Severe Thunderstorm Warning 40, NWS Cheyenne, WY

334 
WWUS55 KCYS 042054
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
254 PM MDT THU JUN 4 2015

WYC021-042115-
/O.CON.KCYS.SV.W.0040.000000T0000Z-150604T2115Z/
LARAMIE WY-
254 PM MDT THU JUN 4 2015

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM MDT
FOR WEST CENTRAL LARAMIE COUNTY...

AT 254 PM MDT...A SEVERE THUNDERSTORM WAS LOCATED NEAR FEDERAL...OR
19 MILES WEST OF CHEYENNE...MOVING SOUTHWEST AT 5 MPH.

HAZARD...QUARTER SIZE HAIL. 

SOURCE...RADAR INDICATED. 

IMPACT...DAMAGE TO VEHICLES IS EXPECTED. 

LOCATIONS IMPACTED INCLUDE...
CRYSTAL LAKE RESERVOIR...CRYSTAL LAKE CAMPGROUND AND FEDERAL. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM IS PRODUCING LARGE HAIL. SEEK SHELTER NOW INSIDE A STURDY
STRUCTURE AND STAY AWAY FROM WINDOWS.

&&

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1000 PM MDT FOR SOUTHEASTERN
WYOMING.

LAT...LON 4138 10499 4122 10494 4115 10500 4113 10519
      4128 10528
TIME...MOT...LOC 2054Z 027DEG 8KT 4123 10514 

HAIL...1.00IN
WIND...<50MPH

$$

HAMMER

322 
WWUS55 KCYS 042112
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
312 PM MDT THU JUN 4 2015

WYC021-042122-
/O.EXP.KCYS.SV.W.0040.000000T0000Z-150604T2115Z/
LARAMIE WY-
312 PM MDT THU JUN 4 2015

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL LARAMIE COUNTY
WILL EXPIRE AT 315 PM MDT...
                
THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSE AN IMMEDIATE THREAT TO LIFE OR PROPERTY. 
THEREFORE THE WARNING WILL BE ALLOWED TO EXPIRE. HOWEVER SMALL HAIL 
IS STILL POSSIBLE WITH THIS THUNDERSTORM.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1000 PM MDT FOR SOUTHEASTERN
WYOMING.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
CHEYENNE.

LAT...LON 4138 10499 4122 10494 4115 10500 4113 10519
      4128 10528
TIME...MOT...LOC 2108Z 058DEG 5KT 4123 10514 

$$

HAMMER

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1258 PM MDT THU JUN 4 2015

.UPDATE...
ISSUED AT 1248 PM MDT THU JUN 4 2015

MAIN FORECAST CONCERNS THIS AFTERNOON WILL BE THE ONGOING FLOODING
ACROSS NIOBRARA COUNTY AND THE POTENTIAL FOR SEVERE WEATHER ACROSS
THE HIGH PLAINS. 0-6KM SHEAR APPEARS TO BE LESS COMPARED TO
YESTERDAY AND GENERALLY AROUND 40 TO 45 KNOTS. THERE IS STILL
PLENTY OF MOISTURE AND INSTABILITY WITH CAPE VALUES FORECAST TO BE
BETWEEN 1500 TO 2500 J/KG TODAY. THERE IS A CONVERGENCE BOUNDARY
NEAR THE LARAMIE RANGE WITH SOUTH WINDS TO THE WEST...AND EAST
WINDS ACROSS THE HIGH PLAINS. BELIEVE THIS WILL BE THE MAIN
FORCING MECHANISM FOR CONVECTION TO INITIATE ONCE THE CAP WEAKENS
SOMETIME THIS AFTERNOON. THESE THUNDERSTORMS MAY BECOME SEVERE
ONCE THEY MOVE ACROSS THE HIGH PLAINS WITH LARGE HAIL...HEAVY
RAINFALL...AND STRONG WINDS POSSIBLE.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 430 AM MDT THU JUN 4 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE WHEN
THE CONVECTION WILL FIRE UP NEXT.

