Severe Thunderstorm Warning 56, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
230 PM MDT SUN MAY 25 2003

SHORT TERM DISCUSSION:  CURRENT CONVECTION OVER MOUNTAINS AND
FOOTHILLS WHERE THETA E RIDGE AXIS RESIDES.  LOCALLY HEAVY RAIN
STILL POSSIBLE AS THE STORMS WILL BE SLOW MOVING. STILL WAITING FOR
CONVECTION TO DEVELOP ALONG URBAN CORRIDOR AND POINTS EAST WHERE
AIRMASS STILL CAPPED.  SURFACE DATA SUGGESTS THAT TEMPERATURES ARE
NEARING THE TRIGGER TEMPERATURE OF AROUND 74 DEGREES...SO IT SHOULD
NOT BE MUCH LONGER BEFORE DEVELOPMENT.  SEVERAL BOUNDARIES SHOWING
UP ON RADAR...WHICH COULD END UP BEING FOCUS FOR STORMS.  RUC SHIFTS
THE THETA E RIDGE AXIS EAST ALONG URBAN CORRIDOR BY 00Z MONDAY AND
SHOULD ALSO AID IN DEVELOPMENT.  GIVEN PRECIPITABLE WATER VALUES
AROUND EIGHT TENTHS OF AN INCH AND LIGHT STEERING WINDS...STORMS TO
BE SLOW MOVING AND CAPABLE OF DUMPING HEAVY RAIN.  A FEW STORMS
COULD BECOME SEVERE WITH LARGE HAIL MAIN THREAT AS THE FREEZING
LEVEL IS FAIRLY LOW.  BUT THE WEAK SHEAR PROFILE SHOULD KEEP THE
ORGANIZED SEVERE THREAT LOW.  THETA E AXIS PROGGED TO SHIFT BACK
INTO THE MOUNTAINS BY 06Z.  SHOWERS AND STORMS WILL PROBABLY NOT
LAST MUCH PAST MIDNIGHT OVER MOUNTAINS...FOOTHILLS AND ADJACENT.
AGREE WITH MIDNIGHT FORECASTER THAT THIS PATTERN SUGGESTS STORMS
ACROSS FAR EASTERN PLAINS GENERALLY LAST PAST MIDNIGHT...SO WILL
KEEP SOME ACTIVITY GOING LATE.  BOUNDARY LAYER WINDS AND HUMIDITIES
SUGGEST THAT LOW CLOUDS AND FOG SHOULD BE EAST OF URBAN CORRIDOR.
HOWEVER...BASED ON THIS MORNING...WILL MENTION FOG ACROSS PLAINS
TONIGHT AND MONDAY MORNING.  AS FOR MONDAY...MODEL CROSS SECTIONS
SHOW MODELS INDICATE DRYING TREND ACROSS MOUNTAINS AND URBAN
CORRIDOR.  HOWEVER...MESOETA SHOWS THETA E RIDGE OVER MOUNTAINS AND
FOOTHILLS BY 18Z AND THE FRONT RANGE BY 00Z...LIKE TODAY.
SURFACE WINDS SUGGEST A DENVER CYCLONE DEVELOPING BY AFTERNOON.
SO...SCATTERED POPS STILL LOOK REASONABLE FOR FOOTHILLS AND ADJACENT
PLAINS.  WILL KEEP THE 20 PERCENT POPS FOR MOUNTAINS...ALTHOUGH
THERE MAY BE MORE COVERAGE.  WITH THE CURRENT PERSISTENT PATTERN IN
PLACE...FAR EASTERN ZONES SHOULD NOT SEE ANY STORMS DURING THE
AFTERNOON UNLESS A STRAY BOUNDARY MOVES INTO THE AREA.  NO CHANGE TO
ANY OF TEMPERATURE FORECASTS.  D-L

