Tornado Warning 12, NWS Denver/Boulder, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
315 PM MDT MON JUN 8 2009

.SHORT TERM...MORNING FRONT STABILIZED MUCH OF THE PLAINS...18Z KDEN
RAOB STILL SHOWING HEALTHY INVERSION ROUGHLY 5000-8000 FEET AGL.
SCATTERED STORMS ACROSS MOUNTAINS AND FOOTHILLS WERE HAVING ROUGH
TIME SUSTAINING THEMSELVES AS THEY MOVED ONTO PLAINS. SURFACE
ANALYSIS SHOWING CONVERGENCE AREA FROM NORTHERN DOUGLAS COUNTY
THROUGH CENTRAL ARAPAHOE AND CENTRAL ADAMS COUNTIES INTO SOUTHEAST
WELD COUNTY. CURRENT LAPS SURFACE ANALYSIS SHOWING CAPE VALUES FROM
1000 J/KG TO 2000 J/KG ALONG THIS AREA WITH MINIMAL CIN. CAPES
NEARING 1000 J/KG EAST OF THIS CONVERGENCE AREA. CONVERGENCE AREA
APPEARS TO BE THE BEST LOCATION FOR THE POTENTIAL OF ANY SEVERE
STORMS. HAIL AND GUSTY WINDS THE MAIN THREAT...THOUGH CANNOT RULE
OUT A BRIEF TORNADO GIVEN CONVERGENCE. ELSEWHERE...WOULD NEED TO GET
ASSISTANCE OF STORM OUTFLOWS FOR ANY SEVERE POTENTIAL. AS FAR AS
POPS ARE CONCERNED...WILL CONTINUE WITH THE CHANCE POPS THIS EVENING
EAST OF THE CONVERGENCE AREA...WITH SLIGHT CHANCE FOR URBAN
CORRIDOR. SCATTERED POPS FOR MOUNTAINS AND FOOTHILLS STILL SEEM IN
ORDER GIVEN LATEST RADAR.  WHERE LAPS SHOWS CAPES NEARING 1000 J/KG
AS STORMS THE URBAN CORRIDOR FOR MOUNTAINS AND FOOTHILLS. STORMS
EXPECTED TO END BY MIDNIGHT AS AIRMASS STABILIZES...BUT ENOUGH
MOISTURE ALONG WITH WEAK OROGRAPHICS WILL KEEP A FEW MOUNTAIN
SHOWERS GOING. ON TUESDAY...FLOW ALOFT BECOMES SOUTHWEST AS UPPER
TROUGH DIGS INTO THE GREAT BASIN. CROSS SECTIONS SHOW QUITE A BIT OF
MOISTURE ACROSS DISTRICT...ESPECIALLY DURING AFTERNOON. QG VERTICAL
VELOCITY PROGS SHOW SOME ASCENT...MAINLY OVER MOUNTAINS. CHANCE POPS
STILL LOOKING ON TRACK THERE. AS FOR PLAINS...SURFACE PROGS SHOW
FRONT MOVING ACROSS AREA AFTER 18Z. FORECAST SOUNDINGS SHOW CAPE
VALUES RANGING FROM AROUND 800 J/KG ALONG FOOTHILLS TO NEAR 1300
J/KG OVER THE NORTHEAST CORNER. CURRENT POPS ARE HIGHEST NEAR THE
CORNER...LOOKS REASONABLE AT THIS POINT. POPS COULD INCREASE ALONG
FOOTHILLS DURING THE AFTERNOON AS FRONT AND UPSLOPE MOVES INTO AREA.
BEST CHANCE FOR ANY SEVERE TO BE NEAR NORTHEAST CORNER WHERE CAPES
ARE HIGHEST. HAIL AND WIND GUSTS TO BE THE MAIN THREATS.
TEMPERATURES A FEW DEGREES WARMER THAN TODAY...THOUGH FRONT AND
CLOUDS COULD SHAVE A FEW DEGREES. CURRENT TEMPERATURE GRIDS SEEM ON
TRACK.

