Special Weather Statement, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
300 PM MDT WED JUL 6 2011

.SHORT TERM...NOT MANY CHANGES FOR THE GRIDS PLANNED FOR THIS
EVENING.  DEEP CONVECTION THAT FORMED OVER THE FOOTHILLS IS MAKING
ITS WAY ACROSS THE URBAN CCRRIDOR AND PALMER DIVIDE.  PW VALUES
1.25-1.5 INCHES WITH DEWPOINTS RANGING FROM THE MID 50S TO LOWER
60S.  AS FAR AS CAPES ARE CONCERNED...VALUES RAINGING FROM 1200 J/KG
AT DENVER TO 2200 J/KG AT AKRON/  STORM MOTIONS 10-15 KTS.  WILL
CONTINUE THE FLASH FLOOD FOR ZONE 35 FOR THE BURN AREAS.  WET
MICROBURSTS WITH MAINLY HEAVY RAIN COULD SEE A FEW SEVERE STORMS
WITH DAMAGING WINDS TO 60 MPH AND HAIL TO ONE INCH.  ALL OF THIS
ALREADY COVERED IN THE FCST SO NO CHANGES EXPECTED.  SHOWERS AND
THUNDERSTORMS WILL DECREASE AFTER MIDNIGHT BUT NOT DIMINISH
ALTOGETHER.  THE NAM12 INDICATES A WEAK CYCLONE OVER THE DENVER AREA
THURSDAY MORNING WITH PLENTY OF BOUNDARY LAYER MSTR ADVECTING INTO
THE URBAN CORRIDOR.  WL ADD PATCHY FOG FOR LATE TONIGHT AND
THURSDAY MORNING.  ON THURSDAY THERE WILL BE SOME DECREASE IN THE PW
VALUES...WITH VALUES STILL OVER ONE INCH.  FCST CAPES LOWER THURSDAY
AFTN...WITH VALUES FM 800-1100 J/KG.  PROBABLY SLIGHTLY LESS
COVERAGE ON THURSDAY BUT STORMS WILL LIKELY STILL PRODUCE BRIEF
HEAVY RAIN...WITH SEVERE POTENTIAL MORE ISOLATED.

.LONG TERM...THE UPPER AIR PATTERN WILL ALLOW MONSOONAL MOISTURE TO
CONTINUE TO FLOW UP FROM THE SOUTHWEST THROUGH THE WEEKEND AT LEAST.
THIS WILL TRANSLATE INTO A DAILY CHANCE OF SHOWERS AND THUNDERSTORMS.

THE UPPER HIGH CENTER WILL BE OVER NORTHERN NEW MEXICO THURSDAY
EVENING THEN SLOWLY DRIFT SOUTHEAST AS AN UPPER TROUGH MOVES OVER
THE US/CANADIAN BORDER THROUGH SATURDAY. FLOW WILL BECOME SOUTHWEST
ALOFT AS THE HIGH STAYS OVER THE LOWER MISSISSIPPI VALLEY AND
TROUGHING OCCURS OVER THE WESTERN US. TEMPERATURES WILL REMAIN JUST
AROUND NORMAL FOR THIS TIME OF YEAR.  EXPECT MAXIMUMS IN THE UPPER
80S TO NEAR 90 OVER THE PLAINS AND IN THE MID 70S TO LOW 80S FOR THE
MOUNTAINS. MINIMUMS WILL BE IN THE LOWER 60S FOR THE PLAINS AND IN
THE MID 40S TO NEAR 50 FOR THE MOUNTAINS. MOISTURE WILL BE PREVALENT
AS PRECIPITABLE WATER VALUES WILL BE BETWEEN 1 AND 1.5 INCHES OVER
THE PLAINS WILL KEEP THE POTENTIAL OF HEAVY RAINS UNDER THE LIGHT TO
MODERATE WINDS ALOFT.

&&

.AVIATION...SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE
AIRPORTS.  COULD SEE BRIEF HEAVY RAIN...SMALL HAIL AND WIND GUSTS TO
45 KTS. CIGS MAY DROP TO LESS THAN 4K FT WITH HEAVY RAIN SHOWERS.
OTHER CONCERN AFTER 09Z WITH THE LOW CLOUDS AND FOG.  MDLS INDICATE
A WEAK DENVER CYCLONE WITH LOW LEVEL MOISTURE ADVECTING IN FROM THE
EAST OVERNIGHT.  POTENTIAL FOR IFR CIGS/VSBYS IN THE 10Z-14Z TIME
FRAME.  SCT-BKN MID LEVEL CIGS EXPECTED AFTER 18Z THURSDAY WITH
ANOTHER ROUND OF THUNDERSTORMS WITH MDT TO HEAVY RAINFALL AFTER
21Z.

&&

.HYDROLOGY...STRONGER THUNDERSTORMS LATE THIS AFTERNOON AND EVENING
WILL BE CAPABLE OF PRODUCING 1 TO 1.5 INCHES OF RAIN IN 45 MINUTES.
MAIN THREAT FOR FLASH FLOODING WILL BE IN THE RECENT BURN AREAS SO
WILL CONTINUE WITH A FLASH FLOOD WATCH FOR THE FOOTHILLS OF BOULDER
AND LARIMER COUNTIES.  SLIGHTLY LOWER THREAT ELSEWHERE WITH STORM
MOTIONS OF 10-15 KTS ELSEWHERE. OTHER AREA OF CONCERN IS THE ST
LOUIS/BIG THOMPSON CREEKS WHERE A QUICK HALF INCH MAY PRODUCE
ADDITIONAL RISES.

