTHERN CANADA THAT PLACES NORTHEAST MONTANA UNDER
ITS RIGHT ENTRANCE REGION. THESE FEATURES ARE FORECAST TO MIGRATE
EASTWARD INTO THE DAKOTAS THROUGHOUT THE DAY TODAY, WITH A STRONGER
700 MB WAVE FORECAST TO DEEPEN OVER SOUTHEAST MONTANA BY THE
AFTERNOON. LEE SURFACE CYCLOGENESIS IS ALSO UNDERWAY IN NORTHEAST
WYOMING EARLY THIS MORNING, AND ITS FORECAST EAST-SOUTHEAST
PROGRESSION WILL MAINTAIN A LOW LEVEL EASTERLY FLOW REINFORCING MID
60S TO MID 70S DEWPOINTS. HIGH PRESSURE OVER ALBERTA/SASKATCHEWAN
WILL BEGIN PUSHING IN FROM THE NORTHWEST THIS AFTERNOON, SQUEEZING
THE LOW LEVEL BAROCLINIC ZONE IN THE VICINITY OF THE ND/SD BORDER.
MAINTENANCE AND INTENSITY OF EARLY MORNING CONVECTION ARRIVING FROM
NORTHEAST MONTANA IS UNCERTAIN. THE DOWNSTREAM ENVIRONMENT IS NOT
TOO DISSIMILAR FROM WHAT ONGOING CONVECTION IS SAMPLING, WHICH IS
YIELDING ISOLATED STRONG TO SEVERE STORMS AT TIMES. MUCAPE IS
SLIGHTLY HIGHER ON THIS SIDE OF THE MONTANA BORDER, AND EFFECTIVE
BULK SHEAR REMAINS VERY STRONG. BUT CAMS ARE NOT UNIVERSALLY SOLD ON
UPSCALE GROWTH ACROSS THE NORTHERN HALF OF THE STATE THROUGH THE
DAY, AND THE EXPANDING HIGH PRESSURE FROM CANADA COULD INHIBIT
DIURNAL GROWTH OF INSTABILITY/BUOYANCY. EVEN A LOWER CAPE SETUP
COULD ALLOW ISOLATED INSTANCES OF SEVERE WEATHER GIVEN THE EXPECTED
50 KTS OF DEEP LAYER SHEAR. ALL THIS KEEPS NORTHWEST AND NORTH
CENTRAL NORTH DAKOTA AT A MARGINAL RISK (LEVEL 1 OUT OF 5) FOR
SEVERE THUNDERSTORMS TODAY.
FARTHER SOUTH, CONFIDENCE IS MUCH HIGHER THAT NOT ONLY WILL
CONVECTION INITIATE IN SOUTHEAST MONTANA OR SOUTHWEST NORTH DAKOTA
LATER THIS MORNING, IT WILL POSE A SEVERE THREAT MOVING THROUGH AN
ENVIRONMENT WITH BOTH HIGH CAPE (AROUND 3000 J/KG) AND HIGH SHEAR
(50-55 KTS IN THE 0-6 KM LAYER). EVEN THOUGH THE STRENGTH OF
SYNOPTIC SCALE FORCING CAN BE CLASSIFIED AS MODERATE BUT NOT STRONG,
THERE SHOULD BE NO ISSUES IN OVERCOMING MLCIN, THOUGH THE INHIBITION
COULD POTENTIALLY DELAY UPSCALE GROWTH. THE EASTERLY LOW LEVEL FLOW
DIRECTLY OPPOSING THE WESTERLY STORM MOTION SHOULD ALSO ASSIST IN
MAINTENANCE OF SEVERE CONVECTION AS IT MOVES THROUGH SOUTHERN ND/
NORTHERN SD THROUGHOUT THE DAY.
FROM A CONCEPTUAL STANDPOINT, THIS IS A CLASSIC SETUP FOR A NORTHERN
PLAINS DERECHO, ALTHOUGH THE TIMING FOR OUR LOCAL AREA IS A LITTLE
UNUSUAL (MID MORNING TO LATE AFTERNOON). BECAUSE THE MCS IS FORECAST
TO ORIGINATE IN OUR AREA, OR PERHAPS JUST TO THE WEST, THERE IS SOME
UNCERTAINTY IN WHETHER IT WILL EVOLVE INTO A HIGHER-IMPACT
SIGNIFICANT DAMAGING WIND EVENT (AKIN TO JUNE 20 EARLIER THIS
SUMMER) BEFORE IT EXITS TO THE SOUTH AND EAST BY EARLY EVENING.
