Severe Thunderstorm Warning 43, NWS Riverton, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1121 AM MDT SAT JUN 22 2013

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

TODAY...RELATIVELY EARLY CONVECTION AND MORE WIDESPREAD CONVECTION
..AS HEIGHT FALLS FROM MAIN SW AXIS SWINGING AROUND BASE OF LIFTING
NW CONUS TROUGH INFLUENCE THE FA. REBUILDING SFC LOW IS POISED TO BE
LOCATED NEAR SCNTRL TO SERN WY BY MID DAY...WITH SFC INVERTED TROUGH
CUTTING DIAGONALLY UP TOWARDS THE CODY AREA ...GIVING US AN AIR MASS
DIFFERENTIAL TO WORK WITH. HOWEVER EASTERLY COMPONENT FLOW WITH
RELATIVELY MOIST LOW-LEVEL UPSLOPE N TO NW OF THE SFC LOW LOOKS TO
ORIENT THE INSTABILITY AXIS FROM SW TO NE FROM ERN SWEETWATER TO
JOHNSON COUNTY EARLY IN THE DAY...WITH MINOR BULLS EYE ACROSS
NATRONA COUNTY. STRONGER STORMS WILL GENERALLY LIE EAST OF THIS
DIVISION FOR THE MOST PART. AVAILABLE VERTICAL SHEAR OF 40 TO 50 KTS
TOGETHER WITH MODERATE MIX LAYER CAPE INSTABILITIES OF 1000 TO 1500
J/KG IN THE SERN PORTION OF THE CWA WILL GIVE THE CHANCE FOR SOME
LOW ROTATING STORMS AND PERHAPS SUSTAINED MULTICELLULAR
THUNDERSTORMS WITH MARGINAL SEVERE HAIL AND A SLIGHT POSSIBILITY OF
A TORNADO. RIGHT NOW...IT'S ALL LOCATION...LOCATION...LOCATION OF
THE SFC SETUP AND LL RETURN FLOW AS UPPER FORCING WILL CERTAINLY BE
AROUND. ALSO RIGHT NOW...TWO THINGS...OVERALL INSTABILITY EXCEPT FOR
NATRONA COUNTY...AND TO A LESSER EXTENT TO THE WEST OR SOUTHWEST OF
NATRONA A BIT...LOW TO NON-EXISTENT CAPPING WILL AID IN KEEPING
CONVECTION FROM BLOWING OUT OF CONTROL...AND BELOW SEVERE
LIMITS...EXCEPT FOR A COUPLE OF ROGUES. EVEN DOWNDRAFT POSSIBILITIES
SEEM RATHER LOW ACROSS THE CWA EXCEPT FOR ERN SWEETWATER AND PERHAPS
ERN FREMONT OR SWRN NATRONA.

TONIGHT AND SUNDAY...CONVECTION ON THE WAY OUT BY EARLY EVENING AS FRONT
AND UPPER WAVE BOTH EXIT STAGE EAST...REPLACED BY HIGH PRESSURE
OVERNIGHT. UPPER LEVEL TRANSITIONAL RIDGING BEGINS SUNDAY WITH
FAIRLY DEEP SOUTHWESTERLIES ON TAP ACROSS THE CWA. WARMING BEGINS.
ALTHOUGH WARMER AND DRIER CONDITIONS WILL BE AROUND THROUGHOUT THE
FA...WINDS WILL NOT GUST ENOUGH OVER THE ZONES WITH CURRENT CRITICAL
FUELS TO RAISE A RED FLAG WARNING FOR SUNDAY.

MONDAY AND MONDAY NIGHT...WARMER WEATHER CONTINUES FOR MOST OF THE
FA EXCEPT FOR THE NWRN CWA. MID LEVEL CLOUDS AND SLIGHT CHANCES FOR
ELEVATED SHOWERS/THUNDER WILL ACCOMPANY INCREASE IN MED LEVEL
MOISTURE FROM THE WEST...ALONG AND AHEAD OF ANOTHER IMPULSE BEING
THROWN AROUND THE BASE OF YET ANOTHER PAC NW TROUGH. SOME CHANCES
FOR PRECIP WILL CONTINUE OVER THE NORTHWEST OVERNIGHT. FIRE WEATHER
CONCERNS HAVE A GOOD CHANCE FOR CROSSING INTO RFW TERRITORY WITH LOW
RH VALUES AND STRONG SWRLY FLOW MIXING OVER FIRE WEATHER ZONES 280
285 AND 300.

