Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 280003
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
703 PM CDT WED MAY 27 2015

.UPDATE...
ISSUED AT 658 PM CDT WED MAY 27 2015

THERE ARE A FEW SHOWERS AND STORMS MOVING IN FROM THE WEST WITH
ABOUT 1000 J/KG OF MUCAPE BUT NO SHEAR TO SPEAK OF. THESE INITIAL
STORMS SHOULD DIE AS THEY DRIFT EAST THIS EVENING. A MORE
ORGANIZED AREA OF SHOWERS AND A FEW STORMS SHOULD MOVE IN FROM THE
WEST OVERNIGHT WITH ABOUT A 40KT LLJ AND STRONG MOISTURE
TRANSPORT. PWATS WILL RISE OVER 1.25 INCHES LATER TONIGHT INTO THU
MORNING. DID SLOW THINGS DOWN A BIT AFTER 06Z-12Z...BUT DID NOT
TOUCH POPS THU.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 255 PM CDT WED MAY 27 2015

FORECAST CHALLENGE FOR THE SHORT TERM CONTINUES TO BE AFTERNOON
CONVECTION POTENTIAL (LOW) AND THE EVOLUTION OF SYSTEM EXPECTED TO
IMPACT REGION BY TOMORROW MORNING AND THROUGHOUT THE DAY ON
THURSDAY. MODELS CONTINUE TO VARY ON EXACT PLACEMENT OF
PRECIP...AND PRIMARILY USED SUPERBLEND AND NAM TO ADD SOME DETAIL.
FOR THE IMMEDIATE SHORT TERM...USING HI RES MODELS FOR GUIDANCE ON
LATE AFTN SHOWERS/TSTMS POTENTIAL.

THIS EVENING...SPC MESOSCALE ANALYSIS SHOWING MU CAPE BLAND ALONG
NORTHERN TIER OF COUNTIES SOUTH OF INTL BORDER AND NORTH OF HWY 2
CORRIDOR...AS FAR EASTWARD AS HALLOCK MN. ML CAPES NOT QUITE AS
IMPRESSIVE AND SFC BASED CIN IS STILL 100 TO 250 IN THAT AREA.
OVERALL SPOTTY CONVECTION DEPICTED BY HRRR IS REASONABLE AND WILL
USE HRRR AS GUIDANCE...WHICH BASICALLY SHOWS HIGHEST CHANCES
THROUGH THE DEVILS LAKE REGION ONTO THE CENTRAL VALLEY. CIN VALUES
DECLINED RIGHT AT 21Z YESTERDAY AND EXPECT SIMILAR SITUATION THIS
AFTN.

TONIGHT...FOCUS THEN TURNS TO EVOLVING SYSTEM EXPECTED TO IMPACT
AREA LATE TONIGHT THROUGH EARLY FRIDAY MORNING. MODELS ARE SLOWER
TODAY AND HAVE DELAYED PRECIP ENTERING WESTERN CWA UNTIL AFT 06Z.
SHOULD SEE SOME SHOWERS AND STORMS DEVELOP OVER CNTRL DAKOTAS AND
MOVE INTO EASTERN ND BY MORNING.

