Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | 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 KUNR 160417
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1017 PM MDT FRI AUG 15 2014

.UPDATE...
ISSUED AT 800 PM MDT FRI AUG 15 2014

HAVE UPDATED THE FORECAST FOR TRENDS IN RADAR AND SATELLITE TO
REDUCE POPS ACROSS MUCH OF THE AREA. MIDLEVEL AND UPPER-LEVEL FLOW
IS STEERING CONVECTIVE ACTIVITY AROUND THE CWA...AND IN ADDITION
THIS AIR IS RELATIVELY DRY ACROSS MOST OF THE CWA.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 218 PM MDT FRI AUG 15 2014

UPPER LEVEL ANALYSIS HAS WEAK RIDGING ACROSS THE SOUTHERN CONUS WITH
A STRONG SHORTWAVE MOVING THROUGH THE RIDGE ACROSS THE NORTHERN
PLAINS...AND STRONGER UPPER LOW SPINNING ACROSS THE PACIFIC
NORTHWEST. 1930Z SATELLITE IMAGE SHOWS A CU FIELD EXTENDING ACROSS
NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA WHILE THE LATEST RADAR
SCAN HAS A FEW SHOWERS CONTINUING OVER SOUTH CENTRAL SOUTH DAKOTA...
WITH THE MAIN BATCH OF ACTIVITY NORTH AND EAST OF THE CWA. AT THE
SURFACE...HIGH PRESSURE IS BUILDING IN FROM THE WEST WITH THE
EXITING BROAD AREA OF LOW PRESSURE OVER CENTRAL SOUTH DAKOTA.

FOR TONIGHT...SURFACE BOUNDARY WILL CONTINUE TO EXTEND ACROSS
CENTRAL SOUTH DAKOTA AND NEAR THE SD/ND BORDER. WEAK STEERING FLOW
ALOFT WILL KEEP STORMS NEARLY STATIONARY. MOISTURE POOL IS EXPECTED
TO EXTEND FROM THE MT/ND BORDER INTO NORTH CENTRAL SOUTH DAKOTA.
THUS HAVE KEPT POPS IN FORECAST FOR TONIGHT FOR MOST OF THE NORTHERN
AND EASTERN AREAS. THE GREATEST POTENTIAL FOR STORMS WILL BE IN FAR
NW SOUTH DAKOTA AND ALONG THE EASTERN FRINGES OF THE CWA.

FOR SATURDAY AND SATURDAY NIGHT...SHORTWAVE UPPER RIDGE TRIES TO
BUILD INTO WESTERN AREAS AS SHORTWAVE TROF SHIFTS EAST. ANTECEDENT
MOISTURE...WEAK ENERGY MOVING ACROSS THE NORTHERN PLAINS...DAYTIME
HEATING AND 50S-60S SURFACE DEW POINTS WILL RESULT IN 1000-1500 J/KG
OF MLCAPE. THIS MAY PRODUCE SOME SCATTERED DIURNAL STORMS WITH AN
ISOLATED STORM OR TWO INTO THE EVENING ACROSS THE BLACK HILLS INTO
NORTHWEST SOUTH DAKOTA. LOW TEMPERATURES WILL FALL INTO THE MID 50S
TO MID 60S.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 218 PM MDT FRI AUG 15 2014

AN UPPER LEVEL TROUGH WILL SLOWLY CROSS THE NORTHERN PLAINS ON
SUNDAY AND MONDAY. THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS
APPEARS TO BE DURING THE PERIOD OF PEAK HEATING ON SUNDAY
AFTERNOON/EVENING WITH SUFFICIENT CAPE/SHEAR ON THE SD PLAINS FOR
ISOLATED SEVERE STORMS. MONDAY LOOKS TO BE MAINLY DRY BUT WITH
CYCLONIC FLOW OVER THE AREA MAY SEE A FEW SHOWERS OR
THUNDERSTORMS...ESP CLOSER TO THE UPPER TROUGH OVER NORTHWESTERN
SOUTH DAKOTA AND OVER AND NEAR THE BLACK HILLS.

THE UPPER LEVEL PATTERN WILL THEN TRANSITION NEXT WEEK WITH THE
MODELS DEVELOPING A LARGE SCALE UPPER TROUGH OVER WESTERN NORTH
AMERICA. THIS WILL RESULT IN SOUTHWESTERLY FLOW ALOFT OVER THE
FORECAST AREA. BLENDING THE MODEL DIFFERENCES WOULD INDICATE NEAR
AVERAGE TEMPERATURES AND LOW POPS GIVEN DRIER AIR MIXING OUT ACROSS
PORTIONS OF THE CWA FROM THE HIGHER TERRAIN TO OUR WEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1012 PM MDT FRI AUG 15 2014

MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. THE
EXCEPTION WILL BE SCT MVFR/IFR CIGS DEVELOPING OVER NWRN SD BY
12Z...POSSIBLY SPREADING ACROSS WCNTRL SD. THE LOW CLOUDS MAY
LINGER IN WCNTRL SD THROUGH LATE MRNG. OTHERWISE...ISOLD TSRA MAY
DEVELOP OVER THE BLKHLS AND FAR NERN SECTIONS OF THE AREA IN THE
AFTN...BUT WOULD DISSIPATE EARLY SATURDAY EVNG.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.

&&

$$

UPDATE...BUNKERS
SHORT TERM...MLS
LONG TERM...10
AVIATION...BUNKERS






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