Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 240951
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
351 AM MDT THU JUL 24 2014

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 258 AM MDT THU JUL 24 2014

SMALL SHORTWAVE TOPPING RIDGE AXIS IS TRIGGERING ISOLATED THUNDERSTORMS
OVER NORTHWESTERN SD THIS MORNING...WHICH WILL CONTINUE TO WEAKEN AS
THEY MOVE EAST. ON THE SURFACE...LEE TROF EXTENDS FROM EASTERN MT
INTO SOUTHEAST WY. SOME THUNDERSTORMS MAY DEVELOP EARLY THIS
MORNING OVER SOUTH CENTRAL SD AS LOW LEVEL JET STRENGTHENS...
INDICATED BY MERRIMAN PROFILER WITH 50 KT AT 850MB.

TODAY...RIDGE AXIS SHIFTS EASTWARD...WITH ANOTHER SHORTWAVE
CROSSING FORECAST AREA ON SOUTHWEST FLOW. ALTHOUGH STRONGER
DYNAMICS WILL BE FARTHER NORTH INTO MT/ND/CANADA...OCCLUDED
FRONT TO SURFACE LOW AND DRYLINE TO THE SOUTH WILL MOVE FROM
EASTERN WY ACROSS SOUTH DAKOTA TODAY...WITH THUNDERSTORMS
DEVELOPING...ESPECIALLY OVER NORTHWESTERN SD WHERE CAPE WILL BE
OVER 2000J/KG. THUNDERSTORMS OVER NORTHEASTERN WY AND SOUTHWESTERN
SD WILL BE MORE ISOLATED...BUT COULD PRODUCE STRONG STRAIGHT LINE
WINDS WITH INVERTED-V SOUNDING PROFILE. TEMPERATURES WILL BE VERY
WARM OVER SOUTHWESTERN SD AS THERMAL RIDGE CROSSES WESTERN SD AND
SOUTHWEST WINDS INCREASE. BEHIND THE FRONT...COOLER DRIER AIR
MOVES INTO THE AREA...WITH WINDS BECOMING NORTHWEST AND SKIES
CLEARING.

UPPER LEVEL FLOW BECOMES ZONAL FRIDAY BELOW THE DEEP UPPER LOW IN
SOUTHERN CANADA. A SURFACE LOW FORMS OVER SOUTHEASTERN WY WITH
RETURN FLOW FROM NE PANHANDLE INTO SOUTHWESTERN SD AHEAD OF AN
INVERTED TROF NORTH OF THE LOW. SOME THUNDERSTORMS MAY DEVELOP
ALONG THE TROF OVER SOUTHWESTERN SD AND BLACK HILLS FRIDAY NIGHT
AND TRACK ACROSS SOUTHERN SD. TEMPERATURES WILL BE ABOUT 10
DEGREES COOLER...AS SURFACE HIGH BUILDS OVER ND-MN...WITH NORTHEAST
WINDS...SO WENT BELOW GUIDANCE TEMPS.

&&

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 258 AM MDT THU JUL 24 2014


UPPER-LEVEL FLOW TRANSITIONS FROM ZONAL TO NORTHWESTERLY DURING THE
WEEKEND AS AN UPPER RIDGE REBUILDS OVER THE WESTERN CONUS. THIS WILL
RESULT IN COOLER TEMPERATURES AND MAINLY DRY CONDITIONS FROM
SATURDAY THROUGH MONDAY. WEAK SHORTWAVE DISTURBANCES WILL BEGIN TO
ROTATE AROUND THE WESTERN RIDGE AND INTO THE NORTHERN PLAINS AGAIN
BY THE MIDDLE OF NEXT WEEK. LOW CHANCE POPS ARE WARRANTED ACROSS
PORTIONS OF THE AREA FROM MONDAY NIGHT THROUGH WEDNESDAY.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT
ISSUED AT 258 AM MDT THU JUL 24 2014

VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD. ISOLATED
THUNDERSTORMS ARE POSSIBLE AGAIN TODAY ACROSS NORTHEAST WY AND
MUCH OF WESTERN SD.

&&

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

$$

SHORT TERM...55
LONG TERM...15
AVIATION...15






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