Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 081758
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1158 AM MDT TUE JUL 8 2014

.UPDATE...
ISSUED AT 1155 AM MDT TUE JUL 8 2014

THIS FORECAST AREA IS BEING SQUEEZED BETWEEN THE DEEP MONSOONAL
MOISTURE TO THE SW AND THE RELATIVELY COOL AND MOIST AIR MASS ON
THE FRONT RANGE. THERE IS NO INDICATION THE FRONT RANGE AIR MASS
IS SIGNIFICANTLY LEAKING WEST OF THE DIVIDE. BUT THE BOUNDARY
ALONG THE DIVIDE WILL PROVIDE A FOCUS FOR AFTERNOON CONVECTION.
THE SW MOISTURE WILL CONTINUE TO SEEP INTO THE FOUR CORNERS
REGION. NO UPPER FORCING SEE TODAY. PWAT VALUES ARE LOWER THAN
MONDAY. THE MORNING SOUNDING INDICATES VALLEY CONVECTIVE TEMP IS
RIGHT NEAR MAX TEMP. 0-6KM STEERING WINDS ARE VERY LIGHT. SO
EXPECT THE FIRST THUNDERSTORMS TO FORM THIS EARLY AFTERNOON OVER
THE SOUTHERN MTNS WITH GUSTY WINDS MORE WIDESPREAD ACROSS THE
SOUTHERN AND CENTRAL VALLEYS INTO THE EARLY EVENING HOURS.
BOUNDARY INTERACTION COULD KEEP SOME CELLS GOING BEYOND SUNSET
AGAIN FAVORING THE SOUTH-CENTRAL ZONES.

MONSOONAL MOISTURE CONTINUES TO OOZE NORTHWARD FROM ARIZONA ON
WEDNESDAY. SOME FORCING SEEN IN THE AFTERNOON WITH A 300MB POT
VORT LOBE LAYING OVER ACROSS THE NORTH. THIS COULD PROVIDE A FOCUS
FOR ENHANCED AFTERNOON CONVECTION WITH ISOLATED TO SCATTERED
STORMS CONTINUING THROUGH WEDNESDAY NIGHT. VERY SLOW STORM
MOTION...NEAR ZERO IN THE FOUR CORNERS AREA...COMBINES WITH PWAT
VALUES AT 1.1 INCH OR MORE ACROSS THE SOUTH. STORMS WILL NOT BE
WELL ORGANIZED WITH LITTLE SHEAR TO SEPARATE THE UPDRAFT-
DOWNDRAFT. BUT ANY GOOD CELL MAY PRODUCE HEAVY RAIN AND THIS
RAISES FLASH FLOODING CONCERNS FOR AREAS SOUTH OF I-70 AND WEST OF
GLENWOOD SPRINGS.

DEEPER MOISTURE LINGERS THURSDAY AND FRIDAY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 407 AM MDT TUE JUL 8 2014

SFC FRONT DROPPING SOUTH ALONG THE FRONT RANGE DRIVING SOME LOW
AND MID LEVEL MOISTURE WESTWARD OVER THE DIVIDE...GENERALLY ACROSS
OUR CENTRAL AND SOUTHERN ZONES. INFLUX HAS BEEN SLOW AND
GRADUAL...BUT SFC SITES SHOWING SOME SIGNS AS DEW POINTS RUNNING
ROUGHLY 5 DEGREES HIGHER AT MOST SITES THIS MORNING VERSUS 24
HOURS AGO. AT THE SAME TIME...UPPER SUPPORT HELPING TO DRIVE THE
FRONT SOUTH WILL BUCKLE THE WESTERN RIDGE A BIT...ALLOWING IT TO
STAND UP MORE AND SLIDE A LITTLE BETTER SUPPORT IN THE WAY OF WEAK
SHEAR TO SUPPORT A FEW LONGER LIVED STORMS THIS AFTERNOON. BEST
CAPE AND LIFT WILL BE FOUND ACROSS THE SAN JUANS AND THE CENTRAL
MOUNTAINS...INCLUDING THE GRAND MESA. WILL HIT POPS A BIT HARDER
IN THESE AREAS THIS AFTERNOON...WITH PEAK CONVECTIVE PERIOD
ARRIVING AROUND 3 PM. SOUTHERN VALLEYS WILL HAVE THE BEST CHANCE
OF SEEING SHOWERS DRIFT OFF WITH CELL MOTION GENERALLY TO THE
SOUTH TODAY UNDER 15 MPH. PRECIPITABLE WATER VALUES EXPECTED TO
CONTINUE RISING TODAY...MAXING AROUND THREE QUARTERS ON AN INCH BY
THIS AFTERNOON...OR NEAR SEASONAL NORMS. THIS SHOULD RESULT IN
SOME WETTING RAINS WITH QPF VALUES IN EXCESS OF A TENTH OF AN INCH
ASSOCIATED WITH THE STRONGER CELLS. WITH SUBTLE INCREASE IN
MOISTURE AND CLOUD COVER...TEMPS MAY DROP A DEGREE OR TWO FROM
YESTERDAYS TEMPS...BUT STILL ON THE POSITIVE SIDE OF NORMAL.