THERE IS ALSO STILL FORECAST UNCERTAINTY IN THE LATITUDINAL
PLACEMENT OF THE MCS. WHILE ALL CAMS SEEM TO FAVOR SEVERE STORMS OF
SOME FLAVOR IN SOUTHWEST NORTH DAKOTA, IT IS POSSIBLE THAT STORMS
COULD DIVE INTO NORTHERN SOUTH DAKOTA BEFORE REACHING LAKE OAHE. BUT
IT IS EQUALLY PLAUSIBLE THAT THE MOST INTENSE STORMS COULD REMAIN
NORTH OF THE BORDER THROUGH THE SOUTHERN JAMES RIVER VALLEY, WITH A
MAXIMUM NORTHERN EXTENT AS FAR AS I-94. ALL THIS HAS PROMPTED OUR
MESSAGING OF SCATTERED TO NUMEROUS SEVERE STORMS WITH POTENTIAL FOR
A SIGNIFICANT DAMAGING WIND EVENT ALONG AND SOUTH OF THE INTERSTATE
THIS MORNING AND AFTERNOON.
MOST CAMS AND ANALYSES OF WIND/SHEAR VECTOR ORIENTATION FAVOR A
LINEAR MODE, WHICH ALSO LENDS CONFIDENCE TO THE MESSAGING OF SEVERE
GUSTS AS HIGH AS 80 MPH. HOWEVER, A FEW RECENT RUNS OF THE HRRR DO
OFFER AN ALTERNATIVE SOLUTION OF A COUPLE DISCRETE SUPERCELLS
BLASTING ACROSS SOUTHERN NORTH DAKOTA, WITH UPSCALE GROWTH INTO A
LINEAR COMPLEX NOT OCCURRING UNTIL STORMS REACH NORTHEAST SOUTH
DAKOTA LATER THIS AFTERNOON. WE DO NOT THINK THIS IS A LIKELY
OUTCOME, BUT IT CANNOT BE COMPLETELY DISREGARDED. A DISCRETE STORM
MODE WOULD BE MORE LIKELY TO PRODUCE GIANT HAIL (AT LEAST TENNIS
BALL TO BASEBALL SIZE, PERHAPS EVEN SOFTBALL), BUT BECAUSE OF OUR
CONFIDENCE IN A LINEAR MODE, WE WILL ONLY MESSAGE PING PONG BALLS
FOR A MOST LIKELY MAXIMUM HAIL SIZE. IT IS ALSO WORTH EMPHASIZING
THAT THE VERY LOW PROBABILITY OUTCOME OF GIANT HAIL WOULD BE A
REPLACEMENT FOR THE SIGNIFICANT WIND THREAT AT ANY GIVEN LOCATION
(THE TWO WOULD NOT OCCUR CONCURRENTLY). REGARDLESS OF STORM MODE AND
CONVECTION EVOLUTION, TODAY'S TORNADO THREAT IS VERY LOW.
THE THREAT FOR SEVERE STORMS FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA WILL END BY EARLY EVENING. AN ACTIVE FLOW PATTERN
TRANSITIONING FROM ZONAL TO NORTHWEST COULD BRING ADDITIONAL ROUNDS
OF SHOWERS AND THUNDERSTORMS ACROSS THE STATE TONIGHT THROUGH
TUESDAY. CAMS ARE DECIDEDLY LESS EXCITED ABOUT THE SEVERE POTENTIAL
ON TUESDAY COMPARED TO TODAY, BUT THE WESTERN HALF OF THE STATE
COULD HAVE 1000-2000 J/KG CAPE WITH LITTLE TO NO CIN AND 50 KTS OF 0-
6 KM SHEAR WITH LONG, STRAIGHT HODOGRAPHS. OVER THE COURSE OF THE
REST OF THE WEEK, THE CANADIAN HIGH PRESSURE SAGGING SOUTH INTO THE
UPPER MIDWEST WILL SHUNT DAILY CHANCES FOR SHOWERS AND STORMS TO THE
THE SOUTH AND WEST (BUT STILL COVERING SOUTHWEST NORTH DAKOTA) AND
KEEP TEMPERATURES BELOW AVERAGE. A SHIFT TO MORE OF A HIGHLY
AMPLIFIED WAVE PATTERN IS THEN BEING ADVERTISED FOR THE WEEKEND.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 649 AM CDT MON JUL 28 2025
SHOWERS AND THUNDERSTORMS ARE PRESENT ACROSS MUCH OF WESTERN
NORTH DAKOTA AT THE MOMENT, AND ARE LIKELY TO PROGRESS EASTWARD
ACROSS MOST OF THE STATE THROUGH THE DAY TODAY. SEVERE
THUNDERSTORMS ARE POSSIBLE, ESPECIALLY FOR THE SOUTHERN HALF OF
THE STATE. A SIGNIFICANT DAMAGING WIND THREAT COULD DEVELOP
ALONG AND SOUTH OF I94 LATER THIS MORNING AND INTO THE AFTERNOON
HOURS. ALONG WITH ANY OF THESE SHOWERS AND THUNDERSTORMS, LOWER
CEILINGS, SIGNIFICANTLY REDUCED VISIBILITY, AND ERRATIC WINDS
ARE EXPECTED. ONCE STORMS CLEAR OUT LATER THIS AFTERNOON OR
EARLY EVENING, VFR CEILINGS AND VISIBILITY SHOULD PREVAIL
THROUGH THE REMAINDER OF THE PERIOD.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...TELKEN
DISCUSSION...HOLLAN
AVIATION...TELKEN
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