785
FXUS63 KFGF 212007
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
307 PM CDT MON APR 21 2025
KEY MESSAGES
- A PERIOD OF RAIN SHOWERS WILL MOVE THROUGH THE REGION LATE
TONIGHT THROUGH TUESDAY, ENDING BY MIDDAY IN THE CENTRAL AND
SOUTHERN RED RIVER VALLEY AND LINGERING NORTH OF HIGHWAY 2
THROUGH THE AFTERNOON.
- THERE ARE ADDITIONAL RAIN CHANCES THURSDAY MAINLY ALONG AND
SOUTH OF I-94 AND ACROSS THE REGION EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 307 PM CDT MON APR 21 2025
..SYNOPSIS
SHORTWAVE RIDGING IN PLACE ALOFT OVER OUR AREA BETWEEN THE STRONGER
MID/UPPER LOW OVER THE GREAT LAKES AND AN SHORTWAVE TROUGH BUILDING
UPSTREAM OUT OF MONTANA. THIS UPSTREAM TROUGH BRINGS OUR NEXT ROUND
OF RAIN TONIGHT INTO TUESDAY. THIS IS FOLLOWED BY A TRANSITION BACK
TO A SPLIT SOUTHWEST FLOW PATTERN THAT BRINGS ANOTHER WEAKER MID
LEVEL TROUGH THROUGH THE REGION WEDNESDAY NIGHT-THURSDAY, THEN
DEEPER SOUTHWEST FLOW AS A LARGER SCALE TROUGH DEVELOPS LATE NEXT
WEEKEND IN TO EARLY NEXT WEEK. THOSE FEATURES BRING OUR NEXT
RAINFALL CHANCES, THOUGH DETAILS ARE MORE UNCERTAIN. THE TENDENCY
WILL BE FOR TEMPERATURES TO REMAIN ABOVE AVERAGE (THOUGH NOT
UNSEASONABLE/ANOMALOUS IN NATURE).
..RAIN LATE TONIGHT-TUESDAY
THE INITIAL AXIS OF RAIN SHOWERS ARRIVES WITH AN AXIS OF WAA LOFT
AHEAD OF THE 700MB TROUGH LATE THIS EVENING IN OUR WEST, THEN
ROTATES THROUGH OUR CWA AS THE 700 MB LOW DEEPENS TUESDAY. INITIALLY
MID LEVEL LAPSE RATES MAY BE STEEP ENOUGH TO SUPPORT SOME CAPE IN
OUR FAR WEST-SOUTHWEST AND ISOLATED LIGHTNING ACTIVITY TONIGHT. RAIN
SHOULD END SOONER IN OUR SOUTH TUESDAY BASED ON HREF/NBM, BUT COULD
LINGER LONGER INTO THE AFTERNOON/EVENING NORTH OF HIGHWAY 2 WHERE A
STALL BAROCLINIC ZONE SETS UP AS THE TROUGH SHIFTS NORTH THEN EAST
THROUGH TUESDAY NIGHT. THE MAIN IMPACTS WILL BE WIDESPREAD LIGHT
RAIN (0.25" OR LESS), WITH A CHANCE FOR GREATER THAN 0.5" (40% BASED
ON HREF AND NBM PROBS). THE BEST CHANCE FOR THOSE HIGHER AMOUNTS
BASED ON ENSEMBLES IS TOWARDS THE DEVILS LAKE BASIN CLOSER TO WHERE
THE PIVOT OF THE 700 MB LOW IS SHOWN TO TRACK, THOUGH POCKETS OF
0.25-0.5" COULD STILL OCCUR JUST DO TO THE CONVECTIVE NATURE OF THE
RAINFALL.
..RAIN CHANCES MIDWEEK AND EARLY NEXT WEEK
A WEAKER/POSITIVELY TITLED 700MB TROUGH ROTATES THROUGH WEST-
SOUTHWEST FLOW WEDNESDAY NIGHT INTO THURSDAY, WITH THE BEST SIGNAL
FOR RAINFALL DEPENDS ON LOCATION OF A BAROCLINIC ZONE/THETA-E AXIS
AS PVA ROTATES THOUGH THE MEAN FLOW. CLUSTERS SHOW QUITE A BIT OF
SPREAD NOW AND MORE COMMON SCENARIOS SHIFTING THIS FARTHER SOUTH AND
LOWERING PROBABILITIES IN THE MAJORITY OF OUR CWA (PROBABILITY FOR
0.5" IS NOW ONLY 15% IN OUR FAR SOUTH).
THERE IS A MUCH BETTER SYNOPTIC SIGNAL FOR RAIN LATER IN THE
WEEKEND/EARLY NEXT WEEK AS A LARGER TROUGH BUILDS OVER THE WESTERN
US. THE GENERAL PATTERN IS SHOWING STRONG CONSISTENCY, HOWEVER
DETAILS REGARDING THE EVOLUTION OF MID/UPPER LOW AND TRACK WILL
DETERMINE POTENTIAL RAIN AMOUNTS, COMPLICATED BY THE STANDARD
CONVECTIVE NATURE OF THE LIKELY RAINFALLS. INSTABILITY ISN'T
CURRENTLY SHOWN TO BE HIGH ENOUGH TO RAISE IMMEDIATE CONCERNS
REGARDING SEVERE POTENTIAL (GEFS BASED MACHINE LEARNING PROBS ALSO
DO NOT SUPPORT THAT). HOWEVER, IT COULD BE ENOUGH TO SUPPORT LOCALLY
HEAVY RAINFALL AS THE EVENT UNFOLDS. THE PROBABILITY FOR GREATER THAN
0.5" OF RAINFALL AT THIS RANGE IS IN THE 20-40% RANGE FOR THAT
SYSTEM.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1248 PM CDT MON APR 21 2025
VFR CONDITIONS WITH SOUTHEAST WINDS 5-11KT CONTINUE THROUGH THIS
EVENING ACROSS EASTERN ND AND NORTHWEST MN. A PERIOD OF RAIN
SHOWERS MOVES WEST TO EAST ACROSS THE REGION AFTER 06Z TONIGHT
THROUGH TUESDAY MORNING, AND MVFR CEILINGS EVENTUALLY OVERSPREAD
OUR TAF SITES. MOST OF THIS RAIN SHOULD EXIT THE REGION AFTER
18Z TUESDAY AT TAF SITES (SOUTH TO NORTH). WINDS EVENTUALLY
INCREASE ABOVE 12KT FROM THE SOUTHWEST THEN WEST AS THIS LOW
PRESSURE SYSTEM MOVES THROUGH THE REGION TUESDAY.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DISCUSSION...DJR
AVIATION...DJR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page