Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KUNR 242111
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
211 PM MST WED DEC 24 2014

.SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT
ISSUED AT 133 PM MST WED DEC 24 2014

UPPER RIDGING COVERS THE WESTERN CONUS...WITH A TROUGH
DIGGING INTO THE WEST COAST. STRATUS CONTINUES TO STREAM IN OVER THE
NORTHERN PLAINS. AXIS OF THE SURFACE TROUGH IS CROSSING THE WESTERN
DAKOTAS...AND WINDS ARE LIGHT AND SOUTHWESTERLY. TEMPS ARE IN THE
30S...WITH SOME 40S ALONG THE EASTERN FOOTHILLS.

UPPER TROUGH WILL DEEPEN AS IT SHIFTS EASTWARD OVER THE WESTERN
STATES TONIGHT...WHILE NORTHERN STREAM CANADIAN LOW BEGINS SWEEPING
A COLD FRONT THROUGH THE NORTHERN PLAINS. AIDED BY JET
COUPLING...SNOW WILL SPREAD FROM MT INTO NORTHEAST WY AND WESTERN SD
OVERNIGHT. NAM HAS A GOOD AMOUNT OF MID-LEVEL FRONTOGENESIS AND
Q-VECTOR CONVERGENCE OVER THE CENTRAL CWA...WHILE THE GFS KEEPS THE
BEST FORCING FARTHER SOUTH. THE NAM/GFS/ECMWF/GEM AGREE THAT SNOW
WILL STRETCH FROM WY THROUGH NORTHEAST SD...BUT THE GFS IS THE
OUTLIER WITH GIVING OUR CWA LESSER AMOUNTS THAN AREAS FARTHER SOUTH.
TRENDED MORE TOWARDS OTHER MODELS WITH POPS...HAVING SNOW SPREADING
FROM NORTHWEST TO SOUTHEAST ACROSS OUR AREA THROUGHOUT CHRISTMAS AND
INTO CHRISTMAS NIGHT. SNOW AMOUNTS HAVE INCREASED SLIGHTLY...GENERALLY
3-6 INCHES...WITH 1-3 INCHES OVER FAR NORTHWEST SD. LOCALLY HIGHER
AMOUNTS ARE POSSIBLE...ESPECIALLY ACROSS CAMPBELL COUNTY...NEAR
THE PINE RIDGE...AND ACROSS THE NORTHERN HILLS. FROUDE NUMBER IS
NOT IMPRESSIVE...THEREFORE DO NOT EXPECT COPIOUS AMOUNTS OF
UPSLOPE SNOW OVER THE NORTHERN HILLS WITH THIS SYSTEM.

NORTHERLY WINDS WILL BE BREEZY ON CHRISTMAS...AT ABOUT 15-25
KTS...AND DIMINISH GRADUALLY OVERNIGHT. THIS WILL BE ENOUGH TO
CREATE SOME PATCHY BLOWING SNOW ACROSS THE AREA...BUT DO NOT EXPECT
AS MUCH BLOWING SNOW AS WITH THE LAST SYSTEM.

ALTHOUGH SNOWFALL MIGHT ONLY BE MARGINALLY ADVISORY CRITERIA FOR
SOME PLACES...FEEL THAT PATCHY BLOWING SNOW AND HOLIDAY TRAVEL
WARRANT A WINTER WEATHER ADVISORY FOR MOST OF THE CWA CHRISTMAS DAY
THROUGH CHRISTMAS NIGHT. WILL LEAVE THE FAR NORTHWEST OUT FOR
NOW...BUT LATER SHIFTS CAN REASSESS IF EXPANSION IS NECESSARY.

LOWS TONIGHT WILL BE IN THE 20S. COLD AIR ADVECTION THROUGHOUT THE
DAY WILL PREVENT TEMPS FROM RISING MUCH ON CHRISTMAS. HIGHS WILL BE
IN THE 20S TO LOWER 30S. CHRISTMAS NIGHT WILL BE FRIGID...WITH LOWS
RANGING FROM THE SINGLE DIGITS ACROSS THE WESTERN CWA TO THE MID
TEENS FARTHER EAST.

.LONG TERM...FRIDAY THROUGH WEDNESDAY
ISSUED AT 133 PM MST WED DEC 24 2014

LIGHT SNOW SHOULD COME TO AN END ACROSS SOUTH CENTRAL
SOUTH DAKOTA FRIDAY MORNING AS SHORTWAVE EJECTS NORTHEASTWARD AND
UPPER TROF AXIS SLIDES ACROSS THE AREA. TEMPERATURES WILL CONTINUE
TO TUMBLE AS ARCTIC HIGH PRESSURE SETTLES INTO THE AREA. DRY AND
COLD CONDITIONS WILL PERSIST INTO SUNDAY MORNING. THE NEXT UPPER
SHORTWAVE WILL CROSS THE NORTHERN PLAINS SUNDAY AFTERNOON INTO
MONDAY...BRINGING ADDITIONAL SNOW TO THE AREA. MODEL SOLUTIONS
VARY WITH THIS WAVE...WITH CONSENSUS POSSIBLY ROUTING THE BEST
SNOWFALL ALONG THE WESTERN AND SOUTHERN PORTIONS OF THE FORECAST
AREA. TEMPERATURES REMAIN BELOW AVERAGE THROUGH THE EXTENDED
PERIOD.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 133 PM MST WED DEC 24 2014

VFR CONDITIONS WILL PREVAIL THROUGH THE EVENING WITH
INCREASING MID/HIGH CLOUDS. ANOTHER STORM SYSTEM WILL BRING SNOW TO
WESTERN AREAS LATE IN THE PERIOD...WITH CONDITIONS DETERIORATING
AFTER MIDNIGHT...AND IFR/LIFR CONDITIONS WITH SNOW EXPECTED AT KGCC
AROUND 12Z AND KRAP AROUND 14Z.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 5 AM TO 11 PM MST THURSDAY FOR
     SDZ012-013-024>026-028-072-073.

     WINTER WEATHER ADVISORY FROM 11 AM MST /NOON CST/ THURSDAY TO 5
     AM MST /6 AM CST/ FRIDAY FOR SDZ027-029>032-041>044-046-047-
     049-074.

WY...WINTER WEATHER ADVISORY FROM 5 AM TO 11 PM MST THURSDAY FOR
     WYZ057-058-071.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 11 PM MST
     THURSDAY FOR WYZ054>056.

&&

$$

SHORT TERM...POJORLIE
LONG TERM...15
AVIATION...15





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.