208
FXUS63 KFGF 190446
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1146 PM CDT SAT APR 18 2026
KEY MESSAGES
- WARM TEMPERATURES RETURN NEXT WEEK, BRINGING NEAR CRITICAL OR
CRITICAL FIRE WEATHER CONDITIONS MONDAY THORUGH WEDNESDAY.
- AN UNSETTLED PATTERN BRINGING RAIN AND THUNDERSTORM CHANCES TO
THE REGION THURSDAY, AND RAIN AND SNOW CHANCES FRIDAY INTO
NEXT WEEKEND.
DISCUSSION
ISSUED AT 253 PM CDT SAT APR 18 2026
..SYNOPSIS
LARGE SCALE PATTERN STILL FEATURES TROUGHING ACROSS THE GREAT
LAKES/UPPER MIDWEST, WITH NORTH-NORTHWEST FLOW OVER THE NORTHERN
PLAINS. SEVERAL EMBEDDED WAVES WITHIN THIS FLOW ARE MOVING INTO THE
REGION AND MAY BRING SHOWER CHANCES LATE AFTERNOON THROUGH THE
EVENING/EARLY OVERNIGHT PERIOD. MID/UPPER LEVEL RIDGING ALREADY
BUILDING OVER THE WESTERN US IS EXPECTED TO MOVE EAST INTO THE
CENTRAL AND NORTHERN PLAINS AND DRIER/WARMER CONDITIONS ARE FAVORED
THROUGH WEDNESDAY. ALL ENSEMBLE SYSTEMS SHOW DEEP LONGWAVE TROUGHING
DEVELOPING ACROSS THE WESTERN US, WITH SOUTHWEST FLOW ACROSS THE
PLAINS LATE NEXT WEEK. THIS TROUGH EVENTUALLY MOVES ACROSS THE
CENTRAL AND NORTHERN PLAINS. THIS PATTERN SHIFT WILL RESULTING
INCREASING PRECIPITATION CHANCES LATE IN THE WEEK INTO THE WEEKEND,
WITH COOLER/BELOW AVERAGE TEMPERATURES RETURNING ONCE AGAIN.
..SNOW SHOWERS THIS AFTERNOON AND TONIGHT
THE MID LEVEL WAVES MOVING THROUGH THE REGION ARRIVE AS STEEP LOW
AND MID LEVEL LAPSE RATES WILL REMAIN IN PLACE, WITH A LAYER OF
ELEVATED INSTABILITY THROUGH THE EVENING EVEN AS LOW LEVELS DECOUPLE
(MU CAPE 50-100 J/KG). THIS ON THE SURFACE ISN'T IMPRESSIVE, BUT MAY
ENOUGH FOR SOME OF THE SHOWERS TO SUPPORT BRIEF/HIGHER RATES AND
LOCALIZED VISIBILITY REDUCTIONS (UNDER 1 MILE). THERE WILL BE
SUBSTANTIAL DRY AIR IN THE LOW AND MID LEVELS THAT COULD LIMIT
COVERAGE AND ANY POTENTIAL FOR ACCUMULATIONS, THOUGH WHERE RATES ARE
HIGH ENOUGH A DUSTING OF SNOW ACCUMULATION ON GRASSY/ELEVATED
SURFACES MAY OCCUR.
..FIRE WEATHER MONITORING EARLY NEXT WEEK
THE PATTERN SHIFT TOWARDS MORE DOMINANT RIDGING/RISING HEIGHTS
SUPPORTS ABOVE AVERAGE TEMPERATURES MONDAY THROUGH WEDNESDAY, WITH
INCREASED MIXING AND GENERALLY SUNNY CONDITIONS. THE FLATTENING OF THE
RIDGE AND SLIGHT SHIFT TOWARDS WEST-SOUTHWEST FLOW WEDNESDAY DOES
TEND TO SUPPORT STRONGER LEE TROUGHING TO THE WEST AND INCREASING
SOUTHERLY LOW LEVEL FLOW. THE PATTERN ALOFT TENDS TO SUPPORT AT
LEAST PERIODS OF INCREASING UPPER LEVEL CLOUDS, BUT ALSO EVEN WARMER
TEMPERATURES AND DEEPER MIXING. WHILE BOTH MONDAY AND TUESDAY MAY
SEE NEAR CRITICAL FIRE WEATHER CONDITIONS OVER PARTS OF THE REGION,
WEDNESDAY IS THE MAIN DAY OF CONCERN FOR POTENTIAL FIRE WEATHER
IMPACTS AN INCREASED CHANCE FOR CRITICAL FIRE WEATHER CONDITIONS/RED
FLAG WARNING CONDITIONS. HDWI PROBABILITIES ARE MAXED OUT FOR
EXCEEDING THE 75TH PERCENTILE ARE VERY HIGH (ACTUALLY MAXED OUT IN
OUR SOUTH) WITH INCREASED CHANCES TO (40% OR GREATER) TO EXCEED THE
95TH PERCENTILE. ADJUSTING FOR BETTER MIXING HEIGHTS TDS MAY FALL
MORE IN LINE WITH NBM 10TH PERCENTILE WITH MANY LOCATIONS NEAR OR
LOWER THAN 25% FOR RH VALUES IN OUR SOUTH. MIXED LAYER WINDS WOULD
SUPPORT GUSTS EXCEEDING 30 MPH AS WELL, WITH SOME GUSTS HIGHER IF
VERTICAL MIXING IS MAXIMIZED.
