Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 160248 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
948 PM CDT TUE APR 15 2014

.UPDATE...
WITH JUST A FEW HOURS REMAINING BEFORE A VIGOROUS UPPER
CIRCULATION OVER SOUTHERN MT/NORTHERN WY WORKS ITS WAY OUT ONTO
THE NORTHERN PLAINS...MODELS SHOULD BE CONVERGING ON A PRECIP
SOLUTION. THAT DOESN`T SEEM TO BE THE CASE THIS EVENING. THE 18Z
GFS/NAM SOLUTIONS /AND NOW THE 00Z NAM SOLUTION/ ALL CONTINUE TO
HIGHLIGHT A LARGE QPF/SNOW ACCUM BULLS-EYE ACROSS PORTIONS OF
CENTRAL AND NORTH CENTRAL SOUTH DAKOTA THROUGH SUNRISE
WEDNESDAY...BUT THE LATEST OUTPUT FROM THE HOURLY UPDATE MODEL
/RAPID REFRESH MODEL/ SUGGESTS LITTLE IF ANY PRECIPITATION WILL BE
FALLING ACROSS SAID AREA BY SUNRISE. ASSUMING THE RAPID REFRESH
MODEL HAS CHECKED OUT FOR A FEW FORECAST CYCLES THIS
EVENING...STILL EXPECTING AN OVERALL INCREASING TREND IN PRECIP
RETURNS/COVERAGE ON RADAR HEADING TOWARD MORNING. PREVIOUS
THINKING STILL HOLDS...STRONG FRONTO-FORCING/LIFT/INSTABILITY
COMBO IN PLACE LATE TONIGHT THROUGH WEDNESDAY AFTERNOON FOR A
MESO-SCALE HEAVY BANDED PRECIPITATION EVENT...WHERE P-TYPE ON THE
FRONT END OF THE EVENT WILL BE EITHER RAIN OR A MIXTURE OF
FREEZING RAIN AND SLEET TRANSITIONING TO SNOW WITH 6 OR MORE HOURS
OF POTENTIAL FOR MODERATE TO HEAVY SNOW BENEATH A MESO-SCALE
BANDED FEATURE /WHERE EVER IT ENDS UP SETTING UP/. TRIED TO
HIGHLIGHT BANDED PRECIP HIGHER AMOUNTS IN WSW UPDATE.
BREEZING/WINDY EASTERLY WINDS FOR A FEW MORE HOURS SWITCHING TO
NORTHERLY AND INCREASING ON WEDNESDAY...SO ALONG AND EAST OF THE
JAMES RIVER VALLEY FROM LATE WEDNESDAY MORNING THROUGH EARLY
WEDNESDAY EVENING THAT SNOW/BLOWING SNOW POTENTIAL WITH MARKEDLY
REDUCED VISIBILITIES IS STILL IN PLACE.

SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT

AN INTERESTING FORECAST TO SAY THE LEAST...WITH PCPN TYPE/AMOUNTS
THE MAIN PROBLEM. FOR TNT DECENT LOOKING SYSTEM OVER THE NORTHERN
ROCKIES WILL BE DIGGING SOUTH AND EJECTING INTO THE NORTHERN
PLAINS. UVM PER VARIOUS OMEGA/Q VECTOR/FRONTOGENESIS/DIVERGENCE
PROGS STILL LOOKS PRETTY IMPRESSIVE ACROSS MY NORTHEASTERN CWA
AFTER ABOUT MIDNIGHT...LASTING UNTIL ABOUT NOON OVER THE FAR EAST.
ONE NOTED CHANGE BETWEEN THE MOST RECENT RUNS AND PAST RUNS IS THE
FASTER CHANGE OVER TO ALL SNOW. BOTH THE GFS/NAM NOW INDICATE
LESSER CHANCES FOR FZRA VS SNOW/SLEET. THIS COULD ADD MORE TO
ACCUMULATION TOTALS VS PREVIOUS THOUGHTS/IDEAS. THE GOOD NEWS IS
THE STORM APPEARS TO BE FAIRLY PROGRESSIVE DESPITE A CLOSING OFF
H7 LOW OVER NORTHEAST SOUTH DAKOTA...SO IMPROVEMENT SHOULD OCCUR
DURING THE MIDDLE TO LATER PART OF THE AFTERNOON AS SYSTEM MOVES
AWAY FROM THE REGION. THE JUXTAPOSITION OF ALL ELEMENTS STILL
APPEARS TO TARGET THE UPPER MISSISSIPPI RIVER VALLEY WITH THE
WORST IMPACTS. NONETHELESS...FEEL AN ADVISORY IS JUSTIFIED OVER MY
NORTHEAST CWA GIVEN OCCURRENCE OF MIXED PCPN TYPE/ACCUMULATING
SNOW/SLEET RIGHT BEFORE THE START OF MORNING TRAVEL TO/FROM WORK
AND SCHOOL. SO AN ADVISORY WILL BE HOISTED FOR LATE TNT THROUGH
THE DAY ON WEDNESDAY OVER NORTHEAST SOUTH DAKOTA AND WEST CENTRAL
MINNESOTA. THE REST OF THE FORECAST LOOKS FAIRLY TRANQUIL AS S/W
RIDGING BUILDS A HEAD OF THE NEXT SYSTEM. TEMPERATURES OVERALL
WILL GRADUALLY BE ON THE REBOUND POST WEDNESDAY...WITH ABOVE
NORMAL TEMPS POSSIBLE BY THE WEEKEND.