LONG TERM DISCUSSION: UPPER RIDGE BUILDING OVER THE ROCKIES IS THE
THEME FOR THE REST OF THE WEEK.  LAST COUPLE RUNS OF THE GFS HAVE
BEEN A BIT STRONGER THAN YESTERDAY...AND ECMWF REMAINS STRONGER BUT
THERE IS NOT AS MUCH DIFFERENCE AS BEFORE.  THE END OF THE ETA RUN
LOOKS SIMILAR...BUT A BIT WEAKER WITH THE HIGH.  A WEAK SHORT WAVE
WILL PASS NORTH OF US ON TUE.  THIS IS LOOKING LIKE IT WILL HAVE
LITTLE EFFECT...BUT SHOULD BRING DRIER AIR IN ITS WAKE.  IT LOOKS
LIKE SLIM MID LEVEL MOISTURE WILL BE SUPPRESSED TO THE SOUTH OF THE
HIGH AND REMAIN THERE...SO I WILL DRY OUT THE MOUNTAINS AS WELL.
THERE WILL PROBABLY BE A GRADUAL CREEP OF MOISTURE NORTHWARD UNDER
THE HIGH...BUT I WILL HOLD OFF MENTIONING STORMS UNTIL FRI.  ON THE
PLAINS...ANYTHING THAT DEVELOPS TUE SHOULD MOVE S OR SE...SO ONLY A
SLIM THREAT NEAR THE FOOTHILLS.  SHOULD BE CAPPED WED AND THU.  GFS
CONTINUING TO BACK OFF ON THE TROUGH DROPPING TO OUR E ON FRI OR
SAT...NOW JUST LOOKING LIKE A WEAK WLY FLOW ALF WITH A WEAK SURGE TO
DROP TEMPS A BIT.  THIS DOES NOT LOOK LIKE A PROMISING MOISTURE
SOURCE...BUT WITH A BIT OF MID LEVEL MOISTURE AND WESTERLY FLOW
RETURNING...I WILL LEAVE THE LOW POPS.  BUMPED UP TEMPERATURES A BIT
MORE AS CONFIDENCE IN A STRONG RIDGE AND LOTS OF SUN INCREASING.
GIMMESTAD

.DEN...NONE.

COZ030>051-261200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1050 AM MDT SUN MAY 25 2003

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

.DAY ONE...TODAY AND TONIGHT

A MOIST AND UNSTABLE AIRMASS RESIDES IN EASTERN COLORADO.
THE LOW CLOUDS AND FOG WILL CONTINUE TO DISSIPATE...ALLOWING FOR
ENOUGH HEATING TO FIRE UP SCATTERED THUNDERSTORMS.  THE STORMS WILL
FIRST DEVELOP OVER THE MOUNTAINS AND FOOTHILLS...THEN ACROSS THE
PLAINS DURING THE AFTERNOON.  A CONVERGENCE BOUNDARY JUST EAST AND
SOUTH OF THE DENVER METRO AREA WILL BE ANOTHER FOCUS FOR
THUNDERSTORM DEVELOPMENT.  AS STORMS DEVELOP...NEW STORM INITIATION
CAN BE EXPECTED ALONG INTERSECTIONS OF OUTFLOW BOUNDARIES.

UPPER WINDS WILL BE WEAK...SO STORMS WILL MOVE SLOWLY...AND DROP
LOCALLY HEAVY RAIN.  THE AIRMASS WILL ALSO BE UNSTABLE ON THE
PLAINS...SO PULSE STORMS MAY PRODUCE LARGE HAIL AND DAMAGING
WINDS...ESPECIALLY EAST OF INTERSTATE 25.  STORMS WILL ALSO CONTINUE
LATE TONIGHT ON THE PLAINS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

LITTLE CHANGE IS EXPECTED ON MONDAY WITH ANOTHER ROUND OF AFTERNOON
AND EVENING THUNDERSTORMS EXPECTED.  THERE WILL BE A SLIGHT RISK OF
SEVERE WEATHER AGAIN.  TUESDAY WILL BE A BIT DRIER...BUT THERE IS
STILL A THREAT OF STORMS.  AN UPPER LEVEL RIDGE WILL BRING HOT DRY
WEATHER FOR THE MIDDLE OF THE WEEK...BUT THUNDERSTORM ACTIVITY IS
EXPECTED TO RETURN BY THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TODAY.

LESZCYNSKI/GIMMESTAD