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000
FXUS63 KFGF 180441
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1141 PM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 1141 PM CDT FRI MAY 17 2013

LOWERED TEMPS A BIT IN THE NORTHWESTERN CWA WHERE READINGS HAVE
ALREADY FALLEN INTO THE MID 50S. THINK THAT TEMPS WILL LEVEL OFF
AROUND 50 AS CLOUDS CONTINUE TO INCREASE BUT TEMPS ALREADY AT
FORECAST LOWS. RADAR SHOWS THAT STORMS CONTINUE TO BE ON TRACK TO
ENTER THE SOUTHWESTERN CWA AFTER MIDNIGHT AND CONTINUE
NORTHEASTWARD. SEE LITTLE REASON TO MAKE MORE ADJUSTMENTS TO THE
TIMING OF POPS AT THIS POINT.

UPDATE ISSUED AT 927 PM CDT FRI MAY 17 2013

ADJUSTED POPS/WX BASED ON CURRENT RADAR TIMING. STORMS FIRING
ALONG THE 850MB WARM AIR ADVECTION IN CENTRAL MN WILL CLIP OUR
SOUTHEASTERN COUNTIES...SO INCLUDED A SCATTERED MENTION FOR THE
REST OF THE EVENING. STORMS FIRING OVER WESTERN ND AND SD WILL
MOVE NORTHEASTWARD INTO THE SOUTHERN RED RIVER VALLEY LATER
TONIGHT. IF CURRENT MOTION HOLDS...THE ACTIVITY SHOULD ARRIVE AT
OUR SOUTHERN BORDER AROUND MIDNIGHT AND MOVE NORTHEASTWARD
THROUGHOUT THE EARLY MORNING HOURS. TWEAKED TIMING OF POPS MOVING
INTO THE AREA WITH LIKELY WORDING TRANSITIONING FROM THE SOUTH
JUST AFTER MIDNIGHT TO THE NORTH BY TOMORROW MORNING. ELEVATED CAP
VALUES ARE AROUND 1000 J/KG ACCORDING TO THE SPC MESOANALYSIS.
THINK THAT THE BEST LLJ WILL STAY TO OUR SOUTH BUT SOME ISOLATED
SEVERE HAIL OR WIND IS NOT OUT OF THE QUESTION AROUND THE 06-12Z
TIME FRAME. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IN
THE GRIDS AT THIS POINT SO WILL JUST KEEP GENERAL THUNDER GOING.

UPDATE ISSUED AT 652 PM CDT FRI MAY 17 2013

ADJUSTED POPS ALONG THE CANADIAN BORDER FOR THE NEXT FEW HOURS TO
ACCOUNT FOR THE WEAK SHOWERS/SPRINKLES DEVELOPING IN THAT AREA.
HOWEVER...THE MAIN PRECIP IS WELL TO OUR SOUTH...SO KEPT THE HIGH
POPS RESERVED FOR AFTER MIDNIGHT AS THE GOING FORECAST HAS.
TWEAKED CLOUDS TO INCLUDE CLEARING IN OUR SOUTHWESTERN COUNTIES
BUT THAT WILL NOT LAST LONG AS BLOW OFF FROM CONVECTION FROM OUR
SOUTHWEST BEGINS TO MOVE IN. SHOULD BE TOTALLY CLOUDY AFTER
MIDNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013

THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.

WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.

THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.

THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013

SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.

MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1141 PM CDT FRI MAY 17 2013

CEILINGS HAVE GONE DOWN TO MVFR AT KFAR AND THE LOWER CONDITIONS
WILL CONTINUE TO SPREAD NORTHWARD THROUGH MUCH OF THE NIGHT.
WEAKENING STORMS WILL ENTER THE FORECAST AREA AFTER
MIDNIGHT...MOVING INTO KFAR AREA AROUND 07-08Z WITH SOME THUNDER
REMAINING AND CONTINUING NORTH AS MOSTLY SHOWERS LATER ON THIS
MORNING. THINK THERE SHOULD BE SOME IMPROVEMENT TO VFR CONDITIONS
ACROSS MOST AREAS DURING THE AFTERNOON ALTHOUGH WILL HAVE TO WATCH
THE NORTHERN SITES WHICH MAY BE ON THE NORTH SIDE OF A WARM FRONT
AND STAY SOCKED IN. KFAR HAS THE BEST CHANCE OF SEEING SOME
CONVECTIVE REDEVELOPENT TOWARDS THE END OF THE PERIOD.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...JR
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...JR