000
FXUS63 KUNR 180101
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
701 PM MDT MON JUN 17 2013

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 214 PM MDT MON JUN 17 2013

THE LATEST WATER VAPOR IMAGES SHOWED AN UPPER LOW MOVING
TOWARD CNTRL ND WITH ANOTHER WAVE MOVING ACROSS SWRN/SCNTRL SD. AT
THE SURFACE WEAK HIGH PRESSURE WAS OVERSPREADING THE CWA. RESIDUAL
MOISTURE AND EVAPOTRANSPIRATION HAVE RESULTED IN DEWPOINTS FROM THE
UPPER 40S TO LOWER 50S...WHICH WHEN COMBINED WITH 7-8 C/KM LAPSE
RATES WAS PRODUCING MLCAPE OF AROUND 1000 J/KG. ISOLD-SCT SHRA/TSRA
HAVE FORMED IN AN AREA OF LOW-LEVEL CONVERGENCE FROM THE NWRN BLKHLS
SEWD INTO NRN NEB. GIVEN THE WEAK FORCING AND MODEST CAPE THE
STORMS HAVE BEEN RELATIVELY WEAK TO THIS POINT.

FOR THE REST OF THIS AFTN AND EVNG THE WAVE OVER SWRN SD WILL
CONTINUE TO MOVE SOUTHEAST. ISOLD-SCT SHRA/TSRA WILL CONTINUE ALONG
THE CONVERGENCE ZONE...EXTENDING WWD INTO NERN WY. HOWEVER...THE
PRECIP SHOULD END QUICKLY THIS EVNG GIVEN THE WEAK FORCING AND LOSS
OF HEATING. SHEAR IS SUFFICIENT FOR A SUPERCELL...BUT MARGINAL AND
THIN CAPE PROFILES SUGGEST THE UPDRAFTS WILL GENERALLY REMAIN IN
CHECK. THE SURFACE WINDS WILL GRADUALLY BECOME SOUTHEAST FOR ALL
OF THE CWA TNGT AS THE SURFACE HIGH CONTINUES TO MOVE EAST.

ON TUESDAY THE SOUTHEAST WINDS WILL HELP PUSH DEWPOINTS INTO THE
MID/UPPER 50S...WHICH WILL HELP BOOST MLCAPE TO 1500-2000 J/KG. AN
UPPER RIDGE WILL MOVE OVER THE CWA AND THUS DIMINISH THE SHEAR TO
VALUES BARELY FAVORABLE FOR SUPERCELLS. A WEAK SHORT-WAVE TROUGH
WILL PUSH THROUGH THE RIDGE TUESDAY AFTN AND NIGHT...WHICH THE
MODELS HAVE BEEN VERY CONSISTENT ABOUT. HOWEVER...THE Q-G FORCING
WILL BE RATHER WEAK...WITH THE BEST SIGNAL IN THE LOW-LEVELS DUE TO
WARM ADVECTION/ISENTROPIC LIFT. AS A RESULT...EXPECT AT LEAST A
SMALL MCS TO DEVELOP LATE TUESDAY AND TRACK ACROSS THE CWA TUESDAY
NIGHT. SOME SEVERE WEATHER IS EXPECTED...BUT GIVEN THE WEAK FORCING
AND MARGINAL SHEAR THIS SHOULD NOT BE A "BIG" EVENT. THE STORMS
SHOULD CONTINUE WELL INTO TUESDAY NIGHT AS THE LOW-LEVEL JET STREAM
STRENGTHENS AHEAD OF THE NEXT WRN CONUS TROUGH.

&&

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 214 PM MDT MON JUN 17 2013

UPPER RIDGE AXIS BEGINS TO PUSH EAST ON WEDNESDAY AS
UPPER LOW MOVES EAST THROUGH THE PAC NW. CAPE WILL BE QUITE
LARGE...BUT WILL LIKELY BE FIGHTING A CAP AS WELL AS DRY SLOTTING AS
SW FLOW ALOFT INCREASES. WILL LEAVE POPS IN FORECAST...HIGHEST IN
THE ERN ZONES...WHILE DRYING THINGS OUT IN THE WRN ZONES. EVEN
THOUGH GUIDANCE IS GOING QUITE WARM...WILL CONTINUE TO UNDERCUT
GIVEN GREENNESS. UPPER LOW WILL CONTINUE PROGRESSING SLOWLY EWD
THROUGH THE NRN ROCKIES LATE IN THE WEEK INTO THE WEEKEND AND INTO
SCNTRL CANADA LATE IN THE WEEKEND. THE SW FLOW ALOFT WILL LEAD TO
PERIODIC TSTM CHANCES AS WELL AS TEMPS GENERALLY NEAR TO SLIGHTLY
ABOVE AVERAGE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 659 PM MDT MON JUN 17 2013
ISOLD TO SCT TSTMS WILL END THIS EVENING OVER WESTERN SD. STRONG
AND ERRATIC WINDS ALONG WITH HAIL POSSIBLE FROM THE TSTMS.
OTHERWISE VFR CONDITIONS EXPECTED THROUGH TONIGHT. ANOTHER CHANCE
OF THUNDERSTORMS ARE EXPECTED TUESDAY AFTERNOON.

&&

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

$$

SHORT TERM...BUNKERS
LONG TERM...JOHNSON
AVIATION...MLS