Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 232127
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
327 PM MDT SAT MAY 23 2015

.SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT
ISSUED AT 307 PM MDT SAT MAY 23 2015

LATEST ANALYSIS PLACES THE CENTER OF THE LARGE UPPER LOW OVER
NERN UTAH THIS AFTN. A 90-KT JET IS ROUNDING THE EAST SIDE OF
UPPER LOW AND HEADING TOWARD THE NORTHERN PLAINS. THE UPPER LOW
WILL GRADUALLY MOVE NORTHEASTWARD INCREASING THE SYNOPTIC SCALE
LIFT AND INSTABILITY OVER THE FORECAST AREA TONIGHT AND ON SUNDAY.
WIDESPREAD RAIN AND ISOLATED TSRA WILL MOVE NORTHWARD INTO THE
FORECAST AREA TONIGHT WITH THE AREA OF RAIN PIVOTING TO THE
NORTHWEST ON SUNDAY. THERE MAY BE A REDUCTION IN CLOUD COVER OVER
PARTS OF SOUTHERN SOUTH DAKOTA ON SUNDAY AFTN WHICH WILL ALLOW
LAPSE RATES TO STEEPEN DUE TO INCREASED DIURNAL HEATING. SHEAR
PROFILES INDICATE THAT ISOLATED SEVERE THUNDERSTORMS WILL BE
POSSIBLE.

WHERE THE PREVIOUS MODEL RUNS PLACED THE UPPER LOW TO THE EAST OF
THE FORECAST AREA ON SUNDAY NIGHT...THE LATEST RUNS ARE IN PRETTY
GOOD AGREEMENT IN SHOWING A SLOWER PROGRESSION OF THE LOW PRESSURE
SYSTEM SO WILL CONTINUE THE CHANCE OF SHRA/TSRA THROUGH SUNDAY
NIGHT.

DUE TO THE POTENTIAL FOR LOCALLY HEAVY RAINFALL TOTALS IN THE
MANY OF THE SAME AREAS THAT HAVE RECENTLY RECEIVED SIG RAINFALL HAVE
ISSUED A FLOOD WATCH FOR PARTS OF NORTHEASTERN WYOMING...THE BLACK
HILLS AREA AND SOUTHWESTERN SOUTH DAKOTA FOR TONIGHT THROUGH
MONDAY. SEE THE HYDROLOGY SECTION BELOW.

.LONG TERM...MONDAY THROUGH SATURDAY
ISSUED AT 307 PM MDT SAT MAY 23 2015

UPPER LEVEL LOW WILL SLOWLY LIFT NORTH AND EAST OUT OF
THE NORTHERN PLAINS AND INTO SOUTH CENTRAL CANADA ON MONDAY.
SHORTWAVE ENERGY ON THE BACK SIDE OF THE SYSTEM WILL KEEP SHOWERS
AND ISOLATED THUNDERSTORMS AROUND THE AREA MONDAY INTO MONDAY
NIGHT...ESPECIALLY OVER NORTHERN AND EASTERN PORTIONS OF THE CWA.
HIGHS ON MEMORIAL DAY WILL REMAIN ON THE COOL SIDE...50S AND LOWER
60S.

BEYOND MONDAY...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH THE WEEK. THE BETTER
CHANCES FOR RAINFALL AT THIS POINT LOOK TO BE WEDNESDAY THROUGH
FRIDAY. SOME STRONGER THUNDERSTORMS COULD DEVELOP ON WEDNESDAY AND
THURSDAY. TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST
AREAS FOR TUESDAY AND THE REST OF THE WORK WEEK.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING
ISSUED AT 307 PM MDT SAT MAY 23 2015

MVFR/IFR CONDITIONS WILL PERSIST ACROSS MUCH OF THE AREA
THIS AFTERNOON...WITH SOME AREAS OF VFR LATE THIS AFTERNOON INTO
EARLY EVENING. SHOWERS AND ISOLATED THUNDERSTORMS WILL GRADUALLY
INCREASE IN COVERAGE ACROSS NORTHEAST WY AND SOUTHWEST SD LATE THIS
AFTERNOON AND EVENING. A MORE STEADY RAIN WITH IFR/LIFR CONDITIONS
WILL DEVELOP OVERNIGHT INTO SUNDAY ACROSS MUCH OF THE CWA.

&&

.HYDROLOGY...
ISSUED AT 307 PM MDT SAT MAY 23 2015

A STRONG LOW PRESSURE SYSTEM WILL BRING WIDESPREAD SHOWERS AND A
FEW THUNDERSTORMS TO THE AREA FROM LATE TONIGHT INTO MONDAY.
RAINFALL OF HALF AN INCH TO AROUND ONE AND A HALF INCHES IS
EXPECTED OVER MUCH OF NORTHEASTERN WYOMING AND WESTERN SOUTH
DAKOTA...WITH THE HEAVIEST RAINFALL GENERALLY FROM MIDNIGHT TO
NOON ON SUNDAY. SOME LOCATIONS COULD POTENTIALLY RECEIVE HIGHER
AMOUNTS...ESPECIALLY ACROSS THE BLACK HILLS AREA AND SOUTHERN
PORTIONS OF NORTHEASTERN WYOMING. RIVERS AND CREEKS ARE RUNNING
HIGH FROM THE RECENT STORMS... ESPECIALLY ACROSS THE BLACK HILLS
AND SOUTHWESTERN SOUTH DAKOTA. THIS ADDITIONAL RAINFALL MAY CAUSE
MORE FLOODING TO DEVELOP ACROSS THESE AREAS SUNDAY AND MONDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR SDZ024>031-041-042-
     072>074.

WY...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR WYZ055-057.

&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...26
HYDROLOGY...10/26


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