National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KUNR 241549
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
949 AM MDT FRI MAY 24 2013

.UPDATE...
ISSUED AT 934 AM MDT FRI MAY 24 2013

CURRENT SURFACE ANALYSIS HAS LOW OVER SOUTHEAST MONTANA AND A
TIGHT PRESSURE GRADIENT ACROSS SOUTH DAKOTA. SOUTHERLY WINDS OF
25-30 KTS WITH GUSTS APPROACHING 40 KTS HAVE BEEN REPORTED ACROSS
SOUTH CENTRAL SOUTH DAKOTA THIS MORNING. BOUNDARY LAYER WINDS ARE
EXPECTED TO BE 25-30 KTS UNTIL MID-AFTERNOON AND THEN GRADUALLY
DECREASE...SO ISSUED A WIND ADVISORY FOR SOUTH CENTRAL SOUTH
DAKOTA. REST OF THE FORECAST LOOKS ON TRACK AT THIS TIME.

UPDATE ISSUED AT 553 AM MDT FRI MAY 24 2013

12Z KUNR SOUNDING SHOWS 55KT WINDS IN THE 800-750MB LAYER...BELOW
STRONG INVERSION. APPEARS THAT INVERSION HEIGHT MAY BE A LITTLE
TOO HIGH FOR DOWNSLOPE WINDS ACROSS THE NORTHERN BLACK HILLS.
THEREFORE HAVE DROPPED THE HIGH WIND WARNING AN HOUR EARLY.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 255 AM MDT FRI MAY 24 2013

CURRENT SURFACE MAP SHOWS TROF OF LOW PRESSURE ACROSS EASTERN
WYOMING INTO CENTRAL MONTANA. WINDS HAVE BEEN DECREASING ACROSS
NORTHEAST WYOMING OVERNIGHT AND WILL LET HIGH WIND WARNING EXPIRE.
KUNR VWP HAS 70KT WINDS JUST OFF THE SURFACE. FORECAST SOUNDINGS
INDICATE INVERSION LEVEL LOWERING OVER THE BLACK HILLS THROUGH THE
NEXT FEW HOURS...THUS INCREASING THREAT FOR HIGH WINDS IN NORTHERN
BLACK HILLS/FOOTHILLS.

SURFACE TROF MOVES EAST TODAY. TIGHT PRESSURE GRADIENT WILL ALLOW
FOR GUSTY SOUTH WINDS ACROSS THE SOUTH DAKOTA PLAINS TODAY...WITH
A PERIOD OF WINDS NEAR LOW END OF ADVISORY CRITERIA. BIGGEST
QUESTION WILL BE HOW MUCH MIXING CAN OCCUR BEFORE LOW LEVEL JET
WEAKENS. WEAK INSTABILITY DEVELOPS ALONG AND AHEAD OF SURFACE TROF
LATER THIS MORNING INTO THIS AFTERNOON. WITH LACK OF UPPER FORCING
AND DECENT CAP...MAY SEE SOME ISOLATED THUNDERSTORMS ACROSS SOUTH
CENTRAL SOUTH DAKOTA THIS AFTERNOON AND EVENING. ISOLATED
THUNDERSTORMS POSSIBLE ACROSS WESTERN SOUTH DAKOTA LATE TONIGHT IN
BROAD AREA OF 850-700MB THETA-E ADVECTION AND 250-500J/KG MUCAPE.

WEAK SURFACE LOW DEVELOPS ACROSS NORTHEAST WYOMING ON
SATURDAY...WITH TROF/WARM FRONT ALONG THE NEBRASKA BORDER.
EASTERLY LOW LEVEL FLOW EXPECTED ACROSS MUCH OF WESTERN SOUTH
DAKOTA...WITH INCREASING INSTABILITY. BY SATURDAY AFTERNOON SBCAPE
REACHES 2000-2500J/KG. MODERATE SHEAR WILL ALLOW A FEW
SUPERCELLS...ESPECIALLY FROM THE BLACK HILLS INTO NORTHWEST SOUTH
DAKOTA.

&&

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 255 AM MDT FRI MAY 24 2013

PERSISTENT TROF ACROSS THE PACIFIC NORTHWEST WILL KEEP THE
NORTHERN PLAINS UNDER ACTIVE SOUTHWEST FLOW LATE IN THE WEEKEND
INTO EARLY NEXT WEEK. DAILY CHANCES FOR TSTMS WILL CONTINUE AS
LIGHT EAST TO SOUTHEAST BOUNDARY LAYER FLOW CONTINUES TO BRING
MOIST AIR INTO THE REGION...AND WEAK ENERGY EJECTS OUT OF THE
WESTERN TROF INTO THE NORTHERN PLAINS. TEMPERATURES WILL REMAIN
ABOVE AVERAGE THROUGH THE MIDDLE OF NEXT WEEK...WITH HIGHS
GENERALLY IN THE 70S AND LOWER 80S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY NIGHT)
ISSUED AT 255 AM MDT FRI MAY 24 2013

MAINLY VFR CONDITIONS ARE EXPECTED THROUGH SATURDAY MORNING. THERE
MAY BE A PERIOD OF MVFR CEILINGS ACROSS SOUTHERN PORTIONS OF SOUTH
DAKOTA...FROM KRAP SOUTH AND EAST THROUGH 18Z THIS MORNING. STRONG
SOUTHEAST WINDS GUSTING TO AROUND 35KTS WILL CONTINUE ACROSS THE
WESTERN SD PLAINS THROUGH THIS AFTERNOON. STRONG WINDS SHOULD
DIMINISH...AND TURN MORE WESTERLY...FROM WEST TO EAST TODAY AS A
SURFACE FRONTAL BOUNDARY MOVES THROUGH.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR SDZ046-047-049.

WY...NONE.
&&

$$

UPDATE...POJORLIE
SHORT TERM...7
LONG TERM...15
AVIATION...15