.LONG TERM...MAIN THREAT FOR THUNDERSTORMS AND SEVERE WEATHER BY
TUESDAY EVENING SHOULD BE SHIFTING TOWARD THE EASTERN PLAINS.  THIS
IS WHERE BEST LOW LEVEL THETA-E RIDGE AND SOUTHEASTERLY LOW LEVEL
FLOW IS EXPECTED TO SET UP IN THE EVENING...HELPING TO FEED STORMS.
ON WEDNESDAY...THE NAM...GFS...AND ECMWF ALL SHOW A WEAK FRONT TO
BACK ACROSS NORTHEAST COLORADO.  WHILE PASSAGE OF THIS FRONT VARIES
FROM LATE TUESDAY NIGHT TO LATE WEDNESDAY AFTERNOON AMONGST THE
MODELS...THERE SHOULD BE HIGHER COVERAGE OF SHOWERS AND
THUNDERSTORMS BY WEDNESDAY AFTERNOON AND NIGHT AS A RATHER
SIGNIFICANT UPPER TROUGH APPROACHES THE FORECAST AREA.  Q-G VERTICAL
VELOCITY FIELDS SHOW DECENT LIFT FOR THIS TIME OF YEAR SO DESPITE A
SLIGHTLY MORE STABLE AIRMASS...WE SHOULD SEE NUMEROUS SHOWERS AND
THUNDERSTORMS.  AMOUNT OF SEVERE WEATHER WOULD LIKELY HINGE ON HOW
MUCH HEATING AND DESTABILIZATION OCCURS...SO WILL HAVE TO WATCH
FRONTAL TIMING AND DEPTH OVER THE NEXT COUPLE DAYS.

FOR THURSDAY THROUGH THE WEEKEND...SOME WEAK UPPER LEVEL RIDGING
WILL OCCUR OVER THE CENTRAL AND SOUTHERN ROCKIES.  THIS SHOULD ALLOW
FOR SLIGHT WARMING AND DRYING OF THE AIRMASS...BUT ENOUGH MOISTURE
AND DAYTIME HEATING TO KEEP AFTERNOON AND EVENING THUNDERSTORMS IN
THE FORECAST.  CANT RULE OUT A FEW SEVERE STORMS AS WELL GIVEN
STRONG ENOUGH MID LEVEL WINDS AND SHEAR PROFILE.

&&

.AVIATION...A FEW STORMS STILL POSSIBLE ALONG URBAN CORRIDOR THROUGH
04Z...THOUGH BEST CHANCE TO BE EAST OF THE AREA. GUSTY WINDS TO 35
KTS ALONG WITH LIGHT TO MODERATE RAIN THE MAIN THREATS. VFR
CONDITIONS TO PREVAIL...ALTHOUGH OCCASIONAL MVFR CEILINGS COULD
OCCUR WITH THE PASSING SHOWERS THROUGH 04Z. CEILINGS NOT EXPECTED TO
REACH ILS CRITERIA AFTER 04Z. DRAINAGE WINDS TO DEVELOP AFTER
04Z...CONTINUING THROUGH 18Z. SURFACE FRONT TO MOVE ACROSS AREA
AROUND 20Z...WITH WINDS SHIFTING TO A NORTHEAST DIRECTION. A SLIGHT
CHANCE OF STORMS AFTER 18Z...CEILINGS AND VISIBILITIES SHOULD REMAIN
VFR THROUGH THE AFTERNOON.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...NONE.

D-L/BARJENBRUCH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1035 AM MDT MON JUN 08 2009

COZ030>051-091200-
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-
1035 AM MDT MON JUN 08 2009

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS AND
FOOTHILLS THIS AFTERNOON AND SPREAD ACROSS THE PLAINS LATE THIS
AFTERNOON AND EVENING.  SOME OF THE STORMS ACROSS THE PLAINS MAY
BECOME SEVERE...WITH GOLF BALL SIZE HAIL...DAMAGING WINDS TO 60 MPH
AND ISOLATED TORNADOES.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A MOIST AND UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE THROUGH
NEXT WEEKEND WITH AFTERNOON AND EVENING THUNDERSTORMS EACH DAY.
THERE WILL BE A THREAT OF A FEW SEVERE STORMS EACH DAY AS WELL GIVEN
SUFFICIENT INSTABILITY AND WIND SHEAR IN THE ATMOSPHERE.  AT THIS
TIME...THE BEST CHANCE OF PRECIPITATION APPEARS TO BE SHAPING UP FOR
WEDNESDAY AND WEDNESDAY NIGHT WHEN ANOTHER UPPER LEVEL DISTURBANCE
IS EXPECTED TO MOVE ACROSS THE STATE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE REQUIRED AFTER 2 PM.

D-L/DBB