628
FXUS63 KBIS 230908
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
408 AM CDT SAT MAY 23 2026
KEY MESSAGES
- DENSE FOG ACROSS WESTERN NORTH DAKOTA THIS MORNING.
- WARMER TODAY WITH HIGHS IN THE MID 60S TO MID 70S. A FEW
ISOLATED SHOWERS OR THUNDERSTORMS COULD DEVELOP THIS
AFTERNOON AND EARLY EVENING.
- WELL ABOVE NORMAL TEMPERATURES THROUGH THE FIRST HALF OF NEXT
WEEK, WITH NEAR-RECORD HIGHS AROUND 90 TO 95 MEMORIAL DAY AND
TUESDAY.
DISCUSSION
ISSUED AT 408 AM CDT SAT MAY 23 2026
A DOUBLE-BARREL UPPER LEVEL LOW IS SPINNING OVER THE REGION
THIS MORNING, WITH THE TWO CIRCULATIONS OVER SOUTHEAST
SASKATCHEWAN AND WHERE THE RED RIVER MEETS THE INTERNATIONAL
BORDER. THE ATTENDANT SURFACE LOW CONTINUES WORK ITS WAY
NORTHEASTWARD INTO THE SOUTHERN RED RIVER VALLEY. AS OF 4 AM
CDT, MOST OF RAIN HAS DEPARTED OUR FORECAST AREA, WITH JUST A
FEW ISOLATED SHOWERS LINGERING IN THE JAMES RIVER VALLEY AND A
BROADER AREA OF LIGHT STRATIFORM RAIN FROM THE TURTLE MOUNTAINS
DOWN TOWARDS RUGBY AND HARVEY. THE ASSOCIATED STRATUS SHIELD
STILL EXTENDS AS FAR WEST AS THE HIGHWAY 83 CORRIDOR. TO THE
WEST OF THE STRATUS, AREAS OF DENSE FOG HAVE SETTLED IN,
ESPECIALLY FROM TIOGA AND STANLEY DOWN TO HETTINGER, BUT ALSO
NOW EXPANDING TO THE NORTHWEST AND EAST OF THAT CORRIDOR.
DIVIDE, MERCER, OLIVER, AND WESTERN MCLEAN COUNTIES WERE ADDED
TO THE DENSE FOG ADVISORY, WHICH REMAINS IN EFFECT UNTIL 10 AM
CDT.
THE FOG AND CLOUDS SHOULD LIFT OR CLEAR BY THE AFTERNOON,
GIVING WAY TO MORE SUN THAN CLOUDS FOR THE REST OF THE DAY. FLOW
ALOFT WILL REMAIN CYCLONIC AS THE WESTERNMOST OF THE TWO UPPER
LOWS DIGS BACK INTO NORTH CENTRAL NORTH DAKOTA. MOST CAMS HAVE
BEEN ADVERTISING ISOLATED SHOWERS OR THUNDERSTORMS DEVELOPING
ACROSS PARTS OF CENTRAL NORTH DAKOTA FROM MID AFTERNOON THROUGH
EARLY EVENING. THE HIGHEST PROBABILITY FOR A SHOWER OR STORM IS
IN NORTH CENTRAL NORTH DAKOTA, BUT IT IS STILL ONLY AROUND A 15
TO 25 PERCENT CHANCE AT ANY GIVEN LOCATION WITHIN THAT AREA.
OTHER PARTS OF THE STATE CANNOT BE RULED OUT OF THIS POTENTIAL,
BUT THE PROBABILITY ELSEWHERE IS EVEN LOWER THAN IN THE NORTH
CENTRAL. THE RISK FOR STRONG TO SEVERE CONVECTION IS VERY LOW
TO NON-EXISTENT, WITH PROJECTED ENSEMBLE MEAN CAPE AROUND 500
J/KG, EFFECTIVE BULK SHEAR AROUND 20 KTS, AND LOW EQUILIBRIUM
LEVELS AROUND 20 KFT. TODAY WILL BE MUCH WARMER THAN YESTERDAY,
BUT STILL NEAR LATE-MAY NORMALS WITH FORECAST HIGHS IN THE MID
60S TO MID 70S. UNEVENTFUL WEATHER IS ANTICIPATED TONIGHT, WITH
LOWS IN THE 40S.
THE LONG-ADVERTISED STRETCH OF WELL ABOVE NORMAL TEMPERATURES
BEGINS ON SUNDAY AS UPPER LEVEL RIDGING STARTS TO BUILD OVER THE
ROCKIES AND PLAINS. CONFIDENCE IN THE HIGH TEMPERATURE FORECAST
THROUGH WEDNESDAY IS VERY HIGH AS THE NBM 25TH-75TH PERCENTILE
SPREAD DOES NOT EXCEED 5 DEGREES OVER THIS TIME PERIOD.
