171
FXUS63 KFGF 162008
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
308 PM CDT TUE SEP 16 2025
KEY MESSAGES
- ISOLATED STRONG THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING
OVER PARTS OF WEST CENTRAL MINNESOTA. IF STRONG THUNDERSTORMS
DEVELOP, SMALL HAIL AND LIGHTING WOULD BE THE MAIN THREATS.
- A WET PATTERN WITH PERIODS OF RAIN IS EXPECTED OVER PARTS OF
EASTERN NORTH DAKOTA INTO NORTHWEST AND WEST CENTRAL MINNESOTA
WEDNESDAY THROUGH FRIDAY. THERE IS A HIGH CHANCE FOR SOAKING
RAINFALL OVER THAT THREE DAY PERIOD, WHICH COULD CAUSE IMPACTS
TO OUTDOOR ACTIVITIES.
DISCUSSION
ISSUED AT 308 PM CDT TUE SEP 16 2025
..SYNOPSIS
WEAK SOUTHWEST FLOW IS CURRENTLY IN PLACE AHEAD OF A DEEPENING
MID/UPPER LOW (CURRENTLY OVER NORTHWEST WY/SOUTH CENTRAL MT). THIS
UPPER LOW TRACKS EAST AND STALLS OVER SD/ND AS A REX BLOCK TYPE
PATTER DEVELOPS, BRINGING A WET PATTERN TO THE REGION, WITH RAIN
COVERAGE DECREASING AS THE TROUGH SHIFTS EAST SATURDAY.
TEMPERATURES SHOULD ALSO TREND BACK TOWARDS GENERALLY SEASONAL
TEMPERATURES INTO SATURDAY (UPPER 60S/LOWER 70S FOR HIGHS). THE
BREAKDOWN OF THIS UPPER LOW AND TRANSITION TO MORE ZONAL PATTERN
IN THE NORTHERN PLAINS OCCURS LATE IN THE WEEKEND INTO EARLY
NEXT WEEK AS RIDGING BEGINS TO REBUILD TO THE WESTERN US. THERE
IS INCREASING SPREAD WITHIN CLUSTERS IN THE AMPLITUDE OF THAT
PATTERN SHIFT WHICH COULD IMPACT TEMPERATURE TRENDS AND ANY FAST
MOVING WEAKER WAVES. IN ANY CASE, WE ARE NOT SEEING AN
ORGANIZED SIGNAL FOR RAIN/THUNDERSTORMS BEYOND SATURDAY IN THAT
PATTERN AND TEMPERATURES SHOULD AT LEAST REMAIN SEASONABLY MILD
WITH SOME CLUSTERS SUPPORTING A TREND TOWARDS ABOVE AVERAGE
TEMPERATURES (UPPER 70S/LOWER 80S).
..STRONG THUNDERSTORM POTENTIAL THIS EVENING
THE WEAK FRONTAL ZONE THAT COULD BE A FOCUS FOR EVENING THUNDERSTORM
DEVELOPMENT IS ALREADY FARTHER SOUTHEAST AND THIS HAS SHIFTED THE
MAIN THETA-E AXIS AWAY FROM OUR CWA. CAPE PROFILES ARE MUCH NARROWER
IN OUR AREA AND VERY ELEVATED, DUE TO DRIER AIR ABOVE THE SURFACE
THAT HAS ADVECTED INTO OUR CWA. SHEAR WAS ALREADY WEAKER IN THAT
REGION OF CONCERN, SO THESE TRENDS LOWER CONFIDENCE IN SEVERE
THUNDERSTORM POTENTIAL. LATEST CAMS DO NOT SHOW INITIATION IN OUR
SOUTHEAST CWA THIS EVENING EITHER, MATCHING THOSE TRENDS. THERE ARE
STILL SOME LESS ORGANIZED IMPULSES THAT ARE ROTATING THROUGH THE
WEAK SW FLOW TO THE SOUTH, AND COULD SUPPORT A FEW SHOWERS OR
THUNDERSTORMS THIS EVENING/TONIGHT. THE LINGERING AXIS OF ELEVATED
INSTABILITY (1000-2000 J/KG MUCAPE) IS STILL IN PLACE WITH STEEP MID
LEVEL LAPSE RATES, SO AN ISOLATED STRONG THUNDERSTORM COULDN'T BE
RULED OUT (IF INITIATION WERE EVENT TO OCCUR).
