465
FXUS63 KBIS 221146
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
646 AM CDT FRI MAY 22 2026
KEY MESSAGES
- SCATTERED TO NUMEROUS SHOWERS ACROSS MUCH OF WESTERN AND
CENTRAL NORTH DAKOTA THIS MORNING, BECOMING WIDESPREAD AND
EXPANDING EASTWARD THROUGH THE AFTERNOON AND EVENING. A FEW
AFTERNOON THUNDERSTORMS COULD PRODUCE HEAVY DOWNPOURS.
- COOLER AGAIN TODAY, WITH HIGHS MOSTLY IN THE LOWER 50S TO
LOWER 60S.
- TEMPERATURES WARM TO WELL ABOVE NORMAL FOR THE FIRST HALF OF
NEXT WEEK, WITH HIGHS MOSTLY IN THE 80S TO LOWER 90S. TUESDAY
AND WEDNESDAY COULD BE WINDY.
- OTHER THAN A FEW ISOLATED SHOWERS OR THUNDERSTORMS ON
SATURDAY, THE HOLIDAY WEEKEND IS EXPECTED TO BE DRY.
UPDATE
ISSUED AT 645 AM CDT FRI MAY 22 2026
OVERALL, THE RAIN IS UNFOLDING AS EXPECTED EARLY THIS MORNING.
MINIMAL CHANGES ARE NEEDED FOR THIS UPDATE, AND WERE BASED ON
OBSERVED AND LATEST MODELED TRENDS. THIS DID INCLUDE REMOVING
THE MENTION OF THUNDER UNTIL LATE MORNING.
DISCUSSION
ISSUED AT 432 AM CDT FRI MAY 22 2026
EARLY MORNING UPPER AIR ANALYSIS SHOWS TWO CLOSED UPPER LOWS
BOOKENDING A TROUGH AXIS FROM SOUTHERN SASKATCHEWAN TO EASTERN
WYOMING. AT THE SURFACE, AN INVERTED TROUGH AXIS LIES ACROSS THE
WESTERN DAKOTAS. THE INVERTED TROUGH HAS BEEN AND WILL CONTINUE
TO BE THE BROAD FOCAL AREA FOR SCATTERED TO NUMEROUS SHOWERS
THROUGH THE MORNING. THERE IS A RELATIVE LULL IN SHOWER ACTIVITY
AT THE TIME OF THIS WRITING, BUT THAT SHOULD QUICKLY CHANGE AS
THE LOW AT THE BASE OF THE UPPER TROUGH SPINS NORTHEASTWARD INTO
WESTERN SOUTH DAKOTA, PUSHING THE CURRENT BATCH OF RAIN OVER
THE BLACK HILLS NORTHWARD. THE CLOSED LOW WILL CONTINUE SPINNING
NORTHEASTWARD THROUGHOUT THE DAY, DRAGGING A SURFACE LOW INTO
SOUTHEAST SOUTH DAKOTA THIS AFTERNOON. STRONG SYNOPTIC SCALE
FORCING FROM MID LEVEL DCVA AND LOW LEVEL WARM AIR ADVECTION TO
THE NORTH AND NORTHEAST OF THE NEARLY-STACKED LOW PRESSURE
SYSTEM IS EXPECTED TO BRING A LARGE SHIELD OF MOSTLY STRATIFORM
RAIN ACROSS THE EASTERN TWO THIRDS OF THE STATE FROM SOUTH TO
NORTH LATER THIS MORNING THROUGH THIS EVENING. MOST OF THE STATE
OUTSIDE OF THE FAR WEST IS FAVORED TO RECEIVE AROUND A QUARTER
TO HALF INCH OF RAIN THROUGH TONIGHT, WHICH IS IN ADDITION TO
WHAT HAS ALREADY FALLEN SINCE YESTERDAY. THE JAMES RIVER VALLEY
HAS HIGHER ODDS FOR EXCEEDING HALF AN INCH, AND EVEN MEDIUM
CHANCES FOR THREE QUARTERS TO ONE INCH OF RAIN. IN CONTRAST,
THERE IS A POTENTIAL FOR A NARROW CORRIDOR OF LOWER RAIN AMOUNTS
OVER CENTRAL NORTH DAKOTA DUE TO AN AREA OF DIFFLUENCE IN THE
LOW LEVEL WIND FIELD, WHICH MAY NOT ALLOW THE AREA OF RAIN
ASSOCIATED WITH THE INVERTED SURFACE TROUGH TO FULLY ADHERE TO
THE NORTHWARD MOVING STRATIFORM RAIN SHIELD. THIS INVERTED DRY
SLOT FOOTPRINT IS QUITE PROMINENT IN THE HREF PROBABILITY-
MATCHED MEAN QPF, WHICH PLACES IT FROM THE TURTLE MOUNTAINS TO
EASTERN MORTON COUNTY. ONE FINAL NOTE ABOUT THE RAIN FORECAST
FOR TODAY IS THAT THERE IS ANOTHER POTENTIAL FOR AFTERNOON
THUNDERSTORMS, MAINLY ALONG THE INVERTED TROUGH AXIS. THE RISK
FOR STRONGER STORMS APPEARS LOWER THAN YESTERDAY, BUT ANY
TRAINING OR NEARLY-STATIONARY CONVECTION WOULD PRODUCE LOCALLY
HIGHER RAIN AMOUNTS.