WIDESPREAD HIGHS IN THE 80S ARE EXPECTED ON SUNDAY. THERE IS
POTENTIAL FOR A SHORTWAVE CUTTING THROUGH THE BUILDING RIDGE
SUNDAY AFTERNOON AND EVENING, WHICH MAY ALLOW A FEW ISOLATED
SHOWERS OR THUNDERSTORMS TO DEVELOP. IN A RELATIVE SENSE, THE
HIGHEST PROBABILITIES FOR CONVECTION ARE ONCE AGAIN IN NORTH
CENTRAL NORTH DAKOTA. HREF MEMBERS SHOW UNCERTAINTY IN THE
CAPE/SHEAR PARAMETER SPACE, BUT THE COMBINED MAXIMUM OF EACH
WOULD BE SUFFICIENT FOR A STRONGER STORM. CONVECTION COULD BE
MUTED THOUGH BY THE OVERALL MID-LEVEL RISING HEIGHT TREND.
FROM MEMORIAL DAY THROUGH WEDNESDAY, THE UPPER RIDGE IS
FORECAST TO BECOME HIGHLY AMPLIFIED AND TAKE ON A NEGATIVE TILT
AS A POWERFUL TROUGH DIGS INTO THE WESTERN CONUS. THE HIGH
TEMPERATURE FORECAST OVER THIS TIME PERIOD HAS TRENDED EVEN
WARMER, WITH HIGH CONFIDENCE IN NEAR-RECORD HIGHS AROUND 90 TO
95 BOTH MEMORIAL DAY AND TUESDAY, AND STILL IN THE 80S ON
WEDNESDAY. STRONG SOUTH TO SOUTHEAST WINDS REMAIN IN THE
FORECAST FOR TUESDAY AND WEDNESDAY, WITH SUSTAINED SPEEDS AROUND
20 TO 30 MPH AND GUSTS MOSTLY AROUND 30 TO 40 MPH. BOTH THE NBM
AND ECMWF EFI INDICATE THE STRONGEST WINDS ARE FAVORED IN
WESTERN NORTH DAKOTA EACH DAY. SHOWER AND THUNDERSTORM CHANCES
REMAIN QUITE LOW THROUGH MID WEEK, BUT DO BEGIN TO INCREASE IN
THE WEST ON WEDNESDAY AS SHORTWAVE ENERGY EJECTS POLEWARD FROM
THE WESTERN CONUS TROUGH. IN THE CASE THERE ARE THUNDERSTORMS ON
WEDNESDAY, PROJECTED MOISTURE AND INSTABILITY/BUOYANCY WOULD BE
SUFFICIENT FOR STRONG TO SEVERE CONVECTION, BUT SHEAR LOOKS
MUCH MORE QUESTIONABLE. NEVERTHELESS, GEFS-BASED MACHINE
LEARNING GUIDANCE CONTINUES TO INDICATE A LOW SEVERE POTENTIAL
IN WESTERN NORTH DAKOTA ON WEDNESDAY.
BY THE END OF NEXT WEEK, THERE IS INCREASING ENSEMBLE SPREAD ON
THE EVOLUTION OF THE WESTERN CONUS TROUGH/UPPER LOW AND THE
DOWNSTREAM BLOCKING RIDGE. REGARDLESS OF THE EVENTUAL OUTCOME,
ALL ENSEMBLE SYSTEMS AND CLUSTERS FAVOR INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS WITH SLIGHTLY COOLER BUT STILL NEAR
TO ABOVE NORMAL TEMPERATURES HEADING INTO THE FIRST WEEKEND OF
JUNE.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 408 AM CDT SAT MAY 23 2026
LOW CEILINGS WILL PREVAIL ACROSS MUCH OF CENTRAL AND EASTERN
NORTH DAKOTA THIS MORNING, PRIMARILY AT IFR TO LIFR LEVELS.
MEANWHILE, DENSE FOG HAS SETTLED OVER MUCH OF WESTERN NORTH
DAKOTA. AFTER THE FOG LIFTS AND CEILINGS SCATTER AND/OR RISE BY
THIS AFTERNOON, VFR CONDITIONS ARE EXPECTED THROUGH THE REST OF
THE FORECAST PERIOD. A FEW ISOLATED SHOWERS OR THUNDERSTORMS
COULD DEVELOP ACROSS CENTRAL NORTH DAKOTA THIS AFTERNOON AND
EARLY EVENING. WINDS WILL BECOME WESTERLY TO NORTHWESTERLY
AROUND 10 KTS LATER THIS MORNING THROUGH THE AFTERNOON.
BIS WATCHES/WARNINGS/ADVISORIES
DENSE FOG ADVISORY UNTIL 10 AM CDT /9 AM MDT/ THIS MORNING FOR
NDZ001-002-009-010-017>020-032-033-040>042-044-055-057-059.
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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