Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 311720
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1120 AM MDT TUE MAR 31 2015

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 250 AM MDT TUE MAR 31 2015

CURRENT SURFACE MAP PLACES WEAK HIGH PRESSURE ACROSS THE
DAKOTAS...WITH TROF ACROSS WESTERN MONTANA/WESTERN WYOMING. WATER
VAPOR SHOWS UPPER LEVEL RIDGE ACROSS THE NORTHERN PLAINS.

FOR TODAY...UPPER RIDGE REMAINS ACROSS THE NORTHERN PLAINS WITH
SURFACE TROF DEEPENING ACROSS EASTERN MONTANA/EASTERN WYOMING.
WITH DEEP LOW LEVEL MIXING...900-850MB TEMPERATURES SUPPORT HIGHS
INTO THE UPPER 70S/LOWER 80S. THIS WILL BE NEAR RECORD HIGHS FOR
MANY LOCATIONS.

RIDGE BREAKS DOWN TONIGHT/EARLY WEDNESDAY AS SHORTWAVE TRACK
ACROSS THE NORTHERN ROCKIES AND CLOSES OFF OVER SOUTHERN
SASKATCHEWAN. STRONG COLD FRONT PUSHES THROUGH NORTHEAST
WYOMING/NORTHWEST SOUTH DAKOTA LATE TONIGHT...AND THROUGH REST OF
FORECAST AREA WEDNESDAY MORNING. 6-9MB/3HR PRESSURE RISES...ALONG
WITH 40-50KT 850MB WINDS WILL RESULT IN WINDY CONDITIONS BEHIND
THE FRONT. LOCATION OF UPPER LOW AND LACK OF STRONG SUBSIDENCE
SHOULD KEEP THIS FROM BEING A HIGH WIND EVENT. ISOLATED SHOWERS
POSSIBLE LATE TONIGHT ACROSS NORTHEAST WYOMING.

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 250 AM MDT TUE MAR 31 2015

BROAD UPPER TROF REMAINS OVER THE NORTHERN PLAINS FOR
THURSDAY AND EARLY FRIDAY. AT THE SURFACE...STRONG PRESSURE GRADIENT
WILL REMAIN ACROSS THE DAKOTAS AS SURFACE LOW SHIFTS INTO THE GREAT
LAKES AREA...AND HIGH PRESSURE MOVES IN FROM THE NORTH. GUSTY
NORTHWEST WINDS WILL CONTINUE ACROSS MUCH OF THE AREA ON
THURSDAY...WITH WINDS FINALLY SUBSIDING THURSDAY NIGHT INTO FRIDAY.
TEMPERATURES WILL BE NEAR SEASONAL NORMS FOR THURSDAY AND FRIDAY.

UPPER LEVEL RIDGE BUILDS INTO THE NORTHERN PLAINS FOR THE WEEKEND
WITH DRY WEATHER AND ABOVE AVERAGE TEMPERATURES EXPECTED. HIGH
TEMPERATURES WILL BE IN THE 60S TO AROUND 70 DEGREES. UPPER LEVEL
FLOW TURNS MORE SOUTHWEST FOR EARLY NEXT WEEK...WITH CHANCES FOR
PRECIPITATION RETURNING TO THE AREA.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY
ISSUED AT 1119 AM MDT TUE MAR 31 2015

VFR CONDITIONS WILL CONTINUE THROUGH LATE TONIGHT...WITH
GUSTY SOUTH TO SOUTHWEST WINDS ACROSS MUCH OF THE PLAINS THIS
AFTERNOON AND EARLY EVENING. A STRONG COLD FRONT WILL MOVE THROUGH
NORTHEAST WY AND FAR NORTHWEST SD LATE TONIGHT AND ACROSS THE REST
OF WESTERN SD EARLY WEDNESDAY MORNING. STRONG NORTHWEST WINDS WILL
DEVELOP BEHIND THE FRONT...ESPECIALLY ACROSS THE NORTHWEST AND WEST
CENTRAL SD PLAINS...WHERE SUSTAINED WINDS OF 25 TO 35 KT AND GUSTS
TO 45 KTS ARE EXPECTED DURING THE DAYTIME HOURS. AREAS OF MVFR
CONDITIONS WITH ISOLATED LIGHT RAIN SHOWERS ARE POSSIBLE ACROSS
NORTHEAST WYOMING EARLY WEDNESDAY MORNING BEHIND THE FRONT.

&&

.FIRE WEATHER...
ISSUED AT 250 AM MDT TUE MAR 31 2015

WARM AND DRY ACROSS THE AREA TODAY WITH UPPER LEVEL RIDGE ACROSS
THE NORTHERN PLAINS.  MINIMUM RELATIVE HUMIDITY WILL BE AS LOW AS
10 PERCENT...ESPECIALLY ACROSS NORTHEAST WYOMING. SOUTH-SOUTHWEST
WINDS INCREASE LATE THIS MORNING/AFTERNOON. BIGGEST ISSUE WAS
WHAT TO DO WITH FIRE WEATHER WATCH ACROSS WESTERN SOUTH DAKOTA.
WINDS LOOK TO STAY JUST BELOW RED FLAG CRITERIA THIS
AFTERNOON...ESPECIALLY IN THE BLACK HILLS. HOWEVER...GIVEN THE DRY
FUELS AND RELATIVE HUMIDITY NEAR 10 PERCENT...WILL GO AHEAD AND UPGRADE
TO RED FLAG WARNING.

UPPER LEVEL RIDGE BREAKS DOWN TONIGHT/EARLY WEDNESDAY. SOUTH-
SOUTHWEST WINDS WILL DECREASE OVERNIGHT AHEAD OF A COLD FRONT.
RESULT WILL BE POOR RELATIVE HUMIDITY RECOVERY. COLD FRONT MOVES
INTO NORTHEAST WYOMING AND NORTHWEST SOUTH DAKOTA LATE
TONIGHT...AND THROUGH THE REST OF WESTERN SOUTH DAKOTA EARLY
WEDNESDAY. WINDS WILL SHIFT TO THE NORTHWEST AND INCREASE TO
20-35MPH...WITH GUSTS REACHING 50 MPH ACROSS THE PLAINS NORTH AND
EAST OF THE BLACK HILLS. THE GUSTY NORTHWEST WINDS WILL CONTINUE
THROUGH THE DAY WEDNESDAY...AS MINIMUM RELATIVE HUMIDITY DROPS TO
AROUND 15 PERCENT. MORE CONFIDENT IN REACHING RED FLAG CONDITIONS
ACROSS WESTERN SOUTH DAKOTA WEDNESDAY VERSUS TODAY. FOR
SIMPLICITY...WILL RUN RED FLAG WARNING FROM THIS AFTERNOON THROUGH
WEDNESDAY EVENING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING UNTIL 9 PM MDT WEDNESDAY FOR SDZ260>266.

WY...RED FLAG WARNING UNTIL 9 PM MDT WEDNESDAY FOR WYZ259-297>299.

&&

$$

SHORT TERM...7
LONG TERM...15
AVIATION...26
FIRE WEATHER...7





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