REGARDLESS OF RAIN AMOUNTS, IT WILL BE A COOL AND CLOUDY DAY
FOR MOST OF THE STATE, WITH HIGHS MOSTLY IN THE 50S. LOWER 60S
COULD BE ACHIEVED ALONG THE MONTANA BORDER IF CLOUDS CLEAR EARLY
ENOUGH, AND ALSO NEAR THE TURTLE MOUNTAINS WHERE RAIN-COOLED
AIR AND THICKER CLOUD COVER MAY NOT ARRIVE UNTIL AFTER PEAK
HEATING. THE RAIN SHOULD DEPART FROM SOUTHWEST TO NORTHEAST THIS
EVENING THROUGH TONIGHT, LEAVING BEHIND A POTENTIALLY FAVORABLE
SETUP FOR FOG FORMATION. FORECAST LOWS TONIGHT ARE MOSTLY IN
THE UPPER 30S TO MID 40S. THERE COULD BE A FEW SPOTS IN
SOUTHWEST NORTH DAKOTA THAT DIP TO NEAR FREEZING, BUT AS OF THIS
WRITING, LOWS IN THE MID 30S OR COLDER ARE NOT EXPECTED TO BE
WIDESPREAD ENOUGH TO WARRANT A FROST ADVISORY.
SATURDAY WILL MARK THE BEGINNING OF A SUBSTANTIAL WARMING TREND
THROUGH THE HOLIDAY WEEKEND, WITH THE NBM PROJECTING HIGHS IN
THE UPPER 60S TO MID 70S ON SATURDAY, UPPER 70S TO MID 80S ON
SUNDAY, AND MID 80S TO LOWER 90S ON MEMORIAL DAY. FLOW ALOFT
REMAINS CYCLONIC ON SATURDAY AS THE DEPARTING MID/UPPER LEVEL
LOW STALLS OVER SOUTHERN MANITOBA. THIS COULD ALLOW A FEW
AFTERNOON SHOWERS AND THUNDERSTORMS TO DEVELOP. FORECAST CAPE
AND SHEAR PARAMETERS DO NOT APPEAR SUPPORTIVE OF SEVERE
CONVECTION ON SATURDAY, BUT A COUPLE OF CAMS DO SIMULATE A FEW
STRONGER STORMS. THE HIGHEST PROBABILITY FOR ISOLATED
THUNDERSTORMS IS IN NORTH CENTRAL NORTH DAKOTA, BUT IS STILL NO
GREATER THAN 20 PERCENT. ON SUNDAY, FLOW ALOFT TURNS QUASI-
ZONAL AS A RIDGE BUILDING OVER THE FOUR CORNERS REGION BEGINS TO
PUSH MID LEVEL HEIGHT RISES INTO THE NORTHERN PLAINS. THERE IS
UNCERTAINTY ON WHETHER AN EMBEDDED SHORTWAVE COULD BRIEFLY
INTERRUPT THE HEIGHT RISES AND INITIATE CONVECTION SUNDAY
AFTERNOON AND EVENING. IN THE 00 UTC SUITE OF GUIDANCE, THIS
FEATURE IS ONLY PRONOUNCED IN THE DETERMINISTIC GFS AND A VERY
LOW-MEMBERSHIP ENSEMBLE CLUSTER, SO WE WILL CONTINUE TO
ADVERTISE DRY WEATHER ON SUNDAY. CONFIDENCE IN DRY WEATHER IS
EVEN HIGHER ON MEMORIAL DAY AS THE UPPER RIDGE BECOMES FULLY
ESTABLISHED OVER THE NORTHERN PLAINS.
