411
FXUS63 KBIS 012052
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
352 PM CDT SUN JUN 1 2025
KEY MESSAGES
- WARM AND DRY THIS AFTERNOON, WITH AREAS OF SMOKE PERSISTING IN
THE EASTERN HALF OF THE STATE.
- MUCH COOLER AND BREEZY ON MONDAY. SHOWERS AND A FEW
THUNDERSTORMS LIKELY TONIGHT THROUGH MONDAY.
- NEAR TO SLIGHTLY BELOW AVERAGE TEMPERATURES FOR THE REST OF
THE WEEK. DAILY LOW CHANCES FOR SHOWERS AND THUNDERSTORMS
RETURN ON WEDNESDAY.
DISCUSSION
ISSUED AT 351 PM CDT SUN JUN 1 2025
AN UPPER LEVEL RIDGE WITH SLIGHT POSITIVE TILT IS ANALYZED FROM THE
CENTRAL ROCKIES THROUGH EASTERN MANITOBA EARLY THIS AFTERNOON. A
SURFACE COLD FRONT EXTENDS SOUTH-SOUTHWEST FROM LOW PRESSURE ON THE
NORTHERN SK/MB BORDER TO NORTHEAST WYOMING, AND HAS REACHED AS FAR
EAST AS BEACH TO STANLEY IN WESTERN NORTH DAKOTA AS OF 330 PM CDT. A
SOUTHERLY BREEZE AND MOSTLY SUNNY SKY WITH TEMPERATURES IN THE MID
80S TO AROUND 90 ARE OBSERVED AHEAD OF THE COLD FRONT, BUT THICKER
NEAR-SURFACE SMOKE IS STILL PLAGUING THE TURTLE MOUNTAINS THROUGH
THE JAMES RIVER VALLEY. SMOKE MODELING GUIDANCE HAD SUGGESTED
DISPERSAL OF THIS SMOKE SEVERAL HOURS AGO, SO IT IS TOUGH TO GAUGE
HOW MUCH LONGER THE DETERIORATED CONDITIONS WILL LAST. THE WORST
CASE SCENARIO WOULD BE FOR SMOKE PROLONGING UNTIL THE ARRIVAL OF THE
COLD FRONT LATE TONIGHT, BUT STILL OPTIMISTIC FOR A GRADUAL
IMPROVEMENT THROUGH THE EVENING. HOWEVER, IT IS POSSIBLE THAT THE
COLD FRONT COULD BRING ANOTHER BATCH OF SMOKE WITH IT AS IT CROSSES
THE STATE FROM WEST TO EAST THROUGH TONIGHT. BUT MODELS SUGGEST THIS
SMOKE SHOULD NOT BE NEARLY AS THICK AS WHAT WE HAVE SEEN THIS
WEEKEND, AND UPSTREAM OBSERVATIONS CONFIRM THIS SO FAR. THE HIGHEST
CHANCES FOR SMOKE REDUCING VISIBILITY WITH THE FRONTAL PASSAGE THIS
EVENING THROUGH TONIGHT ARE NORTH OF HIGHWAY 2. THE COLD FRONT WILL
ALSO BRING BREEZY CONDITIONS ACROSS THE STATE THIS EVENING THROUGH
TONIGHT, WITH NORTHERLY WINDS GUSTING AS HIGH AS 30 MPH.
A SHORTWAVE TROUGH OVER THE PACIFIC NORTHWEST THIS AFTERNOON WILL
CROSS THE NORTHERN ROCKIES TONIGHT AND EJECT INTO THE NORTHERN
PLAINS ON MONDAY. THE SYNOPTIC SCALE FORCING IS EXPECTED TO PRODUCE
SHOWERS AND A FEW THUNDERSTORMS MOVING INTO WESTERN NORTH DAKOTA
LATE THIS EVENING, SPREADING INTO CENTRAL NORTH DAKOTA OVERNIGHT.
MEDIUM TO HIGH CHANCES FOR SHOWERS PERSIST OVER MUCH OF THE STATE
THROUGH THE DAY MONDAY. MOST OF THE ACTIVITY SHOULD DISSIPATE OR
SHIFT EAST OF THE AREA BY MONDAY EVENING, ALTHOUGH A TRAILING LOWER-
AMPLITUDE WAVE COULD PROLONG ISOLATED SHOWERS IN PARTS OF WESTERN
NORTH DAKOTA THROUGH MONDAY EVENING. TEMPERATURES WILL BE MUCH
COOLER ON MONDAY IN THE POST-FRONTAL AIR MASS WITH FORECAST HIGHS
MOSTLY IN THE UPPER 50S TO LOWER 70S, COOLEST SOUTHWEST TO CENTRAL
AND WARMEST SOUTHEAST.
