Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 052003
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
203 PM MDT SAT JUL 5 2014

.UPDATE...
ISSUED AT 201 PM MDT SAT JUL 5 2014

UPDATING TO INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THE
REST OF THIS AFTERNOON AND EVENING OVER THE PLATEAUS AND MTS OF NW
CO...PARTICULARLY THE TAVAPUTS AND ROAN.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 421 AM MDT SAT JUL 5 2014

A FEW SHOWERS LINGERED EARLY THIS MORNING OVER EAST-CENTRAL UTAH
AND THE WESTERN FLANKS OF THE SAN JUAN MOUNTAINS OF SOUTHWEST
COLORADO. IF CURRENT TRENDS HOLD THIS ACTIVITY SHOULD DISSIPATE BY
SUNRISE. MOVEMENT OF SHOWERS INDICATIVE OF THE COMPLICATED
PATTERN OF HIGH PRESSURE OVER THE REGION. TO THE SOUTHEAST...HIGH
PRESSURE OVER THE PANHANDLE REGION WAS MOVING SHOWERS SLOWLY NORTH
OVER SOUTHWEST COLORADO. MEANWHILE...A SMALLER CENTER OF HIGH
PRESSURE OVER THE WESTERN GREAT BASIN WAS DRIVING LIGHT SHOWERS TO
THE SOUTH ACROSS THE EASTERN TAVAPUTS PLATEAU.

AS THE DAY PROGRESSES HIGH PRESSURE OVER THE WESTERN GREAT BASIN
WILL EXPAND EASTWARD OVER NORTHERN UTAH AND NORTHWEST COLORADO.
IN RESPONSE...STEERING WINDS WILL SHIFT TO A NORTH TO NORTHEAST
DIRECTION. HOWEVER...LITTLE WIND OR SHEAR IN THE COLUMN SO
DIURNALLY DRIVEN STORMS WILL BE OF THE SLOW MOVING AND SHORT-
LIVED VARIETY. DEEPER MOISTURE AVAILABLE ACROSS THE FOUR CORNERS
REGION SO EXPECT GREATER STORM COVERAGE ALONG WITH BRIEF
LOCALIZED HEAVY RAIN. FEWER STORMS EXPECTED NORTH WHERE MOISTURE
ALMOST HALF OF WHAT/S AVAILABLE TO THE SOUTH. DYNAMIC FORCING
CLEARLY LIMITED IN THIS LOW FLOW REGIME SO EXPECT STORMS TO BE
ANCHORED TO THE HIGHER TERRAIN FROM LATE MORNING THROUGH THE
AFTERNOON.

TEMPERATURES LARGELY UNCHANGED FOR MUCH OF THE AREA TODAY THOUGH
AN INCREASE OF ROUGHLY 0.1 INCH PRECIPITABLE WATER ACROSS THE
SOUTH SHOULD YIELD A FEW DEGREES OF COOLING.

THE FLOW WILL REMAIN VERY LIGHT THROUGH SUNDAY AND BEYOND AS HIGH
PRESSURE DOMINATES THE REGION. FOR OUR FORECAST AREA...THIS FLOW
DOES TAKE ON A MORE NORTHERLY COMPONENT OVERNIGHT...THEN NORTHEAST
TO EAST ON SUNDAY AS THE CENTER OF THE 700MB ANTICYCLONIC
CIRCULATION SHIFTS UP OVER NORTHWEST UT. THIS WILL TYPICALLY BE A
DRIER FLOW...HOWEVER SINCE IT REMAINS VERY LIGHT...IT WILL ONLY
GRADUALLY ERODE THE MOISTURE FROM THE NORTH TO THE SOUTH.

TODAY`S AFTERNOON CONVECTION WILL DIMINISH AFTER THE LOSS OF
DAYTIME HEATING THIS EVENING. SOME SHOWERS/THUNDERSTORMS WILL
PERSIST AS OUTFLOW BOUNDARIES FROM EARLIER CONVECTION CONTINUE TO
INTERACT. THEN AFTER MIDNIGHT...ISOLATED NOCTURNAL STORMS WILL BE
POSSIBLE...MAINLY ALONG THE SOUTHERN EDGE. CONVECTION WILL AGAIN
DEVELOP SUNDAY AFTERNOON INITIALLY OVER THE MOUNTAINS...THEN
SPREAD INTO SOME VALLEYS AS WELL. THE SOUTHERN HALF...ESPECIALLY
THE SAN JUAN AND ABAJO MOUNTAINS WILL CONTINUE TO BE FAVORED DUE
TO THE BETTER MOISTURE THERE.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 421 AM MDT SAT JUL 5 2014

NOT EXPECTING MUCH CHANGE THROUGH MONDAY AS VERY LIGHT FLOW REMAINS
OVER THE REGION...AND MOISTURE LINGERS UNDER THE DOMINATING RIDGE.
THEREFORE THE DAILY ROUND OF SHOWERS AND THUNDERSTORMS WILL AGAIN
DEVELOP MONDAY AFTERNOON. CONVECTION WILL INITIATE OVER THE
MOUNTAINS...WITH ACTIVITY SPREADING INTO THE SOME OF THE VALLEYS
BY LATE AFTERNOON. THE SOUTHERN PORTION WILL CONTINUE TO BE
FAVORED.

THE RIDGE AXIS EXTENDING FROM THE PANHANDLE NORTHWESTWARD INTO THE
GREAT BASIN WILL CONTINUE TO KEEP THE NORTH FAIRLY DRY WHILE
MOISTURE LINGERS OVER THE SOUTH THROUGH MIDWEEK. AS A RESULT...
DIURNAL STORMS WILL CONTINUE TO FAVOR THE SOUTHERN MOUNTAINS. LATE
IN THE WEEK A SHORTWAVE TROUGH MOVING ACROSS THE NORTHERN ROCKIES
WILL FORCE HIGH PRESSURE TO SHIFT TO THE EAST OPENING THE WAY FOR
A SURGE OF SUBTROPICAL MOISTURE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1034 AM MDT SAT JUL 5 2014

DAYTIME HEATING WILL BRING ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS FROM 18Z THROUGH ABOUT 02Z. NORTH OF ROAN AND
TAVAPUTS PLATEAUS THE STORMS SHOULD BE ISOLATED AND CONFINED TO
THE MOUNTAINS STORMS. FROM THE TAVAPUTS AND ROAN SOUTH...SCATTERED
STORMS SHOULD FORM OVER THE MOUNTAINS WITH ISOLATED STORM OVER THE
LOWER ELEVATIONS. EXPECT AREAS OF MOUNTAIN OBSCURATION ALONG WITH
OUTFLOW WINDS TO 35 MPH. DESPITE SHOWER ACTIVITY...VFR CONDITIONS
WILL CONTINUE OVER AREA TAF SITES THROUGH THE NEXT 24 HOURS...WITH
TAF SITES SOUTH OF INTERSTATE 70 HAVING ABOUT A 15 PERCENT CHANCE
OF A THUNDERSTORMS AFFECTED THOSE AIRPORTS.


&&

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

$$

UPDATE...CC
SHORT TERM...NL/EH
LONG TERM...EH/NL
AVIATION...CC


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