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 042034
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
234 PM MDT MON MAY 4 2015

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 233 PM MDT MON MAY 4 2015

DEEP SOUTHERLY FLOW WILL DEVELOP IN THE PERIOD AS THE SW CONUS
UPPER LOW SHIFTS NE. THIS WILL ALLOW AMPLE LL MOISTURE TO SPREAD
NORTH INTO THE NORTHERN PLAINS WITH INCREASING CHANCES FOR RAIN IN
THE PERIOD...AFTER A SHORT PERIOD OF SHORTWAVE RIDGING TONIGHT.
WEAK IMPULSE IS IN THE PROCESS OF EXITING THE FA THIS
AFTERNOON...WITH ASSOCIATED RAINS DIMINISHING OVER THE SD PLAINS.
OTHERWISE...MARGINAL INSTABILITY OVER THE FAR WESTERN WY ZONES MAY
ALLOW FOR AN ISOLD SHOWER THIS EVENING THERE. CLOUDS WILL THIN
SOME LATE THIS AFTERNOON AND EVENING OVER THE WESTERN HALF.
HOWEVER...DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE REGION
LATE THIS EVENING WITH AN ASSOCIATED INCREASE IN MID/HIGH CLOUD
EXPECTED. THE NEXT SHORTWAVE IMPULSE WILL EJECT OUT OF THE SW
CONUS UPPER LOW...SLOWLY LIFTING NORTH INTO THE REGION TUES
MORNING WITH INCREASING DEEP LAYER LIFT EXPECTED TO SPREAD NORTH
INTO THE FA. FGEN/ISENTROPIC UPGLIDE PROGGED IN AN INCREASINGLY
UNSTABLE ENVIRONMENT PER DIURNAL HEATING. THIS WILL SUPPORT
INCREASING SHOWER/TS CHANCES ACROSS THE FA...SPREADING NORTH-SOUTH
AS DEEPER MOISTURE IS ADVECTED NORTH. BEST COLLOCATION OF DEEP
ASCENT/FGEN/UPGLIDE IS EXPECTED TUE NIGHT AS AN ASSOCIATED LLJ
SPREADS NORTH ACROSS THE AREA. HENCE...RETAINED HIGHEST POPS IN
THE TUE NIGHT PERIOD. SOME UNCERTAINTY PER THE AMOUNT OF COVERAGE.
HENCE...TRIED TO CONCENTRATE THE HIGHEST POPS WHERE THE BEST DEEP
LAYER FORCING IS EXPECTED ALONG A SW/NE BAND THAT IS EXPECTED TO
SHIFT NW OVERNIGHT TUES. TEMPS WILL REMAIN TRICKY IN THE
PERIOD...ESP HIGH TEMPS WITH CLOUD COVER AND INCREASING CHANCES
FOR RAIN POTENTIALLY HAMPERING RISES. BUMPED LOWS UP TUE NIGHT
GIVEN INCREASING LL MOISTURE AND SEMI-MIXED SE BL FLOW.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 233 PM MDT MON MAY 4 2015

A STRONG UPPER LEVEL WAVE WILL EJECT OUT OF THE BROAD WESTERN
TROF INTO THE NORTHERN PLAINS MID-WEEK. RAIN SHOWERS ARE
LIKELY...AND SOME MARGINAL INSTABILITY MAY ALLOW FOR A FEW
THUNDERSTORMS. RAINFALL AMOUNTS OF A QUARTER TO HALF AN INCH
SHOULD BE FAIRLY WIDESPREAD...WITH LOCALLY HIGHER AMOUNTS.

WEAK ENERGY EJECTING OUT OF THE WESTERN TROF WILL KEEP CHANCES OF
SHOWERS AROUND FOR THURSDAY AND FRIDAY. PRECIP CHANCES FURTHER
INCREASE SATURDAY AS WESTERN TROF/CLOSED LOW MOVES INTO THE
NORTHERN PLAINS. BOTH THE ECM AND GFS ARE WRAPPING COLDER AIR
AROUND THE LOW INTO THE CWA...WITH 850MB TEMPS AROUND 0C. THIS
COULD MEAN SOME PRECIP FALLS AS SNOW SATURDAY NIGHT ACROSS THE
HIGHER ELEVATIONS OF THE BLACK HILLS...BUT STILL MUCH UNCERTAINTY
EXISTS WITH THE TRACK OF THIS STORM.

TEMPERATURES FROM MID WEEK INTO THE WEEKEND WILL BE NEAR TO SLIGHTLY
BELOW AVERAGE...IN THE 50S AND 60S WITH THE AMPLE CLOUD COVER AND
PRECIP CHANCES.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z TUESDAY
ISSUED AT 233 PM MDT MON MAY 4 2015

RAIN SHOWERS WILL CONTINUE ACROSS WESTERN SD THIS
AFTERNOON. MVFR CONDITIONS ARE POSSIBLE IN THE SHOWERS...ESPECIALLY
OVER HIGHER TERRAIN. AS PRECIPITATION DECREASES AND SHIFTS NORTHEAST
LATER THIS AFTERNOON...CONDITIONS WILL BECOME MAINLY VFR THROUGH
TUESDAY MORNING.

&&

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

$$

SHORT TERM...JC
LONG TERM...15
AVIATION...15



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