000
FXUS65 KRIW 161009
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
409 AM MDT THU MAY 16 2013

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT

A FEW SHOWERS CONTINUE ACROSS PORTIONS OF NORTHERN AND WESTERN
WYOMING THIS MORNING. SHOWER ACTIVITY WILL WEAKEN...BUT SOME SHOWER
ACTIVITY WILL REMAIN OVER THE AREA THROUGH THE MORNING.

A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE STATE TODAY. THIS
SYSTEM WILL BRING ANOTHER ROUND OF INSTABILITY ACROSS THE STATE.
THUNDERSTORMS WILL BE POSSIBLE...WITH SOME THUNDERSTORM ACTIVITY
POSSIBLE DURING THE LATE MORNING HOURS. THUNDERSTORM COVERAGE AND
LIKELIHOOD WILL INCREASE THROUGH THE AFTERNOON. GUSTY WIND WILL BE
THE PRIMARY THREAT WITH ANY ACTIVITY...THOUGH SMALL HAIL WILL NOT BE
OUT OF THE QUESTION...ALONG WITH INSTANCES OF HEAVY RAIN. PAST
WILDFIRE BURN SCARS WILL BE MONITORED CLOSELY FOR ANY POTENTIAL
FOR FLOODING. ANOTHER DAY OF MILD TO WARM TEMPERATURES MAY ALSO
CONTINUE TO MELT SNOW PACK ACROSS THE HIGHER TERRAINS. RIVER
MONITORING EQUIPMENT WILL CONTINUE TO BE WATCHED FOR ANY
SIGNIFICANT RISES TODAY.

A STRONGER TROUGH OF LOW PRESSURE WILL MOVE TOWARDS THE AREA FRIDAY
MORNING AND AFTERNOON. WITH AN INCREASING SOUTHWEST FLOW...AND A
SLIGHT NEGATIVE TILT TO THE SYSTEM...SHOWERS AND THUNDERSTORMS WILL
AGAIN DEVELOP. SHOWER ACTIVITY WILL BE FOUND ESPECIALLY ACROSS THE
WESTERN MOUNTAINS AND VALLEYS FRIDAY MORNING...WITH COVERAGE
SPREADING TO INCLUDE MUCH OF NORTHWESTERN WYOMING BY FRIDAY
AFTERNOON. CONFIDENCE IS FAIR WITH THE DEVELOPMENT OF THIS PATTERN
AS THERE IS A FAIR AMOUNT OF CONSISTENCY BETWEEN THE VARIOUS MODELS.

THE TROUGH WILL MOVE THROUGH THE AREA ON SATURDAY BRINGING COOLER
TEMPERATURES ACROSS THE FORECAST AREA. ADDITIONALLY...THE PRESENCE
OF THIS SYSTEM WILL BRING WIDESPREAD SHOWERS AND THUNDERSTORMS BY
LATE SATURDAY MORNING. SHOWERS WILL CONTINUE THROUGH THE EARLY
EVENING HOURS...WITH COVERAGE DECREASING WITH THE LOSS OF DAYLIGHT.

.LONG TERM...SUNDAY THROUGH THURSDAY

AN UPPER LOW/TROUGH ASSOCIATED WITH A REX BLOCK ACROSS NORTH
AMERICA WILL AFFECT THE FORECAST AREA SUNDAY AND MONDAY. THIS WILL
RESULT IN COOL AND INCLEMENT WEATHER BOTH DAYS. A SECONDARY COLD
FRONT ASSOCIATED WITH THIS TROUGH IS EXPECTED TO PUSH SOUTH ACROSS
THE FORECAST AREA SUNDAY INTO SUNDAY NIGHT. GLOBAL MODELS ARE
SHOWING THE POTENTIAL FOR UPSLOPE POTENTIAL EAST OF THE DIVIDE IN
WAKE OF THIS FRONT. THE FLOW IS EXPECTED TO BACK MONDAY
NIGHT/TUESDAY AS THE UPPER LOW/TROUGH SHIFTS INTO THE PLAINS
SHUTTING OFF THE UPSLOPE FLOW. ALTHOUGH THERE WILL BE CHANCES FOR
PRECIPITATION ACROSS THE ENTIRE AREA SUNDAY AND MONDAY...THE BEST
CHANCE WILL BE EAST OF THE DIVIDE. PRECIPITATION TYPE WILL BE VALLEY
RAIN AND MOUNTAIN SNOW...WITH A SNOW/RAIN ELEVATION RANGING
ROUGHLY BETWEEN 7500 AND 9000 FEET SUNDAY AND MONDAY.