A VERY STRONG UPPER LEVEL LOW/TROUGH WILL DIG INTO THE WESTERN
CONUS BY TUESDAY, FURTHER AMPLIFYING THE CENTRAL CONUS RIDGE AND
POTENTIALLY SETTING UP AN OMEGA-BLOCKING PATTERN THROUGH THE
END OF MAY. ENSEMBLE GUIDANCE TENDS TO FAVOR THE NORTHERN PLAINS
LYING UNDER THE SOUTHERLY FLOW ALOFT PATTERN BETWEEN THE
UPSTREAM TROUGH AND DOWNSTREAM RIDGE, BUT IN CLOSER VICINITY TO
THE RIDGE. THIS RENDERS LOW PREDICTABILITY FOR ANY SHOWER AND
THUNDERSTORM CHANCES, ALTHOUGH THE NBM DOES HAVE A PERIOD OF
30-40 PERCENT POPS LATE WEDNESDAY THROUGH THURSDAY.
INTERESTINGLY, THERE IS ALSO A WEAK SIGNAL IN GEFS-BASED MACHINE
LEARNING GUIDANCE FOR A LOW-END SEVERE THUNDERSTORM RISK NEXT
WEEK. WHILE MOISTURE AND CAPE WILL CERTAINLY BE AT THE HIGHEST
THEY'VE BEEN SO FAR THIS SEASON, THE SHEAR FORECAST REMAINS
HIGHLY UNCERTAIN. HIGHER CONFIDENCE ASPECTS OF THE FORECAST FOR
NEXT WEEK UNDER THE FAVORED PATTERN ARE TEMPERATURES REMAINING
ABOVE NORMAL AND AN INCREASE IN SOUTHERLY WINDS, BOTH OF WHICH
ARE BEGINNING TO BE HIGHLIGHTED BY THE ECMWF EFI PRODUCTS.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 645 AM CDT FRI MAY 22 2026
SCATTERED TO NUMEROUS SHOWERS WILL CONTINUE ACROSS MUCH OF THE
WESTERN HALF OF THE STATE THROUGH THIS AFTERNOON. MEANWHILE, A
SEPARATE AREA OF RAIN WILL EXPAND NORTHWARD FROM SOUTH DAKOTA
INTO THE EASTERN HALF OF THE STATE LATER THIS MORNING AND
AFTERNOON. THE WIDESPREAD RAIN IS FORECAST TO DIMINISH FROM
SOUTHWEST TO NORTHEAST THIS EVENING INTO TONIGHT. EXPECT PERIODS
OF MVFR TO IFR VISIBILITY WITH HEAVIER SHOWERS AND MORE
PERSISTENT AREAS OF RAIN. A LOW CHANCE OF THUNDERSTORMS RETURNS
TO CENTRAL NORTH DAKOTA THIS AFTERNOON.
CEILINGS ARE FORECAST TO FALL TO MVFR LEVELS FROM SOUTHWEST
NORTH DAKOTA TO BETWEEN KXWA AND KMOT BY MID MORNING, WITH IFR
POSSIBLE AT KDIK. BY LATE MORNING, LOW CEILINGS SHOULD BEGIN
EXPANDING OVER KBIS (PREVAILING MVFR) AND KJMS (MVFR LOWERING TO
IFR). KMOT IS LIKELY TO MAINTAIN A VFR CEILING UNTIL MVFR
ARRIVES THIS EVENING. MEANWHILE, KXWA COULD REMAIN AT VFR
THROUGH THE FORECAST PERIOD. LOW CEILINGS ARE FORECAST TO
PREVAIL OVER MUCH OF CENTRAL AND EASTERN NORTH DAKOTA THROUGH
TONIGHT, RANGING FROM MVFR FROM KMOT TO KBIS TO POSSIBLY AS LOW
AS LIFR AT KJMS. THERE IS ALSO A POTENTIAL FOR FOG DEVELOPING
LATER TONIGHT ACROSS THE WESTERN HALF OF THE STATE.
WINDS TODAY WILL GENERALLY BE NORTHERLY AROUND 5-10 KTS IN
WESTERN NORTH DAKOTA AND EASTERLY AROUND 10-15 KTS IN CENTRAL
AND EASTERN NORTH DAKOTA. LIGHT AND VARIABLE WINDS ARE THEN
EXPECTED FOR THE WESTERN HALF OF THE STATE TONIGHT, WITH A 10
KT WIND TURNING FROM EASTERLY TO NORTHWESTERLY AT KJMS.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...HOLLAN
DISCUSSION...HOLLAN
AVIATION...HOLLAN
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