Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 220542 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1142 PM CST SUN DEC 21 2014

.UPDATE...

SEE UPDATED AVIATION DISCUSSION BELOW.

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

MAIN STORY REMAINS THE LOW PRESSURE SYSTEM SLIDING SOUTHEAST
ACROSS THE DAKOTAS TONIGHT...THEN INTENSIFYING AS IT MOVES EAST.
TONIGHT...MODELS VARY IN QPF BUT ALL HINT AT MOISTURE SURGING
NORTHWARD ACROSS THE I-29 CORRIDOR AND POINTS EAST. GIVEN THE
EXPECTED TEMPS TONIGHT...THIS WILL LIKELY BE A MIX OF
RAIN...FREEZING RAIN...SLEET OR SNOW. FURTHER WEST...THERE IS SOME
QUESTION OVERNIGHT AS TO THE AREAL COVERAGE OF PRECIP THAT MAKES
IT INTO THE WESTERN CWA. INITIALLY...THERE IS A THREAT FOR MIXED
PRECIP...BUT THEN BY MORNING SOUNDINGS APPEAR COLD ENOUGH TO
CHANGE THINGS OVER TO SNOW.

STILL QUITE A BIT OF UNCERTAINTY MONDAY THROUGH TUESDAY IN OVERALL
EVOLUTION OF STORM SYSTEM...ALTHOUGH MODELS ARE IN DECENT
AGREEMENT. THINGS HAVE SLOWED DOWN JUST A BIT...TO WHERE NOW IT
APPEARS THE MAJORITY OF SNOWFALL MAY COME MONDAY NIGHT INTO
TUESDAY. EC AND NAM OFFER UP THIS SOLUTION WHEREAS THE GFS BRINGS
THINGS IN A BIT QUICKER ON MONDAY AFTERNOON. WINDS WILL INCREASE
ACROSS THE WESTERN CWA MONDAY AFTERNOON...BUT NOW IT APPEARS AS IF
THE STRONGER WINDS WILL HOLD OFF ACROSS THE EASTERN COUNTIES UNTIL
TUESDAY. ITS VERY LIKELY THAT THE MORE SIGNIFICANT IMPACTS HOLD
OFF UNTIL MONDAY NIGHT OR TUESDAY ONCE THE WINDS INCREASE. STILL
LOTS TO BE SORTED OUT HERE IN REGARDS TO THIS STORM SO THAT IS WHY
THERE ARE NO HEADLINES CURRENTLY. WILL LET LATER SHIFTS SORT
THROUGH THE 00Z MODEL DATA TO SEE IF IT OFFERS UP MORE CONFIDENCE
IN THE OVERALL OUTCOME OF THE STORM SYSTEM.


.LONG TERM...WEDNESDAY THROUGH SUNDAY
A DEEP UPPER LEVEL TROUGH WILL BE OVER THE MIDDLE PART OF THE
COUNTRY WHEN THE PERIOD STARTS. THE TROUGH PUSHES EAST ON
WEDNESDAY AS ANOTHER WAVE MOVES OVER THE PACIFIC NORTHWEST. THIS
WAVE LOOKS TO TRACK ACROSS EITHER THE NORTHERN OR CENTRAL PLAINS
THURSDAY AFTERNOON/NIGHT...DEPENDING ON THE MODEL...WITH THE GFS
BEING FURTHER NORTH THAN THE ECMWF. THESE SAME DIFFERENCES SHOW UP
IN THE SURFACE PATTERN. AFTER A DAY OF WEAK HIGH PRESSURE ON
WEDNESDAY...A LOW PRESSURE SYSTEM WILL APPROACH THE PLAINS. THE
GFS TRACKS THE LOW ACROSS NORTHERN SOUTH DAKOTA...KEEPING THE
MAJORITY OF THE PRECIPITATION OVER NORTH DAKOTA. THE ECMWF TRACKS
THE LOW ACROSS KANSAS...WITH THE PRECIPITATION OVER SOUTHERN SOUTH
DAKOTA AND NEBRASKA. FOR NOW...WILL STICK WITH THE SUPERBLEND
WHICH SEEMS TO FOLLOW CLOSER TO AN ECMWF SOLUTION. THE REMAINDER
OF THE PERIOD LOOKS TO BE DRY AS HIGH PRESSURE DOMINATES. MODELS
HINTING AT LOW PRESSURE RETURNING LATE IN THE PERIOD...BUT NOT
EVEN CLOSE TO AGREEING ON A SOLUTION...SO WILL JUST LEAVE THE TIME
PERIOD FROM FRIDAY THROUGH SUNDAY DRY.

TEMPERATURES WILL BE RIGHT AROUND NORMAL WEDNESDAY AND THURSDAY
WITH HIGHS MAINLY IN THE 20S TO LOWER 30S. COOLER AIR THEN MOVES
IN BEHIND THE EXITING LOW PRESSURE SYSTEM. HIGHS FRIDAY THROUGH
SUNDAY WILL GENERALLY BE IN THE TEENS TO LOWER 20S...WITH
OVERNIGHT LOWS IN THE SINGLE DIGITS.


&&

.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

IFR CIGS/VSBY WILL CONTINUE TO AFFECT MOST OF THE REGION WITH THE
EXCEPTION OF KPIR THROUGH THE MORNING. AN AREA OF LOW PRESSURE
WILL MOVE ACROSS SD MON AND MON NIGHT. WHILE THERE MAY BE SOME
DRIZZLE OR BRIEF PERIODS OF LIGHT RAIN/SNOW AHEAD OF THE LOW
TEMPERATURES AND FORCING WILL NOT SUPPORT ACCUMULATING SNOW
ANYWHERE BUT BEHIND THE LOW. HAVE PRECIP ENTERING KMBG/KPIR BY
LATE MORNING/EARLY AFTERNOON AS WINDS ALSO SWITCH TO THE NORTHWEST
AND INCREASE. SNOW WILL LIKELY NOT IMPACT KATY OR KABR UNTIL
BETWEEN 0Z AND 6Z TUESDAY.


&&

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

$$
UPDATE...WISE
SHORT TERM...TMT
LONG TERM...PARKIN
AVIATION...WISE

WEATHER.GOV/ABERDEEN






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