423 
FXUS63 KUNR 062011
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
211 PM MDT SUN SEP 6 2015

.SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT
ISSUED AT 207 PM MDT SUN SEP 6 2015

19Z SURFACE ANALYSIS SHOWED COLD FRONT FROM WESTERN MN TO
NORTHWEST KS. MUCH DRIER AIR IS PUSHING INTO THE CWA AS WEAK
SURFACE HIGH PUSHES WITH CLEARING SKIES AND LEFTOVER -SHRA
HEADING EAST OF THE CWA. SKIES WILL BE CLEAR THIS EVENING...BUT
THEN RETURN FLOW RAPIDLY DEVELOPS AS THE HIGH MOVES EAST. 25-35KT
LOW LEVEL JET DEVELOPS WITH NOTABLE 850-700MB THETA-E ADVECTION
LATE TONIGHT/MONDAY MORNING. EXPECT -SHRA/ISOLATED -TSRA TO
DEVELOP AFTER 06Z EAST OF THE BLACK HILLS...HAVE RAISED POPS FOR
CENTRAL SD WHERE BEST FORCING OCCURS. OVERNIGHT LOWS WILL BE NEAR
GUIDANCE...EXCEPT SLIGHTLY COOLER IN THE WEST WHERE CLOUD COVER
WILL BE LOWEST.

MONDAY...MORNING PRECIPITATION MOVES NORTHEAST AS WEAK TROUGH/WARM 
FRONT DEVELOPS FROM SOUTHEAST MT INTO EASTERN NE. MODELS IN 
DISAGREEMENT ON HOW MUCH MOISTURE RETURN WILL OCCUR...BUT SOME 
SHOWING 1.5KJ/KG MLCAPE BY AFTERNOON NEAR BOUNDARY OVER THE SD 
PLAINS. SHEAR WILL BE SUFFICIENT FOR SUPERCELLS DURING PEAK HEATING 
IF THIS OCCURS...BUT BEST CHANCES WILL BE OVER NE. SHORTWAVE TO
ASSIST DEVELOPMENT NOT EVIDENT...SO CONFIDENCE IS LOW IN EXACT
EVOLUTION OF CONVECTION MONDAY AFTERNOON INTO MONDAY NIGHT.
TEMPERATURES WILL BE NEAR GUIDANCE.

.LONG TERM...TUESDAY THROUGH SUNDAY
ISSUED AT 207 PM MDT SUN SEP 6 2015

SEASONABLE TEMPERATURES CAN BE EXPECTED TUESDAY INTO WEDNESDAY AS
ZONAL FLOW ALOFT REMAINS ACROSS THE REGION. WEAK SHORTWAVE ENERGY
WILL CONTINUE TO BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
ACROSS SOUTH CENTRAL SD TUESDAY MORNING.

A DRY COLD FRONT IS PROGGED TO PASS THROUGH THE REGION ON 
WEDNESDAY...BRINGING BELOW AVERAGE TEMPS FOR THE LATTER PART OF THE 
WEEK...WITH A SLIGHT WARMING TREND EXPECTED FOR THE WEEKEND.
 
&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z MONDAY
ISSUED AT 207 PM MDT SUN SEP 6 2015

MAINLY VFR CONDITIONS ARE EXPECTED THROUGH MONDAY AFTERNOON. A
WEAK DISTURBANCE COULD BRING RAIN SHOWERS AND AN ISOLATED
THUNDERSTORM TO THE SOUTH DAKOTA PLAINS OVERNIGHT THROUGH MONDAY
AFTERNOON. MVFR VIS POSSIBLE IN AN HEAVIER SHOWERS THAT DEVELOP.
 
&&

.FIRE WEATHER...
ISSUED AT 207 PM MDT SUN SEP 6 2015

BREEZY SOUTHWEST WINDS WILL DEVELOP THIS AFTERNOON OVER SOUTHERN
CAMPBELL COUNTY...AND COMBINED WITH LOW RELATIVE
HUMIDITIES...WILL PRODUCE CRITICAL FIRE CONDITIONS THROUGH EARLY
EVENING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ259.

&&

$$

SHORT TERM...HELGESON
LONG TERM...15
AVIATION...15
FIRE WEATHER...15