Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 121153
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
653 AM CDT SAT APR 12 2014

.UPDATE...

SEE UPDATED AVIATION DISCUSSION FOR 12Z TAFS BELOW.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH 00Z TUESDAY
MAIN FCST CHALLENGE FACING THE NEAR TERM DEALS WITH PCPN CHANCES
LATER THIS AFTERNOON THROUGH THE OVERNIGHT HOURS.

EARLY ON THIS MORNING...SOME ACCAS SHOWERS HAVE DEVELOPED ACROSS
ERN PART OF CWA IN RESPONSE TO MID LEVEL WAVE TRAVERSING OVER
REGION ALONG WITH 850HPA JET POKING INTO THE AREA. VERY LITTLE IN
THE WAY OF MOISTURE IS HITTING THE GROUND. BY TIME OF ZONE
RELEASE..EXPECT MAJORITY OF PCPN TO HAVE MOVED INTO MN AND OUT OF
CWA...SO SEE NO NEED TO INCLUDE IN ZONE FORECASTS AN EARLY MORNING
PERIOD. OTHERWISE MODELS ARE STILL ADVERTISING ONE MORE MILD
TEMPERATURE DAY TODAY AS 850HPA WAA WILL BE REPLACED BY CAA AOA
18Z THIS AFTERNOON. SHOULD BE ENOUGH MIXING WINDS TO KEEP TEMPS
FROM PLUMMETING TO FAR ONCE COLD AIR BEGINS TO SWEEP INTO REGION.

ATTENTION THEN TURNS TOWARD TIME PERIOD FROM ROUGHLY 00Z SUNDAY TO
18Z SUNDAY. GFS/EC SHOW NEXT 700HPA TROF SLIDING SOUTHEAST THROUGH
REGION IN CYCLONIC 700HPA FLOW. NAM12 IS HIGHLIGHTING PCPN QUITE A
BIT FAR NORTH...AND GIVEN STRENGTH OF SFC HIGH PRESSURE PUSHING
INTO THE CWA DURING TIME PERIOD...HAVE DOUBTS AS TO NORTHWARD
PLACEMENT OF PCPN. LOOKING AT 700HPA AND 850HPA THETA-E SFCS...ESP
ON THE GFS...DOWNGLIDE SEEN THROUGH ENTIRE TIME FRAME...BOLSTERING
FEELING THAT THERE WILL BE A RATHER SHARP AND DISTINCT LINE
BETWEEN PCPN/NO PCPN. FOR NOW PUSHED HIGHER POPS ALONG AND SOUTH
OF I-90 CORRIDOR. ALONG WITH THAT THINKING...COND PRESS DEFS ALSO
SUPPORT THE THINKING OF A SHARP AND DISTINCT LINE ASSOCIATED WITH
CLOUD SHIELD.

STRENGTH OF CAA WOULD SUGGEST THAT WINDS WOULD NEED A BIT OF
BOLSTERING THROUGH THE NIGHT AND SUNDAY. IF PTSUNNY TO MOSUNNY
SKIES DO VERIFY ACROSS THE NRN TIER COUNTIES...MIXING MAY RESULT
IN HIGHER WINDS YET. BASICALLY ADDED A CATEGORY TO ALL WINDS
THROUGH 12Z MONDAY.

VERY SUBTLE 850HPA AND 700HPA THETA-E RIDGE SLIDES ACROSS NERN CWA
DURING THE DAY MONDAY ASSOCIATED WITH WEAK 700HPA VORT DROPPING
THROUGH. HAVE ADDED SOME SLIGHT CHC POPS ACROSS THE FAR NERN
CORNER OF THE CWA TO ACCOUNT FOR THIS. SHOULD BEGIN AS LIGHT
SNOW/FLURRIES AND MAY TRANSITION TO SPRINKLES AS AFTN TEMPS
STRUGGLE INTO THE MID-UPPER 30S.


.LONG TERM...MONDAY NIGHT THROUGH FRIDAY

FORECAST CHALLENGES IN THE EXTENDED RANGE REVOLVE AROUND MIDWEEK PRECIP
CHANCES AND ROLLER COASTER TEMPERATURE TRENDS.

