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000
FXUS63 KUNR 130506
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1106 PM MDT SUN MAY 12 2013

.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 255 PM MDT SUN MAY 12 2013

MASSIVE WESTERN CONUS UPPER RIDGE CONTINUES TO PUSH
EAST WITH DEEP LAYER THETA-E RIDGING ONGOING. LEE SIDE TROUGH
WILL ADVECT EAST AWAY FROM THE ROCKIES ON THE LEADING EDGE OF
UPPER LEVEL HEIGHT RISES...WITH A STRONG UPPER LEVEL TROUGH
EXPECTED TO ADVANCE INTO THE NORTHERN PLAINS MONDAY
NIGHT...SUPPORTING ANOTHER MORE PRONOUNCED LL TROUGH INTO THE
REGION. OVERALL...MAINLY DRY WEATHER EXPECTED...SAVE FOR PORTIONS
OF THE BLACK HILLS WHERE LL THETA-E ADV COUPLED WITH STEEPENING
MID LEVEL LAPSE RATES AND LOCAL OROGRAPHIC CONVERGENCE MAY SUPPORT
ISOLD SHRA/TS LATE THIS AFTERNOON/EARLY EVENING AND AGAIN MONDAY
AFTERNOON/EVENING. OTHERWISE...A SIG WARM NOSE ASSOCIATED WITH THE
ADVANCING RIDGE IS EXPECTED TO KEEP CONVECTION AT BAY ELSEWHERE.

LATE THIS AFTERNOON/TONIGHT...REMOVED LOW POPS OVER THE
CENTRAL/SOUTHERN BH. NEARLY ALL HIRES MODELS DO NOT GENERATE ANY
CONVECTION...WITH THE NAM BEING THE ONLY MODEL/OUTLIER THAT DOES.
LATEST RAP BUFR PROGS INDICATE MID LEVEL WARMING IS STRONGER/FASTER
THAN PREVIOUS INDICATIONS...WITH A DOWNTREND IN CU NOTED IN SAT
TRENDS. OTHERWISE...A WARM NIGHT EXPECTED WITH LOWS IN THE 50S AT
MANY PLACES. THERE IS A SMALL POTENTIAL FOR AN ELEVATED SHOWER
ACROSS THE FAR NORTH GIVEN THETA-E ADV AT THE BASE OVER THE GROWING
WARM NOSE WITH NEGATIVE SW INDICES. HOWEVER...GIVEN THE LOW
POTENTIAL HAVE LEFT OUT AND WILL LET THE NEXT SHIFT ASSESS.

MONDAY...LEAD LL TROUGH WILL ADVECT EAST ACROSS THE AREA IN THE
MORNING...WITH ONGOING DEEP LAYER WAA. INCREASED LL MOISTURE MAY BE
SUFFICIENT ENOUGH TO GENERATE ISOLD CONVECTION OVER THE BH...ESP
WITH A WEAK MESO LOW AS INDICATED IN THE NAM. RETAINED SLIGHT CHANCE
POPS THERE. OTHERWISE...VERY WARM CONDITIONS EXPECTED WITH LOW TO
MID 90S OVER THE SD PLAINS...COOLER WEST. CURRENT FORECAST TEMPS
SURPASSES THE RECORD OF 92 AT THE RAPID CITY AIRPORT...NEARING THE
DOWNTOWN RECORD OF 94. A VERY WARM NIGHT IS IN STORE FOR MONDAY
NIGHT...WITH LOWS IN THE 60S AT MANY PLACES GIVEN ONGOING SFC
PRESSURE FALLS PER THE ADVANCING DEEP NORTHERN STREAM UPPER IMPULSE.
THIS WILL SUPPORT A MIXED BL WITH GUSTY WINDS POTENTIALLY AT MANY
LOCATIONS...ESP OVER THE NORTHERN BH FOOTHILLS...GIVEN A NEAR 5 MB
SFC PRESSURE DIFFERENTIAL FROM THE BH TO THE PLAINS. RECORD HIGH
MIN/S MAY BE SET AT RAPID CITY.

&&

.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 255 PM MDT SUN MAY 12 2013

UPPER LEVEL RIDGE BREAKS DOWN BY TUESDAY MORNING AS A SURFACE LOW
PASSES TO THE NORTH AND A STRONG COLD FRONT SLIDES QUICKLY ACROSS
THE FORECAST AREA DURING THE MORNING. STRONG NORTHWEST WINDS CAN BE
EXPECTED ACROSS THE NORTHWEST AND WEST CENTRAL SOUTH DAKOTA PLAINS
BEHIND THE FRONT. THE STRONGEST WINDS LOOK TO BE NEAR THE ND BORDER.
HAVE DECIDED TO ISSUE A HIGH WIND WATCH FOR HARDING AND PERKINS
COUNTIES...WHERE SUSTAINED WINDS OF 40 MPH OR MORE LOOK POSSIBLE...
ESPECIALLY DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. HIGH
TEMPERATURES WILL RANGE FROM THE LOWER 70S OVER FAR NORTHWESTERN SD
AND PORTIONS OF NORTHEASTERN WY TO THE UPPER 80S ACROSS SOUTH
CENTRAL SD. DEPENDING ON THE EXACT TIMING OF THE FRONT AND HOW
QUICKLY THE DRIER AIR PUSHES IN BEHIND THE FRONT...THERE IS SOME
POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP ACROSS
PORTIONS OF THE SD PLAINS TUESDAY AFTERNOON. WILL LET LATER SHIFTS
HAVE A LOOK AT UPDATED MODEL DATA FOR THIS POTENTIAL AND WHETHER A
FIRE WX WATCH MAY BE NEEDED.

MORE SEASONABLE TEMPS ARE EXPECTED FOR THE REMAINDER OF THE
WEEK...THOUGH STILL ABOVE AVERAGE...AS AREA REMAINS UNDER ZONAL
FLOW. WEAK DISTURBANCES WITHIN THIS FLOW WILL BRING SOME CHANCES FOR
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS LATE IN THE
WEEK...WITH CHANCES LIKELY INCREASING BY THE WEEKEND. LATEST GFS AND
ECMWF BOTH CONTINUE TO SHOW A STRONGER UPPER TROF IMPACTING THE
REGION FROM LATE FRIDAY THROUGH THE WEEKEND...BRINGING THE POTENTIAL
FOR MORE WIDESPREAD PCPN AND OUR FIRST SEVERE WX OF THE SEASON.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1105 PM MDT SUN MAY 12 2013

VFR CONDITIONS ARE EXPECTED THROUGH MONDAY EVENING. OTHERWISE...A
FEW STORMS MAY FORM OVER THE BLKHLS MONDAY AFTN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON
     FOR SDZ001-002.

WY...NONE.
&&

$$

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