Hail in Colorado, May 19, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
420 AM MDT WED MAY 19 2010

.SHORT TERM...LOW PRESSURE OVER EASTERN COLORADO WILL STALL TODAY AS
WARM ADVECTION ALOFT WRAPS NORTH OF THE LOW. BEST QG LIFT WILL BE IN
THIS AREA CLIPPING OUR NORTHERN AND EASTERN BORDERS...BUT COLD POOL
HAS WEAK SHOWERS IN IN OVER NORTHWESTERN COLORADO AND THIS WILL BE
MOVING EAST TODAY. CONVECTIVE CLOUD ALREADY FILLING BACK IN
SOUTHEAST OF DENVER...LIKELY THE RESULT OF SOME COOLING ALOFT. CLEAR
HOLE IN THE MIDDLE OF THE SYSTEM SHOULD FILL IN NICELY WITH
CONVECTION AFTER SOME HEATING THIS MORNING. CAPES LOOK MARGINAL IN
MODEL SOUNDINGS...BUT WE ARE STILL GETTING SOME LIGHTNING ON OUR
EASTERN FRINGE NOW...SO PROBABLY STILL UNSTABLE ENOUGH FOR SOME
THUNDER THROUGH THE DAY THOUGH UPDRAFTS SHOULD BE WEAK. WITH SOME
DRYING ALONG THE FRONT RANGE...DECIDED TO LEAVE POPS AROUND 50
PERCENT ALONE AS THE SHOWERS MAY NOT BE WIDESPREAD. WEAK LIFT
WRAPPING AROUND THE LOW COMES BACK INTO COLORADO FROM THE NORTH THIS
EVENING...SO I HELD ON TO HIGHER POPS LONGER...WITH SOME DECREASE
OVERNIGHT. LIFT IS WEAK BUT STILL A MOIST AND SLIGHTLY UNSTABLE
ENVIRONMENT. WITH WINDS BECOMING NORTHWEST THIS COULD PRODUCE SOME
OROGRAPHIC HELP FOR MOUNTAIN SNOW AND TEMPERATURES WILL BE A LITTLE
COOLER SO THE SNOW LEVEL COULD COME DOWN AS LOW AS 8000 FEET. MAIN
FACTOR IN SNOWFALL WILL LIKELY STILL BE WHERE THE SHOWER ACTIVITY
SETS UP...AND PLENTY OF MELTING.

.LONG TERM...AN UPPER RIDGE IS PROGGED TO MOVE ACROSS THE FORECAST
AREA THURSDAY AND THURSDAY NIGHT...WITH THE FLOW ALOFT BEING
NORTH-NORTHWESTERLY THURSDAY MORNING...BECOMING WESTERLY THURSDAY
NIGHT LATE.  ON FRIDAY AND FRIDAY NIGHT...THE FLOW ALOFT IS
SOUTHWESTERLY.  THE MEAN TROUGH PROGGED TO BE OVER THE WESTERN
UNITED STATES IS COMING IN MUCH SLOWER COMPARED TO MODEL RUNS OF A
COUPLE DAYS AGO.  WEAK DOWNWARD SYNOPTIC SCALE ENERGY IS PROGGED FOR
THE FORECAST AREA THURSDAY INTO FRIDAY MORNING.  THEN WEAK UPWARD
MOTION MOVES IN MID DAY FRIDAY AND CONTINUES THROUGH FRIDAY NIGHT.
THE LOW LEVEL PRESSURE AND WIND FIELDS SHOW WEAK UPSLOPE FLOW IN THE
BOUNDARY LAYER ON THURSDAY...WITH NORMAL DIURNAL WIND FIELDS
THURSDAY NIGHT.  ON FRIDAY...SOUTHEASTERLY BOUNDARY LAYER FLOW IS
PROGGED...WITH SOUTHWESTERLIES FRIDAY NIGHT.  FOR MOISTURE...THERE
IS LOW LEVEL MOISTURE OVER THE PLAINS THURSDAY MORNING...WITH IT
SLOWLY DRYING THURSDAY AFTERNOON.  THERE IS SOME MOISTURE OVER THE
MOUNTAINS...WHICH ALSO DECREASES BY THURSDAY AFTERNOON.  THURSDAY
NIGHT IS PRETTY DRY ON BOTH MODELS...AS IS MUCH OF FRIDAY...WITH
JUST A BIT OF LATE DAY MOISTURE.  FRIDAY NIGHT DRIES OUT EVEN MORE.
THE PRECIPITABLE WATER VALUE PROGGS ARE IN THE 0.55 TO 0.65 INCH
RANGE THURSDAY...0.40 TO 0.45 INCH RANGE THURSDAY NIGHT...0.40 TO
0.60 INCH RANGE FRIDAY...DROPPING TO 0.20 INCH SATURDAY MORNING AT
12Z.  THERE IS SOME CAPE OVER THE FOOTHILLS AND URBAN CORRIDOR LATE
DAY THURSDAY...BUT VALUES ARE FAIRLY LOW.  THERE IS MUCH BETTER CAPE
PROGGED FOR LATE DAY FRIDAY...AND IT IS SIGNIFICANTLY MORE
WIDESPREAD OVER THE FORECAST AREA.  THE LAPSE RATES SHOW A
SIGNIFICANT CAP IN PLACE ON THURSDAY.  ON FRIDAY...THE LAPSE RATES
ARE PRETTY STEEP.  THE QPF FIELDS HAVE A SMIDGEN OF MEASURABLE
PRECIPITATION OVER THE FAR NORTHEAST CORNER ON THURSDAY ONLY ON THE
NAM...THE GFS IS DRY.  THURSDAY NIGHT AND MUCH OF FRIDAY HAS NO
PRECIPITATION...WITH A TAD OVER THE FOOTHILLS/IMMEDIATE PLAINS ON
THE NAM ONLY FOR LATE DAY FRIDAY.  FRIDAY NIGHT IS DRY.  FOR
POPS...WILL KEEP MINIMAL POPS IN FOR THE MOUNTAINS AND NORTHEAST
CORNER EARLY THURSDAY...THEN DRY.  WILL PUT 10%S IN THE FOOTHILLS
AND FRONT RANGE PLAINS FOR LATE DAY FRIDAY.  FOR TEMPERATURES...
THURSDAY'S HIGHS WARM-UP 6-9 C OVER WEDNESDAY'S.  FRIDAY'S READINGS
WARM-UP ANOTHER 4-7 C FROM THURSDAY'S.  FOR THE LATER DAYS...
SATURDAY THROUGH TUESDAY...MODELS KEEP STRONG SOUTHWESTERLY FLOW
ALOFT FOR THE FORECAST AREA ALL FOUR DAYS.  THE UPPER TROUGH NEVER
MOVES OVER US.  THE MOISTURE IS QUITE SPARSE NOW FOR ALL THE
PERIODS.  TEMPERATURES LOOK TO STAY ABOVE SEASONAL NORMALS ALL FOUR
DAYS.  WILL PUT MINOR LATE DAY POPS IN SOME OF THE DAY.