..UNSETTLED PATTERN LATE NEXT WEEK INTO THE WEEKEND
AS SOUTHWEST FLOW DEVELOPS DEEPER MOISTURE ADVECTION BUILDS INTO THE
NORTHERN PLAINS WITH NAEFS HIGHLIGHTING ANOMALOUS PWATS (EXCEEDING
1") THURSDAY INTO THURSDAY NIGHT. EFI HIGHLIGHTS THAT PERIOD FOR
ANOMALOUS INSTABILITY (VALUES EXCEEDING 0.8) THOUGH CLIMATOLOGICALLY
THAT ISN'T AS HARD TO ACCOMPLISH WITH EVEN MODEST INSTABILITY
PRESENT. DEPENDING ON THE EVOLUTION OF THE UPSTREAM LOW PRESSURE
BUILDING OUT OF COLORADO WITHIN THIS FLOW WE MAY SEE ORGANIZED
PERIODS OF RAIN AND EMBEDDED/ELEVATED THUNDERSTORMS THURSDAY INTO
THURSDAY NIGHT, AND THIS WILL BE A PERIOD TO MONITOR. DEPENDING ON
MESOSCALE DETAILS (CLEARING/FRONTAL POSITIONS) STRONG EFFECTIVE
SHEAR COULD COINCIDE WITH ENOUGH ELEVATED INSTABILITY FOR A FEW
STRONG OR EVEN MARGINALLY SEVERE THUNDERSTORMS.
AS FROST DEPTH HAS REACHED ZERO BASED ON OBSERVATIONS IN OUR CWA AS
OF THE LAST WARM-UP WE ARE NOT APPROACHING THIS RAIN EVENT WITH
HYDROPHOBIC TENDENCIES AS WE NORMALLY WOULD IN EARLY SPRING. THUS,
IT WILL TAKE HEAVIER RAIN TOTALS IN SHORTER PERIODS TO CAUSE
EXCESSIVE RUNOFF IMPACTS AS THERE COULD BE AT LEAST SOME STORAGE IN
SOIL. THERE IS A SIGNAL IN NBM FOR 1"+ RAIN TOTALS (10-20% CHANCE),
HOWEVER THE SIGNAL FOR GREATER THAN 2" OF RAINFALL IS CURRENTLY ZERO
AND THOSE TYPES OF TOTALS WOULD LIKELY BE NEEDED FOR AT LEAS SOME
FLOOD IMPACTS.
ENSEMBLE SPREAD INCREASES REGARDING THE EVOLUTION OF THE PATTERN,
LOWERING CONFIDENCE IN PRECIPITATION COVERAGE AND MEASURABLE
PRECIPITATION TIMING/COVERAGE/AMOUNTS. THE COLDER AIR SETTLING INTO
THE REGION DOES RAISE THE POTENTIAL FOR WINTRY PRECIPITATION DEPENDENT
ON EVOLUTION/TIMING. THERE ARE SOME ENSEMBLE MEMBERS THAT SHOW
ACCUMULATING SNOW POTENTIAL AND WPC PWSSI SHOWS A 10-20% PROBABILITY
FOR ADVISORY/MINOR WINTER WEATHER IMPACTS FROM SNOWFALL. HIGHER SNOW
RATES WOULD BE REQUIRED TO OVERCOME WARMER GROUND TEMPERATURES AND
INCREASE IMPACTS AND ALL DETAILS ARE VERY UNCERTAIN AT THIS TIME AND
RANGE.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1145 PM CDT SAT APR 18 2026
NO MAJOR CHANGES TO THIS ITERATION OF TAFS. VFR WILL PREVAIL
THROUGHOUT THE TAF PERIOD. WINDS ARE CURRENTLY OUT OF THE NORTH,
AND WILL REMAIN SO OVERNIGHT THROUGH MUCH OF SUNDAY. LATE SUNDAY
AFTERNOON INTO THE EVENING, WINDS WILL SWITCH TO OUT OF THE
SOUTH AT ALL TERMINALS FROM WEST TO EAST. WINDS WILL REMAIN
UNDER 12 KNOTS THROUGHOUT THE TAF PERIOD.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...DJR
AVIATION...RAFFERTY
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