Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 201459
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
959 AM CDT SAT SEP 20 2014

.UPDATE...
ISSUED AT 959 AM CDT SAT SEP 20 2014

TRYING THE FIGURE OUT TIMING AND AREA OF COVERAGE FOR SHOWER/TSTM
DEVELOPMENT TODAY IS STILL THE MAIN FORECAST CHALLENGE. SPC DAY1
SEVERE OUTLOOK HAS SHIFTED A LITTLE FURTHER SOUTH...NOW CATCHING
ALL OF OUR SOUTHERN FA TOO. THIS FURTHER SOUTH SHIFT SEEMS TO MAKE
SENSE AS CLOUDS WILL PROBABLY PREVENT MUCH HEATING OVER NORTHEAST
ND INTO NORTHWEST MN. THE MOST MORNING SUN WILL OCCUR OVER
SOUTHEAST ND INTO WEST CENTRAL MN. THIS ALSO DOES NOT LOOK LIKE A
LONG DURATION EVENT...IT WILL MOVE THRU THE AREA PRETTY QUICKLY.
RIGHT NOW THE SHOWERS/TSTMS ARE ALREADY MOVING INTO THE WESTERN
AND NW FA. THE SLIGHTLY STRONGER ECHOES ARE CURRENTLY OVER CENTRAL
ND WITH ADDITIONAL CUMULUS DEVELOPMENT DOWN INTO NORTH CENTRAL SD
WHICH DOES FIT THE ABOVE THINKING. PRIMARY THREAT MAY REMAIN
STRONGER WIND GUSTS BUT WILL HAVE TO SEE HOW MUCH HEATING DOES
OCCUR ACROSS THE SOUTH. CURRENT TIMING PUTS THE ECHOES OVER OUR
WESTERN FA INTO THE RED RIVER VALLEY AROUND 18Z...WHICH DOES NOT
GIVE MUCH TIME FOR HEATING.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 357 AM CDT SAT SEP 20 2014

TO START THE DAY...WILL HAVE SOME LOW CLOUDS IN PARTS OF NW MN AND
PATCHY CLOUDS AND FOG IN NE ND. BIG ISSUE TODAY IS UPSTREAM VORT
MAX IN EAST CENTRAL ALBERTA THAT WILL MOVE SOUTHEAST INTO WESTERN
ND AT 18Z AND THEN INTO WEST CNTRL MN AT 00Z SUN. VERY STRONG MID
AND UPPER LEVEL FORCING WITH A 80 KT 500 MB JET AND 130 KT 300 MB
JET WITH THIS VORT...ALONG WITH STRONG UPPER LEVEL DIVERGENCE
CENTERED OVER THE RED RIVER VALLEY EARLY THIS AFTN. SPC WRF AND
RUC AND LOCAL WFO FGF WRF ALL INDICATE ABOUT THE SAME SCENARIO
WITH A POTENTIAL SQUALL LINE ORGANIZING OVER NE ND NEAR NOON-EARLY
AFTN AND MOVING EAST-SOUTHEAST INTO MINNESOTA EARLY TO MID AFTN.
PEAK OF ACTIVITY VIA RADAR PROGS FROM SPC WRF WOULD INDICATE AREAS
FROM ROSEAU TO DETROIT LAKES IN THE PRIME ZONE THEN LINE WILL MOVE
EAST AND WEAKEN TOWARD 00Z JUST EAST OF THE FCST AREA. SPC DAY 1
HAS MUCH OF THE AREA IN SLIGHT RISK USING THE AFOREMENTIONED
PARAMETERS. ONE DOWNSIDE IS THAT THE LOW LEVELS WILL BE MUCH COOLER
THAN YESTERDAY AND THUS INSTABILITY PARAMETERS WILL BE PRETTY WEAK
WITH BARELY BELOW 0C SHOWALTERS WITH SYSTEM. IT IS EXPECTED MID
AND UPPER LEVEL DYNAMICS WILL OVERCOME THIS. WIND SEEMS TO BE THE
MAIN THREAT AS 850 MB WINDS INCREASE TO 45 KTS FOR A TIME MID AFTN
JUST EAST OF THE RRV AS LINE MOVES THROUGH. THUS ANY STRONG STORM
LINE COULD EASILY MIX THIS DOWN. HAIL ALSO A THREAT DUE TO COOLING
AT 500 MB WITH SYSTEM AS TEMPS AT THAT LEVEL DROP TO -20C. TORNADO
THREAT WOULD SEEM LOW...DUE TO LACK OF SFC LOW UNLIKE YESTERDAY.

DID INCLUDE SEVERE WORDING FOR A 2-3 HOUR PERIOD ACROSS THE RRV
INTO MN IN RISK AREA BASED ON TIMING FROM SPC WRF/RUC.

SYSTEM CLEARS EAST TONIGHT...LINGERING CLOUDS IN LAKE OF THE
WOODS BUT CLEARING ELSEWHERE. SUNDAY WILL SEE CLOUDS MOST
PROMINENT IN MN FCST AREA UNDER DEPARTING 500 MB TROUGH.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 357 AM CDT SAT SEP 20 2014

SUN NIGHT INTO MONDAY WILL FEATURE GENERALLY CLEAR SKY AS HIGH
PRESSURE AND DRY AIRMASS MOVES IN.

FOR TUESDAY THROUGH FRIDAY...
LONG WAVE RIDGE OVER WESTERN NORTH AMERICA SHIFTS TO EASTERN
NORTH AMERICA BY THE END OF THE PERIOD. LONG WAVE UPPER RIDGE
PRODUCES MUCH ABOVE NORMAL HEIGHTS BY THE END OF THE PERIOD. SHORT
WAVE TROUGH OFF THE CA COAST IS FORECAST TO MOVE ACROSS ITO THE
NORTHERN PLAINS BY LATE TUE INTO WED. THE GFS AND ECMWF ARE
SIMILAR IN TIMING AT 84 HOURS THE GFS BECOMES THE FASTER SOLUTION
ON THU AND FRI. WILL PREFER THE ECMWF.

TWEAKED POPS UP A LITTLE ON TUE.

LITTLE CHANGE TO TEMPS...INCREASE TEMPS BY A DEGREE ON THU.
ESSENTIALLY NO CHANGES FROM PREVIOUS FORECAST PACKAGE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 707 AM CDT SAT SEP 20 2014

TYPICAL EARLY MORNING AREA OF LOW END MVFR/IFR CIGS ALONG WITH
PATCHES OF FOG IN THE RED RIVER VALLEY INTO MINNESOTA. THE LOW
CLOUDS/FOG WILL MIX OUT BUT REPLACE BY MID AND HIGH LEVEL MOISTURE
FROM UPPER WAVE MOVING SOUTHEAST. TRIED TO TIME BEST RISK OF TSTMS
AT TAF SITES....MOSTLY VERY LATE MORNING IN DVL AND EARLY AFTN IN
GFK AND MID AFTN TVF-FAR AND LATE AFTN BJI. WINDS MAIN ISSUE WITH
THESE STORMS AS A WEST-SOUTHWEST WIND TURNS NORTHWEST WITH LIKELY
HIGH GUSTS FOR A TIME WITH LINE OF SHOWERS/STORMS. WINDS WILL
DIMINISH THIS EVE.

&&

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

$$

UPDATE...GODON
SHORT TERM...RIDDLE
LONG TERM...HOPPES/RIDDLE
AVIATION...RIDDLE






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