648
FXUS63 KBIS 130001
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
701 PM CDT WED AUG 12 2026
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS TONIGHT. ISOLATED SEVERE
STORMS ARE POSSIBLE ALONG AND SOUTH OF THE HIGHWAY 200
CORRIDOR THIS EVENING, THOUGH THE HIGHEST CHANCE IS NEAR THE
SOUTH DAKOTA BORDER.
- NEAR DAILY CHANCES FOR SHOWERS AND MAYBE THUNDERSTORMS THROUGH
FRIDAY NIGHT.
- A COOLING TREND IS EXPECTED THROUGH FRIDAY, FOLLOWED BY A
WARMING TREND THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
UPDATE
ISSUED AT 700 PM CDT WED AUG 12 2026
SHOWERS AND THUNDERSTORMS HAVE LIFTED INTO PORTIONS OF WESTERN
AND SOUTH CENTRAL NORTH DAKOTA BY THE TIME OF THIS EARLY EVENING
UPDATE. A FAIRLY MARGINAL AND UNBALANCED CONVECTIVE ENVIRONMENT
IS FOUND OVER THE FORECAST AREA, WITH MESOANALYSIS REVEALING
SOMEWHAT MODEST MUCAPE VALUES AROUND 500 TO 1250 J/KG, BUT
FAIRLY STRONG 0-6KM BULK SHEAR VALUES AROUND 45 TO 55 KNOTS
ACROSS ALONG AND SOUTH OF HIGHWAY 200. THE CONVECTIVE
ENVIRONMENT REMAINS THE BEST ACROSS THE SOUTH CENTRAL, WHERE A
STRONG TO SEVERE STORMS HAVE DEVELOPED OVER THE COURSE OF THE
LAST FEW HOURS. HERE, THE HIGHEST MID LEVEL LAPSE RATES OF
6.0-6.5 C/KM HAVE BEEN MORE SUPPORTIVE OF LARGE HAIL PRODUCTION,
AND FAIRLY STRAIGHT LOW LEVEL HODOGRAPHS HAVE ALLOWED FOR THE
OCCASIONAL, SHORT- LIVED LEFT-SPLIT SUPER CELL (WHICH ARE
USUALLY MORE PROLIFIC HAIL PRODUCERS). WITH CONDITIONS FURTHER
EAST STARTING TO BECOME WORKED OVER BY EARLIER SHOWERS AND
STORMS, AND WHERE THE CONVECTIVE HAS ALREADY BEEN MORE MARGINAL
THROUGHOUT THE EVENING, MORE DISORGANIZED, CLUSTERED STORMS HAVE
BEEN FOUND. CELL MERGERS BETWEEN THESE STORMS OR INTERACTIONS
WITH A FEW OUTFLOW BOUNDARIES MOVING TO THE NORTHWEST HAVE
ALLOWED A FEW STRONGER STORMS TO DEVELOP, THOUGH EVEN THESE HAVE
BEEN FAIRLY SHORT LIVED. UPSTREAM IN MONTANA, ANOTHER ROUND OF
SHOWERS AND STORMS ARE SLOWLY MAKING THEIR WAY TOWARD OUT
WESTERN BORDER, ARRIVING SOME TIME WITHIN THE NEXT TWO HOURS OR
SO. HAVE TWEAKED POPS, WINDS, AND SKY COVER WITH THIS UPDATE TO
ACCOUNT FOR THE LATEST RADAR, MODEL, AND SATELLITE TRENDS.
DISCUSSION
ISSUED AT 225 PM CDT WED AUG 12 2026
CURRENTLY NEAR ZONAL FLOW EXIST OVER THE NORTHERN PLAINS WITH A
SLIGHT SOUTHWEST TILT OVER MONTANA. A TROUGH AND UPPER LOW DIGS
THROUGH WASHINGTON STATE AT THIS TIME. AT THE SURFACE A LOW
SITS IN EASTERN WYOMING WITH AN INVERTED TROUGH THROUGH EASTERN
MONTANA WITH SHOWERS AND THUNDERSTORMS AROUND THE LOW.
