Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 210932
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
332 AM CST SUN DEC 21 2014

.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 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1142 PM CST SAT DEC 20 2014

WILL KEEP IFR CIGS IN THRU THE TAF PERIOD. CLEARING IN CNTRL ND
JUST ABOUT DVL TO JMS AND HRRR INDICATES IT LIKELY NOT MAKING IT
FURTHER EAST. 925 MB WINDS ARE SOUTHWEST IN THAT AREA NOW AND TURN
MORE SOUTHERLY AGAIN BY 15Z SUN. DVL AIRPORT ONLY SPOT WHERE BRIEF
CLEARING MAY OCCUR...BUT ALSO ALONG THE CLEAR-CLOUD LINE THAT IS
WHERE THE FOG WAS THICKEST FRI NIGHT.


&&

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

$$

SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...RIDDLE





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