Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 172021
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
221 PM MDT THU APR 17 2014

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 157 PM MDT THU APR 17 2014

STRONG WESTERLY FLOW OVER THE PAC OCEAN WILL RESULT IN FAST
EASTWARD MOVEMENT OF A MODERATELY STRONG SHORT WAVE TROF JUST OFF
THE WEST COAST THIS MORNING. THIS TROF WILL MOVE TO OR/WA BY 12Z
FRIDAY AND TO CNTRL MT BY 00Z SAT. FURTHER EASTWARD MOVEMENT OF
THE TROF WILL BE ACCOMPANIED BY A COLD FRONT CROSSING THE CWA
FRIDAY NIGHT.

IN RESPONSE TO THESE DEVELOPMENTS...THE 12Z NAM FCSTS 700MB Q
VECTOR CONVERGENCE...INITIALLY STRONGEST TO OUR NORTH WITH THE
ADVANCING SHORT WAVE...BUT WITH A SIGNIFICANT AREA OF Q CONVERGENCE
DVELPD OVER EASTERN WY ON FRI. THIS AREA THEN STRENGTHENS AND MOVES
SE WARD OVER THE BAROCLINIC ZONE STRETCHING FROM EASTERN CO ACROSS
CENTRAL NE. AT THE SFC...WEAK CYCLOGENESIS IS FCST BY THE NAM
DURING THE DAY ON FRIDAY WITH A 1001MB LOW OVER SW SD AT 00Z SAT,
FCST PRESSURE RISES BEHIND THE COLD FRONT SWAMP THIS LOW AS ACTION
SHIFTS SOUTHWARD INTO CO AND NE.

WENT WITH LOW POPS ACROSS OUR NW ACCOMPANYING THE APPROACHING COLD
FRONT DURING THE DAY FRIDAY...WITH HIGHER POPS IN ASSOCIATION WITH
THE SFC LOW AND 700MB Q CONVERGENCE FRIDAY NIGHT. THESE FOLLOW NAM
PRECIP FCSTS FAIRLY CLOSELY.

NAM FCST SOUNDINGS SHOW A MAX OF 700 J/KG CAPE WITH MORE THAN 40KT
OF SFC TO 6 KM SHEAR OVER KRAP EARLY FRI EVENING. SO TSTMS ARE
LIKELY TO DVLP...BUT AREAL COVERAGE IS EXPECTED TO BE LOW. A
FEW OF THESE STORMS COULD BE STRONG...BUT NOT LIKELY SEVERE.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 157 PM MDT THU APR 17 2014

THE UPPER TROUGH WILL MOVE OFF TO THE EAST ON SATURDAY
AS AN UPPER RIDGE BEGINS TO BUILD IN FROM THE WEST. THE UPPER
LEVEL/THERMAL RIDGE WILL REMAIN OVER THE AREA SUNDAY AND
MONDAY...BRINGING DRY WEATHER AND WARMER THAN AVERAGE TEMPERATURES.
A STRONGER UPPER LEVEL TROUGH WILL CREATE A SLIGHT CHANCE OF
THUNDERSTORMS ON TUESDAY WITH A BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS FROM TUESDAY NIGHT THROUGH THURSDAY AS THE UPPER
TROUGH CROSSES THE NORTHERN PLAINS.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 157 PM MDT THU APR 17 2014

VFR CONDITIONS WILL CONTINUE TONIGHT THROUGH FRIDAY
AFTERNOON. THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS FROM LATE
FRIDAY AFTERNOON THROUGH FRIDAY EVENING.

&&

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

$$

SHORT TERM...BARBER
LONG TERM...10
AVIATION...10





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