Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 272330
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
530 PM MDT FRI MAR 27 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 217 PM MDT FRI MAR 27 2015

20Z SURFACE ANALYSIS HAD WARM FRONT FROM KMIB TO KOGA...STEADILY
MOVING EAST ON 2-4MB/3HR PRESSURE FALLS AND UPPER RIDGE BUILDING
ACROSS THE ROCKIES/PLAINS. MAIN CONCERN THIS FORECAST WILL BE
SHORTWAVE TROUGH CURRENTLY WEST OF THE OR/WA COAST. MODELS ARE IN
PRETTY GOOD AGREEMENT.

TONIGHT...DIURNAL CU NEAR/SOUTHEAST OF THE BLACK HILLS MAY SPIT OUT
A FEW HYDROMETEORS THROUGH EARLY THIS EVENING WITH 50-100J/KG SBCAPE
AVAILABLE. WARM FRONT WILL PUSH EAST AS SHORTWAVE MOVES INTO ID.
WESTERLY COMPONENT TO BOUNDARY LAYER FLOW WILL SUPPORT WARM AIR
ADVECTION AND SLIGHTLY WARMER TEMPERATURES THAN PAST COUPLE OF
NIGHTS.

SATURDAY...UPPER/THERMAL RIDGE PEAKS OVER THE CWA. LEE TROUGH
WILL DEVELOP EARLY AND PUSH EAST DURING THE DAY. BEHIND IT EXCELLENT
MIXING WILL PROMOTE DRY DEW POINTS. 15-25KT BOUNDARY LAYER
WEST/SOUTHWEST FLOW EXPECTED. THERMAL RIDGE WILL BE FURTHER ENHANCED
BY DOWNSLOPE FLOW. TEMPERATURES WELL INTO THE 70S TO LOWER 80S
EXPECTED. SHORTWAVE TROUGH DRIVES COLD FRONT TO THE FAR NORTHWEST
REACHES OF THE CWA LATE IN THE DAY WITH ENOUGH INSTABILITY TO
SUPPORT -TSRA.

SATURDAY NIGHT...SHORTWAVE TROUGH RACES INTO THE MIDWEST DRIVING A
STRONG/FAST MOVING COLD FRONT THROUGH THE CWA. MODELS SUGGEST FRONT
MOVES THROUGH AT 30KTS WITH 8-12MB/3HR PRESSURE RISES. 850MB WINDS
INCREASE TO 40-50KTS BEHIND IT WITH WELL-DEFINED COLD AIR
ADVECTION. A GOOD RECIPE FOR POTENTIAL HIGH WINDS...SO WILL HOIST
HIGH WIND WATCH FOR MOST PROBABLE AREAS...INCLUDING NORTHEAST
WY/NORTHWEST INTO A PORTION OF SOUTHWEST SD. 100-250J/KG SBCAPE
AVAILABLE JUST AHEAD OF FRONT...BUT VERY DRY AIR WILL BE IN PLACE.
HIGH-BASED -SHRA/-TSRA POSSIBLE IN THE EARLY EVENING HOURS.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 217 PM MDT FRI MAR 27 2015

UPPER LEVEL RIDGE REBUILDS OVER THE NORTHERN PLAINS FOR SUNDAY
THROUGH TUESDAY...WITH DRY CONDITIONS AND WELL ABOVE AVERAGE
TEMPERATURES EXPECTED. A STRONG SHORTWAVE TROF WILL SLIDE ACROSS
SOUTHERN CANADA WITH THE SOUTHERN END OF THE TROF CLIPPING
NORTHERN PORTIONS OF THE FORECAST AREA TUESDAY NIGHT...WITH SOME
SHOWERS POSSIBLE. A SURFACE COLD FRONT WILL ACCOMPANY THIS UPPER
DISTURBANCE...WITH WINDS SHIFTING TO THE NORTHWEST AND BECOMING
VERY BREEZY. THE ECM IS CURRENTLY A LITTLE FASTER AND FARTHER
NORTH THAN THE GFS...NOT BRINGING AS MUCH COLD AIR INTO THE CWA.
UPPER FLOW TRANSITIONS TO NORTHWEST FOR THE END OF THE WEEK...WITH
MODELS SHOWING A FEW MORE WEATHER DISTURBANCES MOVING THROUGH.
PRECIP CHANCES INCREASE ACROSS THE AREA THURSDAY INTO FRIDAY.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING
ISSUED AT 524 PM MDT FRI MAR 27 2015

VFR CONDITIONS WILL CONTINUE TONIGHT AND SATURDAY. GUSTY S-SW WINDS WILL
DEVELOP EARLY SATURDAY AFTN. STRONG NORTHWEST WINDS WILL FOLLOW A
STRONG COLD FRONT ACROSS THE AREA FROM LATE SATURDAY AFTN INTO
SATURDAY EVENING.

&&

.FIRE WEATHER...
ISSUED AT 217 PM MDT FRI MAR 27 2015

WARM TEMPERATURES WITH DRY WESTERLY FLOW WILL SUPPORT CRITICAL
FIRE WEATHER CONDITIONS SATURDAY AFTERNOON ACROSS NORTHEAST
WYOMING AND FAR WESTERN SOUTH DAKOTA. MINIMUM RELATIVE HUMIDITIES
NEAR 15 PERCENT WITH WESTERLY WINDS OF 20 TO 30 MPH ARE FORECAST.
IN ADDITION...A STRONG COLD FRONT WILL SUPPORT EVEN STRONGER WINDS
SATURDAY EVENING...ALONG WITH A WIND SHIFT. WINDS MAY GUST TO
AROUND 60 MPH WITH THE COLD FRONT PASSAGE. ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ACROSS MUCH OF THE CWA SATURDAY EVENING. GIVEN
THESE CONCERNS...A RED FLAG WARNING HAS BEEN ISSUED FOR SAT
AFTERNOON/EVENING.

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING FROM NOON TO 9 PM MDT SATURDAY FOR SDZ260>264.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     FOR SDZ001-002-012-025.

     HIGH WIND WATCH FROM SATURDAY EVENING THROUGH LATE SATURDAY
     NIGHT FOR SDZ013-014-026-030>032-042>044-072>074.

WY...RED FLAG WARNING FROM NOON TO 9 PM MDT SATURDAY FOR WYZ259-
     297>299.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     FOR WYZ054>058-071.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING FROM NOON TO 9 PM MDT SATURDAY FOR SDZ260>264.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     FOR SDZ001-002-012-025.

     HIGH WIND WATCH FROM SATURDAY EVENING THROUGH LATE SATURDAY
     NIGHT FOR SDZ013-014-026-030>032-042>044-072>074.

WY...RED FLAG WARNING FROM NOON TO 9 PM MDT SATURDAY FOR WYZ259-
     297>299.

     HIGH WIND WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING
     FOR WYZ054>058-071.

&&

$$

SHORT TERM...HELGESON
LONG TERM...POJORLIE
AVIATION...10
FIRE WEATHER...POJORLIE






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