584
FXUS63 KBIS 060546
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1246 AM CDT TUE MAY 6 2025
KEY MESSAGES
- SCATTERED SHOWERS, ALONG WITH AN OCCASIONAL RUMBLE OF
THUNDER, WILL CONTINUE THROUGH MUCH OF THE NIGHT ACROSS THE
SOUTHWEST AND CENTRAL.
- MOSTLY DRY WITH ABOVE AVERAGE TEMPERATURES AND BREEZY
CONDITIONS AT TIMES THROUGH THE END OF THE WEEK.
UPDATE
ISSUED AT 1246 AM CDT TUE MAY 6 2025
WITH A LOSS OF INSTABILITY, THUNDERSTORM ACTIVITY HAS RAPIDLY
DIMINISHED OVER THE PAST HOUR. AS OF THIS WRITING, THERE HAVE
ONLY BEEN A FEW RECENT LIGHTNING STRIKES OBSERVED ACROSS THE
STATE. SHOWERS REMAIN PRESENT OVER MUCH OF SOUTHWESTERN AND
CENTRAL ND, THOUGH THEY TOO APPEAR TO BE ON THE DOWNTREND.
UPDATED POPS OVER THE NEXT FEW HOURS, BUT BASED ON THE LATEST
TRENDS, CURIOUS JUST HOW MANY RAIN SHOWERS WILL ACTUALLY PERSIST
THROUGH THE DURATION OF THE NIGHT.
UPDATE
ISSUED AT 1039 PM CDT MON MAY 5 2025
SHOWER AND THUNDERSTORM ACTIVITY CONTINUES ACROSS THE SOUTHWEST
AND MUCH OF CENTRAL NORTH DAKOTA, WITH A LOT OF EXPANSION OVER
THE PAST HOUR OR SO. AT THIS POINT, INSTABILITY LOOKS LIMITED
ENOUGH THAT THE SEVERE POTENTIAL IS VERY LOW, BUT COULD STILL
SEE SOME SMALL HAIL AND GUSTY WINDS, WITH THE BACKGROUND
SYNOPTIC WINDS STILL RELATIVELY STRONG ACROSS THE SOUTH CENTRAL.
WE DID FRESHEN UP POPS THROUGH THE DAY TUESDAY WITH THIS UPDATE.
EXPECT CONVECTION TO SLOWLY DIMINISH THROUGH THE NIGHT TONIGHT,
WITH SOME LINGERING LOW POPS THROUGH THE DAY TUESDAY FOR A FEW
SCATTERED SHOWERS IN THE POST-FRONTAL REGIME. NORTHEAST WINDS
WILL BE A BIT BREEZY IN THE JAMES RIVER VALLEY, WITH HIGHS
MAINLY IN THE 60S.
UPDATE
ISSUED AT 711 PM CDT MON MAY 5 2025
QUICK UPDATE TO EXPIRE THE WIND ADVISORY. WE ALSO EXPANDED AND
EXTENDED THE MENTION OF PATCHY BLOWING DUST, IN LINE WITH A FEW
REPORTS THAT HAVE COME IN.
