238
FXUS63 KBIS 190902
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
402 AM CDT WED AUG 19 2026
KEY MESSAGES
- THERE IS A 20 TO 40 PERCENT CHANCE OF ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS TODAY. THE RISK FOR SEVERE WEATHER
IS VERY LOW, BUT A FEW STORMS MAY BECOME STRONG IN CENTRAL
NORTH DAKOTA THIS AFTERNOON AND EVENING.
- NEAR AVERAGE TEMPERATURES ARE FAVORED TO CONTINUE INTO NEXT
WEEK, WITH HIGHS MOSTLY IN THE 80S.
- MOSTLY DRY THURSDAY THROUGH SATURDAY, THEN LOW CHANCES FOR
SHOWERS AND THUNDERSTORMS RETURN TO CLOSE OUT THE WEEKEND.
DISCUSSION
ISSUED AT 401 AM CDT WED AUG 19 2026
A NORTHWEST FLOW PATTERN PERSISTS OVER THE NORTHERN PLAINS
EARLY THIS MORNING BETWEEN A HUDSON BAY LOW AND DESERT
SOUTHWEST HIGH. A SERIES OF MID LEVEL SHORTWAVES EMBEDDED IN
THE NORTHWEST FLOW ARE MOVING THROUGH CENTRAL AND SOUTHERN
SASKATCHEWAN, WHERE A FEW ISOLATED SHOWERS AND AN OCCASIONAL
THUNDERSTORM HAVE BEEN ROAMING AROUND SINCE EARLIER IN THE
NIGHT. MORE RECENTLY, A COUPLE OF SHOWERS HAVE DEVELOPED IN
NORTHWEST NORTH DAKOTA ALONG A TANGENTIAL CORRIDOR OF LOW LEVEL
CONVERGENCE/WARM AIR ADVECTION. THESE FORCING MECHANISMS, ALONG
WITH A SURFACE TROUGH THAT IS DEEPENING FROM WESTERN
SASKATCHEWAN THROUGH NORTH CENTRAL MONTANA, ARE FORECAST TO
SLOWLY MOVE SOUTHEASTWARD THROUGH THE DAY, REACHING CENTRAL
NORTH DAKOTA THIS EVENING. MODEL GUIDANCE IS INCONSISTENT ON
THE MAINTENANCE OF ONGOING ACTIVITY THROUGH THE MORNING, BUT
THINK IT IS LIKELY THAT AT LEAST A FEW SHOWERS AND PERHAPS AN
OCCASIONAL THUNDERSTORM WILL PERSIST IN NORTHWEST AND NORTH
CENTRAL NORTH DAKOTA. LATER IN THE DAY, CAMS PROJECT THAT
DIURNAL HEATING WILL CONTRIBUTE TO AN AREAL EXPANSION OF
ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ACROSS
CENTRAL AND SOUTHWEST NORTH DAKOTA. THE PROBABILITY FOR SEVERE
STORMS IN SOUTH CENTRAL NORTH DAKOTA LATER THIS AFTERNOON AND
EVENING HAS GREATLY DIMINISHED AS THE SURFACE TROUGH IS NOW
FORECAST TO BE MORE DIFFUSE AND LESS PROGRESSIVE, RESULTING IN
A WEAKER DOWNSTREAM MOISTURE RETURN THAT IS NOW FAVORED TO
LIMIT CAPE UNDER 1000 J/KG, AND WITH BUOYANCY DECREASING OVER
TIME. A STRONGER STORM OR TWO STILL CANNOT BE RULED OUT THOUGH
GIVEN DEEP LAYER SHEAR NEAR 30 KTS.
