000
FXUS63 KABR 290134
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
834 PM CDT THU AUG 28 2008

.UPDATE...
MADE A FEW MINOR CHANGES TO THE GRIDS THIS EVENING...MAINLY TO
REMOVE THE MENTION OF STRONGER WIND GUSTS AFTER MIDNIGHT. RUC
MODEL INDICATED SOME WAA IN THE MID LEVELS LATER THIS EVENING WITH
SURFACE WINDS INCREASING AFTER SHORTLY AFTER SUNRISE. BELIEVE THE
AREA WILL SEE MOSTLY CLEAR SKIES AND LIGHT AND VARIABLE WINDS FOR
THE PART OF THIS EVENING SO HAVE DECREASED LOWS A FEW DEGREES.

NEW AVIATION DISCUSSION BELOW.


&&
.PREV DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
FORECAST CHALLENGES INCLUDE TEMPERATURES.

CURRENTLY...HIGH PRESSURE IS BUILDING INTO THE FORECAST AREA.

HIGH PRESSURE WILL STICK AROUND FOR THE NEXT FEW DAYS. RETURN FLOW
MOISTURE STARTS TO MAKE A DENT IN DEWPOINTS BY SATURDAY AFTERNOON.
THERE MAY BE A COUPLE OF ELEVATED SHOWERS OR THUNDERSTORMS TO DEAL
WITH EARLY SATURDAY MORNING. BUT NOT ENOUGH CERTAINTY TO ADD
MENTION IN THE WX/POP GRIDS JUST YET. TEMPERATURES WILL CONTINUE
AT OR BELOW NORMAL UNTIL SATURDAY...WHEN WAA SHOULD NUDGE
TEMPERATURES UP INTO THE MID 80S TO MID 90S CWA-WIDE.

.LONG TERM...SUNDAY THROUGH THURSDAY

MEDIUM RANGE MODELS AGREE FAIRLY WELL ON UPCOMING EXTENDED PERIOD.
AGAIN TODAY THERE ARE STILL SOME PROBLEMS IN THE DETAILS IN LATER
TIMES. ECMWF REMAINS A LITTLE SLOWER AND FARTHER WEST WITH THE
UPPER LEVEL H5 LOW. THIS WILL KEEP SOME TIMING ISSUES ALIVE FOR
THIS FORECAST PERIOD. THE PERIOD OPENS WITH A DIGGING TROUGH ALONG
THE WEST COAST OF THE UNITED STATES. THIS PUTS THIS AREA UNDER
SOUTHWEST FLOW ALOFT. FLOW OVER THE ROCKIES WILL INTRODUCE A LEE
SIDE SURFACE TROUGH AND A NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING NORTHEAST ALONG SURFACE TROUGH AXIS. BY MONDAY UPPER
LEVEL LOW IS OVER SOUTHERN IDAHO WITH VERY STRONG LOW LEVEL WARM
MOIST ADVECTION. TEMPERATURES OVER MUCH OF THE AREA AT H7 RANGE
FROM +10C TO +14C. AT THIS TIME THE H85 LOW LEVEL JET SPEEDS ARE
IN THE LOW 40S KTS. AND THAT HAS DIMINISHED FROM NEARLY 50 KTS
EARLIER IN THE NIGHT. THIS PERIOD WILL SEE VERY STRONG LOW LEVEL
JETS TRANSPORTING MOISTURE TO THE REGION. PRECIPITABLE WATER
VALUES MONDAY AFTERNOON ARE OVER 1.75 IN. AHEAD OF SLOW MOVING
COLD FRONT IN EASTERN SOUTH DAKOTA.  GFS ENSEMBLE MEANS SHOW VERY
GOOD AGREEMENT BETWEEN MEMBERS THROUGH THIS PERIOD. ECMWF IS A
LITTLE STRONGER AND THUS SLOWER WITH THIS SYSTEM. OVERALL THE
DIFFERENCE IS SLIGHT. CONFIDENCE IN THIS SYSTEM CONTINUES TO GROW.
IT IS A LITTLE PREMATURE TO PREDICT PRECIPITATION TRACK OR AMOUNT
HOWEVER GFS ENSEMBLE MEAN WOULD SUGGEST OVER .50 INCH ACROSS
NORTHEAST SOUTH DAKOTA.



&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24 HOURS WITH NO
SIGNIFICANT WEATHER.


&&

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

$$
UPDATE...SD
SHORT TERM...DORN
LONG TERM...KEEFE
AVIATION...SD

WEATHER.GOV/ABERDEEN