Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 221610
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1010 AM CST MON DEC 22 2014

.UPDATE...
ISSUED AT 1010 AM CST MON DEC 22 2014

ATTEMPTING TO PORTRAY THIS WEATHER SITUATION IS DIFFICULT. THE
MAIN HAZARDOUS WEATHER WILL REMAIN ACROSS THE WESTERN FA...WITH
DENSE FOG ACROSS THE PORTION OF SOUTHEAST NORTH DAKOTA...AND
FREEZING DRIZZLE ACROSS THE DEVILS LAKE BASIN (WHERE TEMPERATURES
REMAIN BELOW FREEZING).

THE AIRMASS REMAINS DRY ALOFT...AND ANTICIPATE THE DRIZZLY TYPE
WEATHER TO CONTINUE THROUGH MUCH OF THE DAY. MODEL GUIDANCE 700MB-
500MB RH (DRY LAYER) ALIGNS WELL WITH SATELLITE IMAGERY (WHERE
TEMPS <-12C). THE MODEL GUIDANCE INDICATES SATURATION ALOFT TO
OCCUR FROM SOUTH TO NORTH THROUGH THE DAY...UP THROUGH A LINE FROM
AROUND COOPERSTOWN TO BEMIDJI. THE NORTHERN FA MAY NEVER SATURATE
ALOFT...BUT SOME GUIDANCE DOES SUGGEST IT WILL BY 12Z TUE AND WILL
GO WITH THIS SCENARIO FOR NOW. IN THE FORECAST...WENT WITH
DRIZZLE/FREEZING DRIZZLE WHERE MODELS SUGGEST THE DRY LAYER
ALOFT...AND INTRODUCED SNOW/RAIN WHERE SATURATION ALOFT SHOULD
OCCUR. OVERALL...DID LOWER SNOW AMOUNTS SOME...WITH MOST AREAS
ONLY RECEIVING A DUSTING (POSSIBLY UP TO AN INCH OR TWO IN SPOTS).

EARLIER ISSUED THE WINTER WEATHER ADVISORY FOR MAINLY FREEZING
DRIZZLE ACROSS THE DEVILS LAKE BASIN...WITH DRIZZLY TYPE WEATHER
EXPECTED TO CONTINUE WELL INTO THE OVERNIGHT HOURS. WILL NEED TO
CONSIDER EXPANDING THIS EASTWARD IF CONFIDENCE INCREASES THAT SFC
TEMPS WILL DROP BELOW FREEZING TONIGHT.

EXTENDED THE DENSE FOG ADVISORY UNTIL 19Z...AND WILL NEED TO
MONITOR THIS AREA (WHICH REMAINS IN A SIMILAR SYNOPTIC SETUP) FOR
POSSIBLE EXPANSION INTO TONIGHT.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 346 AM CST MON DEC 22 2014

THE FORECAST THIS MORNING FOCUSES ON THE LIGHT MIXED PRECIP EVENT
EARLY THIS WEEK.

SFC LOW OVER WESTERN DAKOTAS THIS MORNING WILL DIVE SOUTHEAST TO S IOWA
TONIGHT BEFORE LIFTING UP THROUGH THE GREAT LAKES. FORECAST MODELS
HAVE CONTINUED TO HANDLE THIS EVENT POORLY...SO CONFIDENCE
CONTINUES TO BE ON THE LOW SIDE...BUT THE OVERALL TREND HAS BEEN
FOR A WEAKER SYSTEM/LESSER IMPACTS.

THE REGION REMAINS SOCKED IN UNDER LOW CLOUDS...WITH SOME PATCHES
OF FOG EARLY THIS MORNING. TEMPS HAVE REMAINED STEADY OR HAVE
SLOWLY RISEN OVERNIGHT IN THE 30S.

EARLY THIS MORNING...REGIONAL RADAR INDICATED PRECIP DEVELOPMENT
TO THE SOUTH OVER SD/NE. THE GENERAL IDEA IS THAT SOME LIGHT
PRECIP WILL DEVELOP DURING THE MORNING OVER THE AREA AND SPREAD
NORTHWARD. DID CONTINUE HIGH POPS...ALTHOUGH EXPECT PRECIP TO BE
VERY LIGHT TODAY...GIVEN THE WEAK FORCING MOSTLY RELEGATED TO THE
LOW LEVELS. POP TRENDS MAY NEED TO BE ADJUSTED DURING THE
DAY...PENDING HOW ORGANIZED PRECIP BECOMES. PRECIP TYPE WILL ALSO
BE AN ISSUE. LOW LEVEL THERMAL PROFILES GENERALLY WILL BE WITHIN A
FEW DEGREES OF 0C UP TO ABOVE 900 MB...MAKING FOR A TRICKY
FORECAST...BUT WITH SFC TEMPS INTO THE MID 30S IN SPOTS...MAY BE
CONTENDING WITH LIGHT RAIN/DRIZZLE AT TIMES OVER PARTS OF THE VALLEY.
THE AIR MASS WILL BE QUITE MOIST...WITH SEASONABLY HIGH PW VALUES
APPROACHING 0.50 INCHES.