TODAY-TONIGHT:
LATEST RADAR LOOP WAS SHOWING THE BULK OF THE CONVECTION
ROLLING THROUGH SOUTHWEST SOUTH DAKOTA WITH ONLY A FEW SHOWERS IN
THE NEBRASKA PANHANDLE AND A CLUSTER OF SHOWERS AND ISOLATED
THUNDERSTORMS IN NIOBRARA COUNTY. EARLIER TONIGHT CENTRAL AND
SOUTHWEST NIOBRARA COUNTY RECEIVED A HUGE AMOUNT OF RAINFALL. IN
FACT...DUAL POL RADAR ESTIMATES WERE SHOWING RAINFALL AMOUNTS
RANGING FROM 4 TO 6 INCHES BETWEEN MANVILLE AND KEELINE WITH MOST
OF THAT RAINFALL TAKING PLACE IN ABOUT TWO TO THREE HOURS. THESE
INTENSIVE RAINFALL RATES YIELDED TO SEVERAL HIGHWAYS BEING CLOSED
DUE TO HIGH WATER. IN ADDITION...THERE IS FLOOD WAVE TAKING PLACE
ALONG THE NIOBRARA RIVER THAT JUST REACHED THE OUTSKIRTS OF LUSK
DURING THE LAST HOUR OR SO. NOT ONLY HAVE HIGHWAYS BEEN
CLOSED...THERE HAS BEEN EVACUATIONS IN THE TOWN OF MANVILLE AND
LUSK. THE ONLY GOOD THING ABOUT THIS SITUATION IS THAT THE
RAINFALL HAS ENDED ACROSS THIS REGION FOR NOW.

ANOTHER CONCERN THIS MORNING IS THE FOG POTENTIAL ACROSS AREAS
BETWEEN THE I-80 SUMMIT AND CHEYENNE. THIS AREA OF FOG SHOULD
GRADUALLY LIFT BY MID MORNING. ONCE THE CLOUDS EXIT THE AREA...AREAS
ALONG AND EAST OF THE LARAMIE RANGE WILL NEED TO GET PREPARED FOR
THE NEXT ROUND OF STRONG TO SEVERE STORMS. IN FACT...THE INSTABILITY
MAY BE GREATER TODAY THAN YESTERDAY. LAPS DATA IS CURRENTLY IS
SHOWING 1500J/KG OF CAPE AT THIS HOUR...BUT ONCE THE SUN COMES OUT
WE MAY SEE INSTABILITY VALUES CLIMB TO 2500-4000 J/KG EAST OF THE
LARAMIE RANGE WITH HIGHEST VALUES IN THE NEBRASKA PANHANDLE. THE
SHEAR VALUES APPEAR TO BE MORE MARGINAL DUE TO WEAKER FLOW ALOFT
AROUND 6KM. LATEST WATER VAPOR LOOP IS ALSO SHOWING NOT AS MUCH
EVIDENCE OF ANY STRONG WAVES KICKING OUT OF THE SOUTHWEST WHICH
MAY LIMIT THE STRENGTH OF THE MID LEVEL FLOW. AS A RESULT...MOST
OF THE CONVECTION MAY END UP BEING DIURNALLY/OROGRAPHIC DRIVEN
TODAY DUE TO DIFFLUENT FLOW ALOFT. THE CAP MAY ALSO TRY TO HOLD ON
SIMILAR TO YESTERDAY WHICH MAY DELAY THE STORMS FROM GETTING GOING
UNTIL LATER IN THE DAY. ALTHOUGH...IF ANY STORMS DO GET GOING THEY
WILL CERTAINLY HAVE THE POTENTIAL TO BECOME SEVERE WITH LARGE
HAIL/DAMAGING WINDS AND HEAVY RAINFALL BEING THE MAIN THREATS
WHICH COULD LAST UNTIL SUNSET AS THE STORMS SLOWLY PUSH EAST.

FRIDAY-SATURDAY:
THE CLOSED UPPER LEVEL LOW IN THE DESERT SOUTHWEST WILL SLOWLY PUSH
EAST DURING THE NEXT COUPLE OF DAYS. AS THIS OCCURS...WE SHOULD SEE
THE MID LEVEL WINDS INCREASE AGAIN FROM THE SOUTH-SOUTHWEST ON
FRIDAY WHICH MAY BRING OUR NEXT ROUND OF SEVERE WEATHER DUE TO
PLENTY OF INSTABILITY IN PLACE. HARD TO SAY WHAT WILL BE IN STORE
FOR US ON SATURDAY...BUT WITH SUCH HIGH DEWPOINTS REMAINING IN
PLACE COMBINED WITH MORE SUBTLE WAVES MOVING THROUGH THE DIFFLUENT
FLOW WE MAY END UP HAVING ANOTHER ROUND OF STRONG TO SEVERE
STORMS.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 430 AM MDT THU JUN 4 2015

