Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 241737
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1037 AM MST SAT JAN 24 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 229 AM MST SAT JAN 24 2015

09Z SURFACE ANALYSIS HAD LOW PRESSURE OVER CENTRAL AB WITH TROUGH
INTO EASTERN WY AND COOL FRONT INTO NORTHWEST MT. SHORTWAVE ENERGY
NOTED ON WATER VAPOR OVER CENTRAL BC...MOVING SWIFTLY SOUTHEAST
ON 130KT JET STREAK CRASHING ONSHORE OVER SOUTHWEST CANADA. THIS
WAVE WILL BLAST INTO EASTERN SD THIS EVENING WITH THE SURFACE LOW
DROPPING INTO EASTERN ND. SYNOPTIC FORCING AHEAD OF SHORTWAVE WILL
TAP INTO LIMITED MOISTURE AND PRODUCE A BAND OF -SHRASN THIS
MORNING ACROSS PORTIONS OF THE CWA...PARTICULARLY OVER NORTHWEST
SD. ACTIVITY WILL WANE THIS AFTERNOON ON THE PLAINS AS SUBSIDENCE
KICKS IN BEHIND SHORTWAVE/COOL FRONT. EXCEPTION WILL BE OVER THE
NORTHERN BLACK HILLS WHERE UPSLOPE ENHANCEMENT MAY OCCUR. SNOW
AMOUNTS TOUGH GIVEN RATHER WARM BOUNDARY LAYER. MAIN STORY WILL BE
GRADIENT ASSOCIATED WITH THE SYSTEM THIS AFTERNOON. 850MB WINDS
REACH 50KTS FROM K2WX TO KRAP WITH WELL MIXED BOUNDARY LAYER THIS
AFTERNOON. COLD AIR ADVECTION/ISALLOBARIC FORCING NOT THAT
GREAT...BUT THINK SUBSIDENCE/MIXING WILL OVERCOME TO RESULT IN A
HIGH WIND WARNING WINDS IN THE AFOREMENTIONED CORRIDOR. WILL ALSO
EXPAND CURRENT WIND ADVISORY TO COVER ADDITIONAL PORTIONS OF THE
SD PLAINS PER LATEST GUIDANCE. TEMPERATURES WILL MILD FOR THIS
TIME OF YEAR.

TONIGHT/SUNDAY...SUBSIDENCE WILL DOMINATE THE WEATHER EXCEPT OVER
THE FAR WEST WHERE WEAK FORCING ASSOCIATED WITH SURFACE-800MB
BAROCLINIC ZONE MAY PRODUCE A FEW SHOWERS. TEMPERATURES WILL BE
5-10F ABOVE NORMAL ON AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 229 AM MST SAT JAN 24 2015

MEDIUM RANGE MODELS STILL IN AGREEMENT ON AN UPPER LEVEL RIDGE
MOVING EAST ACROSS THE ROCKIES EARLY NEXT WEEK AND FLATTENING OUT
ACROSS THE PLAINS MIDWEEK. VERY MILD AIR WILL BE IN PLACE FOR
MONDAY AND TUESDAY...WITH HIGHS IN THE 50S AND LOWER 60S...WARMEST
OVER THE EASTERN SLOPES OF THE BLACK HILLS. AS THE RIDGE BREAKS
DOWN DURING MIDWEEK...SHORTWAVE ENERGY WILL PUSH THROUGH...BRINGING
INCREASING CLOUDS AND COOLER AIR FOR THE LATTER PART OF THE WEEK.
MODELS DIVERGE SOME TOWARD THE END OF THE FORECAST PERIOD...WITH
GFS SHOWING A STRONGER SHORTWAVE PASSING THROUGH FRIDAY AND FRIDAY
NIGHT. THIS WOULD BRING A CHANCE FOR SNOW AND ANOTHER SHOT OF
COLDER AIR FOR NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 1033 AM MST SAT JAN 24 2015

STRONG NORTHWESTERLY WINDS WILL PERSIST ACROSS THE SD PLAINS THIS
AFTERNOON AS A COOL FRONT CROSSES THE REGION. THE STRONGEST WINDS
WILL GENERALLY BE FROM K2WX TO KRAP...WHERE SOME GUSTS TO NEAR 50
KT ARE EXPECTED THROUGH LATE AFTERNOON. ISOLATED TO SCATTERED
RAIN SHOWERS WILL SHIFT SOUTH BY MID AFTERNOON. VFR CONDITIONS ARE
EXPECTED THROUGH SUNDAY MORNING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL 7 PM MST /8 PM CST/ THIS EVENING FOR SDZ030-
     042>044-046-047-074.

     HIGH WIND WARNING UNTIL 7 PM MST THIS EVENING FOR SDZ001-002-012-
     013-026-031-072-073.

     WIND ADVISORY UNTIL 7 PM MST THIS EVENING FOR SDZ014-025-032.

WY...HIGH WIND WARNING UNTIL 7 PM MST THIS EVENING FOR WYZ071.

&&

$$

SHORT TERM...HELGESON
LONG TERM...26
AVIATION...15





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