Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 211823
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1223 PM CST SUN DEC 21 2014

.UPDATE...
ISSUED AT 1223 PM CST SUN DEC 21 2014

NO CHANGES PLANNED.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 325 AM CST SUN DEC 21 2014

MAIN FORECAST CHALLENGE REVOLVES AROUND UPCOMING PRE CHRISTMAS
SNOW EVENT AND EXPECT SNOW AMOUNTS. CONFIDENCE RISING AS MODELS COMING
INTO BETTER AGREEMENT AND WILL USE MODEL BLEND AND NATIONAL
GUIDANCE FOR ANTICIPATED SNOW AMOUNTS.

AREA OF MAINLY -SN ASSOCIATED WITH CURRENT WAVE AND ZONE OF
ISENTROPIC LIFT WILL CONTINUE TO PROPAGATE EAST AND WILL MONITOR
FOR MORNING POPS. ONCE THIS MOVES THROUGH THIS AM REMAINDER OF THE
DAY SHOULD BE MAINLY DRY WITH PERSISTENT FOG AND LOW CIGS. WITH
SOUTHERLY FLOW...CONTINUED WARM ADVECTION AND WARMER START MOST OF
THE FA WILL BE A FEW DEGREES EITHER SIDE OF 32F.

WAVE WILL DROP INTO DEEPENING TROUGH TONIGHT CLOSING OFF OVER
SD/NE REGION BY MORNING. SURFACE INVERTED TROUGH FROM SD SURFACE
LOW GRADUALLY TAKES SHAPE ACROSS THE CENTRAL DAKOTAS. LOWERING
CONDENSATION PRESSURE DEFICITS AND ISENTROPIC LIFT CONFINED TO THE
SOUTHERN FA SO HAVE HIGHEST POPS THERE TOWARDS MORNING. CLOUDS WILL
HOLD TEMPERATURES UP OVERNIGHT.

STACKED LOW DRIFTS SLOWLY SE MONDAY ALLOWING SFC INVERTED TROUGH
TO SHIFT INTO THE FA. VIA OMEGA FIELDS AND 290K ISENTROPIC SURFACE
LIFT INCREASES DURING THE DAY AND RAISED POPS ACCORDINGLY. HAVE
HIGHEST POPS ASSOCIATED IN ZONE OF 850MB FRONTOGENETIC FORCING
ALTHOUGH AT THIS POINT BANDING SNOW POTENTIAL DOES NOT LOOK GREAT.
ALSO FROM THE 290K SURFACE FULL SATURATION LOOKS SPOTTY. BASED ON
SURFACE TEMPERATURES EXPECT CLOSE TO A 10:1 SNOW RATIO.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM CST SUN DEC 21 2014

LIFT LOOKS MAXIMIZED MONDAY NIGHT AND SHOULD BE THE FAVORED PERIOD
FOR ACCUMULATING SNOW. FORTUNATELY WIND DOES NOT LOOK TO BE A
SERIOUS ISSUE ALTHOUGH COULD SEE SOME DRIFTING IN OPEN AREAS.

LOW BEGINS TO FILL TUESDAY AND ISENTROPIC LIFT DIMINISHES DURING
THE DAY. STILL EXPECT -SN DURING DURING THE DAY BUT SHOULD
DIMINISH FROM WEST TO EAST DURING THE EVENING. COLD ADVECTION WEAK
AND MIXED LAYER VERY SHALLOW SO WINDS SHOULD BE MANAGEABLE.

CONSIDERING HEADLINES...BASED ON MODEL SOLUTIONS AND NATIONAL
GUIDANCE FEEL THIS WILL BE A FAIRLY EXTENDED PERIOD OF MAINLY
LIGHT SNOW. WITH WIND ALSO NOT APPEARING AS A SERIOUS ISSUE DO NOT
FEEL WATCH WARRANTED AT THIS POINT ALTHOUGH FUTURE ADVISORIES
LOOK LIKELY.

WEDNESDAY-SATURDAY...A BIT OF LIGHT SNOW COULD LINGER EAST OF THE
VALLEY ON WEDNESDAY AS THE LOW CONTINUES TO LIFT AWAY FROM THE AREA.
THEREAFTER HAVE MAINTAINED A PRIMARILY DRY FORECAST. THE 00Z
GFS/ECMWF INDICATE A MORE PROGRESSIVE PACIFIC SHORTWAVE TROUGH
CROSSING THE CENTRAL/NORTHERN PLAINS ON CHRISTMAS...WITH PRECIP
SUPPRESSED MAINLY SOUTH OF THE REGION. THERE WILL ALSO BE A FEW
SHORTWAVE TROUGHS DROPPING SOUTHEASTWARD IN AMPLIFYING NORTHWEST
FLOW ALOFT. WHILE ANY OF THESE MAY PRODUCE SOME LIGHT SNOW...THEY
WOULD BE RATHER MINOR. PERHAPS MORE IMPORTANTLY...THIS PATTERN WILL
ALLOW COLDER AIR TO FILTER SOUTHWARD FOR THE LATTER HALF OF THE
PERIOD. THE GFS/ECMWF BOTH INDICATE 850 MB TEMPS DROPPING TO -20C BY
NEXT SATURDAY...BRINGING TO AN END OUR RECENT STRING OF NEAR TO
ABOVE AVERAGE TEMPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1223 PM CST SUN DEC 21 2014

STRATUS HAS FINALLY MADE ITS WAY INTO KDVL...LEAVING ALL TAF SITES
IFR OR LIFR THIS AFTERNOON. THINK THAT THE STRATUS WILL NOT BE GOING
ANYWHERE WITH SOUTHERLY WINDS AND MOISTURE FLOW CONTINUING AS THE
SFC LOW MOVES OUT INTO THE PLAINS. A FEW SITES HAVE VIS ABOVE 6SM
THIS AFTERNOON BUT THINK THAT SOME LIGHT MIST WILL BRING EVERYONE
DOWN TO 3-5SM BY THIS EVENING. THE SFC LOW WILL MOVE DOWN INTO SD
LATE TONIGHT...WITH WINDS SHIFTING MORE TO THE EAST BY TOMORROW
MORNING. WILL HAVE TO WATCH FOR FOG FORMATION AND EVEN SOME FREEZING
DRIZZLE OVERNIGHT...BUT FOR NOW KEPT JUST 1SM WITH BR FOR THE EARLY
MORNING HOURS TOMORROW. SOME PRECIP WILL BEGIN TO MOVE INTO THE KFAR
REGION JUST BEFORE 12Z. TEMPS WILL BE RIGHT AROUND OR EVEN JUST
ABOVE THE FREEZING MARK. FOR NOW WENT WITH A LIGHT RAIN SNOW MIX BUT
WILL TAKE ANOTHER LOOK AS THE PERIOD GETS CLOSER. THE IFR OR LOWER
CIGS AND VIS ALONG WITH PRECIP CHANCES WILL CONTINUE THROUGH THE END
OF THE PERIOD.

&&

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

$$

UPDATE...GODON
SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...JR






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