454
FXUS63 KBIS 210652
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
152 AM CDT THU MAY 21 2026
KEY MESSAGES
- HIGH CHANCES ACROSS THE WESTERN HALF OF THE STATE THURSDAY
THROUGH FRIDAY.
- TEMPERATURES REMAIN CLOSER TO NORMAL THROUGH FRIDAY, THEN WARM
TO WELL ABOVE NORMAL BY THE END OF THE HOLIDAY WEEKEND.
UPDATE
ISSUED AT 151 AM CDT THU MAY 21 2026
SHOWER ACTIVITY HAS GREATLY DIMINISHED OVER THE LAST FEW HOURS,
WITH LITTLE TO NO LIGHTNING BEING OBSERVED. STILL TRACKING THE
REMNANTS OF MID-EVENING CONVECTION THAT FLARED UP IN SOUTHWEST
NORTH DAKOTA, WHICH HAS NOW SHIFTED CLOSER TO LAKE SAKAKAWEA.
ONLY LIGHT AMOUNTS OF RAIN LESS THAN A TENTH OF AN INCH ARE
ANTICIPATED THROUGH THE REST OF THE NIGHT, AND MOST AREAS WILL
REMAIN DRY.
UPDATE
ISSUED AT 936 PM CDT WED MAY 20 2026
FOR THE LATE EVENING UPDATE WE EXPANDED THE POPS IN TIME AND
AREAL EXTENT. A NARROW LINE OF THUNDERSTORMS HAVE RECENTLY
DEVELOPED OVER SOUTHWEST ND IN AN AREA OF FOCUSED WARM
ADVECTION, MODERATE 850MB FG FORCING AND A NARROW BAND OF STEEP
LOW LEVEL LAPSE RATES. THE STEEP LOW LEVEL LAPSE RATES SHOULD
SUBSIDE PRETTY QUICKLY AS CIN INCREASES OVER THE AREA, BUT THE
FG FORCING AND WARM ADVECTION MAY PERSIST FOR AT LEAST A FEW
MORE HOURS, KEEPING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
THROUGH THE EVENING HOURS. ELSEWHERE, NOT MUCH LIGHTNING ANY
MORE BUT THERE ARE A FEW STRIKES OCCASIONALLY. WILL KEEP A
MENTION OF THUNDER THROUGH MIDNIGHT, AND LINGER SHOWERS ACTIVITY
INTO THE OVERNIGHT HOURS. OTHERWISE, THERE IS A LOCAL AREA OF
HEAVIER SHOWERS AROUND THE TURTLE MOUNTAINS. THIS SHOULD LIFT
NORTHEAST OF THAT AREA SHORTLY, BUT THE AREA FROM SOUTHWEST ND
INTO THE TURTLE MOUNTAINS WILL SEE WARM ADVECTION THROUGH THE
NIGHT, THUS KEPT AT LEAST A LITTLE ACTIVITY HERE THROUGH THE
NIGHT. UPDATED TEXT PRODUCTS OUT SHORTLY.
UPDATE
ISSUED AT 535 PM CDT WED MAY 20 2026
UPDATED POPS BASED ON LATEST RADAR. SHOWERS HAVE SPREAD INTO
CENTRAL ND AND HAVE PULLED SLIGHT CHANCE POPS FARTHER EAST.
THERE IS SOME OCCASIONAL LIGHTNING, SO FOR THIS AFTERNOON AND
EVENING UTILIZED COVERAGE TERMS FOR SHOWER AND THUNDERSTORM
ACTIVITY. WILLISTON PICKED UP JUST OVER A QUARTER INCH OF RAIN
AND GUST TO AROUND 35 MPH. UPDATED TEXT PRODUCTS WILL BE
TRANSMITTED SHORTLY.
