Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 042158
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
358 PM MDT SAT JUL 4 2015

.SHORT TERM...(THIS AFTERNOON THROUGH SUNDAY)
ISSUED AT 358 PM MDT SAT JUL 4 2015

POCKET OF DRIER AIR UNDER CLOUD COVER WITH NORTHERLY SURFACE WINDS NEAR
THE MOUNTAINS WILL HINDER THUNDERSTORM ACTIVITY THE REST OF THE
AFTERNOON. PLENTIFUL MAINLY WEAK CONVECTION OVER THE MOUNTAINS
WILL KEEP TRYING TO SPREAD EASTWARD AND MOISTENING FROM ABOVE MAY
EVENTUALLY MAKE A LESS HOSTILE ENVIRONMENT...SO STILL EXPECTING
SOME ISOLATED STORMS TO MAKE IT OFF THE MOUNTAINS IN THE LATE
AFTERNOON AND EARLY EVENING. MEANWHILE RIPE AIRMASS AHEAD OF THE
WIND SHIFT LINE FROM STERLING-AKRON-LIMON IS ONLY WEAKLY CAPPED.
THERE WILL LIKELY BE A FEW STORMS FORMING ALONG OR JUST EAST OF
THAT LINE IN THE LATE AFTERNOON. WITH THE MOIST SOUTHERLY FLOW
FEEDING INTO THE STORMS...THEY COULD BE QUITE PERSISTENT AND SLOW
MOVING...GRADUALLY SAGGING SOUTH AND EAST FROM THE ORIGIN. SOME
THREAT OF SEVERE HAIL AND WIND...ESPECIALLY HAIL WITH THE INITIAL
PULSES...HOWEVER THEY WILL PROBABLY TRANSFORM INTO A LARGER MCS
WITH LOWER SEVERE THREAT AFTER A FEW HOURS...AND ALSO BE SPREADING
OUT OF OUR AREA. WEAK SHOWERS MAY LINGER OVERNIGHT WITH QUITE A
BIT OF CLOUD COVER...ESPECIALLY OVER THE MOUNTAINS.

FOR SUNDAY...INITIALLY A FAIRLY MOIST BUT STABLE ENVIRONMENT.
PRECIPITABLE WATER INCREASES TO 1.25 INCHES WITH VERY WARM AIR
ALOFT...ABOUT AS WARM AS IT GETS AT 500 MB. BETWEEN THE CLOUD
COVER AND THE WARMTH ALOFT STABILITY WILL BE LIMITED. HOWEVER
THERE WILL BE SOME LIFT ARRIVING AHEAD OF THE APPROACHING
SHORTWAVE IN THE AFTERNOON THAT SHOULD BE ENOUGH TO GENERATE SOME
STORMS. EXPECT THE BULK OF THE ACTIVITY WILL BE WITH THE COLD
FRONT...OR OUTFLOW BOUNDARIES FROM THE NORTHWEST THAT BECOME THE
EFFECTIVE FRONT...IN THE LATE AFTERNOON AND EVENING. GIVEN THE
AMOUNT OF MOISTURE AVAILABLE AND A LITTLE COOLING ALOFT
ARRIVING...THESE MORE STRONGLY FORCED STORMS COULD BE STRONG TO
SEVERE WITH THE GREATEST THREAT PROBABLY WIND FROM AN ORGANIZED
COLD POOL WITH THE FRONT. TEMPERATURES WILL STILL BE HOT...BUT
LIMITED BY THE CLOUD COVER...AND THEN COOLING SIGNIFICANTLY WITH
THE FRONT WHEN IT ARRIVES.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 PM MDT SAT JUL 4 2015

HEAVY RAIN RETURNS IN THE EXTENDED WITH COOLER TEMPERATURES TO
START YOUR WEEK.

FOR SUNDAY EVENING INTO MONDAY THE UPPER LEVEL RIDGE FLATTENS OUT
WITH HELP FROM A LOW PRESSURE SYSTEM IN THE PACIFIC AND A TROUGH
THAT DROPS OUT OF CANADA. A COLD FRONT MOVES INTO NE COLORADO
SUNDAY NIGHT INTO MONDAY MORNING. IF THE FRONT CAN MOVE IN TO
COORDINATE WITH MAX INSTABILITY WILL MOST LIKELY HAVE STORMS FIRE
OFF ALONG THE BOUNDARY AS IT MOVES SOUTH. FOR MONDAY THE ATM
STABILIZES BEHIND THE FRONT WITH MOISTURE LEVELS INCREASING. PW
VALUES RANGE FROM 1.00 TO 1.30 IN THROUGH TUESDAY EVENING.
MINIMAL CAPE ON MONDAY WILL NOT BRING HIGH PROBABILITY FOR
CONVECTIVE STORMS BUT WITH DECENT UPSLOPE STARTING AROUND 12Z
MONDAY ACCORDING TO THE GFS ALONG THE FOOTHILLS AND PALMER DIVIDE
WILL BRING MORE STRATIFORM RAIN AND CLOUDS THROUGHOUT THE DAY
MONDAY. TEMPERATURES WILL DROP CONSIDERABLY ON MONDAY BEHIND THE
FRONT WITH HIGHS DROPPING INTO THE LOWER 70S.

