752
FXUS63 KFGF 010058
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
758 PM CDT SAT MAY 31 2025
KEY MESSAGES
- HEAVY SMOKE TODAY THROUGH AT LEAST SUNDAY EVENING WITH
POTENTIAL IMPACTS TO ALL POPULATION GROUPS.
- ISOLATED SEVERE STORMS MONDAY AFTERNOON/EVENING FOR PARTS OF
SOUTHEAST NORTH DAKOTA AND WEST CENTRAL MINNESOTA.
- 40% CHANCE FOR MORE THAN 1 INCH OF RAIN EARLY NEXT WEEK
SOUTHEAST NORTH DAKOTA AND WEST CENTRAL MINNESOTA.
DISCUSSION
ISSUED AT 132 PM CDT SAT MAY 31 2025
..SYNOPSIS
SURFACE ANALYSIS INDICATES A FAIRLY DIFFUSE PRESSURE PATTERN
WITH A PRESSURE RIDGE ACROSS NORTHWEST MINNESOTA. WIDESPREAD
SMOKE CONTINUES TO PREVENT US REALIZING FULL POTENTIAL IN
MAXIMUM TEMPERATURES WITH THE 850 THERMAL RIDGE ON TOP OF US,
HOWEVER TEMPERATURES WILL REMAIN FAIRLY WARM IN THE LOW TO MID
80S THIS AFTERNOON.
THIS TYPE OF PATTERN WILL CONTINUE FOR THE REMAINDER OF THE
WEEKEND AS THE LARGE SCALE RIDGE TRANSLATES EASTWARD SLOWLY BUT
SURELY. WITH THE THERMAL RIDGE ON TOP OF US TOMORROW, HIGH
TEMPERATURES MAY PUSH INTO THE 90S, HOWEVER CERTAINTY IN THE
FORECAST IS LOW GIVEN ONGOING SMOKE.
A STRONG COLD FRONT WILL PUSH THROUGH MONDAY AFTERNOON WITH
VARIABLE FRONTAL TIMING. THIS BRINGS THE CHANCE FOR SHOWERS AND
THUNDERSTORMS AHEAD OF AND BEHIND THE COLD FRONT. SOME SPOTS MAY
GET BRIEFLY HEAVY RAINFALL AND SEVERE STORMS, PARTICULARLY THOSE
AHEAD OF THE FRONT BY PEAK HEATING MONDAY AFTERNOON.
THE UPPER FLOW PATTERN BECOMES FAIRLY WEAK THEREAFTER WITH
LIMITED FLOW ALOFT, CAUSING VERY LIMITED SUPPORT FOR ORGANIZED
THUNDERSTORMS. AS SUCH, THE PROBABILITY FOR WIDESPREAD HAZARDOUS
WEATHER AFTER TUESDAY IS LOW AT THIS TIME.
..SEVERE STORMS MONDAY AFTERNOON/EVENING
AS THE LARGE 500MB RIDGE PUSHES EAST-SOUTHEASTWARD, A STRONG
COLD FRONT WILL ACCOMPANY ITS EXIT FROM OUR CWA. FRONTOGENESIS
LOOKS TO BE FAIRLY STRONG ALONG THIS COLD FRONT THANKS TO THE
TIGHT TEMPERATURE GRADIENT AND THE POTENTIAL FOR CONVERGENCE.
THE MAIN QUESTIONS AT THIS POINT ARE HOW FAST DOES THE FRONT
MOVE THROUGH THE AREA, HOW MUCH INSTABILITY DEVELOPS AHEAD OF
THE FRONT, AND HOW WIDESPREAD ARE THUNDERSTORMS.
