Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 050847
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
247 AM MDT SUN JUL 5 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 242 AM MDT SUN JUL 5 2015

08Z SURFACE ANALYSIS HAD COLD FRONT FROM NORTHEAST ND INTO
SOUTHWEST MT WITH LOW PRESSURE DEVELOPING OVER SOUTH CENTRAL MT
NEAR THE FRONT AND TROUGH FROM THE LOW INTO CENTRAL NE. NOCTURNAL
LOW LEVEL JET PUSHING EAST EARLY THIS MORNING WITH MAIN THETA-E
ADVECTION OVER EASTERN SD/CENTRAL NE ALLOWING TSRA TO END OVER THE
CWA. STILL MIGHT BE AN ELEVATED STORM THROUGH 12Z OVER CENTRAL SD.

TODAY/TONIGHT...ATTENTION TURNS TO COLD FRONT/LOW. LATEST WATER
VAPOUR LOOP HAD UPPER TROUGH MOVING SOUTHEAST OUT OF CENTRAL CANADA
AND THEN ACROSS THE US/CANADIAN BORDERS OF MT/ND. LIFT UNDER RIGHT
ENTRANCE REGION OF 120KT JET SUPPORTING ACTIVE CONVECTION ACROSS
NORTHEAST MT AT 0830Z...WHICH WILL HEAD INTO WESTERN ND THIS
MORNING...MAINLY NORTH OF THE CWA. CONVECTION WILL LIKELY PUT OUT AN
OUTFLOW BOUNDARY...WHICH WILL PUSH COLD FRONT INTO NORTHWEST REACHES
OF CWA THIS MORNING. UPPER LEVEL DIVERGENCE UNDER RIGHT ENTRANCE
REGION OF JET WILL ENHANCE SURFACE LOW ALONG COLD FRONT...WHICH WILL
SLIP TO I-90 EARLY THIS AFTERNOON WITH LOW NEAR KRAP. VERY
WARM/MOIST AIR AHEAD OF LOW WILL POOL ALONG BOUNDARY WITH 2-4KJ/KG
MLCAPE AND 25-50J/KG MLCIN. EFFECTIVE 0-6KM BULK SHEAR AROUND 20M/S
EXPECTED ALONG BOUNDARY. AS CAP BREAKS ALONG/AHEAD OF FRONT...EXPECT
SUPERCELLS TO DEVELOP EARLY THIS AFTERNOON. GIVEN STRENGTH OF
INSTABILITY...VERY LARGE HAIL POSSIBLE. TORNADO THREAT IS THERE
GIVEN NORTHEAST BOUNDARY LAYER FLOW BEHIND COLD FRONT...ELONGATING
HODOGRAPHS IF SUPERCELLS ARE POST FRONTAL...WHICH IS A DISTINCT
POSSIBILITY GIVEN SETUP...BUT MLLCL/S FAIRLY HIGH EXCEPT FOR
FAVORED AREA JUST EAST/NORTHEAST OF SURFACE LOW. ACTIVITY WILL
SLOWLY GROW UPSCALE LATE THIS AFTERNOON/EARLY THIS EVENING AND
MORPH INTO A POTENTIALLY STRONG FORWARD PROPAGATING MCS OVER
CENTRAL INTO EASTERN SD WITH ENHANCED WIND THREAT. GIVEN
PARAMETERS...ENHANCED RISK OF SEVERE WEATHER LOOKS ON TARGET EAST
OF RAPID CITY. COLD FRONT PUSHES SOUTHEAST OF CWA TONIGHT WITH A
PERIOD OF GUSTY NORTH/NORTHEAST WINDS BEHIND IT THIS
AFTERNOON/EARLY THIS EVENING. TEMPERATURES WILL BE TRICKY GIVEN
FRONTAL POSITION.

MONDAY...HIGH PRESSURE BUILDS INTO THE CWA WITH DRIER CONDITIONS ON
TAP.

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 242 AM MDT SUN JUL 5 2015

GENERALLY DRY WEATHER WILL CONTINUE INTO TUESDAY AS STRONG HIGH
PRESSURE SHIFTS EAST INTO THE UPPER MIDWEST. RETURN FLOW ACROSS NE
WY AND FAR WRN SD WILL BRING BACK SOME CHANCES OF STORMS TUE
AFTN/NGHT. BROAD CYCLONIC FLOW IS PROGGED TO DEVELOP ACROSS THE
REGION WED AND THU WITH DAILY CHANCES FOR STORMS. TEMPERATURES
WILL BE NEAR AVERAGE. MODELS ARE DIVERGING GREATLY FOR THE END OF
THE WEEK WITH HOW AN UPPER LOW OVER CA WILL PHASE BACK INTO THE
MAIN FLOW. THE WETTER SOLUTION IS THE GFS WHICH HAS MOST OF THE
ENERGY PUSHING WITHIN THE SW FLOW INTO THE NRN PLAINS. THE ECMWF
KEEP STRONG UPPER RIDGING CENTERED ACROSS THE SRN PLAINS WHICH
KEEPS THE REMNANT LOW PUSHING NE THRU THE NRN ROCKIES...ALONG WITH
THE BEST CHANCES FOR STORMS.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT
ISSUED AT 242 AM MDT SUN JUL 5 2015

A STRONG COLD FRONT WILL CROSS THE AREA TODAY. WITH THIS
FRONT...NUMEROUS SHRA/TSRA WILL DEVELOP ACROSS THE AREA TODAY AND
TONIGHT. SOME STORMS ARE EXPECTED TO BE SEVERE. MVFR/IFR
CONDITIONS ARE EXPECTED WITH THE STRONG STORMS. STORM ACTIVITY
WILL END THROUGH THE NIGHT AS COOLER AND DRIER AIR MOVES IN FROM
THE NW...LEADING TO VFR CONDITIONS.

&&

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

$$

SHORT TERM...HELGESON
LONG TERM...13
AVIATION...13


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