Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 191731 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1231 PM CDT SUN APR 19 2015

.UPDATE...
ISSUED AT 1106 AM CDT SUN APR 19 2015

NO MAJOR CHANGES TO THE FORECAST OTHER THAN THE EARLY REMOVAL OF
POPS WITH DEPARTING SYSTEM...ONLY TO HAVE SCT COVERAGE OF LIGHT
SHOWERS THIS AFTERNOON DUE TO DIABATIC HEATING...WHICH IS WELL
DEPICTED WITHIN A MAJORITY OF HIGH RES GUIDANCE.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 334 AM CDT SUN APR 19 2015

SHOWERS WILL GRADUALLY END FROM WEST TO EAST THIS MORNING AS DRIER
AIR MOVES IN BEHIND THE PASSAGE OF A SURFACE COLD FRONT. THE
CURRENT SHOWERS SHOULD EXIT THIS CWA BEFORE 18Z...WITH A FEW HOURS
OF DRY CONDITIONS LIKELY. WHILE PRECIPITATION WILL END...GUSTY
NORTHWESTERLY WINDS WILL DEVELOP WITH THE STRONGEST WINDS
OCCURRING ALONG AND WEST OF THE MISSOURI RIVER. SUSTAINED WINDS
OF 25 TO 35 MPH WITH GUSTS AROUND 45 MPH ARE LIKELY WEST RIVER
THIS AFTERNOON. AROUND 21Z VARIOUS HI-RES MODELS SHOW INSTABILITY
SHOWERS THANKS TO STEEP LOW LEVEL LAPSE RATES AND WEAK CAPE
VALUES...MOVING INTO THIS CWA FROM NORTH DAKOTA. THESE SHOWERS
SHOULD DIMINISH SHORTLY AFTER SUNSET.

AN AREA OF HIGH PRESSURE BUILDING INTO THE REGION FROM THE
NORTHWEST WILL INCREASE THE PRESSURE GRADIENT ON MONDAY...ESPECIALLY
IN THE EASTERN HALF OF THE CWA. HALF KM WINDS SUGGEST A WIND
ADVISORY WOULD BE NEEDED FOR THE JAMES RIVER VALLEY AND POINTS
EAST. ALSO...THE NAM SHOWS INSTABILITY SHOWERS DEVELOPING AROUND
21Z ALONG THE I-29 CORRIDOR. THIS SEEMS POSSIBLE BASED ON CAPE
VALUES AROUND 150 J/KG AND STEEP LOW LEVEL LAPSE RATES. THE
PREVIOUS FORECAST HAD CHANCE POPS IN THE EAST WHICH LOOKS GOOD
OVERALL. THE REST OF THE PERIOD WILL BE COOL AND DRY. LOWS TUESDAY
MORNING COULD RANGE IN THE 20S FOR MOST LOCATIONS.

.LONG TERM...(TUESDAY EVENING THROUGH SATURDAY)
ISSUED AT 334 AM CDT SUN APR 19 2015

THE LONGER RANGE SOLUTIONS ARE GENERALLY SIMILAR. ALOFT...THE
ECMWF AND CANADIAN MODELS PROPAGATE THE RIDGE/TROF PATTERN
EASTWARD DURING THE PERIOD...ALLOWING FOR THE POTENTIAL FOR S/W
ENERGY TO MOVE EAST-NORTHEAST TOWARD THE REGION DURING THE SECOND
HALF OF THE PERIOD. SUPERBLEND CONTINUES WITH ITS LOW END POPS
MAINLY ACROSS PORTIONS OF THE SOUTHERN HALF OF THE CWA FROM
THURSDAY NIGHT THROUGH SATURDAY. MEANWHILE...IN THE LOWEST
KILOMETER OF THE ATMOS...LOW LEVEL FLOW CONTINUES TO SUPPORT THE
ADVECTION OF COOLISH DRY AIR DOWN OUT OF CANADA ON THE NOSE OF A
SURFACE HIGH PRESSURE SYSTEM PROGGED TO MOVE VERY LITTLE BETWEEN
TUESDAY AND SATURDAY. THE SOMEWHAT MORE PROGRESSIVE ECMWF SUGGESTS
THAT BY FRIDAY...SURFACE HIGH PRESSURE HAS SHIFTED EAST ENOUGH TO
ALLOW FOR RETURN FLOW SOUTHERLY WINDS AND SLIGHTLY WARMER TEMPS BY
THE END OF THE PERIOD VERSUS THE GFS OUTPUT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1227 PM CDT SUN APR 19 2015

BAND OF MVFR STRATUS ACROSS EASTERN SD IS FINALLY STARTING TO
ERODE/EXIT. HOWEVER THERE ARE SOME COLD AIR ADVECTION SHOWERS
MOVING SOUTHEAST OUT OF ND THIS AFTERNOON THAT ARE ACCOMPANIED BY
MVFR CIGS. THESE MAY IMPACT KMBG/KABR OVER THE NEXT FEW HOURS. VFR
CONDITIONS ARE EXPECTED FROM EVENING ONWARD AT ALL TAF SITES.
NORTHWEST WINDS OF 20 TO 35 KTS WILL DIMINISH TO AROUND 15 TO 20
KTS TONIGHT AND THEN INCREASE AGAIN MONDAY MORNING.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR SDZ003-015-
     033>035-045-048.

MN...NONE.
&&

$$

UPDATE...CONNELLY
SHORT TERM...SD
LONG TERM...DORN
AVIATION...WISE









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