541
FXUS63 KFGF 190453
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1153 PM CDT SAT MAY 18 2013
UPDATE
ISSUED AT 1153 PM CDT SAT MAY 18 2013
THOUGHTS REMAIN BASICALLY THE SAME AS BEFORE...BUT DID UPDATE POPS
BASED ON LATEST HRRR. HEAVY RAIN THREAT SEEMS TO BE THE MAIN
CONCERN...ESPECIALLY ACROSS SE ND. SPC HAS ISSUED A SEVERE
THUNDERSTORM WATCH FOR THIS AREA AS WELL...WITH INSTABILITY AROUND
MUCAPE 1000 J/KG AND FORCING TO INCREASE HERE.
UPDATE ISSUED AT 1006 PM CDT SAT MAY 18 2013
THUNDERSTORM COMPLEX APPROACHING FROM THE WEST IS SLOWING DOWN
(WAS MOVING AROUND 20 KNOTS AN HOUR AGO...NOW MOVING AROUND 10
KNOTS). THIS IS CAUSING VERY HEAVY RAINFALL...BUT ALSO MEANS THAT
THIS COMPLEX MAY NOT QUITE MAKE IT INTO THE FA. SOUTHERLY LOW
LEVEL FLOW IS INCREASING AS THE MEAN UPPER TROUGH SHIFTS
EAST...AND THIS IS LIKELY HALTING THE EASTWARD PROGRESS OF THIS
COMPLEX. 01Z HRRR STALLS THIS COMPLEX AND ACTUALLY DISSIPATES THE
ACTIVITY. THE MAIN FOCUS OVERNIGHT APPEARS THAT IT WILL COME FROM
THE SOUTH ALONG WITH INTENSE MOISTURE ADVECTION. SLIGHTLY ADJUSTED
POPS TO ACCOUNT FOR THE ABOVE THINKING. THE SEVERE THREAT STILL
APPEARS LIMITED FOR THIS FA. THE STORMS JUST WEST OF THE FA ARE
SEVERE...BUT THE SLOWING MOVEMENT WILL LIKELY WEAKEN THESE STORMS.
THE LOW LEVEL JET FOR LATER TONIGHT IS ONLY AROUND 25-30
KNOTS...AND ANY SEVERE THREAT GIVEN THE WEAKER INSTABILITY SHOULD
BE LIMITED.
THE MAIN CONCERN IS LIKELY FLASH FLOOD/HEAVY RAIN GIVEN THE SLOW
STORM MOVEMENT ALONG WITH PWATS APPROACHING 1.5 INCHES. WILL
MENTION LOCALIZED HEAVY RAIN IN THE GRIDS...BUT A FLASH FLOOD
WATCH IS NOT NEEDED IF THE ACTIVITY FROM THE WEST FALLS APART
BEFORE THE SOUTHERN ACTIVITY MOVES INTO THE REGION.
SHORT TERM
(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM CDT SAT MAY 18 2013
ALL EYES ON ANY CONVECTIVE DEVELOPMENT LATE THIS AFTN-EVE IN SE
ND-WCNTRL MN. SFC MAP SHOWS A BROAD SFC LOW IN THE MOBRIDGE SD
AREA WITH A BOUNDARY (COULD BE CALLED A WARM FRONT) FROM MOBRIDGE
TO OAKES THEN TO VALLEY CITY THEN TO HILLSBORO THEN EAST TO NORTH
OF DTL-PKD-BRD THEN INTO FAR NW WISCONSIN. IN FAR SE ND AND
ADJACENT PARTS OF WCNTRL CLOUDS CLEARED OUT ENOUGH TODAY FOR SFC
HEATING AND TEMPS IN THE 77 TO 81 DEGREE RANGE. SATELLITE SHOWS
WHAT APPEARS TO BE A CUMULUS CLOUD BOUNDARY FROM HILLSBORO TO
ALONG CLAY-NORMAN CO LINE TO NORTH OF PARK RAPIDS. SOUTH WINDS
SOUTH OF THIS FEATURE NR 10-13 KTS WHILE NORTH WINDS 5-8 KTS
NORTH OF THIS FEATURE. SPC SHOWS LITTLE CIN AND 1500 J/KG CAPE AND
SUFFICIENT BULK SHEAR. BUT UPPER LEVELS DONT SHOW ANY BIG THING TO
SET STUFF OFF. 17-18Z HRRR REFLECTIVITY DOES SHOW ONE CELL TRYING
TO GET GOING IN NORMAN CO. MN 22-23Z PD BUT THEN IT DISSIPATES
THIS EVE.
MUCH OF NORTHEAST SD HAS SEEN HIGH CLOUDS TODAY AND DEW PTS IN THE
50S AND SPC DOES HAVE SOME SFC BASED CIN IN THIS REGION. THUS MAY
BE HARD TO GET ANYTHING GOING THERE. BUT HRRR WANTS TO GENERATE
SOME ACTIVITY AXN-STC AREA BY 03Z.
