Area Forecast Discussion
Issued by NWS Grand Forks, ND

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062
FXUS63 KFGF 160452
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1152 PM CDT FRI MAY 15 2015

.UPDATE...
ISSUED AT 1152 PM CDT FRI MAY 15 2015

CONTINUED TO SLOW DOWN POP PROGRESSION INTO THE SOUTHWESTERN
CWA...AS THE BULK OF THE ACTIVITY STAYS TO OUR SOUTH AND WEST. THE
HRRR HAS SOME DECENT DEVELOPMENT OVER THE SOUTHERN COUNTIES IN THE
NEXT HOUR OR SO...WHILE THE RAP AND NAM KEEP DRY FOR LONGER.
LEANED A BIT IN THE DRY DIRECTION AND LOWERED POPS FOR THE NEXT
FEW HOURS...KEEPING OUT LIKELY UNTIL AROUND 12Z.

UPDATE ISSUED AT 949 PM CDT FRI MAY 15 2015

MADE A FEW MINOR TWEAKS TO POPS. HRRR AND A FEW OTHER HIGH RES
MODELS HAVE SOME SHOWERS MOVING INTO THE FAR SOUTHERN CWA AND THEN
DISSIPATING TONIGHT...BUT THE NAM AND RAP DO NOT HAVE MUCH AT ALL
OVERNIGHT. WITH SOME 850MB WARM AIR ADVECTION EXPECTED TO KICK IN
WILL KEEP SOME POPS GOING FOR THE FAR SOUTH AND WEST...ALTHOUGH
THE LOW LEVEL JET AND THE MAIN PRECIP COMPLEX WILL REMAIN OVER
THE WESTERN DAKOTAS. THE EARLY MORNING PRECIP WILL DISSIPATE AND
THEN IT SEEMS THAT WE WILL NOT HAVE MUCH UNTIL LATER ON
SATURDAY...BUT KEPT SOME POPS GOING TO BLEND WITH NEIGHBORS.

UPDATE ISSUED AT 646 PM CDT FRI MAY 15 2015

MADE A FEW MINOR TWEAKS TO CLOUDS...BUT NO OTHER CHANGES TO THE
GOING FORECAST. ANY PRECIP WILL NOT ARRIVE UNTIL AFTER MIDNIGHT AT
THE EARLIEST.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 332 PM CDT FRI MAY 15 2015

CONCERNS WILL BE THUNDER CHANCES AND SEVERE POTENTIAL. THE OVERALL
MODEL TRENDS ARE FOR A SLOWER EVOLUTION OF THIS SYSTEM...AND ALL
FORECAST CHANGES REFLECT THIS TREND. THERE WILL LIKELY BE SEVERAL
WAVES OF PRECIP THAT MOVE THROUGH THE REGION DURING THIS PERIOD.
THE BEST CHANCES FOR TONIGHT (LIKELY AFTER MIDNIGHT) INTO SATURDAY
MORNING WILL BE WEST OF THE VALLEY. AS THE ENTIRE UPPER TROUGH
SLOWLY PROPAGATES EAST...THE BETTER PRECIP CHANCES ALSO MOVE EAST.

850MB FLOW WILL BE DUE SOUTH FROM THE GULF OF MEXICO BY SATURDAY
AFTERNOON. THIS WILL TRANSPORT A MOIST AIRMASS WHICH SHOULD
PROMOTE WEAK TO MODERATE INSTABILITY SAT AFTERNOON. IT DOES APPEAR
THAT CLOUD COVER/HEATING MAY BE AN ISSUE...WITH FOCUSED FORCING
AND STRONGEST DEEP LAYER SHEAR REMAINING WEST OF THE REGION. WITH
THAT SAID...DO ANTICIPATE AT LEAST SOME STRONGER STORMS SAT
AFTERNOON/EVENING...AND SPC CONTINUES TO INDICATE THE SLIGHT RISK.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 332 PM CDT FRI MAY 15 2015