.LONG TERM...TUESDAY THROUGH SATURDAY

A WEATHER SYSTEM WILL MOVE THROUGH ON TUESDAY WITH A CHANCE FOR
SHOWERS AND STORMS IN THE WESTERN MOUNTAINS AND ACROSS THE NORTH
ZONES. THE CENTRAL AND SOUTH LOOK TO BE MOSTLY DRY TUESDAY. BREEZY
TO WINDY IN THE FAVORED LOCATIONS AND FIRE WX CONCERNS MAY NEED TO
BE ADDRESSED IF CONDITIONS COME TOGETHER TUE PM AND EARLY EVE. A
SLIGHTLY COOLER DAY ON TUESDAY WITH A WEAK FRONTAL PASSAGE. ON
WEDNESDAY A WEST FLOW ALOFT WITH LIMITED MOISTURE IN THE FLOW. HAVE
LEFT IN ISOLATED MOUNTAIN STORMS WED PM AND EARLY EVE. THE LOWER
ELEVATIONS SHOULD BE DRY. THE UPPER RIDGE OF HIGH PRESSURE BUILDS
OVER THE SOUTHWEST THURSDAY THROUGH SATURDAY. THE FLOW PATTERN
AROUND THE HIGH WOULD PUT MOST OF THE REGION IN A WEST TO NORTHWEST
FLOW ALOFT. IF THIS OCCURS THEN THE HOTTEST 700MB TEMPS WOULD STAY
OVER THE WEST AND ANY DISTURBANCE ROTATING AROUND THE UPPER HIGH
COULD SPARK A FEW MOUNTAIN STORMS EACH DAY. ADDED SOME LOW PRECIP
CHANCES TO THE MOUNTAINS ON THURSDAY...THEN ADDED IN THE EAST ZONES
FROM BUFFALO TO CASPER FRIDAY AND SATURDAY AS STORM COVERAGE IN THE
MOUNTAINS MAY INCREASE AS WELL. TEMPS TO WARM WED THROUGH SATURDAY
WITH EACH DAY BEING A FEW DEGREES WARMER THAN THE PREVIOUS DAY. AS
THE GLENN FREY SONG QUOTES...THE HEAT IS ON OH IT'S ON THE STREET...
THE HEAT IS...ON. WIND SPEEDS SHOULD BE LIGHTER DUE TO PROXIMITY OF
THE UPPER HIGH WHICH WILL LIMIT POTENTIAL FIRE BEHAVIOR...BUT WITH
THE LACK OF RAIN THE FUELS WILL JUST GET DRIER.

.AVIATION.../18Z ISSUANCE/

A STRONG DISTURBANCE IS MOVING THROUGH THE AREA THIS AFTERNOON...INITIATING
SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE FORECAST AREA. THE BEST
OPPORTUNITY FOR STRONGER STORM DEVELOPMENT WILL AGAIN BE ACROSS
EASTERN AND NORTHERN WYOMING...INCLUDING
KCPR...KWRL...KBYG...KRIW...AND KLND. THESE AREAS MAY SEE SOME PERIODS
OF STRONG WIND. OTHER AREAS MAY SEE SOME STORM DEVELOPMENT...THOUGH
STORMS WILL BE LESS INTENSE. THE MAIN THREAT WITH THESE STORMS WILL
BE GUSTY WINDS. STORM ACTIVITY WILL BEGIN ENDING FROM SOUTHWEST TO
NORTHEAST...LATE THIS AFTERNOON AND EARLY EVENING...AND BE OUT OF
THE FORECAST AREA BY 03Z. CONDITIONS WILL STEADILY IMPROVE THROUGH
THE EVENING AND OVERNIGHT HOURS...WITH WIDESPREAD VFR CONDITIONS
ANTICIPATED BY 07Z SUNDAY.

.FIRE WEATHER...
BETTER MOISTURE WILL BE MORE AVAILABLE TODAY FOR MOST DISPATCH ZONES
WITH SOME CHANCE FOR SHOWERS AND SOME THUNDERSTORMS OCCURRING NEARLY
ALL ZONES EXCEPT FOR ZONES 277 AND MOST OF 414. STRONGER STORMS WILL
BE POSSIBLE OVER JOHNSON AND NATRONA COUNTIES WITH BRIEF HEAVY
RAINS...GUSTY ERRATIC WINDS AND SMALL HAIL. THE EASTERN HALF OF
SWEETWATER COUNTY WILL ALSO HAVE A CHANCE FOR DRIER MORE ELEVATED
THUNDERSTORMS WITH STRONG GUSTY WINDS AND LIGHTNING. THE WESTERN
PORTION OF SWEETWATER COUNTY WILL REMAIN MOSTLY DRY...BUT WINDS MAY
GUST OUT OF THE WEST TO AROUND 30 MPH AT TIMES. RH VALUES WILL
GENERALLY BE HIGHER FOR ALL ZONES TODAY...STAYING AT LEAST INTO THE
TEENS EVEN OVER ZONES 278 AND 279...WITH 20S TO 50S EVERYWHERE
ELSE.

