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000
FXUS63 KUNR 211706
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1106 AM MDT TUE MAY 21 2013

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 236 AM MDT TUE MAY 21 2013

CURRENT SURFACE MAP PLACES LOW OVER EASTERN SOUTH DAKOTA...WITH
TROF EXTENDING WEST THROUGH WESTERN SOUTH DAKOTA. WIDESPREAD SHOWERS
CONTINUE TO WRAP BACK INTO WESTERN SOUTH DAKOTA. UPSLOPE
ENHANCEMENT ACROSS THE NORTHERN BLACK HILLS WITH STEEP LOW LEVEL
LAPSE RATES. TEMPERATURE IN THE HIGHER ELEVATIONS OF THE BLACK
HILLS IN THE LOWER 30S...WITH DOT WEB CAM BY O`NEIL PASS SHOWING
SNOW ACCUMULATING ON THE GRASSY AREAS. SHOWERS WILL CONTINUE
THROUGH THE DAY. ANOTHER INCH OF RAINFALL POSSIBLE ACROSS THE
NORTHERN BLACK HILLS. GUSTY NORTHWEST WINDS ON THE PLAINS OF
WESTERN SOUTH DAKOTA HAVE BEEN NEAR LOW END OF ADVISORY CRITERIA.
WILL LEAVE ADVISORY IN EFFECT THROUGH THIS MORNING.

UPPER LOW BEGINS TO SHIFT EASTWARD TONIGHT/WEDNESDAY IN RESPONSE
TO STRONG UPPER LOW MOVING INTO THE PACIFIC NORTHWEST. INCREASING
HEIGHTS AND SUBSIDENCE WILL BRING AN END TO THE SHOWERS WEDNESDAY
MORNING.

&&

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 236 AM MDT TUE MAY 21 2013

WEAK RIDGING PUSHES EAST OVER THE REGION ON THURSDAY...WITH SURFACE
LOW DEVELOPING OVER WESTERN WY. A TIGHT PRESSURE GRADIENT WILL BE
IN PLACE TO THE EAST OF THE LOW ACROSS EASTERN WY...EASTERN MT...AND
THE FAR WESTERN DAKOTAS. GUSTY SOUTHEASTERLY WINDS CAN BE EXPECTED
DURING THE DAY...ESPECIALLY ACROSS NORTHEASTERN WY AND FAR
NORTHWESTERN SD. WILL KEEP A SLIGHT CHANCE FOR A SHOWER OR
THUNDERSTORM OVER THE BLACK HILLS IN THE AFTERNOON. WARMER AIR WILL
CONTINUE TO BUILD INTO THE AREA...WITH HIGHS IN THE UPPER 60S AND
LOWER 70S IN MOST AREAS.

THE RIDGE AXIS PUSHES EAST BY FRIDAY...RESULTING IN SOUTHWEST FLOW
ALOFT FOR THE REST OF THE EXTENDED AS AN UPPER LOW STALLS ACROSS THE
PACIFIC NORTHWEST. TEMPERATURES WILL GENERALLY BE ABOVE AVERAGE
THROUGH THE HOLIDAY WEEKEND...WITH HIGHS IN THE 70S AND LOWER 80S.
LOW LEVEL MOISTURE WILL INCREASE AS SOUTH TO SOUTHEAST WINDS
PERSIST. DAILY CHANCE FOR SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED...WITH CHANCES LIKELY INCREASING LATE IN THE WEEKEND. THIS
STILL LOOKS LIKE IT COULD BE AN ACTIVE PERIOD FOR SEVERE WEATHER
ACROSS THE BLACK HILLS AREA AND EASTWARD ONTO THE SD PLAINS...
ESPECIALLY SUNDAY AND MONDAY...AS SURFACE LOW DEVELOPS OVER THE
EASTERN MT/NORTHEASTERN WY AREA. THIS WILL DEPEND SOME ON THE TIMING
OF THE DISTURBANCES PASSING THROUGH. MODELS ARE IN FAIRLY GOOD
AGREEMENT KEEPING THIS PATTERN IN PLACE FOR THE CWA THROUGH THE END
OF THE MONTH.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1102 AM MDT TUE MAY 21 2013

SCATTERED/NUMEROUS SHRA WILL CONTINUE ACROSS MUCH OF THE AREA
THIS AFTERNOON...WITH MVFR/IFR CONDITIONS PERSISTING. ONE
EXCEPTION WILL BE VFR CONDITIONS AT KGCC/PORTIONS NORTHEAST WY THIS
AFTERNOON. SHRA WILL DECREASE IN COVERAGE THIS AFTERNOON AND
ESPECIALLY THIS EVENING FROM WEST TO EAST AS LOW PRESSURE PUSHES
AWAY FROM THE REGION. GUSTY NORTHWESTERLY WINDS WILL SLOWLY
DIMINISH. MVFR/IFR CIGS WILL REMAIN OR REDEVELOP ACROSS THE CWA
TONIGHT AS BOUNDARY LAYER COOLS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL NOON MDT TODAY FOR SDZ001-002-012-013-026-
     030-031-072-073.

WY...NONE.
&&

$$

SHORT TERM...7
LONG TERM...26
AVIATION...HELGESON