TODAY WE ARE IN ANOTHER SEVERE RISK, THIS TIME JUST A LEVEL 1
ACROSS THE SOUTHERN HALF OF THE STATE. GLOBAL MODELS HAVE 1000
TO 2000 J/KG OF MUCAPE WITH 45 TO 50KTS OF SHEAR. THE ACTUAL 18Z
SOUNDING FROM BISMARCK SHOWS 1900 J/KG OF CAPE FROM THE SURFACE
WITH VERY LITTLE CIN AND 53 KTS OF SHEAR. HAZARDS TODAY COULD
BE GOLF BALL SIZE HAIL WITH ALL THAT SHEAR AND 60 MPH WINDS. SO
FAR VERY LIGHT RAIN FROM THE LOW PRESSURE IS IN THE SOUTHWEST
WITH THUNDERSTORMS IN SOUTHEAST MONTANA. A FEW FAILING STORMS
ARE TRYING IN SOUTH CENTRAL NORTH DAKOTA. THE FORCING AND
INDICATOR FOR WHERE THE SEVERE STORMS WILL BE IS THE RIGHT
ENTRANCE REGION OF THE JET STREAK. CURRENTLY THAT AREA IS OVER
SOUTHEASTERN MONTANA, ENTERING INTO SOUTHWEST NORTH DAKOTA.
LOOKING AT RADAR NEW STORMS ARE QUICKLY GROWING IN SOUTHEAST
MONTANA. THAT JET STREAK IS FORECAST TO MOVE EAST WITH THE RIGHT
ENTRANCE REGION STAYING ALONG THE SOUTH DAKOTA BORDER. AFTER
00Z, MODELS WANT TO PULL MOST OF THE CAPE OUT OF THE STATE AND
INTO EASTERN SOUTH DAKOTA AS THE SURFACE LOW MOVES EAST. AFTER
THIS EVENING SHOWERS AND MAYBE A THUNDERSTORM ARE POSSIBLE
THROUGH THE NIGHT.
THE REST OF THIS WEEK THE FLOW WILL TURN SOUTHWEST AND THE
TROUGH CONTINUING TO DIG INTO THE WEST CONUS. THIS, IN TURN,
WILL PRODUCE DAILY CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH
FRIDAY NIGHT, WITH THE HIGHEST CHANCES ACROSS THE WEST EVERYDAY.
TEMPERATURES WILL CONTINUE TO REMAIN AT OR BELOW NORMAL IN THE
70S AND LOWER 80S THROUGH SATURDAY. SLIGHT NORTHWEST FLOW
RETURNS THIS WEEKEND WITH A SLIGHT RIDGE TO START NEXT WEEK.
THEREFORE NORMAL TEMPERATURES IN THE 80S WILL RETURN.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 700 PM CDT WED AUG 12 2026
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF SOUTHERN
AND SOUTH CENTRAL NORTH DAKOTA WILL PROMOTE LOW VFR TO MVFR
CEILINGS AND VISIBILITY AT KDIK, KBIS, AND KJMS THROUGH THIS
EVENING, WITH CHANCES EXPANDING OVERNIGHT TO INCLUDE KXWA AND
KMOT. WHERE THUNDERSTORMS DO DEVELOP, IFR VISIBILITIES AS WELL
AS GUSTY AND ERRATIC WINDS SHOULD BE ANTICIPATED. SHOWERS
SHOULD GENERALLY DIMINISH, AND MVFR CEILINGS LIFT, THROUGH EARLY
TO MID THURSDAY MORNING. EASTERLY WINDS THIS EVENING MAY BECOME
BRIEFLY VARIABLE BEHIND SHOWERS AND THUNDERSTORMS AS THEY PASS,
BUT WILL REORGANIZE OUT OF THE EAST THROUGH EARLY OVERNIGHT.
BREEZY EASTER WINDS, WITH SUSTAINED SPEEDS UP TO 15 KNOT AND
GUSTS UP TO 15 KNOTS, ARE EXPECTED ACROSS WESTERN AND PORTIONS
OF SOUTH CENTRAL NORTH DAKOTA THURSDAY AFTERNOON.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...ADAM
DISCUSSION...SMITH
AVIATION...ADAM
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