Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 280204
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
804 PM MDT WED APR 27 2016

.UPDATE...
ISSUED AT 759 PM MDT WED APR 27 2016

N-S ORIENTED BAND OF SNOW OVER WESTERN SOUTH DAKOTA AND FAR
NORTHEASTERN WYOMING WILL PERSIST THROUGH MUCH OF THE REST OF THE
EVENING WITH CONDITIONS GRADUALLY IMPROVING AFTER MIDNIGHT. AS
TEMPERATURES COOL...THE SNOW IS BEGINNING TO STICK TO THE ROADS.
SLIPPERY AND HAZARDOUS TRAVEL CONDITIONS MAY RESULT...ESPECIALLY
ON BRIDGES AND OVERPASSES...WHICH WILL COOL THE FASTEST. HAVE
ISSUED A WINTER WEATHER ADVISORY TONIGHT FOR PARTS OF FAR
NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA WHERE ADDITIONAL
SNOWFALL AMOUNTS OF 1 TO 3 INCHES ARE POSSIBLE TONIGHT.

&&

.SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT
ISSUED AT 102 PM MDT WED APR 27 2016

LATEST WATER VAPOR IMAGES SHOW A COMPACT CLOSED UPPER LOW OVER
ERN NEB WITH A TROUGH EXTENDING NWWD TO CNTRL MT. ANOTHER UPPER
LOW WAS MOVING SOUTHEAST OFF THE WEST COAST TOWARD CA...WITH UPPER
HIGH PRESSURE OVER SWRN CANADA. A LARGE AREA OF SNOW/RAIN WAS
ALONG THE UPPER TROUGH FROM ERN NEB AND SD INTO ERN MT...WITH
NOTABLE LOW-LEVEL ISENTROPIC LIFT AND FRONTOGENESIS. SNOWFALL
AMOUNTS HAVE BEEN FROM 1-4 INCHES ACROSS PARTS OF NWRN SD INTO
PARTS OF SCNTRL SD.

FOR TONIGHT...THE UPPER LOW WILL DRIFT SLOWLY EAST INTO WRN IA WITH
THE THROUGH HANGING BACK TOWARD CNTRL MT. THE SYNOPTIC FORCING AND
LOW-LEVEL WINDS WILL BE WEAKENING...WITH A CORRESPONDING DECLINE IN
PRECIP INTENSITY OVERNIGHT. NEVERTHELESS...PRECIP WILL LINGER MOST
PLACES GIVEN THE UPPER TROUGH...RESIDUAL LIFT...AND PLENTY OF H2O.
WILL LEAVE THE WINTER WEATHER ADVISORY GOING FOR NWRN SD...BUT IT
MIGHT BE ABLE TO BE CANCELLED BEFORE ITS 06Z EXPIRATION.

ON THURSDAY...THE UPPER TROUGH/SHEAR ZONE WILL CONTINUE TO WEAKEN AS
IT BECOMES POSITIONED BETWEEN A REX-TYPE BLOCK (WITH A LOW OVER THE
SWRN CONUS AND A HIGH OVER SRN CANADA). RESIDUAL MOISTURE AND LIFT
WILL CONTINUE TO SUPPORT SCT SHRASN.

FOR THURSDAY NIGHT...THE UPPER LOW OVER THE SWRN US WILL MOVE TO THE
SRN HIGH PLAINS AND WILL SPREAD MOISTURE AND LIFT TO OUR FAR SRN CWA
LATE...BUT SHOULD NOT MAKE IT HERE BY 12Z. OTHERWISE...WITH WEAK
FLOW ALOFT AND RESIDUAL MOISTURE SOME ISOLD/SCT SHRASN ARE EXPECTED
TO LINGER THROUGH THE EARLY EVNG...BUT WITH OVERALL DECREASING
PRECIP CHANCES.

HIGH TEMPS WILL REMAIN ABOUT 15-20 DEGREES BELOW AVERAGE WITH LOWS
ABOUT 5-10 DEGREES BELOW AVERAGE.

.LONG TERM...FRIDAY THROUGH WEDNESDAY
ISSUED AT 102 PM MDT WED APR 27 2016

COOL/WET CONDITIONS WILL CONTINUE THROUGH THE WEEKEND AND INTO
EARLY NEXT WEEK AS THE NEXT TROUGH DIGS INTO THE CENTRAL PLAINS.
STILL MUCH UNCERTAINTY WITH REGARD TO THE STRENGTH AND TRACK OF
THIS TROUGH AND EVOLUTION OF THE UPPER LOW. HOWEVER...LOOKS LIKE
PRECIPITATION WILL BEGIN FRIDAY AND THEN INCREASE IN INTENSITY
SATURDAY AND SATURDAY NIGHT AS THE MOISTURE WRAPS AROUND THE
LOW...ESPECIALLY IF THE LOW STALLS OVER THE CENTRAL PLAINS. MODELS
ARE ALSO SHOWING SOME SNOW OVER THE WESTERN HALF OF SOUTH DAKOTA
AND IN THE BLACK HILLS...BUT THIS WILL BE HIGHLY DEPENDENT ON THE
AMOUNT OF COLD AIR ADVECTION AND WET BULB ZERO WITH THIS SYSTEM.
AT THIS TIME IT APPEARS THE TRACK WILL BE SIMILAR TO THE CURRENT
SYSTEM...SO DECIDED TO MENTION SNOW IN THESE AREAS.

AS THIS SYSTEM EXITS...WARMER CONDITIONS LOOK TO RETURN BY THE
MIDDLE OF NEXT WEEK WITH ABOVE AVERAGE TEMPERATURES BY NEXT
THURSDAY OR FRIDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 102 PM MDT WED APR 27 2016

WIDESPREAD IFR CONDITIONS WILL CONTINUE THROUGH THURSDAY MORNING
WITH AREAS OF -RA/-SN/BR. LOCAL LIFR CONDITIONS ARE EXPECTED IN
THE BANDS OF HEAVIEST PRECIPITATION OR OVER THE HIGHER TERRAIN OF
THE BLACK HILLS DUE TO FOG.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 4 AM MDT THURSDAY FOR SDZ001-002-
     012-013-024>026-028>031-072>074.

WY...WINTER WEATHER ADVISORY UNTIL 4 AM MDT THURSDAY FOR WYZ057-071.

&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...MLS
AVIATION...MLS



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