Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 200831
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
231 AM MDT SUN JUL 20 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 228 AM MDT SUN JUL 20 2014

08Z SURFACE ANALYSIS HAD WEAK RETURN FLOW OVER THE CWA WITH SOME
PASSING HIGH CLOUDS. WATER VAPOUR SHOWED ZONAL FLOW WHICH WILL
CONTINUE TODAY WITH MINOR HEIGHT RISES OVER THE NORTHERN PLAINS
AND SLOWLY STRENGTHENING THERMAL RIDGE. RESULT WILL BE FILTERED
SMOKY SUNSHINE WITH CAP IN PLACE. TEMPERATURES SHADED TOWARD BIAS
CORRECTED VALUES...WHICH IS GENERALLY LOWER THAN OBJECTIVE
GUIDANCE.

TONIGHT...TROUGH DEVELOPS FROM MT INTO WESTERN NE. WEAK LOW DEVELOPS
ALONG TROUGH AS IT MOVES INTO CENTRAL SD BY 12Z MONDAY. CAP SHOULD
BE SUFFICIENT TO KEEP TSRA AT BAY...BUT THERE IS A SLIGHT HINT THAT
ELEVATED TSRA MAY BRUSH FAR NORTHWEST SD LATE. WILL KEEP POPS IN THE
UNMENTIONABLE CATEGORY FOR NOW GIVEN LACK OF CLEAR TRIGGER.
TEMPERATURES WILL BE BALMY.

MONDAY...AFOREMENTIONED LOW SPINS INTO SOUTHWEST MN DROPPING WEAK
COOL FRONT SOUTH THROUGH CWA. POST FRONTAL TSRA POSSIBLE GIVEN
SHORTWAVE ENERGY OVER-TOPPING RIDGE AND WEAKENING MLCIN DUE TO
850-700MB THERMAL PROFILE COOLING OFF BEHIND FRONT. SHEAR WILL BE
SUFFICIENT FOR ISOLATED SEVERE TSRA...PARTICULARLY FROM K2WX INTO
CENTRAL SD. TEMPERATURES WILL BE INFLUENCED BY VERY WEAK COLD AIR
ADVECTION BEHIND THE FRONT AND MID/HIGH CLOUDS ASSOCIATED WITH
SHORTWAVE.

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 228 AM MDT SUN JUL 20 2014

UPPER LEVEL RIDGE WILL DOMINATE THE WEATHER PATTERN FOR THE FIRST
PART OF THE WEEK...WITH A STRONG UPPER SHORTWAVE FLATTENING THE
RIDGE A BIT FOR THE SECOND HALF OF THE WEEK. WEAK SHORTWAVE ENERGY
TOPPING THE RIDGE WILL KEEP ISOLATED THUNDERSTORM CHANCES IN THE
FORECAST FOR TUESDAY THROUGH FRIDAY. TEMPERATURES WILL BE AT OR
SLIGHTLY ABOVE AVERAGE FOR MUCH OF THE UPCOMING WEEK...WITH A SLIGHT
COOL DOWN FOR FRIDAY INTO THE WEEKEND.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING ISSUED AT
228 AM MDT SUN JUL 20 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

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

$$

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



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