Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 280516
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1116 PM MDT SAT SEP 27 2014

.SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT
ISSUED AT 136 PM MDT SAT SEP 27 2014

WATER VAPOR SHOWS UPPER RIDGE HANGING ON OVER THE NRN
PLAINS...ALTHOUGH IT IS WEAKENING WITH LARGE TROF OVER THE WRN
CONUS MOVING SLOWLY EWD. AT THE SFC...FRONTAL BOUNDARY EXTENDS
FROM NERN ND THROUGH SWRN SD/NEB PANHANDLE. WIDE RANGE IN TEMPS
EARLY THIS AFTN...WITH NEAR 70 IN NERN WY TO THE UPPER 80S IN
SCNTRL SD AHEAD OF THE SFC BOUNDARY.

TONIGHT...SFC BOUNDARY WILL CONTINUE SLIDING SEWD WITH MID/HIGH
CLOUDS ON THE INCREASE AS UPPER LOW CURRENTLY OVER SRN CA WORKS
INTO NV. SCT SHRA/ISOLD TSRA OVER WRN/CNTRL WY MAY CLIP OUR FAR
WRN ZONES BEFORE DAYBREAK AND WILL HOLD ON TO 20 POPS THAT AREA.

SUNDAY...UPPER LOW WILL WORK SLOWLY THROUGH NV AND WHILE SFC LOW
DEEPENS OVER ERN CO. AMS WILL CONTINUE TO MOISTEN ACRS THE CWFA AS
PLUME OF MID/UPPER LEVEL MOISTURE...CURRENTLY EXTENDING FROM JUST
WEST OF THE FOUR CORNERS NWD THOUGH THE NRN ROCKIES...SHIFTS EWD.
E/NE BL FLOW ACROSS MUCH OF OUR CWFA WILL MOISTEN THE LOWER
LEVELS. LOW CLOUDS ARE EXPECTED TO DEVELOP ACRS NERN WY AND NWRN
SD...AND WILL MAKE HIGH TEMPS TRICKY DEPENDING ON FAR S/E THEY
SPREAD. BEST CHANCES FOR PCPN WILL REMAIN ACROSS OUR WRN ZONES.

SUNDAY NIGHT...LEAD SHORT WAVE EJECT THROUGH ERN WY/FAR WRN SD
OVERNIGHT WITH WITH SHRA/ISOLD TSTMS SPREADING NWD INTO NERN WY
AND THE BLKHLS...WITH TAPERING POPS AS YOU HEAD EAST OF THE
BLKHLS. SOME LOCALLY HEAVY RAINS POSSIBLE GIVEN PRECIPITABLE
WATERS INCREASING TO 200 PERCENT OF NORMAL OR HIGHER.

&&

.LONG TERM...MONDAY THROUGH SATURDAY
ISSUED AT 136 PM MDT SAT SEP 27 2014

THE UPPER LOW GRADUALLY WILL PHASE BACK INTO THE MAIN
FLOW MONDAY AS IT BECOMES NEGATIVELY TILTED THROUGH MONDAY NIGHT.
EXTENSIVE SOUTHERLY FLOW WILL FEED MOISTURE INTO THE AREA. SHOWERS
AND ISOLATED STORMS WILL INCREASE IN COVERAGE OVER THE AREA THROUGH
THE DAY MONDAY...WITH THE BEST CHANCES MONDAY NIGHT THROUGH TUESDAY
MORNING WHEN STRONG UPPER-LEVEL DIVERGENCE AND DEEP-LAYER Q-VECTOR
CONVERGENCE ARE PROGGED. STILL IS A SLIGHT CHANCE OF A FEW SEVERE
STORMS OVER SCNTRL SD WHERE 500-1000 J/KG MLCAPE AND 35-45 KTS OF
DEEP LAYER SHEAR WILL BE PRESENT ON MON. SHOWERS WILL CONTINUE THRU
TUESDAY WITH WRAP-AROUND PRECIP SLOWLY EXITING THE AREA INTO TUESDAY
NIGHT. IT APPEARS THAT MANY AREAS COULD SEE OVER AN INCH OF RAIN BY
TUESDAY EVNG. COOLER TEMPS PUSHING INTO THE AREA BEHIND THE SYSTEM
WILL KEEP TEMPERATURES WELL BELOW SEASONAL AVERAGES. CYCLONIC FLOW
REMAINING OVER THE REGION WILL KEEP LOW CHANCE POPS OVER THE AREA
WEDNESDAY THROUGH THURSDAY. SHSN POSSIBLE IN THE BLKHLS BOTH THU AND
FRI MRNGS. AT THIS TIME MODELS ARE SUGGESTING A RIDGE BUILDING FOR
SATURDAY...WHICH WOULD BRING BACK DRIER WEATHER AND NEAR-AVERAGE
TEMPS. HOWEVER...VERY LOW CONFIDENCE IN THIS SCENARIO AT THIS TIME
GIVEN THE MODEL SPREAD AND TENDENCY TOWARD RETROGRESSION OF THE
RIDGE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1058 PM MDT SAT SEP 27 2014

VFR CONDITIONS ARE EXPECTED THROUGH MOST OF SUNDAY SE HALF.
HOWEVER...MVFR/IFR CIGS WILL CONTINUE TO DEVELOP OVER NWRN AREAS
EARLY SUN MORNING AS MOIST LOW-LEVEL NORTHEAST FLOW FAVORS THE
FORMATION OF A LOW STRATUS DECK. KRAP WILL BE ON THE EDGE OF
STRATUS AND HAVE RETAINED A HINT OF THIS WITH SCT 2.5 KFT. MVFR
CIGS WILL LIKELY REMAIN THROUGH MOST OF SUNDAY NW HALF...WITH
MVFR/IFR CIGS SPREADING SOUTH SUNDAY NIGHT AS AN UPPER LEVEL TROUGH
MOVES THROUGH THE AREA. SHRA WILL ALSO MOVE INTO WESTERN AREAS
SUNDAY EVENING...WITH VIS RESTRICTIONS POSSIBLE IN HEAVIER CELLS.

&&

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

$$

SHORT TERM...JOHNSON
LONG TERM...BUNKERS
AVIATION...JC





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