SUNDAY-MONDAY...CONCERNS WILL BE EXCESSIVE RAINFALL
POTENTIAL...AND WINTER WEATHER POTENTIAL. UPPER LOW STRENGTHENS
AND PROPAGATES THROUGH THE REGION. ANTICIPATE PERIODIC SHOWERS
AND THUNDER IN THE WARM SECTOR OF THIS SYSTEM...WITH MORE
WIDESPREAD RAINFALL WITHIN THE DEFORMATION ZONE AREA. ALTHOUGH THE
EXACT TRACK OF THIS SYSTEM IS STILL A BIT UNCLEAR...WHAT IS CLEAR
THAT AN AREA OF 2-3 INCHES QPF LIKELY IN THIS DEFORMATION ZONE
AREA (GIVEN STRENGTH OF THE FORCING COMBINED WITH HIGH PWATS).
CURRENT SIGNALS SUGGEST THE MOST LIKELY AREA WILL BE THE DEVILS
LAKE BASIN INTO THE NORTHERN VALLEY. THIS AREA IS NORTH OF AREAS
THAT HAVE RECEIVED HEAVIER RAINFALL OVER THE PAST COUPLE
WEEKS...SO FLOODING CONCERNS REMAIN MINIMAL.

THE ACTUAL STRENGTH OF THIS SYSTEM WILL DETERMINE WINTER WEATHER
POTENTIAL. THE STRONGER ECMWF AND NAM GENERATE ENOUGH
EVAPORATIONAL COOLING TO SUGGEST THAT THE AIRMASS WILL BE NEAR 32F
AT THE SFC...AND IF THE PRECIP RATES ARE STRONG ENOUGH
ACCUMULATING SNOWFALL WILL BE POSSIBLE. MOST LIKELY AREA WILL BE
THE DEVILS LAKE BASIN...LATER SUN AFTERNOON INTO SUN NIGHT. WITH
STRONG WINDS EXPECTED (LIKELY ADVISORY CRITERIA)...FALLING SNOW
COMBINED WITH THE WIND COULD CAUSE SIGNIFICANT TRAVEL ISSUES.
CONSIDERING THE TIME OF YEAR AND THAT MODELS ARE NOT IN PERFECT
AGREEMENT...WITH DOWNPLAY THIS POTENTIAL UNTIL MORE CONFIDENCE CAN
BE OBTAINED.

STRONG WINDS CONTINUE INTO MONDAY.

TUESDAY-FRIDAY...THE MEAN WESTERN CONUS TROF REMAINS INTACT
THROUGH THE EXTENDED PERIOD BUT THE NORTHERN PLAINS STAYS
RELATIVELY DRY AND QUIET. BOTH THE ECMWF AND THE GFS DEPICT A
RATHER STOUT /1030+/ STOUT SURFACE HIGH PRESSURE AREA DROPPING
INTO THE NORTHERN PLAINS...IN THE WAKE OF THE LARGE DEPARTING
STORM SYSTEM WITH A CORRESPONDING BUT WEAK H5 SHORTWAVE RIDGE
ALOFT. THIS SHOULD RESULT IN GENLY FAIR SKIES AND LIGHT WINDS...
BUT SOMEWHAT COOLER THAT NORMAL TEMPERATURES TUES INTO WED. MODELS
DIVERGE A BIT WED AND THURS WITH THE GFS PUSHING A BIT MORE MOIST
FLOW INTO SOUTHERN ND WHILE THE ECMWF KEEP A BIT DRIER. AS IT
IS...HAVE INTRODUCED SCT SHOWERS INTO OUR FAR SOUTHWESTERN
COUNTIES FOR WED...BUT OTHERWISE REMAIN DRY THE REST OF THE
PERIOD. SOUTHERLY RETURN FLOW EVENTUALLY DEVELOPS FROM THURS INTO
FRI...TEMPERATURES INCREASING TOWARDS SEASONABLE NORMALS BY FRI.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1152 PM CDT FRI MAY 15 2015

VFR CONDITIONS CONTINUE ACROSS THE REGION WITH KFAR SHOWING CIGS
OF AROUND 4000 FT BUT EVERYONE ELSE WITH CIRRUS ONLY. THE CLOUDS
WILL CONTINUE TO INCREASE THROUGHOUT THE NIGHT...BUT CIGS SHOULD
MOSTLY BE ABOVE 5000 FT. THERE HAS BEEN A SLOWING TREND WITH THE
PROGRESSION OF RAIN INTO THE AREA...SO DELAYED THE ONSET OF VCTS A
BIT LONGER INTO TOMORROW AFTERNOON. SOUTHEAST WINDS WILL BEGIN TO
PICK UP BY AFTERNOON.

&&

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

$$

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



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