Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 071709
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1109 AM MDT TUE JUL 7 2015

.UPDATE...
ISSUED AT 1026 AM MDT TUE JUL 7 2015

18Z SFC ANALYSIS PLACES HIGH PRESSURE OVER THE EASTERN
DAKOTAS/NEBRASKA AND WESTERN MINNESOTA...RESULTING IN SOUTHERLY
RETURN FLOW OVER NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA.
WATER VAPOR SAT IMAGE SHOWS INITIAL UPPER SHORTWAVE APPROACHING
FROM THE WEST. FORECAST SEEMS TO BE ON TRACK SO HAVE MADE ONLY
MINOR ADJUSTMENTS TO TEMPS...WIND AND CLOUD COVER.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 225 AM MDT TUE JUL 7 2015

08Z SURFACE ANALYSIS HAD HIGH PRESSURE OVER THE EASTERN
DAKOTAS/UPPER MIDWEST WITH WEAK RETURN FLOW DEVELOPING OVER MT/WY.
WATER VAPOUR HAD NORTHWEST FLOW ALOFT WITH NEXT SHORTWAVE OF
INTEREST OVER WESTERN WY/SOUTHERN ID. UPPER LOW SPINNING OFF THE
CA COAST. EFFECT OF THESE TWO FEATURES MAIN CONCERN THIS FORECAST.

THROUGH WEDNESDAY...WY/ID SHORTWAVE TROUGH SLOWLY SHIFTS
EAST/SOUTHEAST INTO THE CENTRAL PLAINS AS UPPER LOW OFF CA COAST
MOVES INTO CA/NV. ON BACK SIDE OF SURFACE HIGH...LEE TROUGH DEVELOPS
AND MOVES EASTWARD INTO WEDNESDAY...AND THEN SINKS SOUTHEAST
WEDNESDAY NIGHT. MODEST 850-700MB THETA-E RIDGE EXPECTED ALONG/NEAR
LEE TROUGH. DIURNALLY DRIVEN MLCAPE FROM 250-750J/KG EXPECTED BOTH
DAYS. 0-6KM BULK SHEAR 15-20M/S THIS AFTERNOON/EVENING AHEAD OF
SHORTWAVE...WHICH MAY SUPPORT AN ISOLATED STRONG/PERHAPS SEVERE TSRA
OVER NORTHEAST WY/FAR NORTHWEST SD. 00Z NAM MORE SUPPORTIVE OF THIS
SCENARIO THAN 00Z GFS...GFS SHOWS LITTLE MLCAPE. SHRA/TSRA ACTIVITY
WILL SLOWLY OOZE EAST AND BUBBLE THROUGH MOST OF WEDNESDAY WITH
LESS SHEAR EXPECTED. KEPT HIGHER CHANCES POPS IN THE FORECAST
GIVEN EXPECTED COVERAGE. TEMPERATURES WILL CONTINUE COOLER THAN
NORMAL.

WEDNESDAY NIGHT...AHEAD OF CA UPPER LOW...UPPER RIDGE AMPLIFIES INTO
THE NORTHERN PLAINS WHICH SHOULD QUELL POPS AS WELL AS BRING WARMER
TEMPERATURES FOR THE LONG TERM.

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 225 AM MDT TUE JUL 7 2015

AN UPPER LOW ACROSS THE FAR WRN CONUS WILL SLOWLY PHASE BACK INTO
THE MAIN FLOW THROUGH THE END OF THE WEEK. UPPER RIDGE OVER THE
CNTRL CONUS WILL STRENGTHEN BRINGING ABOVE AVG TEMPERATURES AND
DRIER WEATHER TO THE AREA. UPPER WAVES WILL CROSS MT INTO
ND...BRINGING OCCASIONAL SL CHC POPS MAINLY OVER NW SD FOR THE END
OF THE WEEK. OTHERWISE MOST LOCATIONS WILL REMAIN DRY THROUGH THE
LONG TERM. TEMPERATURES WILL GENERALLY REACH THE UPPER 80S TO
LOWER 90S.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY
ISSUED AT 1108 AM MDT TUE JUL 7 2015

SOME MVFR CONDS OVER THE BLACK HILLS WITH LOW CLOUDS
THIS AFTERNOON. SCT -TSRA WILL DEVELOP THIS AFTN ACROSS THE CWA AND
CONTINUE INTO TONIGHT. MVFR CONDS EXPECTED IN HEAVIER PRECIP.
OTHERWISE VFR CONDS EXPECTED.

&&

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

$$

UPDATE...10
SHORT TERM...HELGESON
LONG TERM...13
AVIATION...POJORLIE



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