ON TUESDAY UPPER LEVEL FLOW REMAINS WESTERLY WITH INCREASED LEVELS
OF SUBTROPICAL MOISTURE BEING PULLED UP FROM THE SOUTH. WITH
INCREASED MOISTURE PW VALUES WILL REMAIN ABOVE 1 INCH HOWEVER
UPSLOPE CONDITIONS WILL NOT BE AS GOOD. THE BEST LOCATION FOR
PRECIPITATION WILL BE CLOSER TO THE FOOTHILLS. ANOTHER STRATIFORM
DAY EXPECTED AS INSTABILITY OR CAPE WILL BE LOW DUE TO COOLER
TEMPERATURES IN THE MORNING. SOME MODELS INDICATING INCREASED
CHANCES OF CONVECTION IN THE AFTERNOON BUT WILL DEPEND ON CLOUD
COVER AND IF THE CONVECTIVE TEMP CAN BE REACHED.

FOR THE LATTER HALF OF THE WEEK MID LEVEL MOISTURE WILL STAY HIGH
AS SUBTROPICAL FLOW CONTINUES TO MOVE NORTH. THERE NOT A
CONSENSUS BETWEEN MODELS ON UPPER LEVEL FLOW HOWEVER THE EC HAS
FLOW MOVING MORE NW AS THE PACIFIC LOW MOVES NORTH ALONG THE
COAST. THIS WILL BRING LESS OF A CHANCE FOR HEAVY RAIN VS THE GFS
WHICH KEEPS THE LOW MORE SOUTH THAT HELPS TO MAINTAIN A MORE SW
FLOW. WILL MAINTAIN SLIGHT CHANCE POPS FOR THE EXTENDED WITH
INCREASING TEMPERATURES INTO THE MID TO UPPER 80S WITH LOWER 90S
POSSIBLE BY SATURDAY.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 358 PM MDT SAT JUL 4 2015

VFR THROUGH SUNDAY. ISOLATED STORMS IN THE DENVER AREA THROUGH
EARLY EVENING WITH A SHORT PERIOD OF VARIABLE WINDS GUSTING TO 30
KNOTS LIKELY AT SOME POINT. MOST LIKELY DIRECTION FOR THE GUSTS
WILL BE FROM THE NORTHWEST. THERE WILL BE A BETTER CHANCE OF
THUNDERSTORMS LATE SUNDAY AFTERNOON...AND A HIGHER CHANCE OF
STRONG WINDS WITH THE STORMS.

&&

.HYDROLOGY...
ISSUED AT 358 PM MDT SAT JUL 4 2015

SOME OF TODAYS STORMS WILL PRODUCE HEAVY RAINFALL...BUT THEY WILL
BE MOVING WITH AMOUNTS UNDER A HALF INCH IN 30 MINUTES. THE
EXCEPTION WILL BE NEAR THE EASTERN COLORADO BORDER WHERE STORMS
WILL BE SLOWER MOVING AND COULD PRODUCE AN INCH OR TWO IN AN
HOUR. ON SUNDAY THERE WILL BE MORE MOISTURE IN THE ATMOSPHERE SO
THERE IS A GREATER THREAT OF HEAVY RAIN...BUT STORMS SHOULD BE
MOVING SO THE THREAT OF FLOODING STILL APPEARS LOW.

MONDAY AND TUESDAY THERE WILL BE MORE MOISTURE AND SLOWER MOVING
STORMS...THOUGH THE INSTABILITY WILL BE LIMITED. THESE DAYS WILL
BRING AN INCREASED THREAT OF FLOODING. MOISTURE WILL THEN DECREASE
FOR THE LATER PART OF THE WEEK.

&&

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

$$

SHORT TERM...GIMMESTAD
LONG TERM...BOWEN
AVIATION...GIMMESTAD
HYDROLOGY...GIMMESTAD


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