&&

.AVIATION...SCATTERED SHOWERS WILL REDEVELOP BY EARLY AFTERNOON WITH
CEILINGS IN THE 3000 TO 5000 FT AGL RANGE. MVFR CEILINGS ARE
EXPECTED OVERNIGHT.

&&

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

GIMMESTAD/RJK

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DENVER CO
1146 AM MDT WED MAY 19 2010

COZ030>051-201200-
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-
1146 AM MDT WED MAY 19 2010

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

.DAY ONE...TODAY AND TONIGHT

SHOWERY PRECIPITATION WILL DEVELOP ACROSS MOST OF THE OUTLOOK AREA
THROUGHOUT THE AFTERNOON AND LINGER THROUGH MOST OF THIS EVENING.
THE NORTH CENTRAL MOUNTAINS SHOULD SEE RAIN AND SNOW SHOWERS
SPREADING SOUTH THROUGH THE AFTERNOON AND SNOW LEVELS LOWERING TO
AROUND 8500 FEET BY LATE IN THE DAY. ELEVATIONS ABOVE 10,000 FEET
COULD SEE UP TO 3 INCHES OF NEW SNOW ACCUMULATION BY LATE THIS
EVENING. ON THE HIGH PLAINS...AREAS UP ALONG THE WYOMING BORDER AND
OUT ACROSS THE NORTHEAST CORNER OF THE STATE WILL SEE RAIN SHOWERS
FORMING EARLY THIS AFTERNOON. THESE SHOWERS AND A FEW THUNDERSTORMS
ARE THEN EXPECTED TO SPREAD SOUTH ACROSS THE REMAINDER OF NORTHEAST
AND EAST CENTRAL COLORADO LATER IN THE AFTERNOON. THUNDERSTORMS ARE
NOT EXPECTED TO BE AS STRONG OR AS WIDESPREAD AS THOSE YESTERDAY...
BUT MAY STILL PRODUCE BRIEF HEAVY RAIN AND SMALL HAIL...MAINLY IN
AREAS SOUTH OF INTERSTATE 70. SHOWERS WILL LINGER FOR MUCH OF THE
NIGHT IN MOST AREAS WITH PATCHY FOG FORMING ON THE PLAINS AFTER
MIDNIGHT. IN ADDITION...MOUNTAIN AREAS ROUGHLY ABOVE 8000 FEET COULD
PICK UP ANOTHER INCH OR SO OF SNOW BY MORNING.

AN UPPER ATMOSPHERIC LOW PRESSURE CENTERED OVER EXTREME SOUTHEAST
WYOMING LATE THIS MORNING WILL CONTINUE TO TRACK SOUTHEAST PASSING
OVER NORTHWEST KANSAS BY LATE IN THE EVENING. AS THIS LOW PASSES
OVER NORTHEAST COLORADO THIS AFTERNOON...NORTH TO NORTHEAST WINDS
WRAPPING AROUND THIS CYCLONE WILL USHER IN THE SHOWERY
PRECIPITATION...LOWER CLOUD COVER AND COOLER TEMPERATURES
ANTICIPATED LATER TODAY AND TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE WILL BE A SLIGHT CHANCE FOR THUNDERSTORMS ON FRIDAY...THEN DRY
AND WARMER CONDITIONS ARE EXPECTED FOR THE WEEKEND AS A DRY
SOUTHWEST FLOW DEVELOPS. THE EXCEPTION WILL BE A SLIGHT CHANCE FOR
THUNDERSTORMS ON THE FAR NORTHEAST PLAINS LATE SUNDAY AFTERNOON.

THE NEXT UPPER LEVEL DISTURBANCE WILL MOVE ACROSS COLORADO ON MONDAY
WITH A SLIGHT CHANCE FOR STORMS ACROSS THE ENTIRE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. HOWEVER
SPOTTERS ARE REQUESTED TO RELAY ANY SNOW ACCUMULATIONS TO THE
NATIONAL WEATHER SERVICE IN BOULDER.

BAKER/ENTREKIN