Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 010545
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1145 PM MDT FRI JUL 31 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 354 PM MDT FRI JUL 31 2015

TONIGHT...
THE TONGUE OF DEEP SUBTROPICAL MOISTURE WILL REMAIN POSITIONED
OVER AZ/NM TO THE EASTERN SIDE OF THE COLORADO ROCKIES. SOME OF
THIS DEEPER MOISTURE WILL EXTEND ACROSS OUR SOUTHERN BORDER AND
ACROSS THE SAN JUAN AND ABAJO MOUNTAINS...AND ALONG OUR EASTERN
EDGE NORTHWARD TO AROUND THE CENTRAL MOUNTAINS. MUCH DRIER AIR
COVERS THE NORTHERN PORTION OF THE FORECAST AREA WITH A STRONG
MOISTURE GRADIENT BETWEEN THE TWO. THEREFORE EXPECT SHOWERS AND
THUNDERSTORMS TO CONTINUE TO INCREASE LATE THIS AFTERNOON OVER THE
WETTER AREAS OF THE FORECAST AREA...ROUGHLY SOUTH OF A LINE FROM
THE ASPEN/VAIL PASS AREAS SOUTHWEST TO PAGE AZ. ALSO AN AREA OF
THUNDERSTORMS OVER NORTHWEST NM LOOKS LIKE IT WILL MOVE INTO
SOUTHWEST CO LATE THIS AFTERNOON. GOOD CONVECTION WILL CONTINUE
INTO THE EARLY EVENING WITH COVERAGE OVER SOME VALLEYS INCREASING
FOR A SPELL. AFTER SUNSET...MOST ACTIVITY WILL DIMINISH AND WILL
BECOME MORE SHOWERY (LESS THUNDERY) BY MIDNIGHT. A FEW NOCTURNAL
STORMS WILL BE POSSIBLE OVER THIS WETTER PORTION OF THE AREA.
NIGHTTIME TEMPERATURES WILL REMAIN BELOW NORMAL IN THE DRIER AIR
OVER THE NORTH...AND AROUND NORMAL UNDER THE MORE MOIST AIR MASS
TO THE SOUTH.

SATURDAY AND SATURDAY NIGHT...
NOT MUCH DIFFERENT THINKING FROM PREVIOUS PACKAGE...STILL
EXPECTING SLOW NORTHWARD MOVEMENT OF MID LEVEL MOISTURE A LITTLE
FURTHER INTO CENTRAL PORTION OF THE CWA ON SATURDAY. THEN
EMBEDDED DISTURBANCE IN SOUTHERLY FLOW EXPECTED TO BEGIN MOVING
NORTHWARD AND HELPING TO DRAW THE MOISTURE INTO THE NORTHERN
PORTION OF OUR CWA SATURDAY NIGHT. SO EXPECT LINGERING SHOWERS AND
ISOLATED THUNDERSTORMS SATURDAY NIGHT MAINLY SOUTHERN PORTION OF
OUR CWA. WITH INCREASING CLOUDS SATURDAY NIGHT...MIN TEMPERATURES
SHOULD BE SIGNIFICANTLY MILDER THAN TONIGHT. RAISED MIN
TEMPERATURES IN MOST ZONES FOR SATURDAY NIGHT...AND IN SOME ZONES
THEY MAY NEED TO RAISED EVEN A LITTLE HIGHER.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 354 PM MDT FRI JUL 31 2015

SUNDAY AND SUNDAY NIGHT...
SUNDAY THROUGH SUNDAY EVENING SHOULD BE A RATHER ACTIVE TIME FOR
CONVECTIVE DEVELOPMENT ACROSS OUR CWA...WITH COMBINATION OF
DAYTIME HEATING AND DYNAMIC LIFT...ALONG WITH MORE LOW LEVEL
MOISTURE. PRECIPITABLE WATER VALUES RISE SIGNIFICANTLY DURING THIS
TIME PERIOD...GENERALLY RANGING FROM NEAR 0.75 TO 1.25 OF AN INCH.
STORMS WILL LIKELY BE MOVING RELATIVELY SLOWLY...LIKELY IN THE 10
TO 15 KNOT RANGE...AND THUS WE WILL LIKELY BE DEALING WITH
SOME FLASH FLOODING CONCERNS.

MONDAY THROUGH THURSDAY NIGHT...
DRIER AIR MOVES INTO OUR CWA BY EARLY MONDAY...IN THE WAKE OF THE
SHORTWAVE DISTURBANCE. SIGNIFICANT DOWNTURN IN SHOWERS AND
THUNDERSTORMS THAT SHOULD CONTINUE DURING THIS PERIOD TO THE NORTH
OF AN E-W ELONGATED UPPER HIGH THAT WILL LEAVE OUR CWA UNDER A
DRIER WESTERLY FLOW ALOFT. CONSEQUENTLY...MAX TEMPERATURES WILL
REBOUND. RAISED MAX TEMPS ABOUT 5 DEGREES F FROM PREVIOUS GRIDS
ON MONDAY FOR MUCH OF OUR CWA. AND MAX TEMPERATURES TUESDAY MAY
YET BE A TAD TOO COOL.

FRIDAY...
NOW LOOKS LIKE NEXT SURGE OF MOISTURE FROM THE SOUTH WILL WAIT
UNTIL FRIDAY TO BEGIN SPREADING INTO OUR CWA...AS UPPER HIGH
CENTER SHIFTS A LITTLE FURTHER EAST AND THE FLOW AROUND THE UPPER
HIGH BECOMES MORE CONSOLIDATED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1145 PM MDT FRI JUL 31 2015

ISOLATED -SHRA/-TSRA WILL PREVAIL OVER SW COLORADO OVERNIGHT.
CONVECTIVE STORMS WILL DEVELOP OVER THE HIGHER TERRAIN AFTER 17Z
SATURDAY MORNING...GRADUALLY EXPANDING ACROSS SW COLORADO AND SE
UTAH...INCLUDING POPULATED VALLEYS AND NEARBY TAF SITES. LOCAL
+SHRA AND G30KTS WILL BE POSSIBLE WITH THE STRONGEST CELLS.
PASSING SHOWERS AND STORMS WILL RESULT IN ILS CIGS FOR MOUNTAIN
TAF SITES.

SHRA/TSRA WILL BE SLOW WANE AFTER 02Z SATURDAY EVENING AND EXPECT
ISOLATED STORMS TO LINGER WELL BEYOND 06Z.

NE UTAH AND A THE NW COLORADO CORNER WILL STAY DRY THROUGH THIS
FORECAST PERIOD.

&&

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

$$

SHORT TERM...EH/JRP
LONG TERM...JRP
AVIATION...PF


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