Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 211556 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
956 AM CST SUN DEC 21 2014

.UPDATE...REST OF TODAY

MUCH LIKE YESTERDAY...VISIBILITY HAS TANKED ACROSS A GOOD PORTION
OF NORTHEAST SOUTH DAKOTA. WATERTOWN HAS BEEN DOWN TO 1/4SM AND
ABERDEEN TO 1/2SM. AREA WEB CAMS REVEAL RATHER DENSE FOG ACROSS
THE REGION AS WELL. HAVE THEREFORE ISSUED A DENSE FOG ADVISORY
THROUGH NOON. VISIBILITY SHOULD SLOWLY IMPROVE AROUND THAT TIME
AND THROUGH THE REMAINDER OF THE AFTERNOON. OTHERWISE...HAVE
ADJUSTED CLOUD COVER TODAY TO BRING STRATUS DECK A BIT FURTHER
WEST. TEMPS APPEAR ON TRACK FOR NOW BUT WILL MONITOR THE PIERRE
REGION AS SNOW COVER HAS KEPT HIGHS LOWER THAN FORECAST THE PAST
FEW DAYS.

&&

.PREVIOUS DISCUSSION...

.SHORT TERM...THROUGH TUESDAY

WHILE WE ARE SEEING RETURNS ALONG THE MISSOURI RIVER...CIGS ARE
AROUND 10KFT WITH DRY AIR BELOW. FOG IS ALSO HIT AND MISS ACROSS
THE REGION WITH THE LOWEST VISIBILITY AROUND THE SISSETON HILLS
REGION WHERE LOW CIGS INTERSECT THE GROUND.

THE REST OF THE FORECAST IS FOCUSED ON A WEAK SYSTEM MOVING
OVERHEAD AND THEN DEEPENING JUST TO THE EAST. UNDER THIS
SCENARIO...NOT SURPRISED AT THE EXPECTED TRANSITION THROUGH A
MYRIAD OF PTYPES FROM RAIN AND FREEZING RAIN...FREEZING
DRIZZLE...TO RAIN AND SNOW...TO ALL SNOW AND BLOWING SNOW.
INITIALLY WILL SEE EITHER RAIN OR FREEZING RAIN...ALTHOUGH THE FAR
EAST MAY SEE FREEZING DRIZZLE WHEN THE INFLUENCE OF BROAD SCALE
LIFT INTERACTS WITH OUR PERSISTENT LOW CLOUDS. EVEN WITH H85 TEMPS
COOLING MONDAY AM...REMOVING THE MELTING LAYER...MAY STILL SEE
ISSUES WITH SATURATION WITHIN THE DENDRITIC GROWTH ZONE. WE WILL
ALSO SEE A DRY SLOT DEVELOP ACROSS THE EAST/WESTERN MINNESOTA TO
FURTHER COMPLICATE THE FORECAST. SNOWFALL WILL BE THE PREDOMINANT
PTYPE BY LATE MORNING MONDAY...WITH H85 WINDS INCREASING TO
40-50KTS...AND WITH STEEPENING LAPSE RATES MIXED DOWN WINDS ARE
GENERALLY 20G30KTS. WRAP AROUND QPF WILL SHIFT TO NORTHEAST SOUTH
DAKOTA MONDAY NIGHT. WHILE THE SYSTEM IS DEPARTING TUESDAY...A
LITTLE DIABATIC HEATING WILL INDUCE SOME LOW LEVEL CAPE IN THE
PROFILES RESULTING IN STRAGGLING CONVECTIVE SNOW SHOWERS AND
ADDITIONAL LIGHT QPF.

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY

ONCE AGAIN TNT ONLY MIDDLING AGREEMENT IN THE MODELS. THE PERIOD
STARTS OFF WITH A SOMEWHAT AMPLIFIED H5 PATTERN ACROSS THE CONUS.
ONE STORM/TROF IS MOVING EAST THROUGH THE GREAT LAKES...WHILE THE
NEXT BATCH OF ENERGY IS POISED TO MOVE ON SHORE THE WEST COAST AND
HEAD SOUTHEAST. THIS SYSTEM IS LIKELY TO BRING SOME PCPN TO THE
REGION LATE IN THE WEEK. THE ECMWF/GFS ARE IN FAIR AGREEMENT IN
STREAKING PCPN OUT ACROSS THE PLAINS AT THAT TIME...BUT THE ECMWF
IS A BIT FURTHER SOUTH AND MORE AGGRESSIVE WITH PCPN AMOUNTS.
TEMPERATURES OVERALL WILL FAVOR NEAR TO BELOW NORMAL THROUGH THE
PERIOD.

&&

.AVIATION...

06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

IFR CONDITIONS WILL PERSIST THROUGH THE MORNING AT
KATY/KABR...WITH SOME IMPROVEMENT EXPECTED THIS AFTERNOON. AFTER
SOME MORNING FOG BOTH KMBG/KPIR SHOULD BE VFR THROUGH TODAY.
PRECIPITATION WILL DEVELOP OVER THE REGION THIS EVENING AND
OVERNIGHT. SOME OF THAT WILL LIKELY BE A WINTRY MIX.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...

SD...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR BROWN-CLARK-
     CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-
     MARSHALL-MCPHERSON-ROBERTS-SPINK.

MN...NONE.
&&

$$
UPDATE...TMT
SHORT TERM...CONNELLY
LONG TERM...TDK
AVIATION...TDK

WEATHER.GOV/ABERDEEN





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