SHOWERS AND THUNDERSTORMS WILL AGAIN WIND DOWN DURING THE EVENING
HOURS. HOWEVER DUE TO AN INCREASE IN MOISTURE...THERE SHOULD BE A
BETTER CHANCE OF CONVECTION PERSISTING THROUGH THE NIGHT...
FAVORING THE SOUTHERN HALF.

THE MOISTENING TREND WILL CONTINUE ON WEDNESDAY AS THE AXIS OF
THE HIGH PRESSURE RIDGE ROTATES TO A MORE SOUTH-NORTH ORIENTATION.
WHILE THE FLOW INTO OUR AREA WILL STILL NOT BE OPTIMAL...IT WILL
ALLOW THE SUBTROPICAL MOISTURE A BETTER ROUTE INTO OUR FORECAST
AREA. THEREFORE THE AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE
MORE ROBUST...AND WITH BETTER COVERAGE THAN SEEN EARLIER IN THE
WEEK. TEMPERATURES WILL RESPOND BY DROPPING A FEW DEGREES DUE TO
THE INCREASED CLOUDS/PRECIPITATION.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 407 AM MDT TUE JUL 8 2014

THE CURRENT MODEL RUNS INDICATE THAT THE PEAK IN MOISTURE WILL BE
FROM WED EVENING THROUGH EARLY THU UNDER A MORE SOUTHWEST FLOW.
THEREFORE THE CWA SHOULD SEE BETTER NOCTURNAL COVERAGE OF SHOWERS
AND THUNDERSTORMS...WITH SCATTERED ACTIVITY OVER THE MOUNTAINS
PERSISTING THROUGH THE NIGHT. AFTER A DOWNTURN IN CONVECTION LATE
WED NIGHT THROUGH THU MORNING...DAYTIME HEATING WILL AGAIN
ACTIVATE BETTER INSTABILITY AND THUS ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS. EXPECT THAT COVERAGE THU AFTERNOON WILL BE SIMILAR
TO WHAT DEVELOPED ON WED.

RIDGE AXIS SLIDES TO OUR EAST LATE IN THE WEEK...ALLOWING A LITTLE
DRIER AIR TO MOVE BACK IN...BUT NEVER REALLY SHUTS DOWN THE
DIURNAL CONVECTIVE ACTIVITY AS WE CONTINUE TO RECYCLE AVAILABLE
LOW LEVEL MOISTURE. RIDGE SHIFTS BACK TO THE WEST LATE IN THE
WEEKEND...WITH ANOTHER INCREASE IN CONVECTION EXPECTED IN WEAK
MONSOONAL PATTERN. ANOTHER SYSTEM DRIVES ACROSS THE PACNW AND
INTO THE NORTHERN ROCKIES EARLY NEXT WEEK. THIS MAY SWEEP WHAT
MOISTURE WE HAVE OUT OF THE REGION LATE MONDAY AND TUESDAY...WITH
DRIER AND WARMER CONDITIONS RETURNING. STILL SEVERAL DAYS OUT ON
THIS. OTHERWISE...EXPECT MORE OF THE SAME WITH AFTERNOON AND
EVENING CONVECTION EACH DAY...GENERALLY CONFINED TO THE HIGH
COUNTRY. TEMPERATURES LOOK FAIRLY FLAT THROUGH THE PERIOD...
RUNNING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1155 AM MDT TUE JUL 8 2014

HIGH PRESSURE CENTERED OVER THE GREAT BASIN WILL SLOWLY TRANSLATE
EAST OVER THE NEXT 36 HOURS. THIS WILL ALLOW DEEPER MOISTURE TO
OUR WEST TO SHIFT OVER WESTERN COLORADO LATE THIS AFTERNOON AND
INTO THE DAY ON WEDNESDAY. THIS WILL DRIVE MORE ACTIVE SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH ANOTHER ROUND
EXPECTED ON WEDNESDAY. ACTIVITY TODAY WILL LINGER THROUGH 06Z
TONIGHT. GUSTY WINDS TO 40 MPH THREATEN KDRO KTEX KCNY KMTJ KGJT
UNTIL 03Z. BRIEF HEAVY RAIN WILL BE CONFINED TO THE MTNS AND
POSSIBLY KTEX.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&

$$

UPDATE...JOE
SHORT TERM...JDC/EH
LONG TERM...EH/JDC
AVIATION...JDC


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