THURSDAY...MAIN CHANGES TO ONGOING FCST WILL BE TO GO MORE TSTMS
RATHER THAN SHOWERS WITH ISOLD TSTMS. THIS IS DUE TO SHOWALTERS
BEING MORE NEGATIVE THAN YESTERDAYS 12Z RUNS...ON BOTH THE GFS AND
NAM. GFS HAS MORE IMPRESSIVE 0 TO 6 KM BULK SHEAR VALUES...AROUND
50 KTS WITHIN THE VALLEY AT 00Z FRIDAY. SPC HAS SHIFTED WESTWARD
THEIR MARGINAL RISK...INTO THE HIGHER GFS SHEAR VALUES. THE NAM
BULK SHEAR VALUES CONTINUE TO BE WEAK...DECREASING CONFIDENCE FOR
ANY SIGNIFICANT SEVERE ACTIVITY TOMORROW ALTHOUGH A HAILER OR TWO
IS CERTAINLY POSSIBLE. OVERALL SFC LOW TRACK IS A BIT FURTHER
NORTH AND BETTER SFC HEATING TO MAJORITY OF THE AREA. MODELS BRING
MOST ENHANCED PRECIP ACTIVITY INTO EASTERN ND IN THE 18Z TO 21Z
TIMEFRAME...SHIFTING TO THE MN SIDE OF THE CWA IN THE LATE
AFTERNOON INTO THE EVENING. SHOWALTERS BEGIN TO RISE AFT 06Z
FRIDAY TRANSITION BACK TO SHOWERS FROM NORTH TO SOUTH BY FRI
MORNING. COLD FRONT DROPS INTO NORTHERN CWA BY 12Z FRI...BRINGING
MUCH COOLER AIR INTO THE NORTHWEST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 255 PM CDT WED MAY 27 2015

FRIDAY AND SATURDAY...A VERY COOL AIRMASS ASSOCIATED WITH CANADIAN
HIGH PRESSURE SINKS INTO THE NORTHERN VALLEY. THIS WILL BRING
DAYTIME HIGHS IN THE 50S ACROSS MOST OF THE REGION...WITH SATURDAY
MORNING TEMPS AROUND THE FREEZING MARK IN THE FAR NORTH. WITH SFC
LOW OVER SRN CANADA...SPOTTY FROST IS POSSIBLE IN COUNTIES
ADJACENT TO THE INTL BORDER.

SATURDAY NIGHT THROUGH WEDNESDAY...MID LEVEL ZONAL FLOW WILL
GRADUALLY TRANSITION TO SW FLOW PATTERN SETTING UP POTENTIALLY
ACTIVE...MORE SUMMER TYPE CONVECTIVE PERIOD NEXT WEEK. WEAK
SHORTWAVE WILL TRACK ACROSS S CANADIAN PROVINCES SUNDAY. THIS AND
WARM ADVECTION COULD HELP SET OFF MAINLY SHRA ACROSS THE REGION.
PERSISTENT SOUTHERLY FLOW WILL ADVECT WARMER/MORE UNSTABLE AIR
INTO THE REGION NEXT WEEK. WITH CONTINUED WARM ADVECTION EARLY
NEXT WEEK SPOTTY CONVECTION REMAINS POSSIBLE WITH BEST CHANCES
TOWARDS MID WEEK AS SHORTWAVE AND ASSOCIATED SURFACE BOUNDARY
APPROACHES THE REGION. AS UPPER FLOW TRANSITIONS TO THE SW ABOVE
BOUNDARY WILL PROPAGATE RELATIVELY SLOWLY SETTING UP POTENTIALLY
EXTENDED ACTIVE PERIOD. CAPPING MAY LIMIT BEST CONVECTIVE
POTENTIAL ACROSS THE NORTH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 658 PM CDT WED MAY 27 2015

THE MAIN THREAT WILL BE ANY SHOWERS AND STORMS THROUGH THE PERIOD.
THE BEST CHANCE FOR STORMS SHOULD OCCUR THU AFTERNOON ALONG A COLD
FRONT. SOUTHERLY WINDS WILL INCREASE LATE TONIGHT AND THU...AND
COULD GUST TO 30KT AT TIMES. HAVE NOT GONE THIS HIGH IN THE TAFS
YET...BUT SOMETHING TO WATCH IN LATER FORECASTS. CONDITIONS COULD
FALL INTO THE MVFR CATEGORY NEAR STRONGER SHOWERS LATER TONIGHT
INTO THU...BUT HAVE KEPT THINGS IN VFR RANGE.

&&

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

$$

UPDATE...DK
SHORT TERM...SPEICHER
LONG TERM...SPEICHER/VOELKER
AVIATION...DK



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