GUIDANCE AS OF 12Z VARIES RATHER SUBSTANTIALLY ON FRONTAL
POSITION, WITH ENSEMBLES BEING FAIRLY SLOW, WHILE MORE
MESOSCALE-DRIVEN GUIDANCE IS MUCH FASTER. ADDITIONALLY, THERE IS
STRONG VARIATIONS IN LOW-LEVEL MOISTURE CONTENT HEAVILY DRIVEN
BY SURFACE-850MB MOISTURE ADVECTION DIRECTIONS. THIS TIME OF
YEAR IS FAIRLY EARLY FOR ASSISTANCE FROM EVAPOTRANSPIRATION, SO
THE EXPECTATION IS FOR DEWPOINTS TO MORE LIKELY THAN NOT
APPROACH THE MID TO UPPER 50S WITH THE LOW CHANCE TO PUSH LOW TO
MID 60S. WITH FORCING AS STRONG AS IT IS, THERE SHOULDN'T BE TOO
MUCH ISSUE BREAKING THROUGH ANY CAPPING INVERSION AT THE TOP OF
THE BOUNDARY LAYER. THE MAIN QUESTION FROM A MOISTURE STANDPOINT
WILL BE HOW COOL WOULD DOWNDRAFTS THEORETICALLY BE. THE OTHER
ISSUE THAT ARISES THANKS TO THE STRONG FRONTOGENESIS IS THAT
THUNDERSTORMS MAY DEVELOP FAIRLY QUICKLY AND INTERFERE WITH EACH
OTHER. EVEN RIGHT MOVING SUPERCELL VECTORS HAVE A LARGER FRONT-
PARALLEL COMPONENT THAN IS IDEAL FOR ISOLATED SUPERCELLS SO
CLUSTERING SEEMS TO BE A FAIRLY STRONG CASE FOR WHAT
ARISES.
HAVING SAID ALL OF THIS, SHOWERS AND THUNDERSTORMS ARE LIKELY TO
DEVELOP MONDAY AFTERNOON. LOW-LEVEL HODOGRAPHS ARE FAIRLY SOLID
IN THE VORTICITY DEPARTMENT AND VORTICITY ALONG THE FRONT IS
STRONG, SO ALL HAZARDS APPEAR FEASIBLE IN THIS TYPE OF
ENVIRONMENT, PENDING THERMODYNAMIC LIMITATIONS SUCH AS COLDER
DOWNDRAFTS OWING TO WETBULBING. IN ANY CASE, HAVE MULTIPLE WAYS
TO RECEIVE WARNINGS.
..HEAVY RAINFALL POTENTIAL
HEAVY RAINFALL APPEARS LIKE A POTENTIAL SCENARIO GIVEN THE
LARGELY FRONT PARALLEL FLOW AHEAD OF THE FRONT AND STRONG
FORCING. THIS WILL LARGELY DEPEND ON WHERE STORMS FORM AND IF
THEY CONGEAL/RUN INTO EACH OTHER AND HOW MUCH MOISTURE ADVECTION
WE RECEIVE. THIS DOES APPEAR TO LARGELY BE DRIVEN BY TRAINING AS
THERMAL PROFILES IN THE BOUNDARY LAYER ARE RELATIVELY DRY. IF
STORMS CAN TRAIN, THEN EXPECT AT LEAST SOME POTENTIAL TO EXCEED
AN INCH OF RAIN. THERE IS A 40% CHANCE OF AT LEAST AN INCH OF
RAIN AHEAD OF THE COLD FRONT IN SOME SPOTS PENDING IDEAL
CONDITIONS FOR IT. FLASH FLOODING APPEARS UNLIKELY AS ANTECEDENT
CONDITIONS AND LOCATION SHOULD LIMIT WIDESPREAD IMPACTS.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 743 PM CDT SAT MAY 31 2025
THE MAIN AVIATION IMPACT CONTINUES TO BE SMOKE THROUGH SUNDAY.
HIGH CONFIDENCE IN MVFR TO IFR CONDITIONS FROM NEAR SURFACE
SMOKE REDUCING VISIBILITY UNDER 3SM AS WELL AS CEILINGS INTO
THIS RANGE WHERE SMOKE IS DENSEST.
THROUGH 03Z, THESE CONDITIONS WILL BE MAINLY CONFINED TO NORTH
DAKOTA LOCATIONS LIKE KDVL; HOWEVER, AS NIGHTTIME SURFACE
INVERSION BUILDS TONIGHT, THESE CONDITIONS ARE FORECAST TO
SPREAD EASTWARD INTO MINNESOTA. THERE IS A 30% CHANCE
VISIBILITIES WILL DROP BELOW 1SM, MAINLY BETWEEN 09Z-14Z. AS
DAYTIME MIXING RESTARTS SUNDAY AFTERNOON, SMOKE DENSITY NEAR THE
SURFACE SHOULD LESSEN, HELPING MOST LIKELY VISIBILITY
REDUCTIONS IN THE 3-6SM RANGE.
OTHERWISE, WINDS WILL BE LIGHT AND VARIABLE THROUGH 15Z, TURNING
SOUTHWESTERLY 10-15KT LATE SUNDAY MORNING INTO AFTERNOON.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...PERROUX
AVIATION...CJ
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