.LONG TERM...FRIDAY THROUGH TUESDAY
AN UPPER RIDGE WILL EXTEND ACROSS THE CENTRAL CONUS AT THE ONSET
OF THE PERIOD. HOWEVER...AN UPPER LOW WILL SKIRT ACROSS CANADA
WITH THE ASSOCIATED FRONTAL BOUNDARY SWEEPING ACROSS THE NORTHERN
PLAINS. MOISTURE PROFILES HAVE MID LEVEL DRY AIR IN PLACE
INITIALLY...BUT LOOK TO SATURATE QUICKLY ALONG THE FRONT.
THEREFORE THE FORECAST HOLDS SLIGHT CHANCE TO CHANCE POPS FOR
LIGHT RAIN SATURDAY. OTHERWISE PRETTY QUIET IN THE LONG TERM.
THERE MAY BE SOME WEAK SHORTWAVE ENERGY MOVING ACROSS THE REGION
LATE SUNDAY AND MONDAY...BUT REALLY NO MODEL CONSENSUS WITH THAT
FEATURE. MODELS DO AGREE ON AN UPPER RIDGE BUILDING OVER THE
REGION BY EARLY NEXT WEAK HOWEVER...AND TEMPERATURES SHOULD RETURN
TO MORE SEASONAL VALUES...EVEN ABOVE NORMAL BY EARLY NEXT WEEK AS
MODEL 925 MB TEMPERATURES RISE INTO THE TEENS...MAYBE EVEN 20S BY
MONDAY AND TUESDAY.


&&

.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CIGS/VSBYS AND GUSTY SOUTHEASTERLY WINDS ARE EXPECTED FOR AT
LEAST ANOTHER 6 HOURS BEFORE POTENTIAL FOR DETERIORATING
CONDITIONS STARTS RAMPING UP. FORECASTER CONFIDENCE REMAINS LOW
WITH THE P-TYPE DETAILS ASSOCIATED WITH A LOW PRESSURE SYSTEM
MOVING INTO THE REGION TONIGHT. INITIALLY...BOUNDARY LAYER TEMPS
ACROSS THE WESTERN CWA APPEAR WARM ENOUGH TO SUPPORT RAIN P-TYPE
WHILE THE ATMOSPHERE SATURATES DOWN/COOLS DOWN. ONCE
SATURATED...THE LOWEST THREE TO FOUR THOUSAND FEET AGL ARE
FORECAST TO BE COLD ENOUGH FOR P-TYPE TO BE SWITCHING OVER TO
SNOW. IT`S IN THIS PERIOD OF TRANSITION/SATURATION LATE THIS
EVENING THROUGH EARLY WEDNESDAY MORNING THAT P-TYPE COULD BE
FLIRTING WITH A COUPLE OF HOURS OF FREEZING RAIN AND/OR SLEET.
THE POTENTIAL FOR THIS POSSIBLE MIXTURE OF DIFFERENT WINTER-TIME
P-TYPES WILL EXIST AT KMBG AND KPIR MAINLY BETWEEN APPX 04Z AND
10Z BEFORE P-TYPE IS FORECAST TO BE ALL SNOW. THE TIME RANGE FOR
THIS POTENTIAL FOR VARIOUS P-TYPES WILL ALSO EXIST AT THE KABR AND
KATY TERMINALS...BUT LATER IN TIME...MAINLY BETWEEN 08Z AND 14Z
WEDNESDAY. THE THREAT OF A HEAVY BAND OF PRECIPITATION DEVELOPING
BY MORNING IS ALSO STILL VERY REAL. THE LATEST GUIDANCE FROM THE
18Z GFS SUGGESTS A BAND OF MODERATE TO HEAVY PRECIP WILL DEVELOP
JUST SOUTH OF MOBRIDGE AND EXTEND EASTWARD THROUGH KABR AND ON
INTO WEST CENTRAL MN NEAR WHEATON. CIGS AND VSBYS WILL BE REDUCED
TO IFR CATEGORIES UNDER SNOW OR MIXED PRECIPITATION. WINDS WILL
SWITCH FROM THE SOUTHEAST AROUND TO THE NORTH NORTHEAST
BY MORNING...REMAINING GUSTY THROUGH THE TAF PERIOD. MVFR STRATUS
IS EXPECTED IN THE COLD AIR ON THE BACK SIDE OF THE
SYSTEM...PERSISTING THROUGH THE END OF THE TAF PERIOD.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CDT WEDNESDAY FOR
     CLARK-CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS.

     WINTER WEATHER ADVISORY UNTIL 6 PM CDT WEDNESDAY FOR BROWN-
     EDMUNDS-FAULK-MCPHERSON-SPINK.

MN...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CDT WEDNESDAY FOR BIG
     STONE-TRAVERSE.

&&

$$
UPDATE...DORN
SHORT TERM...TDK
LONG TERM...SERR
AVIATION...DORN

WEATHER.GOV/ABERDEEN





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