Severe Thunderstorm Warning 45, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
342 PM MDT THU JUN 13 2013

.SHORT TERM...MAIN CONCERN IS WITH SEVERE WEATHER POTENTIAL OVER
THE PLAINS THROUGH THIS EVENING AND CRITICAL FIRE WEATHER
CONDITIONS OVER MOUNTAIN VALLEYS AND PALMER DIVIDE.

MOISTURE LEVELS HAVE INCREASED OVER EASTERN COLORADO TODAY WITH
PW VALUES AROUND .75" AND SURFACE DEWPOINTS ARE HOLDING IN THE
LOWER 50S EXCEPT 30 TO 40 OVER DOUGLAS AND ELBERT COUNTIES. WELL
DEVELOPED DENVER CYCLONE AND BOUNDARY HAVE DEVELOPED WITH STRONG
SOUTHEAST LOW LEVEL FLOW OVER THE EASTERN PLAINS. THERE IS A BIT
OF CIRRUS MOVING ACROSS BUT DOES LOOK LIKE BETTER CLEARING BEHIND
IT. SURFACE TEMPERATURES ARE ALREADY AROUND 90 AND SHOULD BE
ENOUGH TO BREAK THE CAP. SEVERE POTENTIAL STILL LOOKS ON TRACK
FROM DOUGLAS/ELBERT COUNTIES AND STRETCHING NORTHEAST OVER THE
PLAINS. MORE UNCERTAINTY OVER THE DENVER AREA BUT CAN'T RULE OUT
FOR A ISOLATED SEVERE STORM OVER DENVER AS WELL.

MODELS INDICATE STORMS WILL DEVELOP INTO MCS SOMEWHERE OVER THE
PLAINS...MOST LIKELY INTO MORGAN AND WASHINGTON COUNTIES BY THIS
EVENING. SURFACE BASED CAPES UPWARDS OF 2000J/KG OVER THE PLAINS
SO LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE. EVEN ISOLATED
TORNADOES POSSIBLE ALONG THE CONVERGENCE LINE.

FOR FRIDAY...THUNDERSTORM POTENTIAL SHIFTS SOUTH A BIT BUT STILL
ISOLATED THUNDERSTORMS WITH EVEN ...SOME SEVERE OVER FAR EASTERN
COLORADO. MOUNTAINS LOOK DRIER AS UPPER WAVE MOVES AWAY FROM
COLORADO. LITTLE CHANGE IN TEMPERATURES BUT RH LEVEL SHOULD BE A
BIT HIGHER.

.LONG TERM...SOME STORMS WILL BE POSSIBLE ACROSS THE AREA FRIDAY
EVENING...MAINLY THE FAR NORTHEAST PLAINS WHERE THERE WILL BE
BETTER LOW LEVEL MOISTURE AND SURFACE CAPES AROUND 1000 J/KG.
MOST OF THE STORMS WILL BE HIGH BASED...PRODUCING GUSTY WINDS BUT
LIMITED RAINFALL. A FEW STORMS OVER THE FAR NORTHEAST PLAINS COULD
PRODUCE BRIEF HEAVY RAIN AND SMALL HAIL. NOT ANTICIPATING SEVERE
STORMS AT THIS TIME DUE TO LIMITED SHEAR. STORMS SHOULD EXIT THE
AREA AROUND MIDNIGHT THOUGH A FEW STORMS COULD LINGER OVERNIGHT
OVER THE FAR NORTHEAST CORNER. OTHERWISE...SKIES TO GRADUALLY
CLEAR. MODELS CONTINUE TO SHOW A COLD FRONT MOVING INTO NORTHEAST
COLORADO LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING WITH
INCREASING LOW LEVEL MOISTURE AND UPSLOPE. FORECAST SOUNDINGS
SHOWING PRECIPITABLE WATER VALUES INCREASING TO AROUND NINE
TENTHS OF AN INCH ACROSS THE PLAINS WITH CAPE VALUES AROUND
1500-2000 J/KG. THE HIGHER VALUES CENTERED ALONG THE PALMER
DIVIDE. FORECAST SOUNDINGS ALSO INDICATING A FAIRLY DECENT CAP
OVER THE AREA...WHICH COULD LIMIT THE POTENTIAL FOR SEVERE STORMS.
STILL CAN'T RULE OUT THE POSSIBILITY OF A SEVERE STORM DUE TO
FAVORABLE SHEAR. AIRMASS TO BE COOLER WITH HIGHS IN THE MIDDLE 80S
ACROSS THE PLAINS. STORMS TO CONTINUE INTO THE EVENING BEFORE
EXITING THE AREA AROUND MIDNIGHT. ON SUNDAY...HIGH PRESSURE BUILDS
OVER THE AREA WITH SLIGHTLY WARMER AND DRIER AIR. STILL ENOUGH
MOISTURE AND LOW LEVEL UPSLOPE DUE TO SOUTHEAST FLOW FOR A SLIGHT
CHANCE OF AFTERNOON AND EVENING STORMS. MODELS CONTINUE TO SHOW
ANOTHER COLD FRONT MOVING INTO THE NORTHEAST PLAINS OVERNIGHT
SUNDAY...LEADING TO INCREASING UPSLOPE AND LOW LEVEL MOISTURE
WHICH COULD INCREASE THE CHANCE FOR AFTERNOON AND EVENING STORMS.
DECENT SHEAR COULD RESULT IN A FEW SEVERE STORMS.

