Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 271750
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1250 PM CDT WED MAY 27 2015

.UPDATE...
ISSUED AT 1250 PM CDT WED MAY 27 2015

FORECAST CHALLENGE FOR TODAY AND THIS EVENING CONTNIUES TO BE
POTENTIAL FOR CONVECTION. SLIGHTLY DRIER DEWPOINTS DUE TO
NORTHERLY WINDS ARE KEEPING CAPES LOWER THAN AT THIS TIME
YESTERDAY AND CIN IS A BIT STRONGER...BUT TRENDS FROM YESTERDAY
WOULD ERODE ANY CIN AROUND 21Z. HI RES MODELS STILL SHOWING SOME
ACTIVITY VERY SCT IN NATURE AND WILL CONTINUE WITH THAT THINKING
THROUGH 06Z...WHEN ATTENTION TURNS TO INCOMING SYSTEM ASSOCIATED
WITH UPPER WAVE AND TRANSITION TO MORE SW FLOW ALOFT. ONLY CHANGES
TO THURSDAY AT THIS POINT (HAVE NOT YET RECEIVED 12Z ECMWF) 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. THEN NAME CONTINUES TO BE WEAK...DECREASING
CONFIDENCE FOR ANY SIGNIFICANT SEVERE ACTIVITY TOMORROW ALTHOUGH A
HAILER OR TWO IS CERTAINLY POSSIBLE. MORE DISCUSSION ON TOMORROW
WITH 21Z FCST ISSUANCE.

UPDATE ISSUED AT 941 AM CDT WED MAY 27 2015

MORNING UPDATE FOCUSES ON SLOWING DOWN SHOWERS AND STORMS EXPECTED
TO MOVE ACROSS NORTH DAKOTA TONIGHT. LATEST RUC AND HRRR SHOW A
DIURNALLY RELATED BAND OF SHOWERS/STORMS IN THE LATE AFTN. DO HAVE
SOME LOW POPS IN WESTERN ZONES FOR THIS ACTIVITY...BUT WILL NOT
ADJUST TOO MUCH UNTIL NEWER RUNS COME IN. 06Z RUNS WERE SLOWER
THAN FCST GRIDS ON MAIN PRECIP ENTERING WESTERN ZONES...AND HRRR
IS SUPPORTING A LATER START TIME (NEARER 06Z). HAVE CUT BACK ON
EVENING POPS PER LATEST GUIDANCE

UPDATE ISSUED AT 659 AM CDT WED MAY 27 2015

NORTH WIND AROUND 10 KTS INTO NE ND/NW MN BRINGING IN SOME DRIER,
MORE STABLE AIRMASS. SOME MID LEVEL MOISTURE....AND DO EXPECT SOME
MID CLOUD PATCHES TODAY. LATE AFTERNOON...HRRR/RAP ARE INDICATING
SOME ISOLD CONVECTION A BIT FARTHER EAST THAN PREV RUNS DID AS FAR
EAST AS FARGO-FERGUS FALLS. THUS DID ADD ISOLD THUNDER FOR A FEW
HOURS LATE AFTN INTO SE ND/W CNTRL MN. THIS MATCHES WELL WITH
ABR/MPX.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 315 AM CDT WED MAY 27 2015

SFC TROUGH PASSED THROUGH LAST EVENING. A BIT MORE STABLE AND
DRIER AIRMASS OVER THE AREA TODAY...BUT LATER THIS AFTN SOME
INSTABILITY RETURNS TO FAR WRN FCST AREA. HRRR/RAP DO HAVE A
COUPLE OF SMALL CELLS IN THAT DVL-VCY AREA SO KEPT OUR LOW POP WE
HAD.

MAIN SHORT WAVE WILL MOVE NORTHEAST FROM WYOMING AND INTO WRN/CNTRL
ND TONIGHT INTO THE RRV 12Z-18Z PERIOD. 30 KT 850 MB JET AND AN
AREA OF ELEVATED INSTABILITY PRESENT WILL BE SUFFICIENT TO KEEP
AN AREA OF SHOWERS AND THUNDERSTORMS IN TACT AS IT MOVES TOWARD
AND INTO THE AREA OVERNIGHT INTO THURSDAY. SPC HAS MARGINAL RISK
OF SEVERE WX THURSDAY. MODELS IN FAIR AGREEMENT WITH MAIN SHORT
WAVE CENTER AND SFC LOW MOVING TO NEAR GFK MIDDAY WITH A COLD
FRONT SOUTHWEST. OUT AHEAD OF THIS COLD FRONT AND SOUTH OF THE LOW
MU CAPES IN THE 1000-1500 J/KG RANGE AND NEGATIVE SHOWALTERSWOULD
SUPPORT THUNDERSTORMS. BUT BULK SHEAR IS WEAK IN THE AFTN WITH THE
COLD FRONT. THUS SEVERE THREAT PRETTY LIMITED.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 AM CDT WED MAY 27 2015

PRECIP CHANCES WILL THU NIGHT AS HIGH PRESSURE AND NORTH WINDS AND
A COOLER AIRMASS MOVE IN FROM THE NORTH. FRIDAY WILL BE BREEZY AND
COOL. HIGH PRESSURE WILL MOVE INTO SW MANITOBA FRI NIGHT AND
CENTER OF RIDGE AND LIGHT WINDS OVER NORTH CENTRAL ND MEANS A GOOD
CHANCE FOR FROST IN THIS AREA.

FOR SATURDAY THROUGH TUESDAY...WILL START OFF WITH NEARLY ZONAL FLOW
ALOFT AND HIGH PRESSURE AT THE SFC. FOR THIS REASON THE FORECAST
WILL START OFF DRY FOR SAT/SAT NIGHT. ALL MODEL SOLUTIONS SHOW A
WAVE PASSING THRU ON SUNDAY...THE GFS A LITTLE FASTER THAN THE OTHER
MODELS...AND BRINGING SOME PCPN TO MOST OF THE AREA. MORE SPOTTY
PCPN FOR SUN NIGHT/MONDAY AS SFC LOW SETS UP OVER THE WESTERN HIGH
PLAINS WITH WARM FRONT EXTENDING OUT TO THE EAST. FLOW SHIFTS TO THE
SOUTHWEST MON NIGHT/TUE WITH MODELS DIVERGING QUITE A BIT IN PCPN
PLACEMENT. HPC GUIDANCE HANDLES THIS BY BROADBRUSHING PCPN CHANCES
EVERYWHERE DURING THIS PERIOD AND WILL KEEP AS IS FOR NOW. TEMPS
START OFF ON THE COOL SIDE FOR SAT/SUN THEN MORE NORMAL BY
MON/TUE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1250 PM CDT WED MAY 27 2015

VFR CONDITIONS EXPECTED THROUGH THE PERIOD. WILL BE MONITORING WDLY
SCT/ISOLD CONVECTION LATE THIS AFTERNOON INTO THE EVENING. BASED ON
HIGH RESOLUTION MODELS THE DEVILS LAKE BASIN HAS THE BEST POTENTIAL
FOLLOWED BY A LESSER EXTENT AT FARGO. WITH SPOTTY NATURE EXPECTED
CONFINED MENTION TO VCSH IN DVL LATE THIS AFTERNOON.

&&

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

$$

UPDATE...SPEICHER
SHORT TERM...RIDDLE
LONG TERM...GODON/RIDDLE
AVIATION...VOELKER


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