Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 200213
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
813 PM MDT TUE MAY 19 2015

.UPDATE...
ISSUED AT 815 PM MDT TUE MAY 19 2015

WESTERLY FLOW HAS DEVELOPED AND SHOWERS ARE MOVING FROM THE
MOUNTAINS TO THE LOWER ELEVATIONS...WEAKENING ON THE WAY. WE HAVE
ALLOWED WINTER STORM WARNING TO EXPIRE...ALTHOUGH SOME SNOW
SHOWERS MAY STILL DOT THE HIGHER ELEVATIONS THIS EVENING.
WE ALSO ALLOWED THE FLOOD ADVISORY FOR BOULDER AND LARIMER
COUNTIES TO EXPIRE THIS EVENING...THESE AREAS WILL SEE LIGHT RAIN
SHOWERS THIS EVENING. LATER TONIGHT WITH COOLING STILL EXTENSIVE
STRATUS...SOME DRIZZLE AND FOG...WITH A LITTLE BIT OF SNOW ALSO
ON THE NORTHEAST PLAINS.

NO CHANGE TO RIVER FLOOD WARNINGS FROM HENDERSON TO BALZAC ALONG
THE SOUTH PLATTE RIVER.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 321 PM MDT TUE MAY 19 2015

UPPER TROUGH OVER THE STATE WILL BEGIN LIFTING NORTHEAST TONIGHT
WITH A SHORTWAVE UPPER RIDGE TO PUSH OVERHEAD WEDNESDAY. HOWEVER
HIGH SURFACE PRESSURE WILL REMAIN OVER THE NORTHERN PLAINS TO KEEP
MOIST EASTERLY FLOW OVER NORTHEASTERN COLORADO. STRATIFORM RAIN
AND SNOW HAS TRANSITIONED TO SHOWERS WITH SOME THUNDERSTORMS
MOVING OVER THE MOUNTAINS. GROUND IS QUITE SATURATED SO EVEN
THOUGH EXPECTED RAIN AMOUNTS LATE THIS AFTERNOON INTO TONIGHT OVER
THE PLAINS AND LOWER FOOTHILLS IS ONLY AROUND A QUARTER INCH AT
BEST...THE GROUND IS NOT ABLE TO SOAK IN MUCH MORE. THE CURRENT
FLOOD ADVISORIES ARE EXPECTED TO EXPIRE THIS AFTERNOON HOWEVER ANY
AREA OF SLIGHTLY ENHANCED RAIN WILL HAVE TO BE WATCHED. COOLER AIR
HAS FILTERED OVER THE NORTHEAST PLAINS TO ALLOW SOME SNOW TO MIX
IN. EXPECT THIS TO CONTINUE OVERNIGHT...BUT LITTLE TO NO
ACCUMULATION IS EXPECTED. LOOKING AT FORECAST SOUNDINGS OVER THE
PLAINS...MID AND UPPER LEVELS BEGIN DRYING OUT OVERNIGHT...SO WILL
LIKELY BEGIN TO SEE MORE FOG AND DRIZZLE ACROSS THE PLAINS
TONIGHT. ALSO...QG VERTICAL VELOCITIES TURN WEAK DOWNWARD.
HOWEVER...WITH THE RIGHT ENTRANCE REGION OF THE JET MOVING
OVERHEAD...COULD SEE A FEW SCATTERED SHOWERS CONTINUE OVERNIGHT.
SNOW LEVELS ARE AROUND 8500 FT...BUT BESIDES THE SHOWERS AND
THUNDERSTORMS...SNOW WILL BE DIMINISHING. ADDITIONAL SNOW AMOUNTS
WILL LIKELY REMAIN BELOW 3 INCHES...EXCEPT FOR LOCALIZED AREAS
UNDER HEAVIER SHOWERS. TEMPERATURES REMAINED COOLER TODAY...SO
HAVE LOWERED MINIMUM TEMPERATURES TONIGHT BY A DEGREE OR TWO.

AS STATED ABOVE...THE SURFACE HIGH WILL CONTINUE TO PUSH IN A MORE
STABLE AND COOLER AIRMASS OVER THE PLAINS TOMORROW. WITH CONTINUED
CLOUD COVER EXPECTED...LOWERED MAX TEMPERATURES TOMORROW. SOME
INSTABILITY TO OCCUR OVER THE HIGH MOUNTAINS...HAVE INTRODUCED A
SLIGHT CHANCE OF SHOWERS OVER THE MOUNTAINS IN THE AFTERNOON. MAY
SEE SOME OF THESE SHOWERS PUSH OVER THE ADJACENT METRO AREAS AND
PALMER DIVIDE IN THE LATER AFTERNOON. OVERALL...LIGHT RAIN UP TO A
TENTH OF AN INCH EXPECTED FROM THESE SHOWERS...BUT GROUND RESPONSE
COULD BE QUICK.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 321 PM MDT TUE MAY 19 2015

SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED TO PUSH
SLOWLY EAST ONTO THE PLAINS THROUGH THE EVENING HOURS...ALTHOUGH
THERE SHOULD BE A GRADUAL WEAKENING AS THEY MOVE INTO THE MORE
STABLE AIRMASS ON THE EASTERN PLAINS.

