604
FXUS63 KUNR 161732
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1132 AM MDT WED OCT 16 2013
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 309 AM MDT WED OCT 16 2013
UPPER LEVEL ANALYSIS HAS LOW PRESSURE LIFTING INTO CANADA...WITH
A TROUGH EXTENDING SOUTHWESTWARD ACROSS THE CENTRAL PLAINS.
SURFACE ANALYSIS SHOWS HIGH PRESSURE ACROSS THE CENTRAL GREAT
PLAINS. TEMPERATURES HAVE COOLED INTO THE 20S AND 30S
OVERNIGHT...WITH LIGHT AND VARIABLE WINDS.
TODAY...WEAK UPPER RIDGING AND SURFACE HIGH PRESSURE WILL DOMINATE
THE WEATHER. MOSTLY SUNNY SKIES ARE EXPECTED WITH HIGHS IN THE
UPPER 40S TO UPPER 50S.
TONIGHT...UPPER LEVEL TROUGH WILL APPROACH THE CWA LATE TONIGHT
WITH LIGHT RAIN AND SNOW SHOWERS DEVELOPING ACROSS NORTHEAST
WYOMING...THE BLACK HILLS...AND NORTHWEST SOUTH DAKOTA AFTER
MIDNIGHT. LOWS WILL FALL INTO THE 20S AND 30S.
THURSDAY...UPPER TROUGH CROSSES THE NORTHERN PLAINS BRINGING MUCH
COOLER AIR ALOFT...ALONG WITH COOLER AIR AT THE SURFACE. STEEP
LAPSE RATES WILL PROMOTE ISOLATED TO SCATTERED RAIN AND SNOW
SHOWERS ACROSS MUCH OF THE AREA. BEST CHANCES WILL BE ACROSS
NORTHEAST WYOMING AND THE BLACK HILLS. TEMPERATURES WILL BE
CHILLY...GENERALLY IN THE 40S...WITH HIGHER ELEVATIONS ONLY IN THE
30S. BREEZY NORTHWEST WINDS WILL MAKE IT SEEM EVEN COLDER.
THURSDAY NIGHT...WEAK SHORTWAVE ENERGY ON THE BACKSIDE OF THE TROF
SHOULD KEEP ISOLATED TO SCATTERED SNOW SHOWERS GOING
OVERNIGHT...MAINLY ACROSS NORTHEAST WYOMING AND FAR WESTERN SOUTH
DAKOTA. SOME LIGHT ACCUMULATION OF SNOW WILL BE POSSIBLE IN
HEAVIER SNOW SHOWERS. LOWS WILL FALL INTO THE 20S AND LOWER 30S.
&&
.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 309 AM MDT WED OCT 16 2013
ANOTHER WEAK SHORTWAVE WILL BRING LOW PRECIPITATION CHANCES FOR
FRIDAY. A RATHER TIGHT PRESSURE GRADIENT COMBINED WITH SOME COLD
AIR ADVECTION WILL BRING BREEZY/WINDY CONDITIONS TO THE SOUTH
DAKOTA PLAINS FRIDAY. A SIGNIFICANTLY AMPLIFIED UPPER AIR PATTERN
WILL THEN PERSIST INTO EARLY NEXT WEEK WITH A LARGE UPPER LEVEL
TROUGH OVER THE EASTERN HALF OF NORTH AMERICA AND A RIDGE OVER THE
EASTERN PACIFIC OCEAN. THE RESULT WILL BE NORTHWEST FLOW ALOFT AND
CONTINUED COOL TEMPERATURES OVER THE NORTHERN PLAINS.
&&
.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 309 AM MDT WED OCT 16 2013
VFR CONDITIONS WILL CONTINUE INTO THE EVENING. MVFR CONDITIONS IN
-SHRA WILL DEVELOP OVER PARTS OF NORTHEASTERN WYOMING AND
NORTHWESTERN SOUTH DAKOTA LATE THIS EVENING...WITH MVFR CONDITIONS
BECOMING WIDESPREAD OVER WESTERN SOUTH DAKOTA OVERNIGHT.
WIDESPREAD IFR CONDITIONS IN -SN ARE EXPECTED OVER NORTHEASTERN
WYOMING AND THE BLACK HILLS OVERNIGHT. CONDITIONS WILL SLOWLY
IMPROVE LATE THURSDAY MORNING.
&&
.HYDROLOGY...
ISSUED AT 309 AM MDT WED OCT 16 2013
MINOR FLOODING WILL CONTINUE ACROSS PARTS OF THE WESTERN SOUTH
DAKOTA PLAINS AS CREEKS AND RIVERS CONTINUE TO RUN HIGH FROM THE
RECENT RAINS. SINCE THE RAIN HAS DIMINISHED...MOST SMALLER CREEKS
AND STREAMS HAVE RECEDES...WITH THE LARGER RIVERS EXPECTED TO
BEGIN TO RECEDE BY THIS AFTERNOON. ADDITIONAL CHANCES FOR
PRECIPITATION THROUGH THE WEEKEND WILL BE MINIMAL...WITH QPF
AMOUNTS LESS THAN A TENTH OF AN INCH. THE FLOOD ADVISORY WILL
REMAIN IN EFFECT FOR PORTIONS OF THE WESTERN SD PLAINS THROUGH
THIS EVENING WITH A FLOOD WARNING CONTINUING FOR THE CHEYENNE
RIVER NEAR PLAINVIEW/BRIDGER...UPSTREAM FROM LAKE OAHE...THROUGH
THURSDAY.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...15
LONG TERM...HELGESON
AVIATION...10
HYDROLOGY...15