Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 201631
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1031 AM MDT SUN JUL 20 2014

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 308 AM MDT SUN JUL 20 2014

NO MAJOR CHANGES IN FORECAST THINKING AS THE NOSE OF A 60+KT JET
STREAK MOVES INTO THE 4 CORNERS REGION TODAY. THIS UPPER LEVEL
SUPPORT WILL ALLOW MORE WIDESPREAD CONVECTION TO FIRE WHILE ALSO
INCREASING MOISTURE CONTENT. GRAND JUNCTION RAOB SHOWED .46 INCHES
OF PWAT YESTERDAY EVENING WHICH THE NAM12 FORECAST FAIRLY WELL.
TODAY...THE NAM12 IS SHOWING AN INCREASE TO ABOUT .8 INCHES BY
THIS AFTERNOON SO 2 INGREDIENTS...LIFT FROM THE JET AND INCREASING
MOISTURE...ARE IN PLACE. LAPSE RATES DO BECOME STEEPER THIS
AFTERNOON WITH FORECAST SKEW-TS SHOWING CONDITIONAL INSTABILITY
ACROSS THE CWA SO WITH ALL 3 INGREDIENTS IN PLACE...STORMS AND
SHOWERS ARE A SOLID BET.  SOME SHEAR ALSO EXISTS WHICH WILL ALLOW
STORMS TO PERSIST A LITTLE LONGER THAN THE POP AND DROP WE`VE SEEN
OVER THE LAST FEW DAYS SO DO EXPECT SOME RAINSHOWERS AND
THUNDERSTORMS TO DRIFT INTO VALLEYS LATER IN THE DAY. HRRR REALLY
LIGHTING UP THE SAN JUANS WHICH IS ALSO FAVORED BY BOTH THE GFS
AND NAM SO HIGH POPS IN PLACE LOOK GOOD.

SHOWERS AND THUNDERSTORMS ARE NOT EXPECTED TO INITIATE AFTER
SUNSET...BUT WILL MAINTAIN ORGANIZATION THROUGH ABOUT MIDNIGHT
WITH THE 60KT JET STREAK AT H3 PLAYING A ROLE.

A WEDGE OF DRY AIR WILL MOVE INTO THE REGION ON MONDAY AS THE LOW
OFF OF THE COAST OF CALIFORNIA RETREATS WEST AND THE UPPER LEVEL
HIGH CAN SHIFT BACK OVER SOUTHERN COLORADO AND NORTHERN NEW MEXICO.
AS MENTIONED BY THE PREVIOUS FORECASTER...THIS IS USUALLY A GOOD
POSITION TO BE PULLING MONSOON MOISTURE TO THE 4 CORNERS...BUT
THE AMPLIFICATION OF THE RIDGE TO THE NORTH WILL BE SUPPRESSED BY
A DIP IN THE POLAR JET STREAM ACROSS THE NORTHERN US BORDER.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 235 AM MDT SUN JUL 20 2014

THIS JET RETREATS NORTHWEST ON TUESDAY AFTERNOON. SOUTHWEST FLOW
WILL PULL SUBTROPICAL MOISTURE BACK INTO SOUTHERN COLORADO
BEGINNING LATE TUESDAY.

THE CENTER OF HIGH PRESSURE WILL WOBBLE OVER OUR FORECAST AREA
FROM WEDNESDAY THROUGH SATURDAY WITH MOISTURE UNDER THE RIDGE RECYCLING
EACH DAY ALLOWING CONVECTION TO FIRE WEDNESDAY INTO THURSDAY.
AFTER THAT...A CLOSED LOW WILL MOVE ACROSS THE US/CANADIAN BORDER
FLATTENING THE HIGH PRESSURE OVER US. THIS FLATTENING WILL CAUSE
WINDS TO BECOME W TO NWLY AND LIMITING THE MEAGER AMTS OF MOISTURE
THAT WERE STREAMING UP FROM THE SOUTH. DUE TO THIS...FRIDAY AND
SATURDAY LOOK TO BE HOT AND DRY WITH LITTLE...IF ANY...PRECIP
EXPECTED.

TEMPERATURES WILL CONTINUE TO RUN HOT...ABOUT 5 DEGREES ABOVE
NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1031 AM MDT SUN JUL 20 2014

A SURGE OF MONSOON MOISTURE WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS TO THE REGION THROUGH 04Z/MON. THIS ACTIVITY WILL
FAVOR THE MOUNTAINS...THOUGH A NUMBER OF CELLS WILL DRIFT OVER
ADJACENT VALLEYS TO THE NORTHEAST. EXPECT AREAS OF MOUNTAIN
OBSCURATION AND STRONG OUTFLOW WINDS FROM 35 TO 45 MPH. TAF SITES
WILL MAINLY EXPERIENCE VFR CONDITIONS...THOUGH THERE IS A 30 TO 40
PERCENT CHANCE STORMS WILL PASS OVERHEAD. STRONGER CELLS COULD
RESULT IN MVFR VSBY IN HEAVY RAIN.

LATER TONIGHT THUNDERSTORM ACTIVITY DIES OFF WITH DRIER AIR
FILTERING OVER THE AREA MONDAY...ESPECIALLY NORTH. AS A
RESULT...EXPECT JUST A FEW STORMS OVER THE SOUTHERN MOUNTAINS
DURING THE AFTERNOON WITH LITTLE CHANCE THAT TAF SITES WILL BE
IMPACTED.

&&

.FIRE WEATHER...
ISSUED AT 308 AM MDT SUN JUL 20 2014

AN APPROACHING UPPER LEVEL DISTURBANCE WILL MOVE OVER UT/CO TODAY
AND MONDAY WITH THE STRONGEST WINDS MOVING OVER MONDAY...ESPECIALLY
FOR NORTHERN PORTIONS OF COLORADO. DEEP MIXING IS FORECAST TO REACH
500MB OR SO ALLOWING SFC WINDS TO REACH 20 KTS WITH OCCASIONAL
GUSTS TO 30 KTS. ALONG WITH THE WINDS...SFC RH`S WILL BE BETWEEN
10 TO 15 PERCENT AS DRY AIR REMAINS ACROSS THE AREA. THIS
COMBINATION WILL CAUSE CRITICAL FIRE WEATHER CONDITIONS FOR CO
FIRE ZONE 200. TO THAT END...WILL ISSUE A FIRE WEATHER WATCH FOR
THAT ZONE ON MONDAY FROM NOON TO 8PM.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR COZ200.

UT...NONE.
&&

$$

SHORT TERM...TGR/JAM
LONG TERM...JAM/TGR
AVIATION...NL
FIRE WEATHER...TGR



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