FOR THE LATER DAYS...TUESDAY THROUGH THURSDAY: UPPER LEVEL RIDGE
REMAINS IN PLACE TUESDAY WITH SLIGHTLY WARMER AND DRIER AIR. STILL
SOME MOISTURE FOR A SLIGHT CHANCE OF LATE DAY THUNDERSTORMS. FOR
WEDNESDAY AND THURSDAY...FLOW ALOFT BECOMES SOUTHWEST AS AN UPPER
TROUGH MOVES INTO THE NORTHERN GREAT BASIN. MODELS SHOW GRADIENT
INCREASING ACROSS COLORADO THURSDAY...WHICH COULD LEAD TO AN
INCREASE IN WIND ALONG WITH LOWER HUMIDITY. TEMPERATURES TO WARM
INTO THE LOWER 90S ACROSS THE PLAINS.

&&

.AVIATION...STILL MAINTAINING NORTHEAST WINDS AT APA/DEN SO
POTENTIAL STILL HOLDS FOR POSSIBLE TS AT THE TERMINALS AS TEMPS
CLIMB AROUND 90. STILL MONITORING IN CASE WE NEED TO BUMP UP TS
CHANCES AT KDEN.

&&

.FIRE WEATHER...RED FLAG WARNINGS CONTINUE IN MOUNTAIN VALLEYS AND
PALMER DIVIDE THROUGH 9 PM. MOUNTAIN VALLEYS ALREADY GUSTING
20-35KT AS RH LEVELS ALREADY BELOW 10 PERCENT. HUMIDITIES NOT
QUITE AS LOW AS OVER THE PALMER DIVIDE WITH HUMIDITIES 10-20
PERCENT. SOME CONCERN THAT STORMS THAT MAY DEVELOP OVER NORTHERN
DOUGLAS AND ELBERT MAY SEND OUTFLOW BOUNDARIES BACK INTO THE BLACK
FOREST FIRE WITH ERRATIC WINDS.

&&

.HYDROLOGY...NO ISSUES.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR COZ211-213-214-
216-241.

&&

SHORT TERM...ENTREKIN
LONG TERM....D-L
AVIATION...ENTREKIN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1045 AM MDT THU JUN 13 2013

COZ030>051-141645-
JACKSON COUNTY BELOW 9000 FEET-
WEST JACKSON AND WEST GRAND COUNTIES ABOVE 9000 FEET-
GRAND AND SUMMIT COUNTIES BELOW 9000 FEET-
SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-
SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/
GILPIN/CLEAR CREEK/SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE
9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-
JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR
CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET-
CENTRAL AND SOUTHEAST PARK COUNTY-
LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-
BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD
COUNTY-
NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND
ARAPAHOE COUNTIES/EAST BROOMFIELD COUNTY-
ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-
NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD COUNTY-MORGAN COUNTY-
CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-
SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN COUNTY-
LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS COUNTY-
1045 AM MDT THU JUN 13 2013

...SEVERE STORMS POSSIBLE OVER THE NORTHEAST PLAINS THIS
AFTERNOON AND EVENING...

