Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 061155
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
655 AM CDT WED MAY 6 2015

.UPDATE...
ISSUED AT 654 AM CDT WED MAY 6 2015

FIRST ROUND OF SHOWERS HAS NEARLY REACHED THE HIGHWAY 2 CORRIDOR
AND WILL CONTINUE TO PUSH NORTH. THE SOUTHERN COUNTIES WILL SEE A
BREAK FOR THE NEXT HOUR OR SO BEFORE MORE SHOWERS PUSH UP FROM
SOUTH DAKOTA. ADJUSTED POPS TO TRY AND REFLECT THIS. THINK THE
WIDESPREAD RAIN WILL HOLD OFF UNTIL THIS AFTERNOON AS THE UPPER
LOW GETS CLOSER. KEPT HIGHEST POPS OUT UNTIL AFTER 18Z.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 401 AM CDT WED MAY 6 2015

TIMING AND AMOUNTS OF PRECIPITATION MOVING INTO THE AREA WILL BE
THE PRIMARY FORECAST CHALLENGE FOR THE PERIOD.

THE MAIN UPPER TROUGH IS STILL DOWN OVER COLORADO AND WESTERN
KANSAS...BUT SOME SCATTERED SHOWERS AND THUNDERSTORMS HAVE ALREADY
MOVED INTO THE SOUTHERN COUNTIES WITH SOME 850MB WARM AIR
ADVECTION. THIS WAA SHOULD CONTINUE TO PUSH NORTHWARD THROUGH THE
MORNING HOURS. THE RAP HAS DONE A DECENT JOB OF CAPTURING THE
LEADING BAND...AND IT HAS A BREAK IN THE PRECIPITATION BEHIND THE
WAA BAND WHICH SEEMS TO FIT RADAR OVER SOUTH DAKOTA AT THE CURRENT
TIME. THINK THAT THE REALLY WIDESPREAD PRECIP WILL HOLD OFF UNTIL
THIS AFTERNOON AS THE MAIN UPPER SYSTEM BEGINS TO LIFT
NORTHEASTWARD INTO NEB/SD AND WE GET MORE WIDESPREAD UPPER
FORCING. CONTINUED THE TREND OF HOLDING OFF ON THE CATEGORICAL
POPS UNTIL THIS AFTERNOON. THERE IS A LITTLE BIT OF ELEVATED CAPE
A FEW LIGHTNING STRIKES OBSERVED...SO WILL KEEP SHOWERS AND
ISOLATED THUNDER MENTION FOR THIS MORNING AND THEN MATCH THUNDER
TO SHOWERS THIS AFTERNOON AS WE GET SOME SFC BASED CAPE MOVING
INTO THE REGION. CLOUDS AND PRECIP WILL KEEP TEMPS FROM RISING A
HUGE AMOUNT TODAY...BUT GIVEN THAT WE ARE STILL IN THE 50S AND
EVEN 60S THE WARM START WILL HELP US REACH THE 70S AGAIN.

TONIGHT...THE MAIN UPPER TROUGH WILL LIFT INTO THE CWA...WEAKENING
AS IT MOVES THROUGH. EVEN WITH THE WEAKENING UPPER SYSTEM THERE
SHOULD STILL BE A DECENT AMOUNT OF SYNOPTIC SCALE LIFT AND
CONTINUED WITH HIGH POPS THROUGHOUT THE OVERNIGHT HOURS. THE UPPER
SHORTWAVE WILL MOVE NORTHEAST INTO CANADA BY THURSDAY AND PHASE
WITH THE NORTHERN BRANCH SHORTWAVE. THAT SHOULD HELP PUSH A COLD
FRONT INTO THE CWA FOR THURSDAY...AND THERE SHOULD BE CONTINUED
PRECIP WITH THE FRONT. THE NAM BRINGS A VIGOROUS SHORTWAVE BEHIND
THE MAIN SHORTWAVE WHICH SETS OFF A LOT OF QPF ALONG THE
FRONT...BUT IS THE ODD MODEL OUT. WILL CONTINUE TO KEEP HIGH POPS
TRANSITIONING OVER TO THE EASTERN CWA AS PRECIP SHOULD TAPER OFF
BEHIND THE COLD FRONT. TEMPS MAY ACTUALLY DROP IN THE NORTHWESTERN
CWA AS THE FRONT COMES DOWN.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 401 AM CDT WED MAY 6 2015

THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE MODELS BRING THROUGH
ANOTHER WEAK SHORTWAVE TROUGH SO CONTINUED TO LINGER SHOWERS AT
LEAST OVER THE EASTERN CWA. TEMPS WILL BE MUCH COOLER AS THERE
SEEMS TO BE GOOD AGREEMENT WITH 850MB TEMPS BELOW ZERO COMING
DOWN...ALTHOUGH FORTUNATELY AFTER THE PRECIP ENDS EARLY FRIDAY
MORNING. MOST OF FRIDAY AND FRIDAY NIGHT SHOULD BE DRY BUT COOL AS
SFC HIGH PRESSURE EXTENDS FROM SOUTHERN CANADA INTO THE NORTHERN
TIER OF THE USA. TEMPS ON FRIDAY WILL BE MARKEDLY COOLER THAN THE
PAST WEEK AND HIGHS SHOULD ONLY TOP OUT IN THE 50S AND COULD DROP
BELOW FREEZING FOR FRIDAY NIGHT.

SATURDAY THROUGH TUESDAY...SPLIT FLOW WAS ACROSS NORTH AMERICA WITH
NORTHERN STREAM OVER SOUTHERN CANADA AND SOUTHERN STREAM OVER THE
CENTRAL AND SOUTHERN PLAINS. LONG WAVE TROUGH/RIDGE OVER THE GULF
OF AK/WESTERN CANADA WILL SHIFT EAST TO THE WEST COAST/CENTRAL
PLAINS RESPECTIVELY BY THE END OF THE PERIOD. BOTH THE GFS AND
ECMWF WERE IN GOOD AGREEMENT WITH LOW MOVING INTO THE NORTHERN
PLAINS ON MON, BUT SURFACE FEATURES WERE FARTHER NORTH AND SLOWER
ON THE ECMWF. WITH THE NORTHERN STREAM, THE PATTERN BECAME 180
DEGREES OUT OF PHASE FOR MON AND TUE. THE GFS HAS BEEN TRENDING
FASTER WHILE THE GFS HAS BEEN TRENDING SLOWER OVER THE LAST COUPLE
RUNS. WILL BLEND THE ECMWF AND GFS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 654 AM CDT WED MAY 6 2015

MVFR AND EVEN SOME IFR CIGS HAVE ENTERED THE CWA AS MOISTURE FLOWS
UP FROM THE SOUTHEAST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS
ARE APPROACHING KGFK AND KDVL...BUT COVERAGE IS HIT OR MISS SO
WILL JUST INCLUDE VCSH FOR NOW. MORE WIDESPREAD RAIN WILL MOVE IN
THIS AFTERNOON...SO WHEN PREVAILING LIGHT RAIN FOR THE AFTERNOON
AND EVENING HOURS. MODELS PERSIST IN LIFTING CIGS A BIT THIS
AFTERNOON SO KEPT PREVIOUS SHIFTS IDEA OF 3500 FT CLOUDS. THINK
THAT RAIN WILL BECOME MORE SPOTTY TOWARDS THE END OF THE
PERIOD...SO TRANSITIONED BACK TO VCSH. CIGS SHOULD BE BACK DOWN TO
MVFR AS WE MOVE TOWARDS THURSDAY MORNING. WINDS WILL REMAIN FROM
THE SOUTHEAST WITH SOME GUSTS ABOVE 20 KTS POSSIBLE AT TIMES THIS
AFTERNOON. WINDS SHOULD GO DOWN TONIGHT AS THE SFC TROUGH
APPROACHES.

&&

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

$$

UPDATE...JR
SHORT TERM...JR
LONG TERM...JR/HOPPES
AVIATION...JR





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