TONIGHT THERE IS PERHAPS A BIT BETTER LOW-LEVEL ISENTROPIC
LIFT/DEFORMATION THAT MODELS FOCUS ACROSS SE ND. WITH CONTINUED
MOIST AIRMASS IN PLACE...TEMPS WILL NOT DROP OFF MUCH. AS A
RESULT...PRECIP TYPE WILL STILL BE A CONCERN IN SOME AREAS. RIGHT
NOW HAVE TRENDED FROM RA/SN TO LIGHT SNOW...BUT WITH LOW-LEVELS
ALREADY SATURATED...AND ONLY SLOW COOLING OF THE LOWER
TROPOSPHERE...THIS TRANSITION WILL NEED TO BE WATCHED. EVERYTHING
CONSIDERED...DO NOT EXPECT HEAVY PRECIP RATES...BUT LOCATIONS
WITHIN MORE PERSISTENT PRECIP BANDS WHERE MORE SNOW DOES OCCUR
COULD PICK UP SOME ACCUMULATIONS UP TO A FEW INCHES THROUGH
TUESDAY. OVERALL...IT DOES NOT CURRENTLY APPEAR THAT THIS SYSTEM
WILL HAVE DRAMATIC IMPACTS FOR THE REGION...BUT STILL SOME
UNCERTAINTY ON THE DETAILS.

TEMPS WILL REMAIN MILD ON TUESDAY WITH WHAT MODEST 850 MB COLD
ADVECTION THERE IS FOCUSED ACROSS CENTRAL ND...BEHIND THE
INCREASINGLY VERTICALLY STACKED LOW. THAT SAID...WINDS WILL BE A
BIT GUSTY ESPECIALLY WEST OF THE VALLEY DURING THE DAY.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 346 AM CST MON DEC 22 2014

SOME LIGHT SNOW MAY LINGER TUES NIGHT ALONG AND EAST OF THE
VALLEY. OTHERWISE...TEMPS WILL REMAIN MILD ON WEDNESDAY AS THE
UPPER AIR FLOW BRIEFLY BECOMES QUASI-ZONAL OVER THE NORTHERN
PLAINS. A SHORTWAVE TROUGH/SFC LOW PUSHING ACROSS SOUTHERN CANADA
MAY BRUSH CANADIAN BORDER AREAS WITH SOME LIGHT SNOW LATER WED/WED
NIGHT...BUT VERY MINOR.

FOR THURSDAY THROUGH SUNDAY PERIOD...MODELS MAINTAIN DIFFERENCES
WITH RESPECT TO NEXT SYSTEM TO MOVE IN FROM THE PAC NW AND
EAST-SOUTHEAST INTO THE NRN PLAINS THU NIGHT-FRI.  PREFER THE
FARTHER SOUTH SOLN OF EMCWF/GEM VS NRN SOLN OF GFS DUE TO STRONG JET
LIKELY TO HELP DIG THE UPPER SYSTEM FARTHER SOUTH THAN MODELS
SHOW...JUST LIKE THIS CURRENT SYSTEM TODAY. WILL MAINTAIN SOME
SLIGHT POPS THOUGH...MAINLY SOTUEHRN HALF OF FCST AREA.  AFTER THIS
COLDER AIR MOVES IN AS TEMPS DROP BACK TO CLOSER TO MORE NORMAL LATE
DECEMBER VALUES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 705 AM CST MON DEC 22 2014

GENERALLY EXPECT CEILINGS UNDER IFR THRESHOLDS THROUGH MUCH OF THE
PERIOD. THERE WILL BE AREAS OF MIST AND DRIZZLE AND REDUCED VSBY...WITH
SOME LIGHT RAIN/SNOW SPREADING NORTHWARD TODAY. A GRADUAL
TRANSITION TO ALL SNOW IS EXPECTED TONIGHT.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NDZ006-007-
     014-015-024-026-028-054.

     DENSE FOG ADVISORY UNTIL 1 PM CST THIS AFTERNOON FOR NDZ038-049-
     052.

MN...NONE.
&&

$$

UPDATE...TG
SHORT TERM...MAKOWSKI
LONG TERM...MAKOWSKI/RIDDLE
AVIATION...MAKOWSKI





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