TODAY IS FORECAST TO BE WARMER THAN YESTERDAY, WITH HIGHS
GENERALLY AROUND 80 NORTHEAST TO NEAR 90 SOUTHWEST. ANOTHER
SHORTWAVE THAT IS OVER NORTHERN BRITISH COLUMBIA EARLY THIS
MORNING IS FORECAST TO REACH THE NORTHERN RED RIVER VALLEY LATE
TONIGHT INTO THURSDAY MORNING. THIS MAY PROLONG ISOLATED TO
SCATTERED SHOWERS THROUGH THE NIGHT FROM THE TURTLE MOUNTAINS
THROUGH THE JAMES RIVER VALLEY AND POINTS EASTWARD. A COLD
FRONT ATTENDANT TO THIS WAVE IS ALSO NOW FORECAST TO DROP
THROUGH THE STATE THURSDAY MORNING, WHICH HAS CAUSED A SLIGHT
COOLING OF THE HIGH TEMPERATURE FORECAST ON THURSDAY TO BE MORE
SIMILAR TO THAT OF TODAY, RATHER THAN A FEW DEGREES WARMER. ON
FRIDAY, THE UPSTREAM RIDGE IS FORECAST TO BECOME HIGHLY
AMPLIFIED OVER THE ROCKIES. DETERMINISTIC GUIDANCE SHOWS HINTS
OF A WEAK SHORTWAVE PASSAGE OVER THE REGION ON FRIDAY, FOR
WHICH THE NBM HAS INTRODUCED SOME LOW POPS ACROSS NORTHERN
NORTH DAKOTA (10 TO 30 PERCENT). THE HIGH TEMPERATURE FORECAST
ON FRIDAY REMAINS SIMILAR ACROSS THE SOUTH, BUT COOLS SLIGHTLY
IN THE NORTH AS A BACKDOOR COLD FRONT TRIES TO PUSH DOWN FROM
CANADA. ENSEMBLES NOW FAVOR SATURDAY TO BE COOLER, ALBEIT BY
ONLY AROUND 5 DEGREES OR LESS AT ANY GIVEN LOCATION. THERE IS
STILL UNCERTAINTY ON THE EVOLUTION OF A POTENT SHORTWAVE
LANDING ON THE PACIFIC NORTHWEST COAST THIS WEEKEND AND HOW IT
WILL INTERACT WITH THE STOUT UPPER RIDGE. MOST SOLUTIONS SEEM
TO FAVOR THE POTENT SHORTWAVE ROUNDING THE TOP OF THE RIDGE
THROUGH THE SOUTHERN CANADIAN PRAIRIE PROVINCES IN THE SUNDAY
TO MONDAY TIMEFRAME. THE NBM STILL ADVERTISES A BROAD 20 TO 30
PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS LATE SATURDAY NIGHT
THROUGH SUNDAY NIGHT, WITH FUTURE FORECAST REFINEMENT TO BE
DETERMINED BY THE TIMING OF THE MORE POTENT SHORTWAVE MOVING
ACROSS SOUTHERN CANADA, AS WELL AS WEAKER SHORTWAVE ENERGY THAT
MAY EJECT OFF THE US NORTHERN ROCKIES. THE UNCERTAINTY IN THE
EVOLUTION OF THE SYNOPTIC PATTERN KEEPS PROJECTED HIGH
TEMPERATURES AT NEAR AVERAGE VALUES MOSTLY IN THE 80S EARLY
NEXT WEEK, BUT THERE DOES APPEAR TO BE A SLIGHT FAVORING OF THE
UPPER RIDGE REBUILDING FROM THE SOUTHERN ROCKIES THROUGH THE
NORTHERN HIGH PLAINS.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 401 AM CDT WED AUG 19 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE FORECAST
PERIOD. ISOLATED SHOWERS AND THUNDERSTORMS COULD MOVE THROUGH
WESTERN AND CENTRAL NORTH DAKOTA THROUGHOUT THE DAY TODAY, BUT
THE PROBABILITY IS TOO LOW TO MENTION IN ANY TAF AT THIS TIME.
LIGHT AND VARIABLE WINDS EARLY THIS MORNING WILL BECOME
SOUTHWESTERLY AROUND 10 KTS EARLY THIS AFTERNOON, TURNING TO
THE NORTHWEST IN WESTERN NORTH DAKOTA BY LATE AFTERNOON.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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