Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KUNR 251730
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1130 AM MDT SAT JUL 25 2015

.UPDATE...
ISSUED AT 1011 AM MDT SAT JUL 25 2015

OVERNIGHT/EARLY MRNG MCS THAT MOVED ACRS WRN SD HAS SHIFTED WELL
EAST OF THE REGION. BIGGEST QUESTION FOR TODAY IS HOW MUCH/QUICKLY
THE ATMOS WILL RECOVER. LATEST MODEL CONSENSUS IS NOT MUCH WILL
REDEVELOP...EXCEPT FOR SCNTRL SD WHICH IS EXPECTED TO REMAIN ON
THE EAST SIDE OF THE SFC TROF WHERE BETTER CAPE WILL EXIST. HOWEVER...HAVE
ELECTED NOT TO REDUCE POPS VERY MUCH ANYWHERE ELSE AS THERE WAS
QUITE A BIT OF ACTIVITY AROUND LATE YESTERDAY AFTN/EVE AND THE
OVERALL UPPER PATTERN IS LARGELY UNCHANGED. BEST SVR
THREAT DOES APPEAR TO OVER SCNTRL SD AND HAVE ADDED SVR WORDING
TO THE FCST. SHEAR IS AMPLE FOR SUPERCELLS FURTHER WEST...THOUGH...SHOULD
STORMS DEVELOP THERE.

&&

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 137 AM MDT SAT JUL 25 2015

LATEST WATER VAPOR IMAGES INDICATED MIDLEVEL HIGH PRESSURE OVER
THE SRN CONUS WITH QUASI-ZONAL FLOW ACROSS THE NRN CONUS. A SHORT-
WAVE TROUGH WAS MOVING ACROSS NRN WY...WHICH WAS SUPPORTING SCT
TSRA FROM NERN WY INTO WRN SD. LOW-LEVEL THETA-E ADVECTION ALSO
WAS STRONG OVER WRN SD AND THUS EXPECT STORMS TO CONTINUE THE REST
OF THE NIGHT AS THE UPPER TROUGH MOVES EAST.

OVERALL THE LARGE MIDLEVEL HIGH OVER THE SRN CONUS WILL SHIFT SLOWLY
EWD A TAD THROUGH 12Z MONDAY WHILE AN UPPER LOW OVER WCNTRL BRITISH
COLUMBIA DEVELOPS/MOVES INTO THE PACIFIC NW. THIS WILL ALLOW FOR A
LOW-LEVEL THERMAL RIDGE TO SETUP OVER THE WRN CWA AND WILL FOSTER
HOT WEATHER FOR THE WEEKEND INTO MONDAY.

FOR TODAY THE S/W TROUGH WILL MOVE TO CNTRL SD WITH THE BEST QDIV
OVER THE ERN CWA BY LATE AFTN. EXPECT THE ABOVE-MENTIONED TSRA
CLUSTER TO TRANSLATE ESEWD TOWARD SCNTRL SD...WHERE THE BEST SVR
WEATHER POTENTIAL APPEARS TO BE THIS AFTN WITH SBCAPE OF 1500-3000
J/KG AND 0-6KM SHEAR OF 40-50 KT. SCT TSRA ALSO MAY REDEVELOP OVER
THE BLKHLS NWD THIS AFTN. BY TNGT THE TSRA SHOULD BE OVER THE ERN
CWA AS THE S/W TROUGH MOVES EAST.

ON SUNDAY A WEAK SHORT-WAVE TROUGH WILL MOVE FROM CNTRL WY INTO WRN
SD. LARGE-SCALE ASCENT AND SHEAR WILL NOT BE AS STRONG AS TODAY...SO
EXPECT LESS COVERAGE AND INTENSITY OF STORMS...WITH THE BEST CHANCES
OVER WRN SD. TSRA WILL AGAIN SHIFT INTO CNTRL SD SUNDAY EVNG. AT THE
SAME TIME A LOW-LEVEL THERMAL RIDGE WILL MOVE OVER ERN WY WITH A
STRONG 850-MB LOW-LEVEL JET STREAM DEVELOPING OVER THE WRN CWA...IN
RESPONSE TO DEEPENING PAC NW UPPER LOW. THIS COULD KEEP TEMPS UP AND
RH RELATIVELY LOW...SO WILL HAVE TO MONITOR THIS FOR LATER FIRE-
WEATHER CONCERNS.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 137 AM MDT SAT JUL 25 2015

UPPER LOW OVER THE PACIFIC NORTHWEST WILL MOVE ACROSS THE NRN
PLAINS/SRN CANADA MONDAY INTO TUESDAY. WARM AND UNSTABLE AIR WILL
ADVECT INTO THE REGION AHEAD OF THE LOW...WITH TEMPS IN THE 90S
AND DEWPOINTS ACROSS THE CNTRL SD PLAINS IN THE 60S MONDAY. DRIER
AIR WILL RESIDE OVER NORTHEASTERN WYOMING...AND WITH BREEZY
WINDS...WILL HAVE TO WATCH THE FIRE POTENTIAL THERE. COULD SEE
STORMS DEVELOP ALONG A COOL FRONT SOUTH OF THE SURFACE LOW MONDAY
INTO MONDAY NIGHT...HOWEVER BEST UPPER LEVEL FORCING APPEARS TO BE
NORTH OF THE CWA. COOLER AND DRIER AIR WILL PUSH IN BEHIND THE
FRONT AND REMAIN FOR THE REST OF THE LONG TERM. TEMPS WILL BE NEAR
TO SLIGHTLY BELOW AVERAGE...WITH A GRADUAL WARMING TREND THROUGH
THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1128 AM MDT SAT JUL 25 2015

THUNDERSTORMS EXPECTED AGAIN ACROSS THE AREA THIS
AFTERNOON/EVENING. MVFR CONDITIONS EXPECTED NEAR ANY STORMS.
OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST
PERIOD.

&&

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

$$

UPDATE...JOHNSON
SHORT TERM...BUNKERS
LONG TERM...POJORLIE
AVIATION...13



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.