Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 050243
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
843 PM MDT MON MAY 4 2015

.UPDATE...
ISSUED AT 820 PM MDT MON MAY 4 2015

PERSISTENT RAINFALL HAS WARRANTED THE ISSUANCE OF FLASH FLOOD
WARNING IN ELBERT COUNTY. RADAR SHOWS THE RAIN TO CONTINUE THERE
FOR A COUPLE MORE HOURS ANYWAY. MODELS KEEP SHOWING WIDESPREAD
RAIN TO CONTINUE ALL NIGHT OVER MUCH OF THE CWA. WILL MAKE SOME
MINOR ADJUSTMENT TO POPS...MAINLY LOWER THEM INT HE FAR NORTHEAST
CORNER. &&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 129 PM MDT MON MAY 4 2015

LIGHTNING HAS BEEN ON THE INCREASE ACROSS THE STATE THIS EARLY
AFTERNOON...WITH A FEW STORMS ALONG THE PALMER DIVIDE. STORM
MOTION HAS BEEN TOWARDS THE NORTH NORTHEAST...AND RAINFALL RATES
THUS FAR OVER THE DIVIDE HAVE BEEN MOSTLY LESS THAN AN INCH AN
HOUR. GIVEN THAT...PRECIPITABLE WATER VALUES ARE IN NEAR RECORD
TERRITORY FOR EARLY MAY...WITH NAM FORECASTING 0.88 INCHES THIS
EVENING. SO WILL HAVE TO WATCH FOR POSSIBLE HEAVY RAIN WITH
STORMS...BUT OVERALL THREAT OF SIGNIFICANT FLOODING IS LOW.
INITIALLY OVER THE ELEVATED TERRAIN THERE MAY BE SOME SMALL HAIL
WITH THESE STORMS. EXPECT CONVECTION TO CONTINUE TO INCREASE THIS
EVENING...THEN A TRANSITION TO MOSTLY RAIN SHOWERS LATER THIS
EVENING...MIXING WITH STATUS AND FOG OVERNIGHT.

LIGHT PRECIPITATION IS EXPECTED TUESDAY EARLY...THEN ANOTHER
ROUND WIDESPREAD SHOWERS AND THUNDERSTORMS IN THE AFTERNOON...
PROBABLY MORE WIDESPREAD AS THE UPPER LOW APPROACHES FROM THE
SOUTHWEST. AGAIN THE MAIN THREAT TUESDAY WILL BE LOCALLY HEAVY
RAIN WITH THE STORMS...BUT CANNOT RULE OUT SMALL HAIL AS LIFT
ASSOCIATED WITH THE UPPER LOW APPROACHES.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 129 PM MDT MON MAY 4 2015

A DAMP AND COOL PERIOD WILL PREVAIL THROUGH MUCH OF THE LONG TERM.
THE MODELS ARE ALL PRETTY CONSISTENT LIFTING THE LOW OVER COLORADO
TUESDAY NIGHT AND WEDNESDAY WITH ATTENDANT QUASIGEOSTROPHIC ASCENT
KEEPING THE PRECIPITATION THREAT HIGH. THERE IS A BIT OF LARGE
SCALE SUBSIDENCE FORECAST TO MOVE OVERHEAD WEDNESDAY EVENING AND
EARLY THURSDAY WHICH WILL PROBABLY RESULT IN LOWER BUT NOT
NECESSARILY ZERO POPS DURING THAT TIME FRAME. INCREASING UPSLOPE
FLOW AND QG ASCENT ASSOCIATED WITH ANOTHER UPPER LEVEL LOW WILL
RETURN LATER THURSDAY AND CONTINUE THROUGH AT LEAST LATE SATURDAY
AND PERHAPS INTO SUNDAY. THIS WILL RAMP UP THE PRECIPITATION
THREAT AGAIN FOR LATER IN THE WEEK...PERHAPS LEADING TO A
SUBSTANTIAL RAIN/SNOW EVENT BY THE WEEKEND...DEPENDING AS
USUAL...ON THE EXACT TRACK OF THE CYCLONE. SUBSIDENCE...DRYING AND
WARMING LOOK TO BE IN STORE FOR EARLY NEXT WEEK AS THIS SECOND
FEATURE MOVES INTO THE GREAT PLAINS.

ALL IN ALL IT LOOKS LIKE THE SEVERE WEATHER THREAT SHOULD REMAIN
RATHER LOW THROUGH MOST OF THIS TIME FRAME BASED ON FORECAST CAPE
VALUES ALTHOUGH THE THREAT OF THUNDERSTORMS WILL BE AROUND...
ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. FORECAST
PRECIPITABLE WATER VALUES ARE HIGH ENOUGH TO ALLOW FOR SOME DECENT
QPF...ESPECIALLY IN HEAVIER SHOWERS AND THUNDERSTORMS. BURN SCARS
IN THE FOOTHILLS COULD HAVE SOME ISSUES IF A STRONGER CONVECTIVE
CELL WERE TO PASS BY.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z TUESDAY EVENING)
ISSUED AT 820 PM MDT MON MAY 4 2015

LOW CLOUDS AND LIGHT TO MODERATE RAINFALL WILL BE A GOOD BET ALL
NIGHT. CEILINGS SHOULD NOT GET ABOVE BKN035 ALL NIGHT AND VISIBILITIES
WILL RANGE FROM 3SM-P6SM WITH THE RAIN AND MAYBE SOME FOG NOW AND
AGAIN.

&&

.HYDROLOGY...
ISSUED AT 840 PM MDT MON MAY 4 2015

AS MENTIONED ABOVE...THE MAIN PROBLEM AREA HAS TURNED OUT TO BE
ELBERT COUNTY WITH SOME TRAINING OF CELLS...BUT MOSTLY ALMOST
STATIONARY CELLS. THE RAINFALL BEGAN IN THE EASTERN HALF OF THE
COUNTY AROUND 2 PM MDT AND HASEN`T REALLY STOPPED SINCE. WE HAVE
BEEN UNABLE TO FIND ANY REAL MEASUREMENTS AS OF YET AND THE RADAR
ESTIMATES HAVE BEEN CONTAMINATED BY PLENTY OF SMALL HAIL. THE
WARNING IS OUT UNTIL 10 PM MDT AND WE MAY NEED TO EXTEND IT.

&&

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

$$

UPDATE...RJK
SHORT TERM...RTG
LONG TERM...ET
AVIATION...RJK
HYDROLOGY...RJK


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