786
FXUS63 KBIS 020545
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1245 AM CDT MON JUN 2 2025
KEY MESSAGES
- MUCH COOLER AND BREEZY TODAY. SHOWERS AND A FEW THUNDERSTORMS
LIKELY THIS MORNING THROUGH MONDAY.
- NEAR TO SLIGHTLY BELOW AVERAGE TEMPERATURES FOR THE REST OF
THE WEEK. DAILY LOW CHANCES FOR SHOWERS AND THUNDERSTORMS
RETURN ON WEDNESDAY.
UPDATE
ISSUED AT 1244 AM CDT MON JUN 2 2025
SHOWERS AND A FEW WEAK THUNDERSTORMS CONTINUE TO DEVELOP BEHIND
THE SURFACE COLD FRONT, EXTENDING IN A LINE FROM SOUTHWESTERN
BOWMAN COUNTY TO RENVILLE COUNTY. SOME LIGHTNING HAS BEEN
OBSERVED IN THE NORTHERN HALF OF THE LINE, WHILE SOME STRONGER
THUNDERSTORMS HAVE DEVELOPED IN SOUTHEASTERN MONTANA. THESE
STORMS COULD MOVE INTO THE AREA WITHIN THE NEXT COUPLE HOURS.
THE STORMS IN GENERAL HAVE MOVED A BIT QUICKER THAN ANTICIPATED,
SO THE MAIN CHANGE WITH THIS UPDATE WAS ADJUSTMENTS TO THE POPS.
UPDATE
ISSUED AT 948 PM CDT SUN JUN 1 2025
NO MAJOR CHANGES TO THE FORECAST WITH THIS MID-EVENING PRODUCT
ISSUANCE. MADE SOME MINOR TWEAKS FOR THE FROPA, OTHERWISE ALL IS
ON TRACK.
UPDATE
ISSUED AT 638 PM CDT SUN JUN 1 2025
THE FORECAST FOR TONIGHT REMAINS ON TRACK. MADE SOME MINOR
ADJUSTMENTS TO THE FROPA TIMING BASED ON LATEST SFC OBS, ALONG
WITH TWEAKS TO SKY COVER AND POPS BASED ON LATEST HIGH RES MODEL
TRENDS.
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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1244 AM CDT MON JUN 2 2025
A COLD FRONT CONTINUES TO SWEEP THROUGH THE AREA, HAVING ALREADY
SHIFTED WINDS TO BE NORTHERLY ACROSS THE ENTIRE AREA APART FROM
THE SOUTHERN JAMES RIVER VALLEY AND KJMS. WINDS AT KJMS ARE
EXPECTED TO SHIFT NORTHERLY WITHIN THE NEXT 3 HOURS. IMMEDIATELY
BEHIND THE FRONT IS A PERIOD OF SLIGHTLY STRONGER GUSTS, BEFORE
MOST LOCATIONS SETTLE INTO SUSTAINED WINDS AROUND 10 TO 15 KTS,
WITH GUSTS UP TO 25 KTS. LAGGING BEHIND THIS FRONT ARE THE
ASSOCIATED SHOWERS AND THUNDERSTORMS, AS WELL AS MVFR CEILINGS
AND OCCASIONAL VISIBILITY REDUCTIONS DUE TO RAINFALL AND SMOKE.
THESE SHOWERS EXTEND FROM SOUTHWESTERN BOWMAN COUNTY TO RENVILLE
COUNTY. SHOWER AND THUNDERSTORM ACTIVITY WILL SLOWLY SPREAD
EASTWARD, IMPACTING ALL TERMINALS THROUGH THE TAF PERIOD. STORMS
SHOULD BEGIN TO EXIT THE AREA AND/OR DISSIPATE AROUND 00Z, ALONG
WITH CEILINGS LIFTING AND WINDS DECREASING AT THE SAME TIME.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...BESSON
DISCUSSION...HOLLAN
AVIATION...BESSON
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