Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 052347
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
547 PM MDT TUE MAY 5 2015

.UPDATE...
ISSUED AT 547 PM MDT TUE MAY 5 2015

SATELLITE SHOWING THE UPPER LEVEL LOW IS CENTERED OVER EASTERN
CENTRAL COLORADO AT THIS TIME. THE HEAVIEST RAIN ASSOCIATED WITH
IT IS OVER THE EASTERN PLAINS. ALONG THE FRONT RANGE AND PALMER
DIVIDE...LIGHT RAIN HAS FALLEN WITH MOST LOCATIONS RECEIVING LESS
THAN A HALF INCH. ADDITIONAL RAINFALL IS EXPECTED TO LIGHT THIS
EVENING AS THE MAIN LIFT MOVES NORTH OF THE STATE. THREAT FOR
HEAVY RAIN CAPABLE OF PRODUCING FLASH FLOODING IS VERY LOW...SO
CANCELED THE FLASH FLOOD WATCH. EXPECT THE WIDESPREAD RAIN TO END
THIS EVENING AS WINDS TURN WESTERLY ALONG THE FRONT RANGE AS THE
LOW LIFTS NORTH OF THE STATE.

MANY STREAMS AND RIVERS ARE RUNNING HIGH AND WILL CONTINUE TO RUN
HIGH FOR THE NEXT SEVERAL DAYS DUE TO RECENT RAINFALL AND SNOW
MELT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 331 PM MDT TUE MAY 5 2015

RAIN BAND CONTINUES TO LIFT NORTHWARD ACROSS NORTHEAST
COLORADO...WITH SCATTERED SHOWERS AND A FEW THUNDERSTORMS FORMING
UNDER THE DRIER AIR ALOFT OVER SOUTHEAST COLORADO. SO FAR RAIN ON
THE PLAINS HAS BEEN PERSISTENT BUT GENERALLY LIGHT. THE HEAVIEST
SHOWERS HAVE BEEN ALONG A WIND CONVERGENCE LINE MOVING SLOWLY
WEST...NOW JUST WEST OF INTERSTATE 25. THIS APPEARS TO BE HOLDING
TOGETHER PRETTY WELL BUT WEAKENING IN INTENSITY A BIT...AND PEAK
RAINFALL RATES UNDER THIS WERE ABOUT A HALF INCH IN AN HOUR.
GREATEST THREATS APPEAR TO BE IF THIS LINE WERE TO FLARE UP AGAIN
OVER THE FOOTHILLS...OR IF THERE IS STRONGER CONVECTION IN THE DRY
SLOT THIS EVENING. STILL ENOUGH OF A THREAT TO HANG ON TO THE
FLASH FLOOD WATCH WHERE WE HAVE IT...AS SOME AREAS COULD HAVE
TROUBLE WITH AN INCH OF RAIN...BUT IT APPEARS THAT THE THREAT OF
HEAVY RAIN IS DIMINISHING.

THE BAND WILL SHIFT NORTHWARD THIS EVENING...BUT THERE WILL STILL
BE SOME SHOWERS ROTATING IN FROM THE WEST. THESE SHOULD BE
WEAKER...BUT WILL HANG ON TO CLOUDS AND SOME LOW POPS THROUGH THE
NIGHT.

AIRMASS WILL BE WARMER AND DRIER ON WEDNESDAY...BUT STILL UNSTABLE
ENOUGH FOR SCATTERED SHOWERS. COULD BE A BETTER CHANCE OF A FEW
THUNDERSTORMS IN THE AFTERNOON WITH THE WARMER TEMPERATURES AND
THE REMAINING LOW LEVEL MOISTURE. BUMPED POPS UP SLIGHTLY FOR
WEDNESDAY AFTERNOON.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 331 PM MDT TUE MAY 5 2015