SUNDAY...A WARM UP BEGINS...WITH HIGHS WARMING SOME 7 TO 9 DEG OVER
SATURDAY HIGHS. IT WILL BE DRY WITH RH VALUES DIPPING INTO THE LOWER
TEENS MOST LOW LAND AREAS...20S IN THE MOUNTAINS. WINDS HOWEVER WILL
BE TEMPERED SOMEWHAT OVER OUR EASTERN FIRE WEATHER ZONES WHERE FUELS
LEAN TOWARDS CRITICAL. DRIEST AND GUSTIEST WEATHER LOOKS TO HOLD
OVER SWEETWATER COUNTY WHERE FUELS ARE STILL OK. MONDAY ON THE OTHER
HAND WILL LEND ITSELF TOWARDS MORE DRY AND WINDY/GUSTY CONDITIONS
WITH SOUTHWEST FLOW INTO THE DRY FUEL AREAS OF ZONES 280 285 AND 300
WHICH WILL ENHANCE FIRE CONCERNS.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
TORNADO WATCH 343 IN EFFECT FOR BIG HORN...WASHAKIE...HOT
SPRINGS...JOHNSON...NATRONA AND FREMONT COUNTIES THROUGH 00Z.

&&

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...LAVOIE
FIRE WEATHER...BRAUN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
1119 AM MDT SAT JUN 22 2013

WYZ001>020-022>030-231100-
ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST-
BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS-
EAST SWEETWATER COUNTY-FLAMING GORGE-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS-
NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN-
NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS-
ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES-
SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN-
SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY-
TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN-
UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN-
WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST-
YELLOWSTONE NATIONAL PARK-
1119 AM MDT SAT JUN 22 2013

...TORNADO WATCH THROUGH 6 PM THIS EVENING FOR CENTRAL...EASTERN AND
NORTHEAST WYOMING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...TODAY AND TONIGHT

A TORNADO WATCH IS IN EFFECT FOR BIG HORN...JOHNSON...FREMONT...
NATRONA...WASHAKIE AND HOT SPRINGS COUNTIES THROUGH 6 PM THIS
EVENING.

STRONG GUSTY WINDS ARE ALSO EXPECTED WITH ANY THUNDERSTORMS THAT
OCCUR ACROSS THE REST OF WYOMING. BE ALERT TO CHANGING WEATHER
CONDITIONS AND TAKE PRECAUTIONS SHOULD ADVERSE WEATHER IMPACT YOUR
LOCATION.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

MONDAY...ISOLATED THUNDERSTORMS ACROSS THE WEST ON MONDAY. DRY...
WINDY AND HOT CONDITIONS WILL OCCUR ACROSS THE SOUTH AND CENTRAL
AREAS MONDAY AFTERNOON AND EARLY EVENING...AS WELL AS INTO
THE OWL CREEK AND SOUTHERN BIGHORN MOUNTAINS AND SOUTHERN JOHNSON
COUNTY. THIS WILL RAISE FIRE WEATHER CONCERNS.

TUESDAY...ISOLATED TO SCATTERED THUNDERSTORMS OVER THE WEST
AND NORTH. STILL WINDY AREAS ACROSS THE CENTRAL AND SOUTH.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED IN JOHNSON AND NATRONA COUNTIES
THIS AFTERNOON AND TONIGHT.  PLEASE REPORT HAIL SIZES AND WIND
DAMAGE AS WELL AS HEAVY RAIN. THANK YOU.

TEAM RIVERTON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1105 AM MDT SAT JUN 22 2013

WYZ009-019-020-221745-
BIGHORN MOUNTAINS SOUTHEAST WY-GREEN MOUNTAINS AND RATTLESNAKE RANGE
WY-NATRONA COUNTY LOWER ELEVATIONS WY-
1105 AM MDT SAT JUN 22 2013

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL NATRONA COUNTY UNTIL 1145
AM MDT...

AT 1100 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM NEAR ERVAY...OR 40 MILES NORTHEAST OF JEFFREY
CITY...MOVING NORTHEAST AT 15 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH FREQUENT DANGEROUS LIGHTNING.

THIS STORM WILL BE NEAR...
WALTMAN REST AREA AROUND 1135 AM MDT.
WALTMAN AND U.S. HWY 20/26 MILE MARKER 50 AROUND 1140 AM MDT.
HELL'S HALF ACRE AROUND 1145 AM MDT.

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 600 PM MDT SATURDAY EVENING
FOR NORTH CENTRAL WYOMING.

REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.

