427
FXUS63 KBIS 181952
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
252 PM CDT MON MAY 18 2026
KEY MESSAGES
- RAIN SHOWERS CONTINUE INTO THIS EVENING SOUTH CENTRAL ND INTO
THE JAMES RIVER VALLEY BEFORE DEPARTING TO THE EAST-NORTHEAST TONIGHT.
SLIGHT CHANCE OF SHOWERS ELSEWHERE.
- LOWS TONIGHT INTO TUESDAY MORNING DIP INTO THE UPPER 20S TO
LOWER 30S. FREEZE WARNINGS AND FROST ADVISORIES HAVE BEEN
ISSUED. COLD TEMPERATURES AGAIN POSSIBLE TUESDAY
NIGHT/WEDNESDAY MORNING, MAINLY EAST.
- UNSETTLED WEATHER PATTERN DEVELOPS MID TO END OF THE WEEK.
GREATEST AND MOST WIDESPREAD CHANCES (ABOUT 30 TO 60 PERCENT)
COME THURSDAY INTO FRIDAY.
DISCUSSION
ISSUED AT 223 PM CDT MON MAY 18 2026
CURRENT SURFACE ANALYSIS PLACES LOW OVER THE UPPER MIDWEST WITH
NOTABLE FRONTAL BOUNDARY STRETCHING TO THE SOUTHWEST THROUGH THE
CENTRAL PLAINS. HIGH REMAINS OVER SOUTHERN SASKATCHEWAN INTO
CENTRAL MONTANA. UPPER LEVEL ANALYSIS PLACES TROUGH OVER
SASKATCHEWAN SOUTHWARD TOWARDS THE CENTRAL ROCKIES. SOUTHEAST
FLOW OVER OUR AREA WITH SOME EMBEDDED SHORT WAVES IS RESULTING
IN BROAD SHOWER ACTIVITY OVER MUCH OF SOUTH DAKOTA INTO
SOUTHEAST/SOUTH CENTRAL NORTH DAKOTA.
FOR TONIGHT, ONGOING SHOWERS WILL CONTINUE INTO THIS EVENING
BEFORE DEPARTING TO THE EAST/NORTHEAST. IN THE MEANTIME, SURFACE
HIGH SETTLES INTO THE AREA, MAINLY WESTERN LOCATIONS, WITH
COOL AIR CONTINUING TO SLIDE IN. THIS WILL RESULT IN SUB
FREEZING TEMPERATURES OVER PARTS OF WESTERN AND NORTH CENTRAL
NORTH DAKOTA, THEREFORE A FREEZE WARNING HAS BEEN ISSUED.
FURTHER EAST, CONFIDENCE IS A LITTLE LOWER AS TO HOW COLD IT
WILL GET GIVEN THE PERSISTANT CLOUD COVER. WITH THAT SAID, LOWS
LOOK TO DIP CLOSE TO OR REACH FREEZING, SO HAVE DECIDED TO GO
WITH A FROST ADVISORY FOR THAT AREA EVEN THOUGH TECHNICALLY
"FROST" WILL NOT FORM, BUT SENSITIVE PLANTS COULD BE DAMAGED,
ESPECIALLY IF TEMPERATURES ARE A DEGREE OR TWO LOWER THAN
FORECAST.
TROUGH PUSHES EAST EARLY TUESDAY, WITH A LOW AMPLITUDE RIDGE
PASSING OVER FOR TUESDAY INTO WEDNESDAY. EXPECT A GRADUAL WARM-
UP FOR HIGH TEMPERATURES, BUT TUESDAY NIGHT MAY SEE SOME
FREEZING LOWS, MAINLY OVER OUR EAST GIVEN THE HIGH PASSING OVER
AND CLEARING SKIES.
NEXT TROUGH DIGS IN OVER THE WESTERN CONUS ON THURSDAY WITH OUR
FLOW SHIFTING SOUTHWESTERLY BEFORE THE SYSTEM CLOSES OFF AND
EJECTS TO THE NORTHEAST TO CLOSE OUT THE WEEK. GREATEST CHANCES
FOR PRECIPITATION COME THURSDAY INTO FRIDAY (ABOUT 30 TO 60
PERCENT CHANCE). WARMING TREND EXPECTED GOING INTO THE WEEKEND
WITH NBM TEMPERATURE SPREADS BEING QUITE CONFIDENT IN SEEING
WELL ABOVE AVERAGE TEMPERATURES BY LATE WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1253 PM CDT MON MAY 18 2026
LOW STRATUS OVER THE STATE WILL CONTINUE TO BRING WIDESPREAD
MVFR WITH LOCALIZED IFR CEILINGS THROUGH THE REST OF TODAY INTO
THE OVERNIGHT HOURS. IMPROVEMENT IS EXPECTED LATE TONIGHT OVER
FAR WESTERN NORTH DAKOTA, THEN OVER MUCH OF WESTERN AND PARTS OF
NORTH CENTRAL NORTH DAKOTA TUESDAY MORNING.
BIS WATCHES/WARNINGS/ADVISORIES
FREEZE WARNING FROM 1 AM CDT /MIDNIGHT MDT/ TO 9 AM CDT /8 AM
MDT/ TUESDAY FOR NDZ001>005-009-010-012-017>020-022-031>033-
040-041-043-044-055>059.
FROST ADVISORY FROM 1 AM CDT /MIDNIGHT MDT/ TO 9 AM CDT /8 AM
MDT/ TUESDAY FOR NDZ013-023-025-035>037-042-046>048-050-051-
060>062.
DISCUSSION...JJS
AVIATION...JJS
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