855
FXUS63 KFGF 020407
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1107 PM CDT TUE SEP 1 2026
KEY MESSAGES
- CHANCE FOR THUNDERSTORMS RETURNS MID TO LATE THIS WEEK. THIS
INCLUDES POTENTIAL FOR STRONG TO SEVERE STORMS. THERE IS A
LEVEL 1 OUT OF 5 RISK FOR SEVERE STORMS THURSDAY.
- LATE SUMMER HEAT FORECAST TO RETURN THIS WEEKEND.
DISCUSSION
ISSUED AT 325 PM CDT TUE SEP 1 2026
..SYNOPSIS
YESTERDAY'S UPPER LOW HAS MIGRATED INTO INTERIOR ON, WITH
INCREASING UPPER MOISTURE/CLOUDS FROM AN APPROACHING WEAK
SHORTWAVE TROUGH IN SD/NE. THIS WEAK SHORTWAVE TO TRAVERSE
THROUGH SD INTO SOUTHERN MN THIS EVENING INTO EARLY WEDNESDAY.
WHILE SOME OF ITS UPPER/MID LEVEL MOISTURE WILL OVERSPREAD OUR
AREA, DRY AIR NEAR THE SURFACE WILL PREVENT MOST RAIN FROM
REACHING THE GROUND OUT OF THE SHOWERS THAT ATTEMPT TO DEVELOP
NEAR THE TRI-STATE AREA THIS EVENING/TONIGHT.
WEDNESDAY WILL BE DRY WITH WEAK WINDS AMID SURFACE HIGH
PRESSURE AND DECREASING CLOUD COVER.
LATE WEDNESDAY INTO THURSDAY, UPPER RIDGING BEGINS TO BUILD
INTO THE NORTHERN PLAINS DOWNSTREAM OF A LONGWAVE UPPER TROUGH
DIGGING INTO THE PACIFIC COAST. THIS WILL PROMOTE MOISTURE
RETURN INTO THE NORTHERN PLAINS AND UPPER MIDWEST THURSDAY. THIS
CONTINUES THROUGH THE REST OF THIS WEEK AS AN OMEGA-BLOCK
PATTERN SETS UP OVER THE CONUS, WITH UPPER RIDGING FURTHER
BUILDING INTO THE PLAINS IN RESPONSE TO THE DIGGING AND NON-
PROGRESSIVE UPPER TROUGHING IN THE WEST. THIS WILL ALLOW SEVERAL
DAYS OF SOUTHWEST FLOW ALOFT OVER THE NORTHERN PLAINS
(INCLUDING OUR REGION), ALLOWING FOR CONTINUED AND SOMEWHAT
LENGTHY PERIOD OF MOISTURE AND HEAT RETURN/REINFORCEMENT THROUGH
THE REST OF THIS WEEKEND. THIS WILL BRING INGREDIENTS INTO THE
NORTHERN PLAINS AND UPPER MIDWEST FOR POTENTIAL SEVERE STORMS AS
WELL AS SUMMER-LIKE HEAT WITH POTENTIAL FOR MINOR HEAT RELATED
IMPACTS.
ENSEMBLE GUIDANCE SUGGESTS THE UPPER TROUGH AND RIDGE WAVE
PACKET BREAKS DOWN INTO EARLY NEXT WEEK, WHICH TYPICALLY WOULD
SIGNAL THE END OF HEAT AND SEVERE POTENTIAL. HOWEVER, THERE ARE
NOTABLE DIFFERENCE BETWEEN ENSEMBLE SYSTEMS IN HOW THIS
BREAKDOWN EVOLVES - THUS CONFIDENCE IN THE EXTENDED FORECAST IS
LOW.
..POTENTIAL STRONG TO SEVERE STORMS MID TO LATE THIS WEEK
MOST RECENT GUIDANCE HAS SOMEWHAT DELAYED THE APPROACH OF THE
INITIAL INITIAL SURGE OF SOUTHWEST FLOW ALOFT TO BRING
MOISTURE/INSTABILITY INTO OUR AREA COMPARED TO YESTERDAY,
PLACING CONFIDENCE IN LATE WEDNESDAY DEVOID OF ROBUST
THUNDERSTORMS. THERE STILL COULD BE SOME ELEVATED ROBUST
CONVECTION CAPABLE OF SMALL HAIL EARLY THURSDAY MORNING,
HOWEVER.