UPDATE
ISSUED AT 639 PM CDT MON MAY 5 2025
COLD FRONT EXTENDS FROM THE TURTLE MOUNTAINS AREA, THROUGH
WASHBURN, TO GRANT COUNTY, WITH SHOWERS AND THUNDERSTORMS
DEVELOPING ALONG THE FRONT. THERE IS A SECONDARY BOUNDARY,
ORIENTED NORTH-SOUTH, CONNECTED TO THE FRONT IN PIERCE COUNTY
AND EXTENDING SOUTH THROUGH KIDDER AND EMMONS COUNTIES. THE MOST
WELL DEVELOPED, ALTHOUGH STILL SUBSEVERE, STORMS HAVE BEEN IN
THE SHERIDAN AND WELLS COUNTY AREAS. AHEAD OF THE FRONT, AS
PREVIOUSLY THOUGHT, SHEAR IS QUITE LOW, WITH THE SPC
MESOANALYSIS PAGE ADVERTISING LESS THAN 25 KNOTS OF 0-6 KM
SHEAR. BECAUSE OF THIS, EVEN THOUGH WE HAVE MODERATE INSTABILITY
AND LAPSE RATES, EXPECTING STORMS TO BE MOSTLY PULSE / POPCORN
THUNDERSTORMS. CAN'T RULE OUT SMALL TO POTENTIALLY EVEN
BORDERLINE SEVERE HAIL, BUT WOULD NOT EXPECT STORMS TO BE LONG-
LIVED SEVERE DUE TO THE LACK OF SHEAR LEADING TO UPDRAFTS BEING
CUT OFF RELATIVELY QUICKLY. FURTHER TO THE WEST, A FEW STORMS
HAVE TRIED TO DEVELOP IN THE WESTERN MORTON AND GRANT COUNTY
AREA, BUT INCREASING SHEAR AND DECREASING INSTABILITY BEHIND THE
FRONT HAS LED TO CONVECTION DYING OFF SOON AFTER IT DEVELOPS.
THE WIND ADVISORY FOR NORTHWEST NORTH DAKOTA IS STILL IN EFFECT
FOR THE NEXT HALF HOUR. THINKING WE WILL BE ABLE TO DROP IT,
WITH WINDS BELOW CRITERIA, BUT WINDS WILL LIKELY STAY STRONG
THROUGH THE NEXT FEW HOURS BEFORE DIMINISHING FURTHER OVERNIGHT.
MEANWHILE, WE DID ISSUE TWO DUST ADVISORIES FOR PARTS OF WESTERN
NORTH DAKOTA, DOWNSTREAM OF THE RAY AND EPPING AREAS.
VISIBILITIES HAVE BEEN ON AND OFF REDUCED IN THE WATFORD CITY
AREA AND SOUTH, AND WE DID JUST GET A REPORT OF SOME DUST IN THE
HAZEN AREA, INDICATING DUST IS BEING CARRIED PRETTY FAR
DOWNSTREAM. AS THE WINDS RELAX, GUESSING THAT THE DUST WILL
BEGIN TO SETTLE. FRESHENED UP POPS WITH THIS UPDATE, AND WILL BE
KEEPING AN EYE ON CONVECTION AND DUST THROUGH THE EVENING.
DISCUSSION
ISSUED AT 230 PM CDT MON MAY 5 2025
CURRENTLY A COLD FRONT IS ACROSS THE STATE SOUTHWEST TO
NORTHEAST. SHOWERS IN THE FAR NORTHWEST HAVE BEEN MIXING DOWN 50
TO 60 MPH WINDS. THE LOWER LEVELS ARE ALSO DRY SO THIS AIDS IN
THE DOWNWARD MOMENTUM. BLOWING DUST PLUMES FROM THE BURN SCARS
IN RAY AND TIOGA HAVE MADE THEIR WAY TO SLOPE COUNTY! WE HAVE AN
SPS OUT FOR THAT AND A WIND ADVISORY OUT FOR WINDS IN THE
NORTHWEST.
CUMULUS HAVE STARTED TO POP ALONG THE EASTERN EDGE OF
THE FRONT IN WESTERN MORTON THROUGH HETTINGER COUNTY. THERE IS
CURRENTLY AROUND 500 J/KG ACROSS THE SOUTH CENTRAL BUT CAPPED.
SO IT SHOULD BE AT LEAST AN HOUR OR TWO FOR ATTEMPTS TO BREAK
IT. THE RAP FORECAST HAS THE CAP BREAKING AT 3PM CT. MIXED LAYER
CAPE IS ALMOST NOTHING. LAPSE RATES ARE CONVECTIVELY OKAY AT
7.5 AND FORECAST TO STAY THE SAME. WIND SHEAR IS 30KTS ALONG THE
FRONT WHERE THE CUMULUS ARE LOCATED. DCAPE IS CONCERNINGLY HIGH
AT 1200 J/KG CURRENTLY, AND FORECAST TO BE 1400 J/KG LATER.
