Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 121746 AAA
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1146 AM CST FRI FEB 12 2016

.UPDATE...
ISSUED AT 1137 AM CST FRI FEB 12 2016

SEE UPDATED AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON)
ISSUED AT 348 AM CST FRI FEB 12 2016

COMPLEX SET OF WEATHER CONDITIONS SETTING UP FOR THE END OF THE WORK
WEEK/WEEKEND. WE ARE ALREADY SEEING THE EFFECTS OF A 1044 MB HIGH
PRESSURE NOSING OUT OF CANADA THIS MORNING WITH TEMPERATURES FALLING
ACROSS THE NORTHERN PLAINS AND SOUTHERN CANADA. OVER OUR
CWA...ANTICIPATE CLEARING SKIES AND FALLING TEMPERATURES TODAY FOR
THE EASTERN HALF OF THE CWA. READINGS TONIGHT WILL PLUMMET EAST OF
THE JAMES VALLEY...HOWEVER WE WILL SEE INCREASING CLOUDS WEST RIVER
AS WEAK MID LEVEL WARM ADVECTION DEVELOPS. THIS PUSH OF MILD AIR
WILL HELP GENERATE SOME LIGHT SNOW...BUT WITH ONLY 1 TO 2 MICROBARS
OF LIFT HAVE MY DOUBTS THIS WILL GENERATE MUCH MORE THAN A DUSTING.

THERE WILL BE A FAIRLY DEEP LAYER...UP TO AROUND 8KFT...OF
SATURATION HOWEVER...AND WITH TEMPERATURES WARMER THAN -10C
THROUGHOUT THAT LAYER...CONCERNED THIS COULD GENERATE SOME FREEZING
DRIZZLE SATURDAY AM FOR THE MISSOURI VALLEY. ALSO...WITH SOUTHEAST
LOW LEVEL FLOW...WINDS WILL INCREASE TO AROUND 20KTS. THIS WILL
GENERATE SOME FINGER DRIFTING BUT ON THE WHOLE WITH VERY LITTLE
ACTUAL SNOW ON THE GROUND SHOULD PRESENT AS ONLY A MINOR PROBLEM.

AND IT GETS MORE COMPLEX AS A NEGATIVELY TILTED SHORTWAVE CRASHES
THE UPPER RIDGE SATURDAY. WHILE NOT UNDER A FAVORABLE JET
REGION...WE DO SEE QUITE STRONG DIVERGENT/DIFFLUENT FLOW AT
300MB...AND THUS THE Q VECTOR BULLSEYE. TRANSLATION...RATHER RAPID
DEVELOPMENT OF PRECIP ACROSS THE CWA SATURDAY AFTERNOON/EVENING.
PROFILES FOR MUCH OF THE AREA ARE COLD ENOUGH WITH ICE INTRODUCTION
FOR MODERATE TO HEAVY SNOW. THE EXCEPTION WILL BE IN OUR SOUTHWEST
COUNTIES WHERE A FINGER OF MILD AIR AROUND 6KFT COULD CAUSE SOME
MELTING. NAM PROFILES SUGGEST THIS LAYER MAY NOT BE WARM/THICK
ENOUGH FOR A TOTAL TRANSFORMATION...AND WITH TEMPERATURES BELOW THE
LAYER AROUND 20F THE END RESULT IS PROBABLY SLEET...SO WILL JUST
BROADBRUSH THE SATURDAY NIGHT TIME PERIOD WITH SNOW. SREF
PROBABILITIES AND NAM/GFS QPF BULLSEYES ARE ALL FOCUSED OVER THE
CWA. AT THIS TIME...WITH SUCH A DYNAMIC WAVE YET TO HIT THE PACIFIC
NORTHWEST...EXPECT THERE WILL BE RATHER SIGNIFICANT CHANGES IN
GUIDANCE OVER THE NEXT 24 HOURS AND THUS WILL FORGO ANY HEADLINES.

OH...AND TO TOP IT OFF...WE WILL SEE VERY FAVORABLE MIXING
CONDITIONS AS THE STORM DEPARTS AND DISLODGES SOME OF THE MILDER AIR
TO THE WEST. THE RESULT WILL BE HIGHS IN THE 30S AND 40S
DESPITE POTENTIALLY QUITE A BIT OF FRESH SNOW COVER.

.LONG TERM...(MONDAY EVENING THROUGH THURSDAY)
ISSUED AT 348 AM CST FRI FEB 12 2016

THE LONG WAVE FLOW FOR THE LONG TERM CONTINUES TO LOOK LIKE A
POSITIVE PHASE PNA PATTERN...FEATURING A RIDGE OVER THE FAR WESTERN
CONUS WITH A TROF IN THE EAST...AND FAST FLOW IN BETWEEN. ONE SYSTEM
WILL BE MOVING AWAY FROM THE REGION EARLY IN THE PERIOD...WITH
ANOTHER ONE EXPECTED FOR MONDAY NIGHT THROUGH TUESDAY.  WHILE THE
MODELS AGREE THAT THERE WILL BE A SYSTEM...THEY DISAGREE ON THE
TRACK...AND THEREFORE WHERE THE PCPN WILL FALL.  GIVEN HOW FAR OUT
THAT IS...THE MODEL BLEND FEATURING LOW POPS FOR THE CWA WILL
SUFFICE FOR NOW...OR AT LAST UNTIL SOME AGREEMENT ON THE STORM TRACK
ENTERS THE PICTURE. AS HAS BEEN THE CASE RECENTLY...THERE WILL
CONTINUE TO BE A LARGE TEMPERATURE GRADIENT FROM WEST TO EAST ACROSS
THE CWA.  HOWEVER THAT SAID...MOST AREAS SHOULD EXPERIENCE ABOVE
NORMAL TEMPS BY THE END OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1137 AM CST FRI FEB 12 2016

VFR CONDITIONS SHOULD PREVAIL FOR ALL TERMINALS EXCEPT KPIR
THROUGH 12Z SATURDAY. KPIR SHOULD CONTINUE SEEING MVFR CIGS
THROUGH THE REST OF THE AFTERNOON THROUGH TONIGHT. A STORM SYSTEM
WILL BEGIN SPREADING LOW CLOUDS AND LIGHT TO THE TERMINALS OF
KMBG AND KPIR AROUND 12Z SATURDAY. THE LIGHT SNOW AND MVFR CIGS
COULD REACH KABR BY THE END OF THE VALID TAF PERIOD. WINDS WILL
ALSO INCREASE ABOVE 12 KNOTS FROM THE SOUTH-SOUTHEAST FOR ALL
TERMINALS AFTER 12Z. STRONGER WINDS ARE LIKELY NEAR THE END OF THE
VALID TAF PERIOD.

&&

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

$$

UPDATE...SD
SHORT TERM...CONNELLY
LONG TERM...TDK
AVIATION...SD


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