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 042310
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
510 PM MDT SAT JUL 4 2015

.SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT
ISSUED AT 212 PM MDT SAT JUL 4 2015

20Z SURFACE ANALYSIS HAS A 1003MB SURFACE LOW OVER EASTERN
MONTANA WITH AN ASSOCIATED COLD FRONT TRAILING ACROSS NORTHEASTERN
AND CENTRAL MONTANA...LEAVING US IN THE WARM SECTOR. SPC
MESOANALYSIS SHOWS QUITE AN UNSTABLE AIR MASS OVER THE UNR
CWA...WITH MLCAPE BETWEEN 2500-3500J/KG AND NO CIN. DESPITE THE
LACK OF CIN OVER THE REGION...SATELLITE REVEALS MAINLY CLEAR
SKIES...WITH ONLY AN AGITATED CU FIELD OVER THE BLACK HILLS WHERE
STORMS HAVE STRUGGLED TO FIRE OFF SO FAR.

CURRENT THINKING IS THAT AN ISOLATED STORM OR TWO COULD FIRE OFF
THE BLACK HILLS LATER THIS AFTERNOON...AND THEN ISOLATED TO
WIDELY SCATTERED STORMS FIRING OFF THE SURFACE TROUGH IN CENTRAL
SOUTH DAKOTA BETWEEN 21Z-00Z. THE CAPE AND SHEAR PARAMETERS
SUPPORT SEVERE STORMS ACROSS THE AREA...SO ANYTHING THAT DOES FIRE
OFF DOES HAVE THE POTENTIAL TO BECOME SEVERE. STORMS SHOULD DIE
DOWN THIS EVENING AFTER THE SUN SETS JUST IN TIME FOR THE
FIREWORKS...WITH THE EXCEPTION OF STORMS THAT FIRE OFF IN CENTRAL
SOUTH DAKOTA WHERE THE LLJ WILL INCREASE IN STRENGTH AND KEEP
STORMS GOING MOST OF THE NIGHT.

BY SUNDAY MORNING...THE COLD FRONT IN MONTANA SHOULD BEGIN TO APPROACH
NORTHWEST PORTIONS OF THE CWA. LATEST NWP GUIDANCE HAS SLOWED DOWN
THE COLD FRONT A BIT...WHICH COULD RESULT IN A MORE STORMIER
SOLUTION FOR THE CWA AS THE FRONT WILL BE PASSING THROUGH DURING
PEAK HEATING ACROSS WESTERN SOUTH DAKOTA. SHEAR AND INSTABILITY
PARAMETERS WILL SUPPORT SEVERE STORMS...WITH THE MAIN THREAT BEING
LARGE HAIL AND DAMAGING WINDS.

.LONG TERM...MONDAY THROUGH SATURDAY
ISSUED AT 212 PM MDT SAT JUL 4 2015

THE SYSTEM LATE IN THE WEEKEND WILL EXIT THE AREA BY MON
MORNING...WITH MAINLY DRY WEATHER EXPECTED INTO AT LEAST EARLY
TUESDAY. FLOW ALOFT WILL BECOME MORE ZONAL BY MIDWEEK...WITH
INCREASING CHANCES FOR SHOWERS AND STORMS LATER TUESDAY THROUGH
WEDNESDAY. COULD SEE A FEW STRONG TO SEVERE STORMS LATE TUESDAY
INTO TUESDAY EVENING. LOOKING TOWARD THE LATTER PART OF THE
WEEK...A TROF IS STILL FORECAST TO DEVELOP ALONG THE WEST
COAST...WITH HIGH PRESSURE EXPANDING OVER THE SOUTHERN PLAINS.
FLOW ALOFT OVER THE NORTHERN PLAINS WILL EVENTUALLY BECOMING
SOUTHWESTERLY. WEAK DISTURBANCES IN THE FLOW COULD BRING AT LEAST
LOW POPS TO PORTIONS OF THE AREA EACH DAY INTO THE WEEKEND.
TEMPERATURES WILL BE BELOW AVERAGE EARLY IN THE WEEK...RISING TO
ABOVE AVERAGE NEXT FRIDAY AND SATURDAY AS THE RIDGE BUILDS TO THE
SOUTH.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 501 PM MDT SAT JUL 4 2015

ISOLATED THUNDERSTORMS WILL BE POSSIBLE THROUGH EVENING...MAINLY
OVER SOUTH CENTRAL SD. LOCAL AND BRIEF MVFR CONDITIONS ARE
POSSIBLE WITH ANY HEAVIER STORMS. OTHERWISE...VFR CONDS EXPECTED
MOST LOCATIONS. A STRONG UPPER LEVEL TROUGH WILL PUSH INTO THE
REGION SUNDAY...WITH SCT SHRA AND TS EXPECTED BY AFTERNOON. SHRA
ARE EXPECTED TO BECOME MORE OVER NE WY LATE SUNDAY
AFTERNOON...WITH MVFR CONDS LIKELY THERE. STRONG NW WINDS CAN BE
EXPECTED BEHIND A COLD FRONT SUN AFTERNOON...ESP OVER NE WY.

&&

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

$$

SHORT TERM...MCKEMY
LONG TERM...26
AVIATION...JC



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