...VERY HIGH FIRE DANGER AGAIN OVER THE PALMER DIVIDE AND HIGH
MOUNTAIN VALLEYS...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...TODAY AND TONIGHT

HIGH MOISTURE LEVELS TODAY WILL LEAD TO THE POTENTIAL FOR SEVERE
STORMS OVER THE PLAINS BY LATER THIS AFTERNOON. A DENVER
CONVERGENCE ZONE WILL SET UP FROM DOUGLAS COUNTY AND EXTEND
NORTHEAST THROUGH CENTRAL PORTIONS OF ADAMS AND ARAPAHOE COUNTIES
BY EARLY AFTERNOON. THIS WILL SPARK STORM INITIATION ALONG THE
BOUNDARY. STORMS WILL THEN MOVE EAST AND NORTHEAST OVER THE
PLAINS THROUGH THIS EVENING WITH SEVERE STORMS POSSIBLE AS THEY
MOVE INTO THE DEEPER MOISTURE. THE BEST CHANCE FOR SEVERE STORMS
WILL BE JUST EAST OF DENVER AND EXTENDING THROUGH ALL THE
NORTHEAST PLAINS. EXPECT LARGE HAIL UP TO 2 INCHES IN
DIAMETER...DAMAGING WINDS TO 60 MPH AND EVEN AN ISOLATED TORNADO
ARE ALL POSSIBLE WITH THE STRONGEST STORMS.

SOUTH TO SOUTHWEST WINDS WILL ALSO DEVELOP THIS AFTERNOON OVER THE
MOUNTAINS AND PALMER DIVIDE...WITH GUSTS IN THE 20 TO 30 MPH
RANGE. THIS WILL CREATE VERY HIGH FIRE DANGER AGAIN...ESPECIALLY
IN AREAS SOUTH AND SOUTHWEST OF DENVER. THE SOUTH WINDS WILL
LIKELY BRING SMOKE FROM THE BLACK FOREST FIRE TOWARDS DENVER AGAIN
THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

IT WILL BE HOT AND DRY OVER MUCH OF THE OUTLOOK AREA FRIDAY AS
SOUTHWEST FLOW ALOFT CONTINUES ACROSS THE REGION. COOLER
CONDITIONS WILL PREVAIL SATURDAY THROUGH MONDAY FOLLOWING THE
PASSAGE OF A COUPLE OF COLD FRONTS. ONE FRONT WILL MOVE ACROSS THE
AREA LATE FRIDAY NIGHT WITH ANOTHER FRONT EXPECTED SUNDAY NIGHT.
THERE WILL BE A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS...WITH
A FEW SEVERE STORMS POSSIBLE DURING THE AFTERNOON AND EVENING
HOURS SATURDAY AND AGAIN MONDAY. A DRY AND WARMER SOUTHWESTERLY
FLOW ALOFT WILL RETURN TO THE REGION ON TUESDAY AND WEDNESDAY OF
NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED OVER THE NORTHEAST PLAINS AFTER 2 PM
THIS AFTERNOON.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
329 PM MDT THU JUN 13 2013

COZ040-041-045-132215-
ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-NORTH
DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE
COUNTIES/EAST BROOMFIELD COUNTY-CENTRAL AND EAST ADAMS AND ARAPAHOE
COUNTIES-
329 PM MDT THU JUN 13 2013

THE NATIONAL WEATHER SERVICE HAS ISSUED A SIGNIFICANT WEATHER
ADVISORY FOR SOUTHEASTERN ADAMS AND CENTRAL ARAPAHOE COUNTIES UNTIL
415 PM MDT.

AT 328 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR STRASBURG...OR 32 MILES EAST OF DENVER...
MOVING NORTHEAST AT 20 MPH.

WIND GUSTS UP TO 50 MPH PRODUCING CONSIDERABLE BLOWING DUST WILL BE
POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE BUT ARE NOT LIMITED TO...
BENNETT...STRASBURG AND BYERS.

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 3957 10426 3957 10461 3984 10446 3984 10402
TIME...MOT...LOC 2128Z 211DEG 19KT 3973 10435

BAKER