WHILE THERE ARE LOW CHANCES FOR THUNDERSTORMS ACROSS MUCH OF THE
STATE TONIGHT THROUGH MONDAY AFTERNOON, THERE ARE TWO PRIMARY AREAS
OF FOCUS EMERGING IN HIGH-RESOLUTION GUIDANCE. THE FIRST IS IN
SOUTHWEST NORTH DAKOTA LATE TONIGHT WHERE RECENT CAMS BRING
ORGANIZED CONVECTION IN FROM WYOMING, THE DEVELOPMENT OF WHICH IS
BEING OBSERVED THIS AFTERNOON. THESE STORMS SHOULD BE ELEVATED, BUT
THERE IS POTENTIAL FOR MUCAPE AS HIGH AS AROUND 500 J/KG AND
EFFECTIVE BULK SHEAR EXCEEDING 30 KTS. THINK HAIL UP TO AROUND THE
SIZE OF PENNIES WOULD BE THE PRIMARY THREAT, THOUGH SURFACE GUSTS AS
HIGH AS 45 MPH ARE BEING SIMULATED BY THE 18Z HRRR. A COUPLE OF CAMS
DO SHOW SOME UH TRACKS, BUT WITH MAXIMUM VALUES MUCH LOWER THAN
TYPICAL SEVERE THRESHOLDS. THIS POINTS TO A STRONGER BUT SUB-SEVERE
STORM OR TWO BEING THE MOST LIKELY OUTCOME IN SOUTHWEST NORTH DAKOTA
LATE TONIGHT. THE SECOND AREA OF FOCUS IS FROM SOUTH CENTRAL TO
SOUTHEAST NORTH DAKOTA MONDAY AFTERNOON WHERE THERE COULD BE A BRIEF
OVERLAP OF FAVORABLE CAPE/SHEAR TO PRODUCE A STRONGER STORM.
HOWEVER, ENSEMBLE PROBABILITIES FOR THIS OUTCOME KEEP TRENDING LOWER
WITH EVERY PASSING FORECAST CYCLE. THESE STORMS WOULD ALSO BE
ELEVATED AND HAVE ONLY SIMILAR CAPE (AT MOST) AND SHEAR TO WORK WITH
AS THE LATE NIGHT POTENTIAL IN THE SOUTHWEST.
ENSEMBLES KEEP THE NORTHERN PLAINS IN A QUASI-ZONAL CYCLONIC FLOW
PATTERN FROM TUESDAY THROUGH AT LEAST THURSDAY, WITH A SLIGHT TILT
TO NORTHWEST FLOW ALOFT FAVORED FOR NEXT WEEKEND. THIS KEEPS
FORECAST TEMPERATURES NEAR TO SLIGHTLY BELOW AVERAGE, WITH HIGHS IN
THE MID 60S TO MID 70S AND LOWS IN THE 40S THROUGH THURSDAY,
FOLLOWED BY A SLIGHT WARMUP HEADING INTO THE WEEKEND. BROAD SURFACE
HIGH PRESSURE IS EXPECTED TO KEEP TUESDAY DRY, THOUGH DIURNALLY-
DRIVEN SHOWERS CAN NEVER BE COMPLETELY RULED OUT UNDER CYCLONIC FLOW
THIS TIME OF YEAR. LOW CHANCES FOR SHOWERS DO RETURN IN THE NBM FOR
WEDNESDAY AS A MORE NOTABLE WAVE PASSES BY TO OUR SOUTH. DAILY
CHANCES (AROUND 20 TO 40 PERCENT) FOR SHOWERS AND THUNDERSTORMS
REMAIN IN THE FORECAST THROUGH THE WEEKEND, ALTHOUGH ENSEMBLE SPREAD
IN ALL FIELDS BEGINS TO INCREASE DRASTICALLY AS EARLY AS SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 103 PM CDT SUN JUN 1 2025
SMOKE IS EXPECTED TO REDUCE VISIBILITY TO MVFR/IFR LEVELS ACROSS THE
EASTERN HALF OF THE STATE, INCLUDING KJMS, THROUGH AT LEAST THIS
AFTERNOON. A COLD FRONT WILL BEGIN ENTERING NORTHWEST NORTH DAKOTA
THIS AFTERNOON AND TRACK SOUTHEASTWARD ACROSS THE STATE THROUGH
TONIGHT. THE FRONTAL PASSAGE MAY BRING ANOTHER BATCH OF SMOKE
THROUGH THE REGION, BUT IT IS NOT EXPECTED TO BE AS THICK AS THE
LAST 24 HOURS. ALSO TRAILING THE FRONT, CHANCES FOR SHOWERS AND
PERHAPS OF FEW THUNDERSTORMS WILL INCREASE ACROSS WESTERN NORTH
DAKOTA LATE THIS EVENING, SPREADING INTO CENTRAL NORTH DAKOTA LATE
TONIGHT INTO EARLY MONDAY MORNING. LIGHT SOUTHERLY WINDS AHEAD OF
THE FRONT WILL SWITCH TO NORTHERLY WITH THE FRONTAL PASSAGE AND MAY
BECOME GUSTY UP TO AROUND 25-30 KTS.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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