MAIN ATTENTION WILL TURN TOWARD NEXT STORM SYSTEM DROPPING
SOUTHWARD ALONG THE CALIFORNIA COAST. THIS WILL BRING INCREASING
MOISTURE...AND AN EMBEDDED SHORT WAVE MOVING AHEAD OF THIS
FEATURE IS EXPECTED TO REACH COLORADO THURSDAY NIGHT. AHEAD OF
THIS...AIRMASS WILL DESTABILIZE ACROSS THE MOUNTAINS AND MAY EVEN
SEE ENOUGH DAYTIME HEATING ON THURSDAY TO HELP SURFACE BASED
CONVECTION DEVELOP ON THE NEARBY PLAINS. MAIN SHOT OF MORE
SIGNIFICANT AND WIDESPREAD PRECIPITATION IS EXPECTED TO ARRIVE
THURSDAY NIGHT AND FRIDAY AS THE LEAD SHORT WAVE PUSHES ACROSS
THE STATE. THERE IS ONCE AGAIN PLENTY OF LOW/MID LEVEL MOISTURE
AND HIGH PRECIPITABLE WATER VALUES TO BRING A THREAT OF LOCALLY
HEAVY RAINFALL. THIS SYSTEM IS WARMER AS WELL...SO COULD SEE RAIN
ON TOP OF SNOWPACK AS SNOW LEVELS MAY HOVER CLOSER TO 11 THOUSAND
FEET.

BY FRIDAY NIGHT AND SATURDAY...DEPENDING ON EVENTUAL TRACK OF
SYSTEM COULD SEE MORE NUMEROUS SHOWERS AND A FEW STORMS CONTINUE
ESPECIALLY IF UPPER LEVEL TROUGH HANGS A BIT FARTHER SOUTH AND
WEST WHICH IS ENTIRELY POSSIBLE LIKE THE ECMWF. HOWEVER...IF THE
GFS IS CORRECT WITH A FARTHER NORTH AND MORE OPEN WAVE THEN LOWER
COVERAGE OF SHOWERS AND STORMS. EVEN THEN...SHOULD STILL SEE A
DECENT CHANCE AS AIRMASS WILL REMAIN RATHER MOIST AND UNSTABLE
UNDER GENERAL TROUGHINESS. THE SAME CAN BE SAID THROUGH SUNDAY.

THERE SHOULD BE SOME GRADUAL MODERATION IN TEMPERATURES AND THE
EXTREMELY WET WEATHER PATTERN AS WE HEAD INTO MONDAY OR TUESDAY OF
NEXT WEEK AS THE FLOW TURNS MORE WESTERLY. HOWEVER...WILL HAVE TO
KEEP A CHANCE OF SHOWERS AND STORMS IN THE FORECAST EACH DAY WITH
LINGERING MOISTURE AND POTENTIAL FOR EMBEDDED BUT WEAKER DISTURBANCES.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z WEDNESDAY LATE AFTERNOON)
ISSUED AT 815 PM MDT TUE MAY 19 2015

LOW CLOUDS TO PREVAIL THROUGH TONIGHT. CEILINGS AROUND 1500-3000
FEET WILL LOWER OVERNIGHT...LIKELY BELOW 1000 FEET BY 12Z
WEDNESDAY...WITH AREAS OF DRIZZLE AND FOG. RAIN SHOWER COVERAGE WILL
CONTINUE TO DECREASE. A WEAK DENVER CYCLONE MAY KEEP
FORMING...WITH EASTERLY FLOW AT DIA AND NORTHEAST AT BJC.
WEDNESDAY WILL START WITH LOW CLOUDS AND VISIBILTIES...IMPROVING
TO VFR AROUND MIDDAY...THEN SCATTERED CONVECTION IN THE AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 815 PM MDT TUE MAY 19 2015

RAINFALL AMOUNTS WILL CONTINUE TO DECREASE OVERNIGHT....WITH MOST
AREAS SEEING LESS THAN A TENTH OF AN INCH OF RAIN. SOILS REMAIN
SATURATED OVER MOST OF NORTHEAST COLORADO...BUT THE THREAT OF ANY
ADDITIONAL FLOODING WILL BE LOW TONIGHT.

THE FLOOD WARNING REMAINS IN EFFECT FOR THE CACHE LA POUDRE NEAR
GREELEY...AND THE SOUTH PLATTE FROM THE HENDERSON GAGE TO THE
BALZAC GAGE..ALTHOUGH THE FORECAST CRESTS ARE A LITTLE BIT LOWER
ON THIS EVENINGS FORECAST.


&&

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

$$

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


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