Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 310846
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
246 AM MDT FRI JUL 31 2015

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 245 AM MDT FRI JUL 31 2015

THE BROAD UPPER HIGH WILL CONTINUE TO SHIFT FURTHER WEST AND
NORTH ACROSS THE GREAT BASIN TODAY. THIS WILL ALLOW SOME
ADDITIONAL MOISTURE TO ALSO SEEP INTO COLORADO WHERE INTEGRATED PW
VALUES HAVE ALREADY INCREASED AROUND A THIRD OF AN INCH IN THE
PAST 12 HOURS OVER THE FRONT RANGE. STILL THOUGH MID LEVEL
INVERSION AROUND 500MB WILL LIMIT CONVECTION THROUGH THIS
AFTERNOON. NAM SEEMS THE MOST BULLISH ON MOISTURE AND STORM
POTENTIAL WHILE THE THE RAP IS THE DRIEST. EXPECT MAJORITY OF
STORMS WILL BE OVER EAST SLOPES AND HIGHER TERRAIN. SOME OF THIS
MAY SPILL OUT OVER THE ADJACENT PLAINS BY LATER THIS AFTERNOON.
NOT MUCH HELP UPSTAIRS AS QG FIELDS SHOWING SOME SUBSIDENCE IN THE
700MB LAYERS AND NEUTRAL FORCING ALOFT. ISOLATED POPS ON THE
PLAINS WITH HIGHER SCATTERED CHANCES IN THE MOUNTAINS SHOULD
SUFFICE. EXPECT TEMPERATURES WILL BE SIMILAR TO THURSDAY READINGS.
CONVECTION WILL DIMINISH DURING THE EVENING HOURS WITH LACK OF ANY
UPPER AIR SUPPORT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 207 AM MDT FRI JUL 31 2015

BY SATURDAY MORNING...A NEGATIVELY TILTED UPPER RIDGE IS STILL OVER
THE WRN CONUS WITH THE 500MB HIGH OVER SERN NEW MEX. AT THE SFC...
BROAD CLOCKWISE CIRCULATION AROUND A STG HIGH IN NWRN ARKANSAS
CONTINUES TO ADVECT INCREASING AMOUNTS OF LOW-LEVEL MOISTURE
NORTHWARD ALONG THE COLORADO/KANSAS BORDER. MEANWHILE THE MID-LEVEL
NWLY FLOW CONTINUES TO DRY ON THE SOUTH SIDE OF AN 80-90KT JET
SEGMENT. BY LATE AFTERNOON...MODELS SHOW A NEARLY NEUTRAL TILT UPPER
RIDGE MIGRATING EASTWARD OVER ERN UTAH/COLORADO CAUSING THE MID-
LEVEL FLOW OVER THE FCST AREA TO BECOME N-NWLY. AT THE SAME TIME
SELY BNDRY LAYER FLOW EAST OF THE MTNS CONTINUES TO TRANSPORT LOW
LEVEL MOISTURE UP INTO THE FCST AREA. MODELS SHOW MEAN LAYER PW
VALUES PUSHING AN INCH ACRS SERN SECTIONS OF THE CWA BY EVENING.
HOWEVER...MOISTURE APPEARS RELATIVELY SHALLOW...CAPPED BY A MUCH
DRIER N-NWLY FLOW ABOVE 650 MBS. OVERNIGHT SELY SFC WINDS ON THE
PLAINS TURN SWLY WHICH FLUSHES OUT SOME OF THE MOISTURE UP ALONG
THE FRONT RANGE.

DRY OUT IS SHORT-LIVED AS THE GFS...SREF AND NAM SHOW A RETURN TO A
MOIST SELY FLOW DURING THE DAY SUNDAY. MODELS SHOW MEAN LAYER PW
VALUES APPROACH 1.25 INCH OVER NRN PORTIONS OF THE I-25 URBAN
CORRIDOR BY LATE AFTERNOON. THIS TIME THE MOISTURE LAYER APPEARS
DEEPER AND WITH LIGHT/VARIABLE TRANSPORT WINDS SLOW STORM MOTIONS
WOULD CONCEIVABLY RESULT IN LOCALLY HEAVY RAINFALL. ALTHOUGH QPF
FIELDS DO NOT INDICATE ANYTHING LIKE THAT HAPPENING APPARENTLY DUE
TO A LACK OF CAPE AND SOME KIND OF FORCING MECHANISM SUCH AS A
FRONTAL BNDRY OR DEEP UPSLOPE FLOW. HOWEVER MODELS INDICATE CAPES IN
THE 1000-1500 J/KG RANGE...AND ON THE NAM AS HIGH AS 2000 J/KG...AND
DECENT LOW-LEVEL CONVERGENCE/SHEAR ALONG THE PALMER DIVIDE. ITS MORE
LIKELY HERE THAT A FEW SUPERCELLS CAPABLE OF HEAVY RAINFALL...HAIL
AND STG GUSTY WINDS WILL FORM AND TRACK EAST-SOUTHEAST ALONG THE
DIVIDE DURING THE LATE AFTERNOON AND EVENING HRS ON SUN. THE SRN
FRONT RANGE FOOTHILLS AND SOUTH PARK IS ANOTHER AREA WHERE THERE`S
AN ELEVATED POTENTIAL FOR T-STORMS AT THIS TIME DUE TO THIS MOIST
AND UNSTABLE SELY FLOW. ACTUALLY THERE`S A GREATER POTENTIAL FOR
STORMS PRODUCING HEAVY RAINFALL IN PARK COUNTY WITH THIS SET UP.

