Area Forecast Discussion
Issued by NWS Rapid City, SD

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827
FXUS63 KUNR 082130
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
230 PM MST MON FEB 8 2016

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 224 PM MST MON FEB 8 2016

20Z UPPER AIR ANALYSIS REVEALS A HIGHLY AMPLIFIED TROUGH AND
RIDGE IN THE EASTERN AND WESTERN CONUS...RESPECTIVELY...WITH OUR
CWA IN STRONG NORTHWESTERLY FLOW ALOFT. AT THE SURFACE...WINDS ARE
QUITE BREEZY ACROSS THE SOUTH DAKOTA PLAINS...WITH MANY AREAS
STILL SEEING 20 TO 30 MPH WINDS WITH 40 MPH GUSTS. SHOULD SEE
WINDS SUBSIDE SOME LATE THIS AFTERNOON AND EVENING AS THE PRESSURE
GRADIENT RELAXES ACROSS THE CWA.

HIGH AND MID LEVEL CLOUDS WILL INCREASE OVERNIGHT AS A WEAK SHORTWAVE
EMBEDDED WITHIN THE NORTHWESTERLY FLOW APPROACHES THE REGION.
PREVIOUS FORECAST HAD CHANCES FOR SNOW SHOWERS IN THE BLACK HILLS
REGION STARTING LATE MONDAY/EARLY TUESDAY...BUT LATEST MODEL
GUIDANCE HAS COME IN A BIT DRIER. FORECAST SOUNDINGS DO SHOW
MID-LEVEL MOISTURE...BUT ITS GENERALLY UNDER FIVE THOUSAND FEET
IN DEPTH...AND THE LOW LEVELS OF THE ATMOSPHERE LOOK DRY FOR ANY
PRECIPITATION TO FALL THROUGH. HAVE DECIDED TO DROP POPS FOR SNOW
SHOWERS AND INSTEAD MENTION FLURRIES IN THE HILLS STARTING AFTER
06Z.

BY TUESDAY...A BAROCLINIC BOUNDARY BEGINS TO SET UP ACROSS THE SOUTH
DAKOTA PLAINS. FORCING ALONG AND ON THE COOL SIDE OF THE BOUNDARY
LOOK WEAK...BUT STRONG ENOUGH TO GENERATE CLOUDS AND SOME LIGHT
PRECIPITATION. P-TYPE COULD BE INTERESTING...AS FORECAST SOUNDINGS
SHOW SATURATED CONDITIONS BETWEEN 0 TO -10 C AND DRIER AIR IN THE
DGZ...WHICH WOULD BE CONDUCIVE FOR FZDZ/-FZRA. HOWEVER...SURFACE
TEMPERATURES LOOK TO BE AT OR JUST ABOVE FREEZING FOR MOST OF THE
DAY TUESDAY. FOR NOW...WILL KEEP FORECAST WITH SLIGHT CHANCE OF
-RA/-SN FOR TUESDAY AFTERNOON AND EVENING...BUT MIGHT NEED TO
INCLUDE THE MENTION OF FZDZ-/-FZRA IN FUTURE FORECASTS IF MODEL
GUIDANCE COMES IN WITH COOLER SURFACE TEMPS.

THE BAROCLINIC BOUNDARY GRADUALLY PUSHES EASTWARD THROUGH THE DAY
TUESDAY...AND NEARLY OUT OF THE CWA BY WEDNESDAY MORNING WITH DRIER
AND WARMER AIR WORKING ITS WAY INTO THE REGION.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 224 PM MST MON FEB 8 2016

AMPLIFIED ACTIVE NW FLOW WILL PERSIST IN THE PERIOD. WESTERN NOAM
POSITIVE MID LEVEL HEIGHT ANOMALY WILL REMAIN CENTERED JUST WEST
OF THE REGION...WITH ACTIVE NW FLOW TO THE EAST. MID/LEVEL
IMPULSES PASSING TO THE EAST OF THE FA WILL PUSH A BACKDOOR COLD
FRONT WEST IN THE REGION WITH THE EASTERN HALF OF THE FA COOLING
DOWN FRIDAY-SAT. A STRONGER WAVE WILL ADVECT THROUGH THE RIDGE
SUN- MON...SUPPORTING BETTER CHANCES FOR RAIN/SNOW OVER AREA...ESP
NE WY AND THE NORTHERN BLACK HILLS. HOWEVER...MILD NW FLOW LOOKS
TO PERSIST BEHIND THIS WAVE AS ARCTIC AIR WILL REMAIN BOTTLED TO
THE NORTH PER FLOW BLOCKING OVER CENTRAL CANADA. OVERALL...LOOK
FOR MILD CONDS FOR MUCH OF THE AREA WED-THUR...WITH COOLER TEMPS
OVER THE EASTERN HALF FRI-SAT BEFORE MILD WEATHER RETURNS ALL
AREAS EARLY NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 224 PM MST MON FEB 8 2016

VFR CONDITIONS EXPECTED THROUGH THE PERIOD. GUSTY NW WINDS UP TO
35KTS EXPECTED THROUGH THE DAY...PRIMARILY ON THE SD PLAINS. SOME
WIND SHEAR IS EXPECTED ON THE WY PLAINS THIS EVENING AS STRONG
FLOW REMAINS ABOVE THE SFC.

&&

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

$$

SHORT TERM...MCKEMY
LONG TERM...JC
AVIATION...JC



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