Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 131734 AAC
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1234 PM CDT SUN APR 13 2014

.UPDATE...
THE AVIATION DISCUSSION HAS BEEN UPDATED FOR THE 18Z TAF ISSUANCE.

REMOVED ALL MENTION OF SNOW FOR THE FAR SOUTHWEST CWA FOR THE REST
OF THE MORNING AS RADAR ECHOES HAVE PRETTY MUCH VANISHED. WEB CAMS
ACROSS LYMAN COUNTY ALSO SHOWING NO SNOW. ALSO SEEING A DECENT
AMOUNT OF CLEARING WORKING SOUTH ACROSS THE CWA SO HAVE ADJUSTED
SKY GRIDS ACCORDINGLY. CURRENT HIGHS APPEAR ON TRACK SO NO CHANGES
THERE. EARLIER WAS WORRIED HIGHS WOULD STRUGGLE TO CLIMB ALL TOO
MUCH WITH ALL THE CLOUD COVER...BUT NOW THAT SOME CLEARING IS
WORKING ITS WAY IN...WILL LEAVE TEMPS ALONE FOR THE TIME BEING AS
THEY SHOULD BE CLOSE.

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH TUESDAY

MAIN FCST CHALLENGE FACING THE NEAR TERM REVOLVES AROUND WHAT
TEMPS WILL DO TODAY...ALONG WITH WINDS NEARING WIND ADVRY
CRITERIA.

2-3MB PRESSURE RISES PER 3HRS ARE HELPING TO KEEP WINDS UP A BIT
OVERNIGHT...RESULTING IN LOWER LAYERS REMAINING WELL MIXED. ALL
SHORT TERM MODELS ARE ADVERTISING STRONG CAA REMAINING THROUGH THE
DAY...SO WINDS ARE EXPECTED TO STAY UP AS WELL THROUGH THE DAY.
WINDS WILL BUMP UP AGAINST WIND ADVRY CRITERIA THROUGH THE
DAY...BUT NOT SURE THEY WILL STAY SOLID IN CRITERIA...SO WILL
FORE GO ANY MENTION ATTM. ALSO...WITH EXTENSIVE CLOUD SHIELD IN
PLACE...NOT SURE THERE WILL BE MUCH RECOVERY IN THE TEMPS. HAVE
WORKED THE HOURLY TEMP GRIDS TO SHOW MAYBE A 1-3 TEMP RISE THROUGH
THE AFTERNOON...BUT OVERALL STEADY TEMPS ARE EXPECTED WITH THE
HIGH FOR THE DAY ALREADY OCCURRING AT MIDNIGHT. BASED ON COND PRES
DEFS HAVE ALSO HELD ONTO MOCLOUDY/CLOUDY SKIES A BIT LONGER
THROUGH THE DAY BEFORE CANADIAN HIGH PRESSURE SCOURS OUT THE
CLOUDS.

OTHERWISE REMAINDER OF SHORT TERM RATHER UNEVENTFUL. MONDAY
APPEARS TO BE A QUIET BUT COOL DAY AS CHILLY AIRMASS REMAINS IN
PLACE. WAA PUSH BEGINS MONDAY EVENING/NIGHT AHEAD OF NEXT
500HPA/700HPA TROFS TO AFFECT THE REGION TUESDAY NIGHT AND
WEDNESDAY. GOOD WAA AHEAD OF FEATURES COULD PUSH TEMPS ACROSS THE
SCENTRAL PART OF THE CWA WARMER THAN CURRENT FCST SHOWS...BUT
GIVEN SOME MODEL UNCERTAINTY AS TO STRENGTH AND NORTHWARD PUSH OF
WAA...WILL REMAIN CONSERVATIVE ACROSS THE FAR SW CWA.

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY

PRIMARY FORECAST CHALLENGES IN THE EXTENDED ARE PRECIPITATION CHANCES
AND P-TYPE ASSOCIATED WITH THE SYSTEM MID-WEEK.

TUESDAY NIGHT AND WEDNESDAY...FORECASTER CONFIDENCE: LOW

FAIRLY HIGH UNCERTAINTY REGARDING THE EVOLUTION OF THE SYSTEM
PERSISTS WITH THIS MODEL CYCLE. A PROGRESSIVE SHORTWAVE TROUGH IS
EXPECTED TO TRACK ACROSS THE NRN PLAINS TUESDAY NIGHT AND
WEDNESDAY. THIS WILL INDUCE A DEEPENING SFC/850MB LOW...ALTHOUGH
THE EXACT MAGNITUDE AND TRACK REMAIN IN QUESTION. THE 00Z GEM/NAM
ARE DEEPER/STRONGER WITH THE LOW WHEREAS THE 00Z GFS/ECMWF ARE
WEAKER AND MORE PROGRESSIVE. BASED ON PERFORMANCE THIS
WINTER/SPRING...WOULD GENERALLY GIVE MORE CREDENCE TO A ECMWF/GFS
BLEND AT THIS FORECAST RANGE. WITH THAT SAID...EXPECTING A BAND
OF WAA PRECIPITATION TO DEVELOP TUESDAY NIGHT...WITH IMPACTS
MAINLY AFFECTING ND/MN. AS THE SYSTEM SHIFTS EWD ON WEDNESDAY...A
MAJORITY OF THE MODELS INDICATE A MID-LEVEL FRONTOGENETIC
SIGNATURE DROPPING SWD THRU THE CWA. THE STRENGTH OF A CORRESPONDING
BAND OF PRECIP REMAINS PROBLEMATIC...WITH QPF AMOUNTS VARYING
FROM A TENTH TO UPWARDS OF A HALF AN INCH OF LIQUID. PTYPE SHOULD
BEGIN AS RAIN OR A RAIN/SNOW MIX WITH A GRADUAL TRANSITION TO ALL
SNOW AS COLDER AIR WRAPS IN FROM THE NORTH. A FEW MODELS ALSO
INDICATE THE POTENTIAL FOR A BRIEF PERIOD OF FREEZING
RAIN/SLEET...SO WILL NEED TO MONITOR THIS TREND AS WELL. BOTTOM
LINE...QUITE A FEW DETAILS NEED TO BE IRONED OUT OVER THE NEXT
COUPLE DAYS...AND FURTHER ADJUSTMENTS TO THE FORECAST ARE LIKELY.

WEDNESDAY NIGHT THROUGH SATURDAY...FORECASTER CONFIDENCE: MODERATE

IN THE WAKE OF THE AFOREMENTIONED SYSTEM...THE 00Z DETERMINISTIC
MODELS HAVE TRENDED CONSIDERABLE DRIER FOR THE END OF THE WEEK AS A
LARGE AREA OF COLD...BUT DRY HIGH PRESSURE BUILDS INTO THE REGION.
BASED ON COLLABORATION WITH NEIGHBORING OFFICES DECIDED TO CUT THE
MENTION OF PRECIPITATION FOR MOST LOCALES ON THURSDAY THROUGH SATURDAY.
TEMPERATURES WILL BEGIN MUCH BELOW NORMAL ON THURSDAY...WITH A
GRADUAL WARMING TREND INTO THE WEEKEND.

&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

MOST OF THE MVFR CIGS WILL END OVER THE FORECAST AREA THIS
AFTERNOON. MEANWHILE GUSTY WINDS WILL CONTINUE INTO THE EARLY
EVENING BEFORE LOSING THEIR GUSTINESS. ANOTHER DECK OF LOWER VFR
CLOUDS IS EXPECTED TO MOVE IN LATE TNT OR MONDAY MORNING.

&&

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

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

WEATHER.GOV/ABERDEEN







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