Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 290619 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1219 AM CST THU JAN 29 2015

.UPDATE...
WIND SPEEDS AT ALL SURFACE OBSERVING SITES HAVE DROPPED BELOW WIND
ADVISORY CRITERIA. THEREFORE...ALLOWED THE WESTERN CWA HEADLINE TO
EXPIRE...AND CANCELED THE HEADLINE FOR COUNTIES FURTHER EAST.

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
FORECAST CHALLENGES REVOLVE AROUND STRENGTH OF WINDS TONIGHT...AS
WELL AS A LOW END PROBABILITY OF SOME LIGHT FREEZING DRIZZLE
PRIMARILY ALONG AND EAST OF A LINE FROM LEOLA TO HAYTI.

CURRENTLY...TEMPERATURES RANGE FROM THE LOWER 30S OVER THE FAR
NORTHEAST CORNER OF THE CWA TO ALMOST 60 DEGREES OVER THE FAR
SOUTHWESTERN CORNER OF THE CWA. A COLD FRONT IS APPX TWO-THIRDS OF
THE WAY THROUGH THE CWA RIGHT NOW...WITH SOME OF THE STRONGER
NORTHWEST WINDS NOW BEGINNING TO PICK UP STEAM ACROSS NORTHWESTERN
SOUTH DAKOTA. THERE IS ALSO AN IFR/MVFR LAYER OF STRATUS SCREAMING
SOUTHWARD TOWARD THIS CWA.

TONIGHT...AS A SUBTLE NW FLOW MID-LEVEL SHORTWAVE TROF SWEEPS
THROUGH THE REGION...IT MAY BE ABLE TO GENERATE ENOUGH LIFT TO
INDUCE A FEW HOURS OF SOME PATCHY LIGHT DRIZZLE/FREEZING DRIZZLE
ACROSS THE CWA /SUB-FREEZING TEMPERATURES...BUT NOT COLD ENOUGH TO
ACTIVATE ICE/. HIGHEST PROBABILITY OF OCCURRENCE CENTERS ACROSS THE
PRAIRIE COTEAU EASTWARD INTO MINNESOTA WHERE MODELS PROG THE
DEEPEST LAYER OF SATURATED/NEAR SATURATED STRATUS CLOUDS TO BE
OVERNIGHT. GRIDS HAVE THIS COVERED NOW...INCLUDING SOME SPOTTY
0.01 INCH OF ICE ACCUM IN THE ICE ACCUM GRIDS. ALSO...DURING THE
OVERNIGHT HOURS...THE CORRIDOR OF STRONG NORTHWEST WINDS WILL PUSH
SOUTHEAST INTO NE/IA/MN...SO COLLABORATED AN EXTENSION OF THE WIND
ADVISORY OVER TO THE SODAK/MN BORDER THROUGH THE LATE NIGHT/EARLY
THURSDAY MORNING HOURS. THE PRESSURE TENDENCY PROG SHOWS
INCREASING VALUES OF RISING PRESSURE OVERNIGHT. THAT AND LOW LEVEL
LAPSE RATES OFF THE NAM MODEL IN BUFKIT SUGGEST THE BOUNDARY LAYER
MAY NOT DECOUPLE OVERNIGHT...ALLOWING FOR SOME OF THESE STRONGER
MIXED LAYER WINDS TO TRANSLATE ALL THE WAY DOWN TO THE GROUND AT
TIMES OVERNIGHT.

THURSDAY -> FRIDAY NIGHT...FOR THE TIME BEING THESE FORECAST
PERIODS ARE DRY...WITH COLD AIR KNOCKING TEMPERATURES DOWN CLOSER
TO CLIMO NORMAL THURSDAY/THURSDAY NIGHT. LOW LEVEL WAA TRIES TO
RE-ASSERT ITSELF OVER THE CWA FRIDAY BEFORE ANOTHER COLD FRONT
SWEEPS THROUGH FRIDAY NIGHT...SETTING THE TABLE FOR A MULTIPLE
DAY-LONG PERIOD OF COLD.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

NORTHWEST FLOW WILL DOMINATE FLOW ALOFT THOUGH THE
EXTENDED...WHILE ARCTIC AIR WILL BECOME ENTRENCHED EAST OF THE
REGION EARLY IN THE PERIOD AND DICTATE CONDITIONS THOUGH A
MAJORITY OF THE PERIOD...DESPITE THE CORE OF COLDEST AIR SITUATED
MAINLY TO THE EAST. MODELS FEATURE A CLIPPER SYSTEM LATE
SATURDAY...THANKS TO POTENTIALLY FAVORABLE PLACEMENT OF A JET EXIT
REGION. WITH ARCTIC AIR DROPPING IN UNDERNEATH THE
CLIPPER...PROFILES SHOW A DEEP DENDRITIC GROWTH ZONE FOR A FEW
HOURS. A 1040MB HIGH MOVES IN SUNDAY...WITH ANOTHER CLIPPER SYSTEM
FOR MONDAY NIGHT.

&&

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

MVFR STRATUS CLOUDS WILL CONTINUE TO STREAM OVER ALL TERMINALS
THROUGH TONIGHT INTO THURSDAY. WITH DRIER AIR FILTERING IN ALONG
WITH SURFACE HIGH PRESSURE BUILDING IN...EXPECT THE CLOUDS TO
BREAK UP AND CLEAR OUT INTO THURSDAY AFTERNOON AND EVENING. STEADY
NORTH WINDS AT 15 TO 20 KNOTS WITH GUSTS TO AROUND 25 KNOTS WILL
FALL OFF INTO THURSDAY.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...SERR
SHORT TERM...DORN
LONG TERM...CONNELLY
AVIATION...MOHR

WEATHER.GOV/ABERDEEN





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