Flood in Wyoming, June 6 to 15, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1147 PM MDT SAT JUN 6 2015

UPDATE...ADDED 06Z AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 223 PM MDT)

LARGE POSITIVELY TILTED TROF ALOFT WITH CLOSED LOW CENTERED OVR THE
DESERT SW...BEING DRAGGED AND STRETCHED SLOWLY TO THE NE AND INTO
THE ROCKY MOUNTAIN STATES. GENERALLY WEAKENING FLOW ALOFT...WITH
MODEST JET OFF TO THE SE OF THE FA. MINOR SW IS LOCATED JUST EAST OF
THE FA...WITH ANOTHER WEAK VORT LOBE NEAR THE SW PORTION OF WY.

SFC SHOWS COLD FRONT THRU AND OFF TO THE SE INTO NERN CO...WITH
STATIONARY PORTION OF SAME FRONT STRETCHING OFF TO THE WEST...ACROSS
SRN WY. WEAK P GRADS AT SFC UNDER WEAK(ENING) FLOW ALOFT IS MAKING
FOR POOR FORCING AND VERY SLOW MOVEMENT FOR ANY SHOWERS/STORMS THAT
DO GET STARTED. STRONGEST T-STORM PARAMETERS RESIDE ACROSS THE ERN
COUNTIES...WHERE MORE SUNSHINE IS GETTING THRU...ALTHOUGH THE LOWER
LEVELS ARE CURRENTLY CAPPED. MOUNTAINS ARE ALLOWING CI....BUT THESE
STORMS ARE HAVING A HARD TIME MOVING AWAY FROM THE HILLS AND
SURVIVING ATTM. TO THE WEST...LESS CAP BUT ALSO LESS IN THE WAY OF
DYNAMICS. MOISTURE HOWEVER...ESPECIALLY ACROSS THE CNTRL...NRN AND
ERN CWA...IS AVAILABLE IN COPIOUS FASHION WITH PWS AOA 1 INCH COMMON.
ALTOGETHER...FLASH FLOOD POTENTIAL WILL AGAIN BE HIGH TODAY AND THIS
EVENING WITH THE SLOW MOVING NATURE OF THE STORMS AND A STRONG
LIKELIHOOD OF SOME LOCALIZED POPCORN STORMS PRODUCING FROM 1 TO 3
INCHES OF PRECIP. OVERNIGHT...UPR TROF AXIS CONTINUES EWD...WITH
PRECIP POTENTIAL FOLLOWING...LEAVING NATRONA COUNTY AND BACK INTO
ECNTRL WY THE LAST TO GIVE UP THE RAINFALL. SUNDAY...MOUNTAINS AND
THE SRN PORTION OF THE CWA WILL BE THE PREFERRED LOCATIONS FOR NEW
CONVECTION...HOWEVER THE FLASH FLOODING POTENTIAL LOOKS TO BE ON THE
DECREASE AS PWS DECREASE BY SOME 15 TO 30 PERCENT.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

BY SUNDAY NIGHT THE CLOSED LOW WILL HAVE SHEARED OUT AND WE WILL BE
LEFT WITH A COL REGION JUST TO OUR SOUTH. THERE WILL BE A LINGERING
MID LEVEL CIRCULATION IN SOUTHWEST WY SUNDAY EVENING SO WILL KEEP
THE TREND FOR HIGHEST POPS/QPF TOWARD SOUTHWEST WYOMING SUNDAY
EVENING. A RIDGE OF HIGH PRESSURE WILL ESTABLISH ITSELF ON MONDAY
AND TUESDAY SO WE ARE EXPECTING DRIER WEATHER DURING THAT TIME
FRAME. THE RIDGE WILL NOT BE THAT STRONG SO WILL LEAVE LOW POPS IN
THE MTNS FOR AFTERNOON/EVE CONVECTION. FOR TUESDAY CAPES WILL
INCREASE IN THE NW ALONG WITH NEGATIVE LIFTED INDICIES INCREASING
THROUGHOUT SO HAVE THE HIGHEST POPS IN THE NW MTNS. TUESDAY SHOULD
TURN OUT TO BE THE HOTTEST DAY OF THE WEEK WITH THE BIG HORN BASIN
PUSHING OR EXCEEDING 90 DEGREES BEFORE THE NEXT SHORTWAVE TRACKS
ACROSS THE AREA WED NT THROUGH THU NT DURING WHICH TIME WE WILL SEE
AN INCREASE IN LATE DAY CONVECTION AND COOLER TEMPS. WARMING AND
DRYING EXPECTED TOWARD NEXT WEEKEND AS A FOLD OVER RIDGE BUILDS INTO
THE AREA.

