737
FXUS63 KBIS 211933
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
233 PM CDT THU MAY 21 2026
KEY MESSAGES
- WIDESPREAD RAIN SHOWERS DEVELOPING IN WESTERN NORTH DAKOTA
LATE THIS AFTERNOON, CONTINUING AND SPREADING EAST THROUGH
FRIDAY.
- AXIS OF HIGHER RAIN AMOUNTS IN WESTERN NORTH DAKOTA, WHERE UP
TO 1 INCH OF RAIN COULD FALL THROUGH FRIDAY.
- NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES THROUGH FRIDAY,
WARMING TO WELL ABOVE NORMAL BY THE END OF THE HOLIDAY
WEEKEND.
DISCUSSION
ISSUED AT 230 PM CDT THU MAY 21 2026
CURRENTLY A MEDIUM SIZE TROUGH AND UPPER LOW IS SITTING OVER
MONTANA AND WYOMING. UPSTREAM IN THE PACIFIC NORTHWEST A RIDGE
OR ZONAL FLOW IS FORMING. AT THE SURFACE THE COLLOCATED SURFACE
LOW IS IN SOUTHERN CANADA, WITH A STATIONARY FRONT SITTING IN
AN INVERTED TROUGH PLACED OVER WESTERN NORTH DAKOTA. ALONG THE
POSITIVE VORTICITY SIDE OF THE UPPER LEVEL TROUGH IN EASTERN
MONTANA, SHOWERS HAVE BEEN ON GOING. THIS AFTERNOON AS SURFACE
TEMPERATURES INCREASE, AROUND 1500 J/KG OF CAPE WILL BE PRESENT
ALONG THE FRONT. WITH SHEAR AROUND 30KTS, THUNDERSTORMS WILL
FORM AND TRAIN SOUTH TO NORTH ALONG THE FRONT SINCE THE SHEAR
VECTOR WILL BE PARALLEL TO THE FRONT. WITH VERY SKINNY CAPE
PROFILES AND HIGH RELATIVE HUMIDITIES THROUGH THE UPPER LEVELS,
THERE IS ONLY A SMALL CHANCE OF SEVERE HAZARDS. SO THE HIGHEST
RISK FROM THE STORMS WILL BE HEAVY DOWNPOURS. THE CAMS AGREE ON
THE LOCATION BEING SOMEWHERE BETWEEN BEACH, AND GLEN ULLIN.
TIMING LOOKS TO BE BETWEEN 5 AND 7PM CT. WITH THE FRONT
REMAINING STATIONARY ALONG WITH THE INVERTED TROUGH, THE STORMS
SHOULD STAY WEST OF THE MISSOURI RIVER THROUGH THE EVENING.
TONIGHT A SURFACE LOW MOVING OUT OF WYOMING FROM THE BOTTOM OF
THE UPPER LEVEL TROUGH WILL START TO MOVE NORTHEAST. BY FRIDAY
MORNING IT WILL FORM INTO IT'S OWN STACKED LOW AND BE IN
NORTHERN SOUTH DAKOTA. THEREFOR FRIDAY WILL BE SLIGHTLY COOLER
WITH WIDESPREAD RAIN ACROSS MOST OF THE STATE. THIS RAIN WILL
LAST THROUGH MOST OF THE DAY, ENDING WEST TO EAST AS THE LOW
CONTINUES INTO NORTHERN MINNESOTA FRIDAY NIGHT. AN AXIS OF
HIGHER QPF IS WILL OCCUR WITH THE THUNDERSTORMS THIS EVENING,
AND THE FRONT ENHANCING LIFT THROUGH FRIDAY IN WESTERN ND. THERE
IS A MEDIUM TO HIGH CHANCE OF 1 INCH OF QPF ON A NORTH SOUTH
LINE CENTERED ON DICKINSON BETWEEN SOUTH DAKOTA AND NEW TOWN.
ANOTHER HIGHER AREA OF QPF IS FORECAST IN SOUTHEAST ND WHEN THE
LOW WRAPS UP AND MOVES THROUGH. THE MAJORITY OF THAT QPF WILL
FALL FRIDAY AFTERNOON.
THROUGH THIS WEEKEND ZONAL FLOW WILL SETUP ACROSS THE NORTHERN
PLAINS LEADING TO VERY WARM TEMPERATURES, BOTH ALOFT AND AT THE
SURFACE. BY MONDAY EXPECT HIGHS NEAR 90 IN THE WEST AND
CENTRAL. THESE ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH
THE WEEK. IN THE LATTER PART OF NEXT WEEK A LARGE UPPER LEVEL
LOW COULD MOVE THROUGH, ALTHOUGH THERE IS AN INCREDIBLE AMOUNT
OF UNCERTAINTY IN LOCATION AND TIMING IF IT DOES OCCUR. NBM DOES
HAVE LOW POPS FOR THIS, AND TEMPERATURES LOOK TO STAY IN THE
UPPER 70S OR LOWER 80S.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1235 PM CDT THU MAY 21 2026
VFR TO MVFR CIGS THIS AFTERNOON, BECOMING MVFR CIGS AND OR VIS IN
THE SHOWERS AND THUNDERSTORMS THIS EVENING AND OVERNIGHT. THE
SHOWER AND THUNDERSTORM CHANCES WILL INCREASE LATER THIS
AFTERNOON IN THE WEST, AND WILL STAY WEST OF THE MISSOURI RIVER
TODAY. WINDS OVERALL WILL BE BREEZY WITH GUSTS TO 25KTS FROM
THE NORTHWEST IN WESTERN ND, AND FROM THE SOUTHEAST IN CENTRAL
AND EASTERN TERMINALS. THUNDERSTORM CHANCES SHOULD BE DONE
SHORTLY AFTER SUNSET, BUT THE RAIN WILL CONTINUE AND SPREAD EAST
THROUGH FRIDAY.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...SMITH
AVIATION...SMITH
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