BY SUNDAY NIGHT...THE NAM...GFS AND ECMWF ALL NOW SHOW A MID-LEVEL
SHORTWAVE TROUGH LIFTING NEWRD ACRS THE STATE WITH THE UPPER RIDGE
COLLAPSING AS IT CONTINUES TO SHIFT EAST. WAVE IS FCST TO REACH THE
FRONT RANGE URBAN CORRIDOR BY EARLY MONDAY MORNING. ITS PASSAGE
COULD ENHANCE OR EXTEND SHOWER/T-STORM DEVELOPMENT IN THE HIGH
COUNTRY THROUGH THE LATE EVENING HRS. NOT SURE THIS DISTURBANCE WILL
HAVE MUCH OF AN IMPACT ON AREAS EAST OF THE MTNS OVERNIGHT.

ON MONDAY...MOISTURE...INSTABILITY AND MODEST QG LIFT ASSOCIATED
WITH THE PASSING SHORTWAVE EXPECTED TO PRODUCE MORE CLOUD COVER AND
A SLIGHTLY GREATER CHANCE OF SHOWERS/T-STORMS FOR THE ENTIRE FCST
AREA. MOST MODELS SHOW THIS FEATURE EXITING THE STATE BY EVENING
WITH DRYING AND STABILIZATION IN ITS WAKE AS THE UPPER RIDGE AXIS
MOVES OVERHEAD OVERNIGHT.

TUESDAY SHOULD BE A DRIER AND SLIGHTLY WARMER DAY WITH ANY STORM
DEVELOPMENT RELEGATED TO THE HIGH COUNTRY. ON WEDNESDAY... TEMPS
CONTINUE TO WARM BOTH SFC AND ALOFT...AND HUMIDITIES LOWER WITH
THE UPPER RIDGE AMPLIFYING OVER THE CENTRAL ROCKIES. HOWEVER STILL
CANNOT RULE OUT A FEW LATE DAY GUSTY T-STORMS IN THE HIGH COUNTRY.

BY THURSDAY...MEDIUM RANGE MODELS SHOW THE UPPER RIDGE MOVING OVER
THE GREAT PLAINS PLACING COLORADO UNDER SWLY FLOW ALOFT. COULD SEE
SUBTROPICAL MOISTURE CARRIED NORTH BY THIS FLOW IN TANDEM WITH A
SHORTWAVE TROUGH THAT MODELS SHOW SWINGING OUT OF THE 4-CORNERS
REGION LATE IN THE DAY. AS A RESULT COULD SEE A MODEST INCREASE IN T-
STORM CHANCES MAINLY FOR THE HIGH COUNTRY. OTHERWISE THURSDAY TEMPS
LITTLE CHANGED FROM THE DAY BEFORE.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 207 AM MDT FRI JUL 31 2015

SURFACE TROF OVER DENVER WITH HEALTHY S-SW WINDS OVER DEN/APA AND
NW WINDS AT BJC. WINDS EXPECTED TO TURN SOUTHEAST OVER ENTIRE AREA
THIS AFTERNOON. MOISTURE LEVELS A BIT HIGHER TODAY AND EXPECT
ISOLATED COVERAGE OF STORMS BY LATER THIS AFTERNOON. HOWEVER AREAL
COVERAGE TOO LOW TO MENTION IN TERMINAL FORECASTS FOR NOW. EXPECT
BRIEF RAIN AND GUSTY WINDS WITH ANY POTENTIAL SHOWERS IN THE
AREA.

&&

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

$$

SHORT TERM...ENTREKIN
LONG TERM...BAKER
AVIATION...ENTREKIN



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