Area Forecast Discussion
Issued by NWS Aberdeen, SD

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KABR 210124
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
824 PM CDT SUN JUL 20 2014

.UPDATE...

TWO MAIN CHANGES WERE MADE TO THE FORECAST THIS EVENING. RADAR
IMAGERY NICELY DEPICTS THE DENSITY GRADIENT WEST OF ABR. THIS
BOUNDARY HAS ACTUALLY BEEN RETREATING TO THE NORTHWEST...ALONG
WITH THE MORE ABUNDANT MOISTURE. DEWPOINTS WILL LIKELY REMAIN HIGH
AHEAD OF IT...THEREFORE ADJUSTED MIN TEMPS UP SLIGHTLY TO BETTER
REFLECT CURRENT THINKING. SECONDLY...REMOVED PRECIP CHANCES FROM
THE NORTHEAST AS 00Z SOUNDING DEPICTS VERY STRONG BOUNDARY LAYER
INHIBITION. VISIBLE SATELLITE IMAGERY IS ALSO DEVOID OF ANY
CUMULUS WHATSOEVER. THE REST OF THE FORECAST LOOKS GOOD WITH A
CONTINUED EMPHASIS ON THE SEVERE WEATHER THREAT TOMORROW.

&&
.PREVIOUS DISCUSSION...
..SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
TIMING OF SEVERE STORMS ON MONDAY WILL BE THE MAIN FORECAST CHALLENGE.

THE CWA IS CURRENTLY BISECTED BY A NORTH/SOUTH DRY LINE WITH DEW
POINTS IN THE LOWER 70S IN THE EAST...TO THE MID 60S AND LOWER
FURTHER WEST. A FEW RUNS OF THE RAPID REFRESH AND THE 12Z NSSL WRF
TRY TO DEVELOP CONVECTION ALONG THE DRY LINE OVER THE EXTREME NE
PORTION OF THE CWA WHERE H7 TEMPS ARE BELOW 12C. THUS WILL
MAINTAIN A LOW POP FOR THIS EVENING. A MOIST ENVIRONMENT WILL
REMAIN ACROSS THE CWA TONIGHT WHICH WHEN COMBINED WITH LIGHT WINDS
COULD LEAD TO PATCHY FOG OR MORE LIKELY LOW LEVEL STRATUS.
CONTINUED WAA IN THE LOW TO MID LEVEL MAY LEAVE THE LOW STRATUS IN
PLACE THROUGH THE MID MORNING HOURS BEFORE LIFTING.

THERE IS REASONABLE AGREEMENT AMONG MODELS WITH THE PLACEMENT OF A
SURFACE LOW PRESSURE SYSTEM AND QUASI-STATIONARY FRONT DISPLAYED
ACROSS THE DAKOTAS. MOST MODELS NOW SHOW THE FRONTAL BOUNDARY
DISPLACED A LITTLE FURTHER NORTH...OR BETWEEN THE ND/SD BORDER AND
I-94. AN EXTREMELY UNSTABLE ENVIRONMENT WITH ML-CAPE VALUES
EXCEEDING 4000 J/KG ALONG AND SOUTH OF THE FRONTAL BOUNDARY WILL
DEVELOP BY THE AFTERNOON ON MONDAY. A S/W TRACKING ACROSS THE
REGION DURING PEAK HEATING WILL CAUSE CONVECTION TO DEVELOP ALONG
THE FRONT WITH SUPERCELL/MULTICELLS POSSIBLE. THUNDERSTORMS COULD
CONSOLIDATE INTO A FORWARD PROPAGATING MCS WITH DESTRUCTIVE WINDS
HIGHLY LIKELY. CONVECTION SHOULD TRACK SE ACROSS AT LEAST THE
NORTHEASTERN PORTION OF THE CWA BETWEEN 0-6Z TUESDAY...OR AS THE
NAM/ECMWF/HI-RES ARW/NMM WOULD INDICATE. ONLY THE GFS KEEPS THIS
LOCATION MOSTLY THUNDERSTORM FREE DUE TO A STOUT EML WITH 700 MB
TEMPS EXCEEDING 13C. WHILE THE STORM MOTION IS AROUND 20
KNOTS...PWATS ARE EXTREMELY HIGH...OVER TWO INCHES PER THE NAM12
IN NE SD AND WEST CENTRAL MN. THUS PRECIPITATION AMOUNTS EXCEEDING
ONE INCH SEEMS LIKELY.