AGAIN ALL THIS IS BASED OFF THE RAP. SPC HAS A MARGINAL RISK
(ISOLATED) FROM THE SOUTHWEST TO THE CENTRAL PART OF THE STATE,
INCLUDING BIS/MAN. THE MAIN THREATS ARE WINDS AROUND 60 MPH
BASED ON THE DRY LOWER LEVELS OF THE ATMOSPHERE AND STORM MODE.
MODEL SOUNDINGS HAVE AN INVERTED V HINTING AT DRY AIR DOWN LOW
THAT WILL ACCELERATE THE DOWNDRAFTS OF THE STORMS. STORM MODE
WILL BE LINEAR AS THE WIND SHEAR VECTOR IS NEAR PARALLEL WITH
THE FRONT. QUARTER SIZE HAIL IS POSSIBLE AS STORMS DEVELOP BUT
THEN IT WILL MAINLY BE A WIND THREAT. THE CAMS HAVE SLOWED THE
TIMING DOWN TO AROUND 23Z, BUT WILL KEEP A VERY CLOSE EYE ON THE
CUMULUS THAT ALREADY STARTED. THE SEVERE THREAT SHOULD END
AROUND 10PM CT, BUT SHOWERS AND THUNDERSTORMS WILL CONTINUE IN
THE SOUTH AND EAST THROUGH 5AM CT WITH WRAP AROUND MOISTURE WITH
THE SURFACE LOW. ALL THIS IS IN SOUTHWEST FLOW, WHICH WILL
CHANGE TO A RIDGE UNTIL FRIDAY. TUESDAY WILL BE SLIGHTLY COOLER
BEHIND THE FRONT IN THE 60S AND 70S. THEN THE WARMER AIR WITH
THE RIDGE MOVES IN. FRIDAY THE FLOW CHANGES TO ZONAL, ALLOWING
SOME SHORTWAVES OFF THE MONTANA MOUNTAINS TO GIVE A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS AGAIN. THIS WEEKEND ANOTHER
RIDGE MOVES OVER, ALLOWING TEMPERATURES TO POSSIBLE CLIMB INTO
THE UPPER 80S! SUNDAY NIGHT INTO MONDAY WHERE THE ACTIVE
SOUTHWEST FLOW SETS BACK UP. TEMPERATURES COULD ALSO BE IN THE
UPPER 80S, ALLOWING THUNDERSTORMS TO FORM.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1246 AM CDT TUE MAY 6 2025
SHOWERS CONTINUE OVER PARTS OF SOUTHWESTERN AND MUCH OF CENTRAL
NORTH DAKOTA. HOWEVER, THUNDERSTORM ACTIVITY HAS RAPIDLY
DIMINISHED OVER THE PAST HOUR. THESE SHOWERS, ALONG WITH AN
OCCASIONAL RUMBLE OF THUNDER, REMAIN LIKELY THROUGH THE NIGHT.
HOWEVER, MORE ORGANIZED THUNDERSTORM ACTIVITY SEEMS TO HAVE
ENDED AND COVERAGE OF SHOWERS WILL LIKELY CONTINUE TO DECREASE
AS THE NIGHT GOES ON. A FEW SHOWERS MAY LINGER OVER PARTS OF
NORTH DAKOTA THROUGH THE DAY TUESDAY, BUT OVERALL, EXPECT MOSTLY
DRY CONDITIONS. NORTHEASTERLY WINDS WILL REMAIN BREEZY IN THE
SOUTH AND EAST THROUGH THE DAY TUESDAY. VFR CEILINGS AND
VISIBILITY ARE GENERALLY EXPECTED TO PREVAIL AT MOST LOCATIONS
THROUGH THE PERIOD. HOWEVER, MVFR CEILINGS ARE LIKELY TO
ENCROACH INTO FAR SOUTHWESTERN ND TONIGHT. THESE ARE FAVORED TO
STAY SOUTH OF KDIK, THOUGH IT WOULDN'T BE TOTALLY SURPRISING
EITHER IF THEY AT LEAST BRIEFLY REACH THE TERMINAL.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...TELKEN
DISCUSSION...SMITH
AVIATION...TELKEN
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