ALSO SOME STORMS NR BLACK HILLS IN WRN SD. SOME WRF MODELS
INDICATE THIS AREA ORGANIZING MUCH LIKE LAST EVENING AND MOVING
EAST-NORTHEAST INTO SE ND-WCNTRL MN OVERNIGHT. SO VARIOUS
SCENERIOS TO PLAY OUT.
OVERALL WOULD EXPECT ORGANIZATION OF SOME ACTIVITY THIS EVE IN
ND/SD/MN BORDER REGIONS AND THEN SPREAD NORTH AND EAST TONIGHT SO
WILL STICK WITH HIGH POPS TONIGHT THOUGH CONFIDENCE AT ANY ONE
HOUR IS LOW. ALSO QPF AMOUNT IS NOT CERTAIN. PLUS ONLY AREA THAT
MUCH MORE THAN 1 INCH OF RAIN LAST NIGHT WAS EASTERN OTTER TAIL
COUNTY WITH 0.50 TO 1 INCH NRN WILKIN-SE CLAY INTO WADENA
COUNTIES. THIS AREA COULD TAKE THE RAIN. OTHERWISE...RAIN AMOUNTS
IN THE VALLEY WERE MOSTLY 0.50 OR LESS WITH A FEW EXCEPTIONS. WITH
UNCERTAINITY IN HOW THINGS WILL PLAY OUT TONIGHT DID NOT FEEL
CONFIDENT IN ISSUING ANY FLASH FLOOD WATCHES FOR OUR FCST AREA.
MODELS ACTUALLY BRING IN HIGHER PWAT (1.6) INTO AREA SUN AFTN-NIGH IN
GENERAL RAINFALL AROUND THE UPPER LOW IN SD AND THIS IS IN WHEN
MOST WIDESPREAD HEAVIER RAINFALL MAY OCCUR. THUS IF TRUE...GIVES
US TIME TO SEE WHAT FALLS THIS EVE BEFORE ISSUING ANY HEADLINES.
KEPT HIGH POPS SUNDAY INTO SUN NIGHT MOST ALL AREAS.
LONG TERM
(MONDAY THROUGH SATURDAY)
ISSUED AT 300 PM CDT SAT MAY 18 2013
UPR LOW AND SFC LOW WILL BE OVER SRN SD MONDAY INTO TUESDAY WITH
MOISTURE WRAPPING AROUND INTO ND/NW MN MON-TUES PERIOD WITH
GENERAL RAINFALL. KEPT POPS HIGH.
FOR TUESDAY NIGHT-FRIDAY...MODELS HAVE BEEN MOST CONSISTENT IN
BEGINNING TO MOVE THE STACKED NRN PLAINS LOW PRESSURE SYSTEM EWD
IN THE MID WEEK PERIOD. TUESDAY NIGHT INTO WEDNESDAY SHOWS THE
TAPPERING OFF OF VERY LIGHT RAIN WITH PERSISTENT NORTH-EASTERLY
BLAYER WINDS. INTRUDING DRY AIR FROM WRN ONT SHUD LEAD TO MARKEDLY
DIMINISHING CLOUD CLOVER WED EVENING. INCREASING HIGH PRESSURE
OVER WRN ONT AND THE LK SUPERIOR AREA ON THURS AND FRI SHUD SWING
WINDS FROM THE SOOUH EAST AND KEEP AN OVERALL DRYING AIRMASS OVR
THE RRV AND MOST OF MINNESOTA. A WARMIG RIDGE ALOFT AND INCREASED
LOW PRESSURE IN EASTERN MT DOES INCREASE THE RISK FOR SCT SHOWERS
AND TSTMS INTO EASTERN ND BY LATE FRIDAY AND ACROSS THE FA BY
SATURDAY.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1153 PM CDT SAT MAY 18 2013
LIFR AFFECTING KBJI SHOULD IMPROVE BY SUNRISE.
OTHERWISE...INCREASING CHANCES FOR SHOWERS AND
THUNDERSTORMS...ALONG WITH LOWERING CIGS WILL BE THE MAIN CONCERN.
HYDROLOGY
ISSUED AT 300 PM CDT SAT MAY 18 2013
WHEN NCRFC RAN THE MODEL TODAY USING 24 HOUR QPF IT BROUGHT SEVERAL
POINTS ABOVE FLOOD STAGE. THESE INCLUDE FARGO/SABIN/DILWORTH/HAWLEY
AND HENDRUM. SINCE THESE RISES ARE BASED ON FORECAST PCPN WENT AHEAD
AND ISSUED A RIVER POINT FLOOD WATCH FOR THESE 5 POINTS. THE FORECAST
QPF ALSO BROUGHT WAHPETON/EAST GRAND FORKS AND OSLO BACK ABOVE
ACTION STAGE SO ISSUED RIVER STATEMENTS ON THESE. ONLY DRAYTON AND
PEMBINA REMAIN IN A FLOOD STATEMENT.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
UPDATE...TG
SHORT TERM...RIDDLE
LONG TERM...RIDDLE/GUST
AVIATION...TG
HYDROLOGY...GODON
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