MONDAY NIGHT THROUGH TUESDAY...FORECASTER CONFIDENCE: MODERATE

SYNOPTIC PATTERN EARLY IN THE EXTENDED FEATURES A LONGWAVE TROUGH
EXTENDING FROM THE GREAT LAKES AREA SWD INTO THE SRN PLAINS...WITH
ANOTHER UPPER LEVEL SHORTWAVE MOVING ONSHORE ALONG THE PAC NW. AT
THE SFC...WEAK HIGH PRESSURE WILL BE REPLACED BY FALLING PRESSURE
ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE MOVING IN THE FROM
WEST. EXPECTING DRY CONDITIONS THROUGH TUESDAY EVENING DUE TO
MINIMAL FORCING/LIFT AND A RESIDUAL DRY LOWER ATMOSPHERE.
TEMPERATURES WILL BE CHALLENGING...AS THE 00Z ECMWF SHOWS A MORE
PRONOUNCED LOW LEVEL WAA PATTERN THAN THE OTHER GLOBAL SPECTRAL
MODELS DUE TO A MORE NORTHERLY TRACK OF THE H8 LOW. A CONSENSUS
APPROACH...WITH A BIT MORE WEIGHT TO THE USUALLY MORE SKILLFUL
ECMWF APPEARED REASONABLE.

TUESDAY NIGHT THROUGH FRIDAY...FORECASTER CONFIDENCE: LOW TO MODERATE

MORE UNSETTLED WEATHER APPEARS POISED TO RETURN MIDWEEK AS THE THE 00Z
SUITE OF DETERMINISTIC MODELS SHOW A SERIES OF DISTURBANCES TO
IMPACT THE NORTHERN PLAINS. UNFORTUNATELY AT THIS RANGE /DAY
4-6/...THE USUAL ISSUES WITH TIMING...MAGNITUDE...AND PLACEMENT OF
FRONTAL BOUNDARIES LEADS TO A LESS THAN STELLAR AGREEMENT ON
MESOSCALE DETAILS. THE GENERAL CONSENSUS INDICATES AN ENHANCED
POTENTIAL FOR ONE OR MORE ROUNDS OF PRECIPITATION FROM TUESDAY
NIGHT TO WEDNESDAY NIGHT. THE 00Z GFS SUGGESTS PRECIPITATION
LINGERING EVEN LONGER /THRU THURSDAY NIGHT/ BUT WILL DISCOUNT THIS
OUTLIER SOLUTION FOR THE TIME BEING. PRECIPITATION TYPE WILL ALSO
BE AN ISSUE AS A SIGNIFICANT SURGE OF COLD AIR IS EXPECTED TO WRAP
IN FROM THE NORTH. KEPT THE MENTION OF RAIN OR SNOW IN THE
FORECAST FOR NOW...WITH HIGHS GENERALLY UP IN THE 40S. BUT WOULD
NOT BE SURPRISED IF SOME LOCATIONS PICK UP A FEW INCHES OF SNOW
MID TO LATE WEEK...ESPECIALLY IF THE COLDER RAW MODEL OUTPUT IS
CORRECT. OLD MAN WINTER IS NOT QUITE READY TO GIVE UP JUST YET. BY
NEXT WEEKEND...TEMPS LOOK TO REBOUND WITH READINGS TRENDING BACK
TOWARD SEASONAL AVERAGES.


&&

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

PREVAILING VFR CONDITIONS ARE EXPECTED FOR ALL TERMINALS THROUGH
THE DAYTIME PERIOD...WITH JUST SOME HIGH CIRRUS CLOUDS PASSING THROUGH.
A COLD FRONT WILL DROP SWD THROUGH THE DAKOTAS LATE THIS AFTERNOON
AND EVENING. THIS WILL SHIFT WINDS OUT OF THE NORTH/NORTHWEST AND BECOME
GUSTY. SCATTERED SHOWERS WILL ALSO BE POSSIBLE ALONG THE FRONT IN
SOUTHERN SOUTH DAKOTA. ALTHOUGH OF FEW SHOWERS COULD IMPACT
KPIR...WILL LEAVE OUT OF THE KPIR TAF FOR NOW DUE TO LOW
PROBABILITY OF OCCURRENCE. BEHIND THE COLD FRONT...A MUCH COLDER AIRMASS
WILL LIKELY LEAD TO LOW STRATUS CLOUD DEVELOPMENT. INSERTED MVFR
CIGS AT ALL TERMINALS AFTER 06Z TONIGHT...ALTHOUGH WILL NEED TO
MONITOR POTENTIAL FOR EVEN LOWER IFR TYPE CIGS.


&&

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

$$
UPDATE...FOWLE
SHORT TERM...HINTZ
LONG TERM...FOWLE
AVIATION...FOWLE

WEATHER.GOV/ABERDEEN





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