WEAK RIDGING IS EXPECTED ACROSS THE FORECAST AREA TUESDAY...IN
BETWEEN AN UPPER LOW ACROSS THE MIDWEST AND A STRONGER UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST. THIS WILL RESULT IN WARMER AND
DRIER CONDITIONS TUESDAY. HOWEVER STILL CANNOT RULE OUT SOME
CONVECTION ESPECIALLY EAST OF THE DIVIDE.

GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE STRONG UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST LATE TUESDAY INTO TUESDAY NIGHT
WILL REMAIN ACROSS PACIFIC NORTHWEST AREA WEDNESDAY AND THURSDAY.
THE MAIN RESULT FOR THE FORECAST AREA WILL BE WARMING TEMPERATURES
AND INCREASING SOUTHWEST FLOW. MOISTURE APPEARS TO BE SOMEWHAT
LIMITED IN THE SOUTHWEST FLOW AHEAD OF THIS UPPER LOW...BUT ENOUGH
TO WARRANT SLIGHT CHANCE POPS...MAINLY ACROSS THE WEST AND
NORTHWEST.

&&

.AVIATION.../12Z ISSUANCE/

VERY ISOLATED SHOWERS WILL REMAIN POSSIBLE OVER A GOOD CHUNK OF THE
REGION THROUGH THE MORNING. WILL WAIT UNTIL CLOSER TO 12Z TAF
ISSUANCE TO DECIDE IF THERE IS A NEED TO MENTION MORNING SHOWER
ACTIVITY AT ANY TAF SITE. ISOLATED TO SCATTERED CONVECTION IS
EXPECTED THIS AFTERNOON INTO THE EVENING. THE BEST CONCENTRATION
SHOULD BE ACROSS THE NORTHWEST...BUT ALL TAF SITES WILL HAVE THE
POSSIBILITY OF BEING IMPACTED BY THUNDERSTORM ACTIVITY THIS
AFTERNOON. MOST OF THIS ACTIVITY WILL WANE AN HOUR OR TWO AFTER
SUNSET...EXCEPT ACROSS THE NORTHWEST...INCLUDING KJAC...WHERE
CONVECTION WILL LINGER THROUGH THE NIGHT...ALONG AN UPPER LEVEL
FRONT. VFR CONDITIONS ARE EXPECTED AT TAF SITES...EXCEPT FOR BRIEF
PERIODS OF MVFR/IFR CONDITIONS ASSOCIATED WITH ANY
SHOWER/THUNDERSTORM ACTIVITY. THE EXCEPTION COULD BE AFTER 06Z
FRIDAY ACROSS THE NORTHWEST WHERE A SIGNIFICANT MVFR AREA COULD
DEVELOP AS STEADIER PRECIP DEVELOPS. THIS COULD IMPACT KJAC
TERMINAL...BUT WILL KEEP VFR CONDITIONS FOR NOW.

&&

.FIRE WEATHER...

ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY.
WITH INCREASED CLOUD COVER TODAY...HUMIDITY WILL BE SLIGHTLY HIGHER
TODAY THAN WAS EXPERIENCED ON WEDNESDAY. HOWEVER...SOME AREAS WILL
STILL BE IN THE LOW TO MID TEENS...ESPECIALLY ACROSS THE CENTRAL AND
EASTERN BASINS. WIND WILL BECOME GUSTY IN THE AFTERNOON HOURS THE
NEXT COUPLE OF DAYS...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES. ERRATIC AND STRONGER WIND WILL BE POSSIBLE WITH
THUNDERSTORM ACTIVITY. AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE FOR THE NEXT COUPLE OF DAYS. A STRONGER TROUGH OF LOW
PRESSURE WILL MOVE ACROSS THE AREA ON SATURDAY...BRINGING COOLER
TEMPERATURES AND WIDESPREAD SHOWER ACTIVITY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...WM
FIRE WEATHER...BRANHAM