MEDIUM-RANGE MODEL GUIDANCE PROGS THE UPPER LOW CENTERED OVER NEVADA
AND UTAH TO WEAKEN INTO AN OPEN WAVE AS IT CROSSES THE CENTRAL ROCKIES
AND GREAT PLAINS THIS WEEKEND. UPPER LEVEL DIFFLUENCE COMBINED WITH
PASSING WEAK DISTURBANCES AND MOIST CONVERGENT LOW LEVEL FLOW WILL KEEP
SCATTERED SHOWERS AND TSTORMS IN THE FORECAST SATURDAY NIGHT THROUGH
SUNDAY NIGHT. A BIT LESS CONVECTIVE COVERAGE EXPECTED MONDAY AS BETTER
MOISTURE AND LIFT WILL BE SITUATED OVER COLORADO. A DRIER AND SOMEWHAT
MORE STABLE AIR MASS RETURNS TUESDAY AND WEDNESDAY AS A UPPER RIDGE
DOMINATES THE CWA. CANNOT COMPLETELY RULE OUT ISOLATED DIURNAL CONVECTION
OVER THE SNOWY...SIERRA MADRE AND SOUTH LARAMIE RANGES AS WELL AS EASTERN
WY INTO NORTHERN NE PANHANDLE. TEMPERATURES WILL WARM 3 TO 5 DEGREES
EACH DAY WITH HIGHS IN THE 70S TO LOW 80S TUESDAY AND WEDNESDAY. IT
WILL TURN SLIGHTLY COOLER THURSDAY FOLLOWING THE PASSAGE OF A WEAK
PACIFIC FRONT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1214 PM MDT THU JUN 4 2015

LOW STRATUS DECK REMAINS IN PLACE OVER THE WESTERN NEBRASKA
PANHANDLE THIS AFTEROON WITH MOSTLY MVFR. MVFR TO CONTINUE THROUGH
TODAY THEN LIKELY DROPPING TO IFR TONIGHT WITH THE STRATUS AND
POSSIBLY FOG MOVING WESTWARDS INTO SOUTHEAST WYOMING. ALSO SHOWERS
AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON WITH SOME
THUNDERSTORMS CONTINUING INTO THE OVERNIGHT HOURS. LARGE HAIL WILL
BE POSSIBLE WITH SOME STORMS.

&&

.FIRE WEATHER...
ISSUED AT 338 AM MDT THU JUN 4 2015

SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL
PERSIST ACROSS THE AREA THROUGH THE WEEKEND. THIS WILL RESULT IN
MOIST SOIL CONDITIONS WHICH WILL SUPPRESS ANY FIRE STARTS OR
WILDFIRE BEHAVIOR. THESE SATURATED SOILS WILL ALSO ALLOW FOR THE
GREEN-UP CONDITIONS TO CONTINUE.

&&

.HYDROLOGY...
ISSUED AT 338 AM MDT THU JUN 4 2015

TORRENTIAL RAINFALL ACROSS SOUTHERN NIOBRARA COUNTY LAST NIGHT
PRODUCED FLASH FLOODING. RADAR ESTIMATES 4 TO 6 INCHES FELL IN 2
TO 3 HOURS WITH A FLOOD WAVE PUSHING ALONG THE NIOBRARA RIVER
DOWNSTREAM. LAW ENFORCEMENT OFFICIALS EVACUATED RESIDENTS ALONG
THE RIVER NEAR MANVILLE.

MEANWHILE...THE LARAMIE RIVER NEAR FORT LARAMIE AND AT LARAMIE AS
WELL AS THE UPPER NORTH PLATTE RIVER AT SARATOGA WILL CONTINUE TO
DEAL WITH HIGH WATER LEVELS DUE TO SNOWMELT RUNOFF...RAINFALL AND
RESERVOIR RELEASES. ALONG THE LOWER NORTH PLATTE...HENRY NE WILL
FLUCTUATE BETWEEN 5.2 AND 5.4 FEET TODAY THEN SLOWLY FALL TO 5
FEET THIS WEEKEND. MITCHELL NE WILL FALL SLOWLY FROM 8.4 FEET BUT
REMAIN ABOVE FLOOD STAGE THROUGH SATURDAY NIGHT. THESE FORECASTS
ARE SUBJECT TO CHANGE GIVEN THE ADDITIONAL RAINFALL AND RELEASES
FROM THE GLENDO AND GUERNSEY RESERVOIRS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

UPDATE...TJT
SHORT TERM...REC
LONG TERM...MAJ
AVIATION...SML
FIRE WEATHER...REC
HYDROLOGY...MAJ

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
448 AM MDT THU JUN 4 2015

WYZ101>119-051100-
CONVERSE COUNTY LOWER ELEVATIONS-NIOBRARA COUNTY-
NORTH LARAMIE RANGE-FERRIS/SEMINOE/SHIRLEY MOUNTAINS-
SHIRLEY BASIN-CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY-
EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY-
NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY-
SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE-
LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS-
CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY-
448 AM MDT THU JUN 4 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL
WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING.

