Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 190208
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
808 PM MDT MON MAY 18 2015

.UPDATE...
ISSUED AT 815 PM MDT MON MAY 18 2015

FORECAST MOSTLY ON TRACK WITH SHOWERS AND THUNDERSTORMS SLOWLY
PUSHING TO PLAINS. LOOKS LIKE FOOTHILLS WILL BE UNDER A NEAR
CONTINUAL FEED OF SHOWERS AND THUNDERSTORMS UNDER SOUTHWEST
FLOW TONIGHT AND TOMORROW...ISSUED A FLASH FLOOD WATCH...WITH
MAIN CONCERN BEING THE BURN AREAS WHICH STILL CAN HAVE FLOODING
WITH A QUICK 0.75 INCHES OF RAIN.

TEMPERATURES LOOK FAIRLY WARM ALOFT...ALTHOUGH HIGH PASSES ARE
GETTING TO UPPER 20S. BUT SIGNIFICANT SNOW IN THE MOUNTAINS LOOKS
TO BE ABOVE 10000 FEET. REDUCED SNOW AMOUNTS BELOW THAT LEVEL. THE
WINTER STORM WARNING REMAINS...BUT MAIN IMPACTS EXPECTED TO BE IN
THE HIGHER PASSES.

COORDINATED WITH MISSOURI BASIN RIVER FORECAST CENTER...AND WITH
FORECAST RAINFALL AMOUNTS THROUGH TOMORROW...THE RIVERS ARE
EXPECTED TO RESPOND...WITH MOST GAGES GETTING BACK TO MINOR
FLOODING...AND KERSEY LIKELY GETTING TO BACK TO MODERATE FLOOD
STAGE. ISSUED A RIVER PRO FLOOD WATCH ALONG THE PLATTE FROM
GREELEY TO BALZAC. WITH FORECAST QPF FLOOD STAGES ARE EXPECTED TO
BE REACHED WEDNESDAY INTO THURSDAY.


&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 310 PM MDT MON MAY 18 2015

MAIN CONCERNS ARE HEAVY SNOW OVER THE MOUNTAINS AND POTENTIAL FOR
FLOODING ON THE NORTHEAST PLAINS. STRONG UPPER LOW OVER
CALIFORNIA WILL INTO UTAH ON TUESDAY WHILE STRONG ENERGY ROTATES
THROUGH COLORADO LATER TONIGHT AND TUESDAY. STRONG QG ASCENT OVER
AREA FROM MIDNIGHT THROUGH 18Z TUESDAY BEFORE SHIFTING INTO
NEBRASKA BY LATE TUESDAY AFTERNOON AND EVENING. SHOWERS WILL
DECREASE A BIT FROM SOUTHWEST TO NORTHEAST DURING TUESDAY
AFTERNOON. WILL HAVE CATEGORICAL POPS FOR MUCH OF THE AREA BY
MIDNIGHT TONIGHT. INCREASING SOUTHEAST WINDS TONIGHT WILL FAVOR
THE NORTHERN FRONT RANGE FOOTHILLS AND OVER THE CYS RIDGE. COULD
BE LESSER AMOUNTS NORTH OF THE PALMER DIVIDE THROUGH DENVER AND
ADJACENT POINTS TO THE EAST. LOOKS LIKE HEAVIEST SNOW WILL REMAIN
ABOVE 10000 FEET WITH SNOW LEVEL VARYING FROM 8000 TO 9500 FEET.
THERE WILL BE SOME SNOW ACCUMULATION IN THE HIGHER FOOTHILLS BUT
MOST LIKELY NOT ENOUGH FOR ANY HILITES.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 310 PM MDT MON MAY 18 2015

RAIN AND MOUNTAIN SNOW WILL CONTINUE TO DECREASE TUESDAY EVENING
AS UPPER SYSTEM LIFTS FURTHER OFF TO THE NORTHEAST. COULD SEE
ANOTHER INCH OR TWO IN THE NORTHERN MOUNTAINS AS OROGRAPHICS ARE
FAIR THERE. HOWEVER...LARGE SCALE SUBSIDENCE AND STABILIZATION
SHOULD BRING AN END TO MOST OF THE PRECIPITATION ON THE PLAINS DURING
THE COURSE OF THE EVENING. THERE IS A SLIGHT RISK OF A BIT OF SNOW
MIXED IN WITH THE RAIN OVER THE FAR NORTHERN BORDER AREA TOWARD
SIDNEY...BUT STRONGER WARM ADVECTION SHOULD BE ENOUGH TO BRING
ALMOST ALL RAIN.

ON WEDNESDAY...A FLAT UPPER LEVEL RIDGE WILL BUILD ACROSS
COLORADO. THE AIRMASS IS RATHER STABLE ON THE PLAINS SO MOST OF
THE INSTABILITY AND CONVECTION WILL HAVE TO FIRE OVER THE HIGH
COUNTRY DURING THE AFTERNOON...AND THEN SPREAD EAST ACROSS THE
FOOTHILLS AND PLAINS LATER IN THE DAY INTO THE EVENING HOURS.

