Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 061759
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1259 PM CDT WED MAY 6 2015

.UPDATE...
ISSUED AT 1256 PM CDT WED MAY 6 2015

FIRST BATCH OF LIGHT RAIN SHOWERS NOW ALONG THE MANITOBA/NORTH
DAKOTA. NEXT BATCH SE ND INTO NE ND. DRY SLOT BRIEFLY SOUTH AND
SOUTHEAST OF THIS BATCH OVER SW MN INTO NCNTRL IOWA WHERE SOME
CLEARING OCCURRING. SEEING A FEW STORMS FIRING IN THIS HEATED AERA
EAST OF SIOUX FALLS. ALSO FEW SHOWERS AND MAYBE STORMS SOUTH OF
BISMARCK INTO CNTRL SD. IDEA IS FOR THE BATCH OF SHOWERS IN SE ND
WILL MOVE NORTH. A DRY SLOT OR BREAK MAY IMPACT SE ND/WCNTRL MN
FOR A TIME AFTER THIS MID AFTN AND THEN ENOUGH INSTABILITY ARRIVES
TONIGHT FOR ISOLD T AND A FEW SHOWERS TONIGHT. INSTABILITY IS
MOSTLY CONFINED TO CNTRL MN HOWEVER. OVERALL TREND IN GRIDS IS TO
KEEP A HIGH POP DUE TO FAST MOVEMENT OF THESE BANDS.


&&

.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 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1256 PM CDT WED MAY 6 2015

LARGE COLORADO LOW TYPE SYSTEM NOW ENVELOPING THE NORTHERN PLAINS
WITH WIDESPREAD MVFR SIGS AND VSBYS IN LIGHT RAIN... WITH SUCCESSIVE
WAVES OF HEAVIER RAIN AND ASSOCIATED IFR CIGS AND VSBYS. WIDESPREAD
DEEP CONVECTION WITH TSTMS IS NOT ANTICAPATED EXPECTED..THO AN
ISOLATED TSTM IS POSSIBLE ALONG THE BAND EXPECTED LIFT THROUGH THE
SOUTHERN RRV LATER THIS AFTERNOON AND EARLY EVENING. MODERATE
SOUTHEASTERLY BLAYER FLOW WILL PERSIST THROUGH TODAY...BECOMING
LIGHT AND VARIABLE EARLY THURSDAY MORNING...TURNING NORTHWESTERLY
THURSDAY AFTERNOON.

&&

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

$$

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





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