DISCUSSION
ISSUED AT 208 PM CDT WED MAY 20 2026
HIGH TEMPERATURES ARE FORECAST TO WARM INTO THE 60S AND 70S THIS
AFTERNOON. SURFACE HIGH PRESSURE HAS SHIFTED OFF TO THE
SOUTHEAST OVER MINNESOTA AS SURFACE LOW PRESSURE MOVES INTO
EASTERN MONTANA. THIS HAS LEAD TO BREEZY TO WINDY CONDITIONS
ACROSS THE CENTRAL AND EASTERN HALF OF THE STATE DUE TO A
TIGHTER NORTH SOUTH ORIENTATED PRESSURE GRADIENT. AN UPPER
LEVEL LOW IS FORECAST TO MOVE INTO SOUTHERN SASKATCHEWAN
TONIGHT. THIS LOW HAS BROUGHT TWO UPPER LEVEL WAVES TO THE
REGION. WATER VAPOR IMAGERY SHOWS THE FIRST WAVE WHICH IS
MOVING ACROSS THE NORTH CENTRAL INTO THE NORTHEAST WHILE THE
SECOND WAVE IS FORECAST TO MOVE THROUGH EASTERN MONTANA INTO THE
WEST THIS AFTERNOON AND EVENING. MAJORITY OF THE PRECIPITATION
WILL REMAIN SCATTERED TO ISOLATED ACROSS THE WEST FROM THE
SECOND WAVE.
THE AFOREMENTIONED UPPER LEVEL LOW IS FORECAST TO STALL OUT
OVER SOUTHERN SASKATCHEWAN THURSDAY AND FRIDAY. HI-RES MODELS
ARE SHOWING A BAND OF PRECIPITATION THAT WILL TRAVERSE WEST TO
EAST THURSDAY INTO FRIDAY. HOWEVER, THE HREF HAS THIS BANDED
PRECIPITATION STALLING ACROSS THE WEST MAYBE BARELY MAKING IT
TO THE HWY 83 CORRIDOR. STORM TOTAL QPF ON THE HREF IS UP TO
AROUND AN 1.5 INCHES IN SOME AREAS WITH LOCALLY HIGHER AMOUNTS
POSSIBLE THIS IS SUPPORTED BY DECENT RAINFALL RATES AND
RESIDENCE TIME OF BANDED PRECIPITATION. THIS MEAN CENTRAL AND
EASTERN NORTH DAKOTA WILL LIKELY MISS OUT ON THE MAJORITY OF
RAIN THE NEXT TWO DAYS. THIS COOLER PATTERN WILL KEEP
TEMPERATURES IN THE 60S TO 70S THURSDAY AND FRIDAY UNTIL WARMING
UP BY THE WEEKEND. SATURDAY MORNING THERE IS A CHANCE OF SOME
PATCHY FROST IN THE SOUTHWEST. THE NBM 25TH BEGINS TO PUSH THE
HIGH TEMPERATURES INTO THE UPPER 70S TO LOWER 80S AND THE 75TH
PERCENTILE HAS THE LOWER 90S BY EARLY NEXT WEEK. THERE IS FAIRLY
HIGH CONFIDENCE FOR WARM WEATHER TO START OFF NEXT WEEK. THE
PATTERN COULD SHIFT AGAIN BY THE END OF NEXT WEEK AS AN UPPER
LEVEL TROUGHING COULD RETURN TO WESTERN CONUS.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 151 AM CDT THU MAY 21 2026
A FEW LIGHT RAIN SHOWERS WILL CONTINUE TO MEANDER ABOUT WESTERN
AND CENTRAL NORTH DAKOTA THROUGH THE NIGHT AND INTO THURSDAY
MORNING, WITH VFR CONDITIONS EXPECTED. FROM THURSDAY AFTERNOON
THROUGH THURSDAY NIGHT, A SIGNIFICANT INCREASE IN SHOWERS IS
EXPECTED ACROSS WESTERN AND INTO NORTH CENTRAL NORTH DAKOTA,
WITH EMBEDDED THUNDERSTORMS IN THE LATE AFTERNOON AND EVENING.
CEILINGS COULD FALL TO MVFR LEVELS UNDER RAIN, AND THE HEAVIEST
SHOWERS AND STORMS COULD BRIEFLY REDUCE VISIBILITY TO IFR
LEVELS. WESTERN NORTH DAKOTA WILL SEE VARIABLE WINDS AROUND 5-10
KTS THROUGH THE FORECAST PERIOD, WHILE CENTRAL NORTH DAKOTA
MAINTAINS A SOUTHERLY BREEZE OVERNIGHT, INCREASING BACK TO
AROUND 15-25 KTS THURSDAY AFTERNOON.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...HOLLAN
DISCUSSION...JOHNSON
AVIATION...HOLLAN
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