.DAY ONE...TODAY AND TONIGHT
MORE SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON WITH SOME OF THESE STORMS BECOMING SEVERE. THE MAIN
THREAT WITH THESE STORMS WILL BE LARGE HAIL AND DAMAGING WINDS.
THE STORMS WILL GENERALLY MOVE FROM WEST TO EAST AT SPEEDS OF 10
TO 20 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY
THE THREAT FOR MORE THUNDERSTORMS IS EXPECTED TO LINGER THROUGH
THE WEEKEND. SOME OF THESE STORMS WILL ONCE AGAIN HAVE THE CHANCE
OF BECOMING STRONG OR SEVERE.

.SPOTTER INFORMATION STATEMENT...
SKYWARN SPOTTER ACTIVATION WILL BE POSSIBLE TODAY AND THIS
EVENING. SPOTTERS ARE URGED TO REPORT SEVERE WEATHER TO THE
NATIONAL WEATHER SERVICE TODAY AND THIS EVENING.

NEZ002-003-019>021-054-055-095-096-051100-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-
448 AM MDT THU JUN 4 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN
NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

MORE SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON WITH SOME OF THESE STORMS BECOMING SEVERE. THE MAIN
THREAT WITH THESE STORMS WILL BE LARGE HAIL AND DAMAGING WINDS.
THE STORMS WILL GENERALLY MOVE FROM WEST TO EAST AT SPEEDS OF 10
TO 20 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE THREAT FOR MORE THUNDERSTORMS IS EXPECTED TO LINGER THROUGH THE
WEEKEND. SOME OF THESE STORMS WILL ONCE AGAIN HAVE THE CHANCE OF
BECOMING STRONG OR SEVERE.

.SPOTTER INFORMATION STATEMENT...
SKYWARN SPOTTER ACTIVATION WILL BE POSSIBLE TODAY AND THIS
EVENING. SPOTTERS ARE URGED TO REPORT SEVERE WEATHER TO THE
NATIONAL WEATHER SERVICE TODAY AND THIS EVENING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
126 PM MDT THU JUN 4 2015

WYZ102-108-042015-
GOSHEN COUNTY WY-NIOBRARA COUNTY WY-
126 PM MDT THU JUN 4 2015

...SPECIAL WEATHER STATEMENT...

AT 124 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM
WITH HEAVY RAINFALL OVER LUSK. THIS STORM WAS NEARLY STATIONARY.

HALF INCH HAIL WILL BE POSSIBLE WITH THIS STORM. THIS STORM WILL
IMPACT CLEAN UP EFFORTS IN LUSK FROM LAST NIGHTS HEAVY RAINFALL.

LOCATIONS IMPACTED INCLUDE...
LUSK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS OCCURRING WITH THIS STORM...AND MAY LEAD TO
FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED ROADWAYS.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

&&

LAT...LON 4274 10461 4288 10454 4284 10419 4259 10431
TIME...MOT...LOC 1924Z 288DEG 4KT 4277 10444

TJT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
137 PM MDT THU JUN 4 2015

WYZ117-118-042015-
SOUTH LARAMIE RANGE FOOTHILLS WY-CENTRAL LARAMIE COUNTY WY-
137 PM MDT THU JUN 4 2015

...SPECIAL WEATHER STATEMENT...

AT 137 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
WHITAKER...OR 15 MILES NORTHWEST OF CHEYENNE...MOVING SOUTHEAST AT 5
MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 30 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
RANCHETTES...NORTH CHEYENNE AND WHITAKER.

THIS INCLUDES INTERSTATE 25 IN WYOMING BETWEEN MILE MARKERS 15 AND
32.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 4135 10504 4149 10482 4132 10456 4113 10496
TIME...MOT...LOC 1937Z 326DEG 5KT 4135 10493

TJT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
216 PM MDT THU JUN 4 2015

WYZ102-108-042100-
GOSHEN COUNTY WY-NIOBRARA COUNTY WY-
216 PM MDT THU JUN 4 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL NIOBRARA AND
NORTHWESTERN GOSHEN COUNTIES UNTIL 300 PM MDT...

AT 216 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
RAWHIDE BUTTES...OR 9 MILES SOUTHWEST OF LUSK...MOVING SOUTH AT 15
MPH.

DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
RAWHIDE BUTTES AND JAY EM.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 4268 10466 4273 10443 4248 10427 4243 10460
TIME...MOT...LOC 2016Z 343DEG 12KT 4264 10452

FINCH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
227 PM MDT THU JUN 04 2015

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

0224 PM     HAIL             12 SSE HORSE CREEK      41.25N 105.09W
06/04/2015  E1.50 INCH       LARAMIE            WY   CO-OP OBSERVER

&&

SML