784 
FXUS63 KUNR 041713
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1113 AM MDT SUN MAY 4 2014

.UPDATE...
ISSUED AT 929 AM MDT SUN MAY 4 2014

15Z SURFACE ANALYSIS HAD HIGH PRESSURE OVER NORTHEAST ND WITH
RETURN UPSLOPE SOUTHEAST FLOW OVER THE CWA. PRESSURE FALLS OVER MT
CAUSING BREEZY SPOTS ON THE SD PLAINS/NORTHEAST WY. ST/SC IN PLACE
ACROSS PORTIONS OF FAR NORTHEAST WY/NORTHWEST/FAR SOUTHWEST SD.
12Z KUNR SOUNDING SHOWED RATHER DEEP INVERSION WITH MOISTURE
TRAPPED BELOW IT. 1KM VISIBLE LOOPS SHOWED ST/SC STARTING TO ERODE
ACROSS FAR SOUTHERN SD. LATEST GUIDANCE SUGGESTS ST/SC WILL MIX
OUT THIS AFTERNOON...BUT GIVEN UPSLOPE FLOW SUSPECT IT WILL BE
SLOWER THAN EXPECTED SO TWEAKED TEMPERATURES DOWN A BIT OVER
NORTHWEST SD. ALSO MOVED POPS FURTHER WEST WHERE BEST CLEARING EXPECTED.
WEAK THETA-E ADVECTION LATER TONIGHT STILL SUGGESTS SHRA POSSIBLE
ACROSS NORTHEAST 2/5THS OF CWA.

&&

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 249 AM MDT SUN MAY 4 2014

CURRENT SURFACE MAP PLACES HIGH PRESSURE ACROSS SASKATCHEWAN INTO
THE EASTERN DAKOTAS/MINNESOTA...WITH STATIONARY FRONT ACROSS
CENTRAL MONTANA INTO WYOMING/NORTHEAST COLORADO. ISOLATED
SHOWERS/THUNDERSTORMS ACROSS CENTRAL SOUTH DAKOTA...IN 850-700MB
THETA-E MAXIMUM. LOW CLOUDS ACROSS NORTHEAST WYOMING/WESTERN SOUTH
DAKOTA...WITH FOG IN THE HIGHER TERRAIN OF THE BLACK HILLS. 

FOR TODAY...RETURN FLOW ON BACK SIDE OF HIGH WILL KEEP MOIST
EAST/SOUTHEAST LOW LEVEL FLOW ACROSS MUCH OF THE FORECAST AREA.
LOW CLOUDS WILL BE SLOW TO DISSIPATE TODAY...ESPECIALLY ACROSS
NORTHWEST SOUTH DAKOTA. 

FLAT UPPER LEVEL RIDGE REMAINS ACROSS THE AREA TONIGHT...WITH
LARGE OF LARGE SCALE FORCING. WEAK 850-700MB THETA-E ADVECTION MAY
BE SUFFICIENT FOR A FEW SHOWERS/THUNDERSTORMS...MAINLY ACROSS
NORTHWEST SOUTH DAKOTA. SURFACE LOW DEVELOPS ACROSS SOUTHEAST
WYOMING ON MONDAY...WITH WARM FRONT LIFTING TOWARDS THE
NEBRASKA/SOUTH DAKOTA BORDER. A FEW THUNDERSTORMS POSSIBLE OVER
NORTHEAST WYOMING/WESTERN SOUTH DAKOTA. BETTER CHANCE OF
THUNDERSTORMS MONDAY NIGHT WITH MUCH STRONGER 850-700MB THETA-E
ADVECTION IN RESPONSE TO RIGHT ENTRANCE OF JET STREAK TRACKING
ACROSS NORTH DAKOTA. 

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 249 AM MDT SUN MAY 4 2014

.LONG TERM...A SPLIT FLOW TROF IS PROGGED TO CROSS THE ROCKIES WITH 
STRONGER SWRLY FLOW DEVELOPING TOWARDS MID-WEEK...BRINGING GREATER 
SHOWER/THUNDERSTORM CHANCES. DRIER WEATHER MAY RETURN BY THE END OF 
THE WEEK AS FLOW SHIFTS W/NWRLY...THOUGH WILL LEAVE SOME LOW POPS IN 
AS CYCLONIC FLOW/WEAK DISTURBANCES POTENTIALLY CONTINUE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1112 AM MDT SUN MAY 4 2014

MVFR DECK OVER LARGE PORTIONS OF NE WY AND WRN SD...WITH LIFR
CIGS OVER THE BLACK HILLS...WILL GRADUALLY IMPROVE TO VFR THIS
AFTERNOON. ISOLD -SHRA WILL BE POSSIBLE THIS AFTERNOON AND
TONIGHT...MAINLY OVER NW SD. LCL MVFR VIS WILL BE POSSIBLE IN
PRECIP.

&&

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

$$

UPDATE...HELGESON
SHORT TERM...7
LONG TERM...77
AVIATION...13