LAT...LON 4331 10705 4295 10676 4282 10734 4295 10745
TIME...MOT...LOC 1706Z 237DEG 14KT 4294 10730

C. BAKER

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1146 AM MDT SAT JUN 22 2013

WYZ006-008-009-011-221830-
BIGHORN MOUNTAINS SOUTHEAST WY-BIGHORN MOUNTAINS WEST WY-SOUTHEAST
BIG HORN BASIN WY-SOUTHEAST JOHNSON COUNTY WY-
1146 AM MDT SAT JUN 22 2013

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN JOHNSON AND EASTERN
WASHAKIE COUNTIES UNTIL 1230 PM MDT...

AT 1144 AM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A STRONG THUNDERSTORM 6 MILES EAST OF BIG TRAILS...OR 21 MILES
SOUTHEAST OF TEN SLEEP...MOVING EAST AT 45 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH FREQUENT DANGEROUS LIGHTNING.

THIS STORM WILL BE NEAR...
STATE HWY 191 MILE MARKER 10 AND MAYOWORTH AROUND 1215 PM MDT.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 600 PM MDT SATURDAY EVENING
FOR NORTH CENTRAL WYOMING.

REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.

LAT...LON 4415 10675 4350 10663 4351 10731 4414 10752
TIME...MOT...LOC 1746Z 264DEG 37KT 4379 10718

C. BAKER

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1153 AM MDT SAT JUN 22 2013

WYZ015-017>019-222200-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-LANDER FOOTHILLS-
WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-
1153 AM MDT SAT JUN 22 2013

THUNDERSTORMS ARE DEVELOPING FROM THE SOUTH PASS AREA AND OFF THE
WIND RIVER MOUNTAINS...MOVING INTO CENTRAL PORTIONS OF THE WIND
RIVER BASIN. THESE STORMS ARE QUICKLY MOVING TO THE NORTHEAST...
CAPABLE OF PRODUCING DANGEROUS LIGHTNING...SMALL HAIL UP TO A HALF
INCH...AND STRONG WIND GUSTS TO 50 MPH.

A TORNADO WATCH IS ALSO IN EFFECT FOR FREMONT COUNTY THROUGH 6PM.

PEOPLE IN CENTRAL...EASTERN...AND SOUTHERN FREMONT COUNTY...INCLUDING
THE SOUTHERN WIND RIVER MOUNTAINS...SOUTH PASS...BEAVER RIM...AND
SHOSHONI SHOULD BE PREPARED TO MOVE TO SAFE SHELTER IF THUNDERSTORMS
APPROACH.

TEAM RIVERTON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1222 PM MDT SAT JUN 22 2013

WYZ003-221930-
CODY FOOTHILLS-
1222 PM MDT SAT JUN 22 2013

THUNDERSTORMS COMING OFF OF THE ABSAROKA MOUNTAINS WILL
MOVE THROUGH THE CODY FOOTHILLS INCLUDING THE CITIES OF
CODY AND POWELL THROUGH 2 PM MDT.  SMALL HAIL...DANGEROUS
LIGHTNING AND WIND GUSTS TO 45 MPH WILL BE POSSIBLE
WITH THIS LINE OF THUNDERSTORMS.

IF THUNDERSTORMS APPROACH YOUR AREA...SEEK SHELTER.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
1228 PM MDT SAT JUN 22 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1202 PM     HAIL             FORT WASHAKIE           43.01N 108.93W
06/22/2013  E0.88 INCH       FREMONT            WY   PUBLIC

&&

DLIPSON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
1238 PM MDT SAT JUN 22 2013

WYZ008-009-011-221915-
BIGHORN MOUNTAINS SOUTHEAST WY-BIGHORN MOUNTAINS WEST WY-SOUTHEAST
JOHNSON COUNTY WY-
1238 PM MDT SAT JUN 22 2013

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN JOHNSON COUNTY UNTIL
115 PM MDT...

AT 1235 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A A LINE OF STRONG THUNDERSTORMS 6 MILES WEST OF MAYOWORTH...OR 15
MILES NORTHWEST OF KAYCEE...MOVING EAST AT 40 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH FREQUENT DANGEROUS LIGHTNING.

THIS STORM WILL BE NEAR...
MAYOWORTH AND STATE HWY 191 MILE MARKER 10 AROUND 1245 PM MDT.
I25 EXIT 265...STATE HWY 196 MILE MARKER 270...I25 MILE MARKER 270...
I25 MILE MARKER 260 AND STATE HWY 196 MILE MARKER 260 AROUND 1255 PM
MDT.

THIS INCLUDES INTERSTATE 25 IN WYOMING BETWEEN MILE MARKERS 237 AND
281.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 600 PM MDT SATURDAY EVENING
FOR NORTH CENTRAL WYOMING.

REPORT HAZARDOUS WEATHER TO THE NATIONAL WEATHER SERVICE OFFICE IN
RIVERTON AT 1-800-211-1448.

LAT...LON 4409 10641 4350 10640 4351 10704 4410 10710
TIME...MOT...LOC 1837Z 250DEG 36KT 4381 10688

C. BAKER