COOLER AND LESS HUMID CONDITIONS ARE EXPECTED FOR TUESDAY AND
TUESDAY NIGHT.

.LONG TERM...WEDNESDAY THROUGH SUNDAY
THE MODELS AGREE WELL THROUGH THE LONG TERM WITH THE UPPER LEVEL
AND SURFACE FEATURES. THE PERIOD BEGINS WITH THE MODELS SHOWING A
CLOSED UPPER LEVEL HIGH PRESSURE AREA CENTERED OVER CO/NM WITH 50H
RIDGING EXTENDING NORTHWARD INTO CENTRAL CANADA. ALSO...A STRONG
UPPER LEVEL LOW PRESSURE AREA WILL BE MOVING INTO THE PACIFIC
NORTHWEST. THIS UPPER LOW PRESSURE AREA WAS SHOWN BY THE MODELS TO
MOVE INTO AND ACROSS SOUTHERN CANADA THROUGH THE END OF THE WEEK
DROPPING SOUTHEAST AND INTO THE GREAT LAKES REGION BY SUNDAY EVENING.
AT THE SURFACE...CANADIAN HIGH PRESSURE EAST IN OUR REGION WILL
BRING A COUPLE BELOW NORMAL TEMPERATURE DAYS MAINLY TO THE EASTERN
CWA WITH HIGHS IN THE UPPER 70S TO THE LOWER 80S FOR WEDNESDAY AND
THURSDAY.

SOUTH WINDS BEHIND THE RETREATING SURFACE HIGH PRESSURE AREA WILL
BRING IN MOISTURE AND INSTABILITY UNTIL A SURFACE FRONT COMES
THROUGH FRIDAY AND FRIDAY NIGHT. THE WINDS WILL THEN TURN NORTHWEST
FOR SATURDAY AND SUNDAY WITH A COOL DOWN...ESPECIALLY FOR SUNDAY
ALONG WITH INCREASING WINDS. SUNDAY SHOULD BE BACK IN THE UPPER
70S ACROSS THE EASTERN CWA. HAVE IN SEVERAL CHANCES OF STORMS
THROUGH THE PERIOD AS SHORT WAVES COME OVER THE REGION FROM THE WEST
INTERACTING WITH THE MOIST AND UNSTABLE AIR UNTIL A SURFACE FRONT
FROM THE WEST COMES THROUGH FRIDAY AND FRIDAY NIGHT. THERE MAY
THEN BE SOME COOLER AIR INSTABILITY SHOWERS/STORMS FOR SATURDAY
AND SUNDAY MAINLY EAST IN THE CWA.


&&

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

AREAS OF LOW CLOUDS AND FOG IS POSSIBLE AT KATY AND KABR BETWEEN
12Z-15Z MONDAY MORNING. OTHERWISE VRF CONDITIONS ARE EXPECTED TO
PREVAIL THROUGH THE PERIOD.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY FROM 11 AM CDT /10 AM MDT/ TO 9 PM CDT /8 PM MDT/
     MONDAY FOR BROWN-BUFFALO-CLARK-CODINGTON-DAY-DEUEL-FAULK-
     GRANT-HAMLIN-HAND-HUGHES-HYDE-JONES-LYMAN-MARSHALL-ROBERTS-
     SPINK-STANLEY-SULLY.

MN...HEAT ADVISORY FROM 11 AM TO 9 PM CDT MONDAY FOR BIG STONE-
     TRAVERSE.

&&

$$
UPDATE...TVT
SHORT TERM...SD
LONG TERM...MOHR
AVIATION...SCARLETT

WEATHER.GOV/ABERDEEN





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.