ON THURSDAY...ANOTHER UPPER LEVEL TROUGH WILL MOVE INTO CALIFORNIA
WITH SOUTHWESTERLY FLOW DEVELOPING OVER THE AREA. AT THE
SURFACE...HIGH PRESSURE WILL CONTINUE TO AFFECT NORTHEAST
COLORADO WITH COOL SOUTHEAST LOW LEVEL FLOW. STILL THINK THE ECMWF
HAS A BETTER HANDLE ON HIGH TEMPS OVER NORTHEAST COLORADO WILL
KEEP READINGS MAINLY IN THE UPPER 50S TO LOWER 60S. AS FAR AS
PRECIP GOES...THE AIRMASS ACROSS THE PLAINS WILL REMAIN RATHER
STABLE WITH THE BEST INSTABILITY REMAINING OVER THE HIGHER
TERRAIN. THUS WILL KEEP THE BEST POPS OVER THE MOUNTAINS....WITH
LOWER CHANCES ON THE EASTERN PLAINS.

FOR THURSDAY NIGHT AND FRIDAY...AN UPPER LEVEL LOW WILL BE MOVING
VERY SLOWLY EAST ACROSS THE DESERT SOUTHWEST. AT THE SAME
TIME...LARGE SCALE Q-G LIFT IS EXPECTED TO INCREASE ACROSS THE
FORECAST AREA. THIS SHOULD SET UP ANOTHER WIDESPREAD RAIN EVENT
WITH POTENTIAL FOR MORE SIGNIFICANT PRECIPITATION ONCE AGAIN.
TEMPERATURES DO LOOK WARMER SO EXPECT SNOW LEVELS DURING THIS
PERIOD TO BE RATHER HIGH...WITH MOST OF THE ACCUMULATING SNOW
ABOVE TIMBERLINE. HAVE INCREASED POPS FOR THIS WETTER
PERIOD...WHILE KEEPING TEMPERATURES COOL WITH MOSTLY CLOUDY SKIES
AND SHOWERS/STORMS AROUND.

THIS NEXT UPPER TROUGH IS DIFFICULT TO TIME SO EFFECTS MAY VERY
WELL LINGER INTO FRIDAY NIGHT AND SATURDAY. MOST MODELS AGREE
THAT THE LOW DOES KICK A BIT MORE TO OUR NORTH THAN THIS CURRENT
STORM...SO MORE WIDESPREAD PRECIPITATION SHOULD BE SHIFTING NORTH
AND EAST OF THE FORECAST AREA. HOWEVER...THERE WILL BE SUFFICIENT
MOISTURE AND INSTABILITY UNDER THE UPPER LOW SO WILL CONTINUE A
CHANCE OF SHOWERS AND A FEW STORMS.

BY SUNDAY AND MONDAY PRECIPITATION CHANCES SHOULD DECREASE A BIT
IN BETWEEN WEATHER SYSTEMS...BUT THERE IS STILL PLENTY OF
RESIDUAL MOISTURE AROUND. THIS WILL KEEP TEMPERATURES SEVERAL
DEGREES BELOW NORMAL AND A FEW SHOWERS IN THE FORECAST.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z TUESDAY LATE AFTERNOON)
ISSUED AT 310 PM MDT MON MAY 18 2015

BOUNDARY HAS BEEN SLOWLY CRAWLING ACROSS DIA...THIS APPARENTLY
TIED TO INCREASING SOUTHWESTERLY WINDS ALOFT...ORIGINAL THINKING
WAS BRISK SOUTHEASTERLIES WOULD HOLD...BUT THAT NOT THE CASE. NOW
IT LOOKS THAT A DENVER CYCLONE HAS DEVELOPED...AND THIS MAY STAY
THROUGH THE NIGHT. WILL CONTINUE TO MONITOR...BUT DIA MAY NOT GET
BACK TO SOUTHEASTERLY WINDS TONIGHT. VFR CEILINGS WILL HOLD FOR
MUCH OF THE NIGHT...WITH MORE MVFR/ IFR CONDITIONS DEVELOPING
TOWARDS SUNRISE. SHOWERS WILL BECOME WIDSPREAD OVERNIGHT ALONG
WITH SOME THUNDERSTORMS. EXPECT SOME IMPROVING CONDITIONS TUESDAY
AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 815 PM MDT MON MAY 18 2015

AS MEINTIONED ABOVE...WE HAVE A FLASH FLOOD WATCH OUT FOR THE
FOOTHILLS FOR TONIGHT AND TUESDAY...AND RIVER FLOOD WATCHES ALONG
THE SOUTH PLATTE FOR POSSIBLE FLOODING WEDNESDAY INTO THURSDAY.

RAIN IS STILL EXPECTED TO BECOME WIDESPREAD OVER THE PLAINS
TONIGHT AND CONTINUE THROUGH TUESDAY. LATEST QPF FROM MODELS
SHOWING ANYWHERE FROM .50 TO 1.5 INCHES OF RAIN ON THE PLAINS AND
UP TO 2 INCHES POSSIBLE OVER THE FRONT RANGE FOOTHILLS. LOWEST
AMOUNTS OVER THE PALMER DIVIDE AND THROUGH DENVER AS SOUTHEAST
FLOW NOT AS FAVORABLE.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR COZ035-036.

WINTER STORM WARNING UNTIL 6 PM MDT TUESDAY FOR COZ033-034.

&&

$$

UPDATE...RTG
SHORT TERM...ENTREKIN
LONG TERM...BARJENBRUCH
AVIATION...ENTREKIN
HYDROLOGY...ENTREKIN


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