Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 171725
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1025 AM MST WED DEC 17 2014

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 201 AM MST WED DEC 17 2014

LARGE UPPER TROUGH COVERS THE WESTERN CONUS. WATER VAPOR IMAGERY
SHOWS AN EMBEDDED SHORTWAVE MOVING THROUGH MT/WY. SURFACE LOW IS
OVER CENTRAL WY...AND WINDS ACROSS THE CWA ARE FROM THE SOUTHEAST.
FOG/LOW STRATUS COVERS MUCH OF THE NORTHERN PLAINS...WITH MID/HIGH
CLOUDS DRIFTING IN AHEAD OF THE SHORTWAVE. KRCA REPORTED FREEZING
DRIZZLE A BIT AGO...AND THERE MAY BE A LITTLE ICING FORMING OUT OF
THE FOG...SO UPDATED WEATHER GRIDS FOR FREEZING FOG EARLY THIS
MORNING. TEMPS ARE MAINLY IN THE TEENS.

SHORTWAVE/WEAK TROUGH WILL PASS THROUGH THE REGION TODAY...PUSHING
IN SOME WARMER AIR. STILL LOOKS LIKE THERE MAY BE A FEW LIGHT SNOW
SHOWERS ALONG THE BAROCLINIC ZONE TODAY...POSSIBLY LINGERING A BIT
INTO THE EVENING. BEST FORCING SHOULD BE EAST OF THE AREA BY
MIDNIGHT...SO EXPECT THE REST OF THE NIGHT TO BE DRY...ALTHOUGH
HARDLY ANY PRECIPITATION IS EXPECTED FROM WHAT DOES FALL. SOUTHEAST
WINDS WILL CONTINUE THROUGH THE DAY AND OVERNIGHT...AND SO EXPECT LOW
CLOUDS TO STICK AROUND THROUGH THE NIGHT...ESPECIALLY ACROSS THE SD
PLAINS. MAY BE SOME CLEARING ACROSS NORTHEASTERN WY. LOWERED HIGHS
A BIT TO ACCOUNT FOR CLOUDS...RANGING FROM THE LOWER 20S IN THE
EAST TO THE LOWER 30S FARTHER WEST. LOWS WILL BE IN THE TEENS.

ON THURSDAY...WINDS WILL SHIFT TO THE SOUTHWEST AS THE SURFACE
TROUGH PASSES THROUGH...AND CLOUDS WILL FINALLY BE PUSHED OUT OF THE
CWA. HIGHS WILL WARM INTO THE 30S...WITH SOME LOWER 40S POSSIBLE
ACROSS THE EASTERN FOOTHILLS.

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 201 AM MST WED DEC 17 2014

EXTENDED MODELS IN DECENT AGREEMENT FOR THE WEEKEND INTO EARLY
NEXT WEEK...WITH RIDGE BUILDING ALONG THE PACIFIC COAST AND
DOWNSTREAM TROF DIGGING ACROSS THE UPPER MIDWEST/GREAT LAKES. THIS
LEAVES NORTHWEST FLOW ALOFT FOR THE NORTHERN PLAINS...WITH SERIES
OF SHORTWAVES TRACKING ACROSS THE AREA. WEEKEND STILL ON TRACK FOR
DRY WEATHER WITH TEMPERATURES NEAR AVERAGE. STRONGEST SHORTWAVE
CROSSES THE NORTHERN PLAINS LATE SUNDAY/MONDAY AS LOW LEVEL
BAROCLINIC ZONE SLIPS INTO THE AREA. THERMAL PROFILES SUPPORT SOME
RAIN/SNOW. INCREASING NORTHWEST BL-850MB FLOW WILL ALLOW FOR
UPSLOPE ENHANCEMENT ACROSS THE BLACK HILLS. AS DEEP UPPER TROF
MOVES INTO EASTERN CONUS MID-WEEK...SIGNIFICANT TROF STARTS
DIGGING THROUGH PACIFIC NORTHWEST INTO THE GREAT BASIN. ECMWF/GFS
DIFFER SOME IN STRENGTH AND TRACK...BUT BOTH OFFER UP POTENTIAL
FOR SNOW ON CHRISTMAS DAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY)
ISSUED AT 1014 AM MST WED DEC 17 2014

CURRENT SATELLITE AND OBS SHOW MUCH OF WESTERN SD AND PARTS OF
NORTHEASTERN WY IN LOW STRATUS AND CLOUDS WITH IFR/LIFR CIGS.
MODEL SOUNDINGS KEEP THE LOW LEVEL MOISTURE LOCKED INTO WESTERN
SD... INCLUDING KRAP... AND SURFACE WINDS MAINTAIN AN EASTERLY
COMPONENT FOR THE REST OF THE FORECAST PERIOD. THESE CONDITIONS
ARE CONDUCIVE FOR PERSISTENT LOW CLOUDS/STRATUS... AND AS A
RESULT... HAVE GONE WITH IFR/LIFR CIGS FOR REST OF
AFTERNOON AND EVENING IN WESTERN SD.

MEANWHILE... NORTHEAST WY WILL CONTINUE TO SEE CLEARING OF LOW
CLOUDS/STRATUS THIS AFTERNOON WITH A FEW HIGH CLOUDS MOVING IN.
WHILE PATCHY FOG/STRATUS COULD DEVELOP OVERNIGHT... DO NOT EXPECT
IT TO BE WIDESPREAD... AND HAVE LEFT IT OUT OF KGCC TAF FOR THE
CURRENT TIME.

&&

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

$$

SHORT TERM...POJORLIE
LONG TERM...7
AVIATION...MCKEMY





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