Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 111128
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
528 AM MDT FRI JUL 11 2014

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 258 AM MDT FRI JUL 11 2014

UPPER LEVEL RIDGE CENTERED OVER THE SW CONUS WILL RETROGRADE AND
BUILD NORTH INTO WESTERN CANADA IN THE PERIOD...AS AN ANOMALOUSLY
DEEP UPPER TROUGH SHIFTS SE ACROSS THE CANADIAN PRAIRIE PROVINCES
AND INTO THE GREAT LAKES. ACTIVE NORTHERN RIDGE PERIPHERY FLOW
WILL SUPPORT ANOTHER ROUND OF SHRA/TS ACROSS THE CENTRAL/NORTHERN
PLAINS THIS AFTERNOON AND INTO THE EVENING. SFC RIDGE AND
ASSOCIATED DRY PUSH WILL THEN SPREAD SOUTH ACROSS THE REGION
SATURDAY...WITH LL NEGATIVE THETA-E ADV SUPPORTING DRIER WEATHER
ACROSS THE FA.

TODAY...ANOTHER APPRECIABLE MID LEVEL SHORTWAVE TROUGH WILL BRING
CHANCE FOR SHRA/TS TO THE  REGION TODAY. THETA-E RIDGE HAS SHIFTED
SOUTH OF THE FA THIS MORNING PER LAST EVENING/S IMPULSE.
HOWEVER...THE NEXT WAVE IN ACTIVE SW FLOW WILL SUPPORT A POS THETA-E
ADV RESPONSE ACROSS THE WESTERN FA...WITH THE BULK OF DEEP LL
MOISTURE REMAINING SOUTH OF THE FA ALONG A PSEUDO WARM FRONT ACROSS
NE. INCREASING LSA COUPLED WITH DIURNAL HEATING WILL SUPPORT TS
DEVELOPMENT OVER WY THIS AFTERNOON...WITH ACTIVITY SPREADING EAST
THROUGH EVENING. GIVEN THE LOCATION OF THE AXIS OF DEEPER MOISTURE
/INDICATED WELL IN H7 AND H85 THETA-E CHARTS/ AND THE POSITION OF
THE MID LEVEL JET...THE MOST FAVORABLE LOCATION FOR ORGANIZED TS
CLUSTERS WILL BE ACROSS NORTHERN NE. THIS IS ALSO WHERE THE BEST
DYNAMICS WILL BE FOR SEVERE STORMS...WITH BULK DEEP LAYER SHEAR IN
EXCESS OF 40 KNOTS AND ML CAPE IN EXCESS OF 1500 J/KG.
HOWEVER...FORECAST MODELS INDICATE THAT CAPE WILL BE LIMITED ON THE
SD SIDE OF THE STATE LINE...WITH VALUES GENERALLY LESS THAN 1000
J/KG. HENCE...THE STRONGEST STORMS WILL LIKELY REMAIN SOUTH OF THE
FA. OTHER SCT-ISOLD STORMS ARE POSSIBLE THIS AFTERNOON OVER THE
BLACK HILLS AND ALONG A SECONDARY AXIS OF LL THETA-E ACROSS THE NW
SD PLAINS. HOWEVER...UPPER LEVEL SUPPORT LOOKS WEAK TO MARGINAL. NOT
TOO EXCITED ABOUT OVERALL LOCAL SEVERE THREAT AND WILL LEAVE MENTION
OUT OF THE GRIDS. DID RETAIN HEAVY RAIN MENTION ACROSS THE SW AND
FAR SOUTHERN FA GIVEN PW OF 1.25 TO NEARLY 2 INCHES WITH OVERALL
WEAK STEERING FLOW...COUPLED WITH THE POTENTIAL FOR A SLOW MOVING
MCS PUSHING ACROSS THOSE LOCATIONS THIS EVENING...SIMILAR TO LAST
EVENING.

ACTIVITY WILL SHIFT EAST AND WANE OVERNIGHT...WITH LARGE SCALE
SUBSIDENCE BEGINNING TO SPREAD ACROSS THE REGION NW-SE SATURDAY
MORNING...BEHIND THE LEADING EDGE OF THE DEEP UPPER TROUGH IN
SOUTHERN CANADA. NOT TOO EXCITED ABOUT RAIN CHANCES SAT GIVEN
INCREASING SINK FLOW WITH A DRYING BL. FEEL THE BEST CHANCES FOR ANY
SHOWERS AND PERHAPS A TS WILL BE ACROSS THE SOUTHERN BLACK HILLS AND
SOUTHERN PORTIONS OF OUR NE WY ZONES...WHERE DEEPER MOISTURE WILL BE
LINGERING INTO AFTERNOON...SUPPORTING INCREASED INSTABILITY. DID DRY
THINGS OUT THROUGH THE SATURDAY/SAT NIGHT PERIOD.

AS FOR TEMPS...BUMPED HIGHS UP SOME ON THE SD PLAINS TODAY GIVEN
LL THERMAL FIELDS WITH SOME 90S EXPECTED THERE.

&&

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 258 AM MDT FRI JUL 11 2014

UPPER LEVEL RIDGING WILL REMAIN IN PLACE ACROSS THE FAR WESTERN
CONUS DURING THE EXTENDED PERIOD. MAINLY DRY NORTHWESTERLY FLOW
ALOFT WILL DEVELOP OVER THE NORTHERN PLAINS AS AN UNSEASONABLY
STRONG AND COOL UPPER LOW SETTLES SOUTH ACROSS SOUTH CENTRAL CANADA
AND INTO THE GREAT LAKES REGION. A FEW SHOWERS AND THUNDERSTORMS
COULD LINGER OVER SOUTHERN PORTIONS OF THE CWA ON SUNDAY AS A COLD
FRONT PUSHES SOUTH OF THE REGION. OTHERWISE...A DRY AND COOL
PATTERN WILL SETTLE INTO THE AREA FOR AT LEAST THE FIRST HALF OF
NEXT WEEK. TEMPERATURES LOOK TO BE 10 TO 20 DEGREES BELOW AVERAGE ON
MONDAY AND TUESDAY...WITH HIGHS IN THE 60S AND 70S.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 527 AM MDT FRI JUL 11 2014

VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH THE MORNING AND INTO
THE EARLY AFTERNOON. SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS
MUCH OF THE AREA THIS AFTERNOON AND EVENING...WITH MVFR/IFR
VSBYS...HAIL...STRONG WINDS...AND HEAVY RAIN ACCOMPANYING THE
STRONGER STORMS.

&&

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

$$

SHORT TERM...JC
LONG TERM...26
AVIATION...26





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