460
FXUS63 KFGF 131850
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
150 PM CDT SAT SEP 13 2025
KEY MESSAGES
- THERE IS A LEVEL 1 OUT OF 5 RISK FOR SEVERE THUNDERSTORMS
SUNDAY INTO MONDAY. THE MAIN HAZARDS WILL BE HAIL TO THE SIZE
OF QUARTERS AND GUSTY WINDS TO 70 MPH. TORNADOES ARE POSSIBLE
AS WELL.
- WELL ABOVE AVERAGE TEMPERATURES CONTINUE INTO NEXT WEEK.
ACTIVE PATTERN CONTINUES THROUGH EARLY NEXT WEEK, INCLUDING
PERIODIC CHANCES FOR STRONG TO SEVERE THUNDERSTORMS.
DISCUSSION
ISSUED AT 124 PM CDT SAT SEP 13 2025
..SYNOPSIS
SURFACE ANALYSIS THIS AFTERNOON SHOWS A WEAK SURFACE LOW OVER
EASTERN SOUTH DAKOTA THAT HASN'T MOVED PARTICULARLY MUCH OVER
THE LAST 6 HOURS. PROPAGATION LOOKS TO REMAIN VERY SLOW WITH NOT
MUCH FORWARD MOTION, SO FORCING FOR ASCENT SHOULD REMAIN TO THE
WEST OF THE RED RIVER VALLEY MAINLY THROUGH TOMORROW MORNING.
SHOWERS AND A FEW THUNDERSTORMS WILL LINGER ACROSS SOUTHEAST
NORTH DAKOTA AND AREAS WEST OF THE RED RIVER VALLEY THROUGH THE
REMAINDER OF THE DAY TODAY.
FORWARD PROPAGATION OF THE SURFACE LOW SHOULD INCREASE TOMORROW
AFTERNOON AS THE MAIN UPPER LOW UNDERGOES LEE CYCLOGENESIS AND
PROGRESSES NORTHWARD TOWARDS OUR AREA. AN ATTENDENT LOW AND MID-
LEVEL JET SHOULD PROVIDE SOLID MOISTURE ADVECTION AND SHEAR FOR
ORGANIZED SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON THROUGH
MONDAY MORNING, ALTHOUGH THE SPATIAL EXTENT OF THUNDERSTORMS IS
OF LOW CONFIDENCE.
AS THE LOW PROGRESSES AWAY FROM OUR REGION, MOISTURE ADVECTION
IS CUT OFF BUT FORCING FOR ASCENT SHOULD CONTINUE TO LINGER
THROUGH THE WEEK. PREDICTABILITY FOR SEVERE CONVECTION IS LOW,
BUT PERIODIC SHOWERS AND THUNDERSTORMS CAN CONTINUE TO BE
EXPECTED THROUGH THE WORK WEEK. THE STRONGEST SIGNALS FOR
PRECIPITATION ARE WEDNESDAY AND FRIDAY.
..SEVERE STORM POTENTIAL TOMORROW
A MOSTLY STATIONARY UPPER LOW SHOULD BEGIN TO EJECT OFF THE
ROCKY MOUNTAINS TOMORROW, FORCING CYCLOGENESIS AND AN
INTENSIFYING PRESSURE GRADIENT AT THE BASE OF THE LOW. AS THIS
OCCURS, FORWARD PROPAGATION FOR THE LOW WILL INCREASE AND PUSH
THE SURFACE LOW OVER SOUTH DAKOTA INTO OUR AREA BY EARLY
TOMORROW AFTERNOON. SURFACE THETA-E ADVECTION FROM THE SOUTHEAST
SHOULD PROVIDE FOR SOLID DESTABILIZATION NEAR THE SURFACE. THE
MAIN QUESTION RIGHT NOW IS IF ENOUGH DESTABILIZATION OCCURS FROM
BOTH ADVECTIVE AND DIURNAL HEATING. WEAK WARM AIR ADVECTION WILL
BE ONGOING ACROSS MUCH OF THE REGION IN ADVANCE OF THE LOW, SO
SKY CLEARING MAY BE DIFFICULT TO COME BY. ADVECTIVE PROCESSES
MAY BE ENOUGH TO INDUCE SURFACE-BASED THUNDERSTORM DEVELOPMENT
AS THE LOW PROGRESSES THROUGH THE AREA.
IF THUNDERSTORMS DO FORM, THE MAIN HAZARDS SHOULD BE SEVERE HAIL
AND DAMAGING WIND GUSTS. VERY LARGE HAIL PRODUCTION IS UNLIKELY
AS THE ORIENTATION OF THE UPPER LOW KEEPS THE ELEVATED MIXED
LAYER AWAY FROM OUR AREA, SO WE END UP WITH MUCH SKINNIER CAPE
PROFILES. CLUSTERING OF STORMS APPEARS TO BE THE LESS LIKELY
SOLUTION AS FORCING REMAINS MOSTLY TO THE WEST AND SHEAR VECTORS
ARE MOSTLY PERPENDICULAR TO THE BOUNDARY. IF STORMS REMAIN
ISOLATED, SUPERCELLS CAN BE A POSSIBILITY AS EFFECTIVE LAYER
SHEAR APPROACH 30 KNOTS WITH WEAK VEERING IN THE LOWEST 3 KM.
DIRECTIONAL SHEAR COULD FACILITATE A TORNADO THREAT,
PARTICULARLY WHERE THE LOW-LEVEL JET ALIGNS WITH STORMS, WHICH
SHOULD HAVE THE MOST INTENSE VEERING. THIS WILL DEPEND ON TRACK
OF THE LOW AND IF STORMS CAN REMAIN ISOLATED, BUT IT IS AN
IMPACTFUL ENOUGH THREAT TO BEGIN MESSAGING.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1235 PM CDT SAT SEP 13 2025
CEILINGS SHOULD CONTINUE TO SLOWLY LIFT INTO VFR BY LATE THIS
AFTERNOON FOR ALL TAF SITES. LIGHT RAIN WILL BE POSSIBLE AT BOTH
DVL AND FAR THROUGH THE AFTERNOON ALTHOUGH CONFIDENCE IS LOW IN
WHERE AND WHEN THIS OCCURS. WINDS WILL REMAIN MOSTLY FROM THE
SAME DIRECTION THROUGH THE ENTIRE TAF PERIOD. AS WE PROGRESS
INTO THE OVERNIGHT HOURS, CEILINGS WILL FALL ONCE AGAIN,
PARTICULARLY IN NORTHWEST MINNESOTA. MVFR TO IFR CEILINGS CAN BE
ANTICIPATED FOR MOST TAF SITES WITH ISOLATED VFR BY 08Z.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...PERROUX
AVIATION...PERROUX
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