..WET PATTERN WEDNESDAY THROUGH FRIDAY
THERE IS STRONG ENSEMBLE CONSENSUS ON THE MID/UPPER LOW STALLING
OVER SD AND SOUTHERN ND WITH DEEP CYCLONIC FLOW ADVECTING DEEPER
MOISTURE INTO THE REGION, WITH NAEFS PWATS ABOVE THE 90TH PERCENTILE
(IN THE 1.2-1.6" RANGE). AT LEAST SCATTERED SHOWERS ARE EXPECTED
ACROSS MUCH OF THE AREA, WITH MORE ORGANIZED AREA OF RAIN ROTATING
AROUND THE UPPER LOW. A DEFORMATION ZONE MAY ALSO HELP ORGANIZE RAIN
INTO AREAS/BANDS WITH LOCATION/DURATION DEPENDENT ON 700MB LOW
CENTER. INSTABILITY SHOULDN'T BE HIGH ENOUGH FOR SEVERE RISK AND ML
SYSTEMS DO NOT SHOW ANY SEVERE RISK IN OUR CWA. HOWEVER THE
INSTABILITY WILL BE ENOUGH WHEN COMBINED WITH THE STRONGER FORCING
AND DEEP MOISTURE TO SUPPORT LOCALLY HEAVY RAIN RATES WHERE
THUNDERSTORMS DO DEVELOP. WETTING RAIN (GREATER THAN 0.1") IS LIKELY
ACROSS MUCH OF OUR CWA EACH DAY, THOUGH THE SIGNAL FOR HIGHEST RAIN
TOTALS IS GENERALLY SOUTH OF HIGHWAY 2. NBM QMD 24HR PROBABILITIES
OF GREATER THAN 0.5" OF RAIN EXCEED 60 PERCENT EACH DAY OVER PARTS
OF SOUTHEAST ND AND WEST CENTRAL MN, AND 72HR PROBABLES FOR AT LEAST
1" RAINFALL ARE 80% ACROSS THOSE SAME AREAS.
THE MAIN IMPACTS IN THIS PATTERN WILL BE TO OUTDOOR
ACTIVITIES/OUTDOOR ACTIVITY PLANNING. EXCESSIVE RUNOFF/AREAL FLOOD
RISK IS DECREASED IN OUR CWA DUE TO ANTECEDENT CONDITIONS. THESE
INCLUDE DRIER SOILS THAT HAVE BEEN IN PLACE AND CROPS OR CROP
STUBBLE FROM RECENT HARVEST SLOWING DOWN RUNOFF FROM FIELDS.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1238 PM CDT TUE SEP 16 2025
VFR CONDITIONS SHOULD PREVAIL THROUGH THE TAF PERIOD ACROSS
EASTERN ND AND NORTHWEST MN. THERE ARE A FEW POCKETS OF VERY
LIGHT SHOWERS/VIRGA MOVING ACROSS NORTHEAST ND AND FAR
NORTHWEST MN, WHICH SHOULD PROGRESS EAST THROUGH THE AFTERNOON.
ADDITIONAL SHOWERS OR AN ISOLATED THUNDERSTORMS MAY DEVELOP IN
FAR SOUTHEAST ND AND WEST CENTRAL MN, BUT THE PROBABILITY FOR
IMPACTS AT TAF SITES IS LOW (LESS THAN 30%). WINDS REMAIN
LIGHTER (LESS THAN 12KT) THROUGH THE TAF PERIOD DUE TO WEAK
SURFACE GRADIENT REMAINING IN PLACE. THE TREND SHOULD BE FOR
WINDS TO BE OUT OF THE WEST-NORTHWEST DURING THE DAYTIME PERIOD
THIS AFTERNOON/EARLY EVENING AND PREVAIL FROM THE NORTHEAST
AFTER SUNRISE WEDNESDAY.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...DJR
AVIATION...DJR
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