FOR WEDNESDAY NIGHT THE UPPER TROUGH WILL SHIFT TO THE NORTHEAST
WITH A WEAK FRONT ASSOCIATED WITH A BUILDING SURFACE HIGH MOVING
INTO THE FRONT RANGE FROM THE NORTH. LOW LEVEL MOISTURE WILL
SPREAD BACK INTO THE REGION WITH SHALLOW UPSLOPE DEVELOPING. AS A
RESULT...THERE COULD BE A MIX OF LIGHT RAIN..DRIZZLE OR FOG
WEDNESDAY NIGHT INTO THURSDAY MORNING. ON THURSDAY...THE FRONTAL
BOUNDARY WILL REMAIN ALONG THE FRONT RANGE AND PALMER DIVIDE WITH
THE SURFACE HIGH CONTINUING TO BUILD OVER THE NORTHEAST PLAINS. A
CLOSED WILL BE DROPPING INTO CENTRAL CALIFORNIA WITH A DIFFLUENT
SOUTHWESTERLY FLOW ALOFT OVER COLORADO. THE BEST
CONVERGENCE...LIFT AND INSTABILITY WILL BE ALONG THE FRONT
RANGE/PALMER DIVIDE WITH SOME ELEVATED CONVECTION POSSIBLE. BEST
AREA WILL BE OVER THE PALMER DIVIDE WITH SFC BASED CAPES OF
600-800 J/KG...GENERALLY AROUND 400 J/KG FOR THE FRONT RANGE. FLOW
ALOFT WILL GO FROM A DRIER WESTERLY COMPONENT THURSDAY MORNING TO
A MOIST SOUTHWESTERLY FLOW ALOFT IN THE AFTERNOON AND EVENING.
OVERRUNNING TYPE OF PROFILE WILL CONTINUE THURSDAY NIGHT AND AGAIN
ON FRIDAY. UPSLOPE/QG ASCENT WILL NOT BE STRONG SHOULD BE MORE OF
A STEADY LIGHT RAINFALL THURSDAY NIGHT. ANOTHER SURGE OF HIGH
PRESSURE MAY HELP TO ENHANCE PCPN ALONG THE FRONT RANGE/PALMER
DIVIDE ON FRIDAY. THE UPPER LOW AT THAT TIME WILL BE CENTERED OVER
SOUTHERN CALIFORNIA WITH A WEAK SOUTHWESTERLY FLOW ALOFT OVER
COLORADO. FRIDAY NIGHT INTO SATURDAY...THE UPPER LOW WILL SHIFT
NORTHEAST TO NEAR THE FOUR CORNERS REGION BY 12Z SATURDAY.
INCREASING MID AND UPPER LEVEL QG ASCENT WILL OCCUR...WITH
MODERATE TO STRONG QG ASCENT BY 18Z SATURDAY. AS A RESULT...IT
STILL LOOKS LIKE A WIDESPREAD PCPN EVENT FOR THE AREA. SOUTHERLY
MID LEVEL FLOW SATURDAY MORNING BECOME EASTERLY SATURDAY
AFTERNOON/EVENING THEN NORTHERLY SATURDAY NIGHT AS THE SYSTEM
SHIFTS NORTHEAST INTO NEBRASKA. GOOD COLD AIR ADVECTION ON SUNDAY
WITH THE SNOW LEVEL DROPPING TO AROUND 7 THOUSAND FEET BY 12Z
SUNDAY. AS A RESULT...SHOULD SEE RAIN TRANSITION OF SNOW OR
RAIN/SNOW MIX IN THE FOOTHILLS SATURDAY NIGHT. SUNDAY AND SUNDAY
NIGHT...WRAP AROUND MOISTURE OVER NORTHEASTERN COLORADO ON THE
BACKSIDE OF THE TROUGH. SHOULD START TO SEE MORE SUN VS CLOUDS ON
MONDAY WITH AN UPPER RIDGE TO THE WEST AND A DRIER NORTHWESTERLY
FLOW OVER THE CWA.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z WEDNESDAY LATE AFTERNOON)
ISSUED AT 331 PM MDT TUE MAY 5 2015

MVFR CONDITIONS WILL PREVAIL THROUGH EARLY EVENING WITH LOCALIZED
LIFR IN AREAS OF HEAVIER RAIN. CONDITIONS WILL IMPROVE BETWEEN 03Z
AND 06Z WITH VFR CONDITIONS AFTER THAT. HIGHER CEILINGS MAY STILL
REQUIRE INSTRUMENT APPROACHES TO KDEN INTO WEDNESDAY MORNING.


&&

.HYDROLOGY...
ISSUED AT 331 PM MDT TUE MAY 5 2015

RAINFALL RATES HAVE MAINLY BEEN BETWEEN A TENTH AND QUARTER INCH
PER HOUR...EXCEPT UP TO A HALF INCH IN AN HOUR IN A RAIN BAND
ALONG I-25 NORTH OF DENVER WHICH HAS SINCE WEAKENED. STILL SOME
THREAT OF STRONGER CONVECTION TRAINING...BUT OVERALL IT IS LOOKING
LIKE THE INTENSITY WILL CONTINUE TO BE TOO WEAK FOR MUCH OF A
THREAT. WILL HOLD ON TO THE FLASH FLOOD WATCH FOR THE TIME BEING
WAITING TO SEE IF THERE IS ANY MORE INTENSE CONVECTION DEVELOPING OVER
THE NEXT FEW HOURS. IF NOT...WE MAY BE ABLE TO DROP THE WATCH
EARLY.

&&

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

$$

UPDATE...MEIER
SHORT TERM...GIMMESTAD
LONG TERM...COOPER
AVIATION...GIMMESTAD
HYDROLOGY...GIMMESTAD


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