Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 061710
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1110 AM MDT FRI MAY 6 2016

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 229 AM MDT FRI MAY 6 2016

08Z SURFACE ANALYSIS HAD COLD FRONT FROM NORTHEAST ND INTO
SOUTHEAST MT TO NORTHWEST WY...PUSHING SLOWLY SOUTHEAST AS SURFACE
HIGH OVER SOUTHWEST CANADA NOSES INTO THE NORTHERN PLAINS/ROCKIES.
LOW LEVEL JET AHEAD OF COLD FRONT STRUGGLING TO PRODUCE ACCAS AT
THIS POINT...BUT MAY YET STILL DEVELOP BEFORE SUNRISE. WATER
VAPOUR SHOWED UPPER LOW OFF CA COAST...AND THIS WILL BE THE MAIN
WEATHER MAKER IN THE SHORT TERM.

TODAY/TONIGHT...UPPER LOW MOVES INTO THE FOUR CORNERS AREA BY 12Z
SATURDAY AS NOSE OF 120KT JET AT BASE OF UPPER LOW PUSHES INTO CO.
DIVERGENCE ON NOSE OF JET WILL PRODUCE SYNOPTIC LIFT OVER CO/WY
TODAY...SPREADING INTO CWA LATE THROUGH THIS EVENING. SURFACE
COLD FRONT SLIDES SOUTHEAST INTO NE THIS EVENING WITH
NORTHEASTERLY BOUNDARY LAYER FLOW BEHIND IT. UPSLOPE FLOW
COMBINES WITH UPSIDENCE UNDER DIVERGENCE TO PRODUCE HIGH POPS
ALONG FRONTAL BOUNDARY FROM WY INTO SOUTHWEST SD TONIGHT. FOR THIS
AFTERNOON...UP TO 1500J/KG MLCAPE WITH LITTLE MLCIN POOLS AHEAD OF
COLD FRONT. SHOULD SEE TSRA DEVELOP LATE THIS AFTERNOON OVER
WY/HIGHER TERRAIN AND PERSIST INTO THE EVENING HOURS AS IT SPREADS
EAST/NORTH. GIVEN MODEST INSTABILITY AND 0-6KM EFFECTIVE
SHEAR...SUSPECT AN ISOLATED SEVERE TSRA OR TWO MAY DEVELOP OVER
SOUTHWEST QUARTER OF CWA DURING/SHORTLY AFTER PEAK INSOLATION.
MARGINAL HAIL/SEVERE WIND GUSTS POSSIBLE. TEMPERATURES
TODAY/TONIGHT WILL BE NEAR GUIDANCE.

SATURDAY...UPPER LOW MOVES THROUGH CO INTO SOUTH CENTRAL WY.
AFOREMENTIONED FORCING WANES IN THE MORNING AS DRIER AIR CIRCULATES
INTO CWA FROM THE EASTERN DAKOTAS. BY AFTERNOON...SURFACE LOW
DEVELOPS OVER WESTERN NE IN RESPONSE TO ENERGY ROTATING AROUND
UPPER LOW. FLOW TURNS SOUTHEAST WITH MOISTURE RETURN. POPS
INCREASE LATER IN THE DAY AND INTO THE NIGHT ACROSS SOUTHERN
PORTIONS OF THE CWA AS WEAK INSTABILITY COMBINES WITH SYNOPTIC
SCALE LIFT. TEMPERATURES WILL BE NEAR GUIDANCE.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 229 AM MDT FRI MAY 6 2016

THE GREAT BASIN UPPER LOW WILL SLOWLY SLIDE TOWARD THE REGION
THROUGH THE FIRST HALF OF NEXT WEEK AS A TROUGH MOVES INTO THE NRN
ROCKIES. THIS SYSTEM WILL BRING UNSETTLED WEATHER TO THE AREA
THROUGH TUESDAY TO WEDNESDAY. RIGHT NOW THE BEST CHANCES FOR
SHOWERS WILL BE SUNDAY THROUGH TUESDAY. THIS SYSTEM WILL ALSO
BRING NEAR TO SLIGHTLY BELOW AVERAGE TEMPS. SLIGHTLY DRIER WEATHER
IS EXPECTED PAST MIDWEEK...BUT UNCERTAINTY REMAINS WITH THIS TYPE
OF PATTERN.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 1110 AM MDT FRI MAY 6 2016

CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE ACROSS
NORTHEAST WY...THE BLACK HILLS...AND FAR SOUTHWEST SD BY LATE THIS
AFTERNOON AS AN UPPER LEVEL DISTURBANCE APPROACHES. SHOWERS AND
EVENING THUNDERSTORMS WILL SPREAD EAST-NORTHEAST ACROSS THE REST
OF SOUTHWEST AND SOUTH CENTRAL SD TONIGHT...WITH CHANCES
DIMINISHING NORTHWARD ACROSS NORTHWEST SD. AREAS OF MVFR
CONDITIONS ARE MAINLY EXPECTED ACROSS NORTHEAST WY AND THE BLACK
HILLS TONIGHT. BREEZY NORTH TO NORTHEAST WINDS CAN BE EXPECTED
ACROSS MUCH OF THE PLAINS THROUGH TONIGHT AS A COLD FRONT PASSES
SOUTH AND EAST OF THE CWA LATER THIS AFTERNOON.

&&

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

$$

SHORT TERM...HELGESON
LONG TERM...13
AVIATION...26


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