Area Forecast Discussion
Issued by NWS Rapid City, SD

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968
FXUS63 KUNR 061037
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
437 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 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 437 AM MDT FRI MAY 6 2016

THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
TONIGHT. THE BEST CHANCES WILL BE ACROSS NORTHEAST WYOMING...THE
BLACK HILLS AREA...AND SOUTHWEST SOUTH DAKOTA. MVFR CONDITIONS ARE
POSSIBLE NEAR ANY PRECIP. OTHERWISE VFR CONDITIONS ARE EXPECTED.
WINDS WILL BECOME BREEZY FROM THE NORTH TO NORTHEAST TODAY.

&&

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

$$

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



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