CONFIDENCE HAS GROWN IN THE JUXTAPOSITION OF MODERATE TO STRONG
INSTABILITY AND MODERATE SHEAR ENOUGH TO INTRODUCE A LEVEL 1
OUT OF 5 RISK FOR SEVERE STORMS THURSDAY OVER OUR ENTIRE AREA,
BUT BY NO MEANS IS THIS A CONFIDENCE FORECAST. THERE ARE STILL
IMPORTANT QUESTIONS REGARDING DEGREE OF CAPPING, SUFFICIENT
FORCING FOR ASCENT, AND STORM MODE/EVOLUTION THAT ARE YET TO BE
RESOLVED CONFIDENTLY. HOWEVER, THERE IS A POTENTIAL SCENARIO
THAT BRINGS AT LEAST SUFFICIENT FORCING TO SUSTAIN ROBUST
THUNDERSTORM DEVELOPMENT AMID THE INSTABILITY/SHEAR SPACING THAT
COULD RESULT IN SUPERCELLS WITHIN EASTERN ND THURSDAY
AFTERNOON/EVENING. THIS INCLUDES POTENTIAL FOR LARGE HAIL
(PERHAPS VERY LARGE) AND TORNADOES GIVEN RICH LOW LEVEL MOISTURE
AND THE POTENTIAL FOR SURFACE LOW HELPING LOW LEVEL SHEAR -
BOTH OF WHICH WOULD BE DEPENDENT UPON MATURE DISCRETE/SEMI-
DISCRETE SUPERCELL MODES. ON THE OTHER HAND, THERE ARE SCENARIOS
THAT FAVOR MORE LINEAR STORM MODE FAVORING GUSTY WINDS AS MAIN
HAZARD, AS WELL AS A SCENARIO THAT IS GENERALLY DEVOID OF ROBUST
CONVECTION WITHIN OUR AREA ALTOGETHER - HENCE, LOWERED
CONFIDENCE FOR THURSDAY.
WITH NON-PROGRESSIVE PATTERN ALLOWING OVERALL INCREASED LOW
LEVEL MOISTURE, ALONG WITH CONTINUED FEED OF STEEPENED LAPSE
RATES ALOFT SOURCED FROM THE CENTRAL ROCKIES, THE POTENTIAL FOR
STRONG TO SEVERE STORMS EXISTS ALMOST DAILY THROUGH THE WEEKEND.
THIS IS BACKED BY ML/AI GUIDANCE HIGHLIGHTING OUR REGION LATE
THURSDAY THROUGH SATURDAY FOR SEVERE POTENTIAL.
IT IS WORTH NOTING THIS PATTERN COULD RESULT IN LOCALLY HEAVY
RAIN AND POTENTIAL FOR FLASH FLOODING GIVEN THE LONGER DURATION
OF MOISTURE FLOW AND AN UPPER PATTERN THAT IS NON-PROGRESSIVE
POTENTIALLY ALLOWING FOR SEVERAL SHORTWAVE IMPULSES TO TRAVERSE
THROUGH OUR REGION. CONFIDENCE IN THIS IS LOW, HOWEVER, AS THERE
ARE UNKNOWN MESOSCALE INFLUENCES THAT ARE NECESSARY FOR FLASH
FLOODING YET TO BE CORRECTLY RESOLVED BY MODELED GUIDANCE.
..LATE SUMMER-LIKE HEAT THIS WEEKEND
ENSEMBLE GUIDANCE CONTINUES TO STRONGLY SUGGEST IN STRONG UPPER
RIDGING INTO THE UPPER MIDWEST THIS WEEKEND. THIS WILL PROMOTE
INCREASING TEMPERATURES ALOFT, AS WELL AS THE MIGRATION AND
POOLING OF MOISTURE NEAR THE SURFACE. THIS WILL NOT ONLY ALLOW
OPPORTUNITY FOR 90S BACK INTO THE FORECAST, BUT ALSO HIGH
HUMIDITY. AS OF NOW, FRIDAY AND SATURDAY LOOK TO BE THE DAYS
WHERE THESE TWO MAY ALIGN TO BRING HEAT INDICES WELL INTO THE
90S, AND PERHAPS INTO THE LOW 100S (20 PERCENT CHANCE OF
OCCURRING). WHILE SATURDAY LOOKS TO BE HOTTEST WITHIN THE
FORECAST PERIOD, THIS COULD ALSO EXTEND INTO SUNDAY, ALTHOUGH
CONFIDENCE IS LOW IN THIS.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1107 PM CDT TUE SEP 1 2026
VERY LITTLE IN THE WAY OF AVIATION IMPACTS THROUGHOUT THE TAF
PERIOD. HOWEVER, IF THERE WERE TO BE ANY IMPACTS, THEY WOULD
OCCUR WEDNESDAY MORNING, AS A FEW PATCHES OF FOG MAY DEVELOP
OVERNIGHT. WITH HIGH PRESSURE CREEPING IN, WINDS HAVE ALREADY
DROPPED BELOW 5 KNOTS AREA WIDE. IF CLOUDS CAN CLEAR BY SUNRISE,
A FEW POCKETS OF FOG WOULD NOT BE SURPRISING. HOWEVER,
CONFIDENCE IN WHERE/DURATION OF FOG IS LOW. THEREFORE, I DID
NOT ADD ANY MENTION INTO THE TAF AT THIS TIME. BEYOND ANY FOG
WEDNESDAY MORNING, THE REMAINDER OF THE MORNING AND AFTERNOON
LOOKS TO BRING BEAUTIFUL FLYING WEATHER, WITH NO/FEW CLOUDS,
WINDS UNDER 10 KNOTS, AND NO WIND GUSTS. THESE OPTIMAL
CONDITIONS WILL PREVAIL THROUGH THE END OF THE TAF PERIOD.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...CJ
AVIATION...RAFFERTY
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