Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 251130 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
530 AM CST TUE NOV 25 2014

.UPDATE...
SEE UPDATED AVIATION DISCUSSION BELOW.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH THURSDAY
THE MAIN FORECAST CHALLENGE WILL CENTER AROUND A CLIPPER SYSTEM
PASSING ACROSS THE REGION LATER THIS AFTERNOON THROUGH WEDNESDAY
MORNING. THERE IS A REASONABLE AGREEMENT AMONG MODELS WITH THE
OVERALL TRACK OF THIS SYSTEM WHICH LEADS TO HIGH FORECASTER
CONFIDENCE. THE MAIN QUESTION LEFT UNANSWERED IS WHETHER OR NOT
CENTRAL SD SEES ANY ACCUMULATING SNOWFALL.

A CLIPPER SYSTEM...CURRENTLY OVER SW SASKATCHEWAN...WILL TRACK
SOUTHEASTWARD ACROSS THE NORTHERN PLAINS LATER THIS AFTERNOON AND
TONIGHT. MODELS HAVE SLOWED DOWN THE OVERALL PROGRESSION OF THIS
SYSTEM WITH PCPN LIKELY NOT REACHING THE JAMES RIVER VALLEY UNTIL
AFTER 21Z. BASED ON THE AMOUNT OF WARM AIR AHEAD OF THIS
SYSTEM...PCPN COULD BEGIN AS RAIN...ESPECIALLY AROUND THE PIERRE
AREA. HOWEVER DECENT CAA DEVELOPS BEHIND THE SURFACE LOW WITH RAIN
CHANGING OVER TO ALL SNOW BY LATER THIS EVENING. BASED ON THE
CURRENT LOW TRACK...THE NE PORTION OF THE CWA WILL LIKELY SEE ALL
SNOW WITH THE POTENTIAL FOR TWO TO FOUR INCHES BY WEDNESDAY
MORNING. THE SURFACE LOW DOES TAKE A NEGATIVE TILT ON WEDNESDAY
WITH THE POTENTIAL FOR ADDITIONAL SNOWFALL ON THE EASTERN SIDE OF
THE PRAIRIE COTEAU.

STRONG NORTHERLY WINDS WILL DEVELOP BEHIND THIS SYSTEM WITH THE
HIGHEST SUSTAINED WINDS OCCURRING ALONG THE MISSOURI RIVER. WINDS
SHOULD EASILY EXCEED WIND ADVISORY LEVELS AFTER 0Z TONIGHT. THOUGHT
ABOUT ISSUING A WIND ADVISORY FOR THIS AREA...HOWEVER AM UNCERTAIN
ON SNOWFALL AMOUNTS. IF THE MISSOURI RIVER SEES ACCUMULATING
SNOWFALL...THEN A WINTER WX ADVISORY MAYBE NEEDED INSTEAD.

AN ARCTIC HIGH PRESSURE DRIFTING ACROSS THE REGION BEYOND
WEDNESDAY AFTERNOON WILL BRING MOSTLY DRY CONDITIONS TO THE AREA.
UNFORTUNATELY THIS HIGH PRESSURE WILL ALSO BRING MORE SIGNIFICANT
BELOW NORMAL TEMPERATURES THROUGH THANKSGIVING.


.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
UPPER LEVEL NORTHWEST FLOW WILL BE IN PLACE WHEN THE EXTENDED
PERIOD STARTS...WITH A SHORTWAVE SET TO TRACK ACROSS THE STATE
OVERNIGHT. A MORE ZONAL PATTERN THEN SETS UP...WITH JUST A SLIGHT
SHIFT TO SOUTHWESTERLY FLOW ON MONDAY.

AT THE SURFACE...HIGH PRESSURE WILL BE EAST OF THE REGION WITH A
LOW PRESSURE SYSTEM EXTENDING FROM THE PACIFIC NORTHWEST TO
MONTANA TO THE LEE OF ROCKIES. THE MODELS AGREE THAT MUCH OF THE
PRECIPITATION WITH THIS SYSTEM WILL STAY NORTH OF THE CWA...BUT
THAT THE NORTHEAST MAY GET CLIPPED...SO WILL LEAVE A SMALL POP IN
THAT AREA. MAY SEE A LITTLE LIGHT SNOW ACROSS THE WESTERN CWA ON
SATURDAY BEFORE HIGH PRESSURE DROPS IN AND BECOMES DOMINANT
THROUGH THE DAY MONDAY. OTHERWISE...THE REST OF THE EXTENDED
PERIOD LOOKS TO BE DRY.

WILL SEE WAA OVER THE AREA ON FRIDAY AS H85 TEMPS RISE INTO THE +2
TO +10 DEGREE RANGE. HIGHS WILL GENERALLY BE IN THE 30S AND
40S...WITH A FEW AREAS POSSIBLE HITTING 50 DEGREES SOUTH OF
INTERSTATE 90. THE WARMER AIR WILL BE SHORT LIVED AS ANOTHER COLD
PUNCH BEGINS ON SATURDAY AND CONTINUES THROUGH THE END OF THE
PERIOD. HIGHS ON SATURDAY WILL BE IN THE 20S TO LOWER 30S...THEN
MOST AREAS WILL SEE HIGHS MAINLY IN THE TEENS AND 20S SUNDAY AND
MONDAY.


&&

.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH THE MORNING
HOURS. MVFR CIGS WILL MOVE OVER THE NORTHERN AND EASTERN PARTS OF
THE CWA BEGINNING SOMETIME THIS AFTERNOON IN ASSOCIATION WITH A
CLIPPER SYSTEM. LIGHT SNOW/RAIN WILL START OVER THE NORTHWESTERN
CWA DURING THE AFTERNOON...THEN WILL BECOME ALL SNOW AS IT
SPREADS EASTWARD THROUGH THE EVENING AND OVERNIGHT HOURS. VSBYS
WILL LIKELY FALL INTO THE MVFR CATEGORY AT TIMES AT KMBG...KABR
AND KATY. NORTHWEST WINDS WILL INCREASE INTO THE 15 TO 30 KNOT
RANGE ON THE BACKSIDE OF THE SYSTEM OVERNIGHT...WITH THE STRONGEST
WINDS LIKELY TO OCCUR ACROSS THE WEST. THE WINDS MAY AID IN
FURTHER VSBY REDUCTIONS DUE TO BLOWING SNOW...ESPECIALLY ACROSS
THE EAST LATE TONIGHT.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CST
     WEDNESDAY FOR BROWN-CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-
     GRANT-HAMLIN-MARSHALL-MCPHERSON-ROBERTS-SPINK.

MN...NONE.
&&

$$
SHORT TERM...SD
LONG TERM...PARKIN
AVIATION...PARKIN

WEATHER.GOV/ABERDEEN




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