MOST RIVER AND STREAM FLOWS HAVE TRENDED SLIGHTLY LOWER IN THE LAST
24 HOURS AS TEMPERATURES COOLED SLIGHTLY AND SNOWMELT RATES
DECREASED.  MORE LOCALLY HEAVY RAINFALL MAY ADD TO RUNOFF ISSUES
THIS AFTERNOON THROUGH TONIGHT.  WATCHING SEVERAL ALREADY SWOLLEN
CREEKS AND STREAMS THAT WOULD NOT BE ABLE TO TAKE MUCH MORE WATER.

FLOOD ADVISORIES...BIG THOMPSON RIVER THROUGH ESTES PARK UNTIL NOON
THURSDAY. ST LOUIS CREEK IN SOUTHEASTERN GRAND COUNTY UNTIL LATE
THURSDAY EVENING.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FOR THE NORTHERN FRONT RANGE FOOTHILLS UNTIL 10 PM
MDT THIS EVENING...ZONE 35.

&&

COOPER/KRIEDERMAN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1019 AM MDT WED JUL 06 2011

COZ030>051-071200-
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-
1019 AM MDT WED JUL 06 2011

...FLASH FLOOD WATCH NORTHERN FRONT RANGE FOOTHILLS FROM NOON UNTIL
10 PM MDT THIS EVENING...

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL AND POSSIBLE SEVERE
WEATHER ARE EXPECTED TO DEVELOP ACROSS THE REGION THIS AFTERNOON AND
CONTINUE INTO THE EVENING.  THE STRONGER STORMS ARE EXPECTED TO FIRE
OVER THE MOUNTAINS AND FOOTHILLS BY MIDDAY.  THEY WILL THEN SPREAD
AND DEVELOP EASTWARD ACROSS THE PLAINS THROUGH THE AFTERNOON AND
EVENING.  THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING 1 TO 1.5
INCHES OF RAIN IN 30 MINUTES...ALONG WITH WIND GUSTS TO 60 MPH AND
HAIL TO AROUND 1 INCH IN DIAMETER.

THE HEAVIER RAINFALL RATES WILL BRING A THREAT OF FLASH FLOODING
MAINLY TO THE RECENT BURN SCARS IN THE FRONT RANGE FOOTHILLS.
HOWEVER...THE POSSIBLE INTENSE RAINFALL RATES MAY ALSO PRODUCE
STREET FLOODING IN URBAN AREAS...AS WELL AS LEAD TO AN INCREASE IN
STREAMFLOWS ALREADY SWOLLEN FROM SNOWMELT.

A MORE MOIST AND UNSTABLE ENVIRONMENT WILL BRING THE THREAT OF
SEVERE WEATHER AND HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

WILL CONTINUE TO SEE SCATTERED SHOWERS AND THUNDERSTORMS EACH DAY
THROUGH THE PERIOD AS MOISTURE CONTINUES TO STREAM UP FROM THE SOUTH
OVER THE HIGH PRESSURE RIDGE NEARBY. FLOW WILL GENERALLY BE LIGHT SO
STORMS WILL CONTINUE TO HAVE THE POTENTIAL TO PRODUCE HEAVY
RAINFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE REQUIRED AFTER 1 PM THIS AFTERNOON.

COOPER/KRIEDERMAN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
200 PM MDT WED JUL 6 2011

COZ036-062030-
JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR
CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET CO-
200 PM MDT WED JUL 6 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY FOR

  SOUTHWESTERN DOUGLAS COUNTY

AT 200 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL.  THIS STORM WAS
LOCATED 3 MILES WEST OF WESTCREEK...OR 30 MILES NORTHWEST OF COLORADO
SPRINGS...MOVING EAST AT 20 MPH.

LOCATIONS IN THE ADVISORY INCLUDE BUT ARE NOT LIMITED TO WESTCREEK.

LAT...LON 3913 10530 3918 10528 3918 10507 3913 10507
      3913 10508
TIME...MOT...LOC 2000Z 276DEG 16KT 3914 10518

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
402 PM MDT WED JUL 6 2011

COZ038-042-062230-
NORTHEAST WELD COUNTY CO-
LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY CO-
402 PM MDT WED JUL 6 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A SIGNIFICANT
WEATHER ADVISORY FOR

  NORTHEASTERN WELD COUNTY

AT 402 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
THUNDERSTORM CAPABLE OF PRODUCING MARBLE SIZE HAIL...AND WIND GUSTS
TO AROUND 50 MPH.  THIS STORM WAS LOCATED 7 MILES NORTHEAST OF
GROVER...OR 49 MILES NORTHEAST OF GREELEY...MOVING SOUTHEAST AT 35
MPH.

LOCATIONS IN THE ADVISORY INCLUDE BUT ARE NOT LIMITED TO PAWNEE
BUTTES...NEW RAYMER...KEOTA...HEREFORD AND GROVER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM MDT
WEDNESDAY EVENING FOR NORTHEASTERN COLORADO.

&&

LAT...LON 4053 10414 4100 10432 4100 10387 4063 10366
TIME...MOT...LOC 2202Z 330DEG 32KT 4090 10409