&&

.AVIATION.../06Z ISSUANCE/

AN EAST TO WEST ELONGATED AREA OF SHOWERS AND ISOLATED THUNDERSTORMS
OVER NORTH AND CENTRAL WYOMING WILL CONTINUE TO SLOWLY PUSH
SOUTHWARD THROUGH SUNDAY MORNING.  THIS AREA OF
PRECIPITATION...HIGHER MTN OBSCURATIONS AND LCL MVFR CONDITIONS
SHOULD BE ALONG A VCNTY KBPI-KLND-KCPR LINE BY 14Z...AND THEN SLOWLY
DISSIPATE BY SUNDAY AFTERNOON.  MOST SHOWER AND ISOLATED
THUNDERSTORM ACTIVITY WILL BE CONFINED WILL BE MAINLY CONFINED OVR
THE MTNS 18Z SUN-03Z MON.

&&

.FIRE WEATHER...

FIRE DANGER SHOULD REMAIN LOW THROUGH MONDAY. AN UPPER LEVEL
DISTURBANCE WITH PLENTY OF MOISTURE WILL MOVE ACROSS THE FORECAST
AREA TODAY AND TONIGHT...WITH GOOD CHANCES FOR SHOWERS AND
THUNDERSTORMS...SOME PRODUCING HEAVY RAIN AND SMALL HAIL. SOMEWHAT
DRIER AND WARMER WEATHER WILL RETURN BEGINNING TUESDAY. OTHER THAN A
SMALL CHANCE FOR FIRE STARTS THROUGH LIGHTNING STRIKES...AND ERRATIC
BEHAVIOR WITH GUSTY WINDS NEAR THUNDERSTORMS...FIRE BEHAVIOR SHOULD
BE RELATIVELY TAME.

&&

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

&&

SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...AEM
FIRE WEATHER...BRAUN

HAZARDOUS WEATHER OUTLOOK...RESENT
NATIONAL WEATHER SERVICE RIVERTON WY
621 PM MDT SAT JUN 6 2015

WYZ001>020-022>030-070530-
YELLOWSTONE NATIONAL PARK-ABSAROKA MOUNTAINS-CODY FOOTHILLS-
NORTH BIG HORN BASIN-SOUTHWEST BIG HORN BASIN-
SOUTHEAST BIG HORN BASIN-OWL CREEK AND BRIDGER MOUNTAINS-
BIGHORN MOUNTAINS WEST-BIGHORN MOUNTAINS SOUTHEAST-
NORTHEAST JOHNSON COUNTY-SOUTHEAST JOHNSON COUNTY-
TETON AND GROS VENTRE MOUNTAINS-JACKSON HOLE-
WIND RIVER MOUNTAINS WEST-WIND RIVER MOUNTAINS EAST-
UPPER WIND RIVER BASIN-WIND RIVER BASIN-LANDER FOOTHILLS-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-
NATRONA COUNTY LOWER ELEVATIONS-CASPER MOUNTAIN-STAR VALLEY-
SALT RIVER AND WYOMING RANGES-UPPER GREEN RIVER BASIN FOOTHILLS-
UPPER GREEN RIVER BASIN-SOUTH LINCOLN COUNTY-
ROCK SPRINGS AND GREEN RIVER-FLAMING GORGE-EAST SWEETWATER COUNTY-
621 PM MDT SAT JUN 6 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND WESTERN WYOMING.

.DAY ONE...TONIGHT

ISOLATED TO SCATTERED EVENING THUNDERSTORMS. SOME STORMS WILL
STILL SEE THE THREAT OF STRONG THUNDERSTORMS WITH SMALL
HAIL...GUSTY WIND AND LOCALLY HEAVY RAIN...ESPECIALLY IN NATRONA
AND JOHNSON COUNTIES.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SUNDAY...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS.

MONDAY AND TUESDAY...ISOLATED THUNDERSTORMS POSSIBLE...MAINLY OVER
THE MOUNTAINS AND ADJACENT FOOTHILLS.

WEDNESDAY AND THURSDAY...A BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT HAIL SIZES...WIND SPEEDS OVER 45
MPH...AND ANY FLOODING. THANK YOU.

TEAM RIVERTON