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000
FXUS63 KUNR 211729
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1129 AM MDT MON JUL 21 2014

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 223 AM MDT MON JUL 21 2014

08Z SURFACE ANALYSIS HAD LEE TROUGH FROM NORTHWEST MT INTO WY
WITH FRONTAL BOUNDARY FROM SOUTHERN AB INTO CENTRAL ND. WATER
VAPOUR LOOP HAD UPPER RIDGE FROM THE SOUTHWEST US INTO THE UPPER
MIDWEST...SOUTHWEST FLOW ALOFT OVER THE CWA. SHORTWAVES NOTED OVER
THE GREAT BASIN AND ACROSS SOUTHERN BC. THESE WAVES WILL MOVE
RAPIDLY INTO THE NORTHERN PLAINS/SOUTH CENTRAL CANADA TODAY
CREATING A SURFACE LOW OVER SOUTHEAST MT...WHICH WILL MOVE INTO
EASTERN SD BY 00Z TUESDAY. THE LOW WILL DRAG FRONTAL BOUNDARY
SOUTH AS A WEAK COOL FRONT...PUSHING SOUTH OF I-90 LATE THIS
AFTERNOON. AHEAD IT...SUMMERY THERMAL RIDGE IN PLACE WITH
POTENTIAL TEMPERATURES SURPASSING 100F. 2-4KJ/KG SBCAPE WILL
DEVELOP AHEAD OF LOW PRESSURE SYSTEM THIS AFTERNOON...BUT SHOULD
PUSH EAST OF THE CWA BEFORE SBCIN IS BROKEN. FURTHER WEST...STEEP
LAPSE RATES WILL BE IN PLACE WITH 0.5-1KJ/KG MLCAPE IN THE
AFTERNOON WITH ERODING MLCIN. AS SHORTWAVE ENERGY MOVES IN FROM
THE WEST AND OVERTOPS SURFACE FEATURES...WOULD EXPECT HIGH BASED
CONVECTION TO DEVELOP WITH ISOLATED SEVERE WIND GUSTS POSSIBLE.
COMBINATION OF HIGH TEMPERATURES/DEW POINTS OVER SOUTH CENTRAL SD
WILL CAUSE APPARENT TEMPERATURES WILL PUSH INTO THE HEAT ADVISORY
CATEGORY FOR MOST OF THE AFTERNOON AND THUS WILL HOIST HEADLINES.

TONIGHT...ORGANIZED CONVECTION PUSHES EAST OF THE CWA WITH WEAK COOL
AIR ADVECTION BEHIND FRONT AS IT DROPS SOUTH OF THE CWA.
TEMPERATURES WILL BE NEAR GUIDANCE.

TUESDAY...SURFACE HIGH PUSHES EAST OF THE MO RIVER WITH
RETURN/UPSLOPE FLOW OVER NORTHEAST WY/FAR WESTERN SD. UPPER RIDGE
REBUILDS OVER THE NORTHERN PLAINS. AS TAIL END OF COOL FRONT MORPHS
INTO LEE TROUGH OVER WESTERN PORTIONS OF THE CWA...ENOUGH
CONVERGENCE WILL BE PRESENT FOR ISOLATED LATE AFTERNOON TSRA.
INVERTED-V SOUNDINGS SUGGESTS ISOLATED SEVERE WIND GUST THREAT.
TEMPERATURES WILL BE 5-10F LOWER THAN TODAY GIVEN THICKNESS CHANGE
AND FORECAST POTENTIAL TEMPERATURES.

&&

.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 223 AM MDT MON JUL 21 2014

UPPER-LEVEL RIDGE WILL DOMINATE THE WEATHER PATTERN FOR THE FIRST
PART OF THE WEEK...WITH A STRONG UPPER TROUGH MOVING ACROSS
SOUTHERN CANADA...FLATTENING THE RIDGE FOR THE SECOND HALF OF THE
WEEK. WEAK SHORT-WAVE TROUGHS TOPPING THE RIDGE WILL KEEP ISOLATED
TO SCATTERED THUNDERSTORM CHANCES IN THE FORECAST FOR WEDNESDAY
INTO SATURDAY... WITH THE BEST CHANCES COMING WEDNESDAY AFTERNOON
AND EVENING. TEMPERATURES WILL BE NEAR AVERAGE FOR WEDNESDAY
THROUGH SUNDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z TUESDAY
ISSUED AT 1128 AM MDT MON JUL 21 2014

MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.
ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON...
MAINLY ACROSS NORTHWEST SD. ISOLATED SHOWERS AND THUNDERSTORMS ARE
THEN POSSIBLE ACROSS NORTHEAST WY AND WESTERN SD LATE TODAY AND THIS
EVENING AS ANOTHER DISTURBANCE PASSES ACROSS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR SDZ046-047-049.

WY...NONE.
&&

$$

SHORT TERM...HELGESON
LONG TERM...15
AVIATION...26