Area Forecast Discussion
Issued by NWS Grand Junction, CO

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KGJT 040553
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1153 PM MDT MON AUG 3 2015

.UPDATE...
ISSUED AT 819 PM MDT MON AUG 3 2015

CONVECTION ACROSS WESTERN COLORADO IS DISSIPATING. HOWEVER...AN
AREA OF INSTABILITY OVER EAST CENTRAL UTAH IS HOLDING TOGETHER
WHICH PRODUCED A COUPLE OF SEVERE THUNDERSTORMS WEST OF GOBLIN
VALLEY. THESE STORMS HAVE BEEN PULSING BUT ARE EXPECTED TO
DISSIPATE AND BECOME A LINE OF LIGHT RAIN WITH AN ISOLATED
EMBEDDED THUNDERSTORM WITHIN THE NEXT COUPLE OF HOURS AS IT HEADS
TOWARD CANYONLANDS...ARCHES NATIONAL PARK...AND CASTLE VALLEY.

&&

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 359 PM MDT MON AUG 3 2015

THE NATURE OF THE CONVECTION HAS CHANGED THIS AFTERNOON AS WE ADD A
BIT OF DRIER AIR AND STRONGER WINDS ALOFT. BRIEF HEAVY RAINFALL CAN
NOT BE RULED OUT BUT STORM MOVEMENT AND STRONGER UPDRAFTS SUGGEST
THE THREAT OF GUSTY OUTFLOW WINDS AND SMALL HAIL WILL BE MORE OF A
CONCERN THROUGH SUNSET. WATER VAPOR IMAGERY SHOWS A CLEAR PICTURE
OF WHAT IS HAPPENING THIS AFTERNOON AS A CYCLONE IS LIFTING
NORTHEAST OUT OF THE GREAT BASIN. THE MONSOON PLUME HAS BEEN
PUSHED EAST OF THE ROCKIES BY THE INFLUX OF STRONGER WESTERLY FLOW
WRAPPING INTO THE LOW. RESIDUAL LOW LEVEL MOISTURE AND THE DRY AIR
ALOFT IS EFFECTIVELY PRODUCING MODERATELY UNSTABLE CONDITIONS.
LOOKING UPSTREAM...THE NOSE OF A PACIFIC JET IS MOVING INTO
SOUTHERN NEVADA FORCING CONVECTION TO FIRE OVER EAST CENTRAL
PORTIONS OF THAT STATE. WITH THE LOSS OF HEATING THE SHOWERS
SHOULD EXHIBIT THE NORMAL DIURNAL DOWNTREND NEAR SUNSET. HOWEVER A
PORTION OF THE UPSTREAM JET WILL BE MOVING OVER OUR WESTERN CWA
OVERNIGHT AND OVER-RUNNING AN AREA OF RATHER STEEP LAPSE RATES AT
THE TOP OF THE EML. HAVE KEPT A MENTION OF ISOLATED STORMS PAST
MIDNIGHT IN OUR WEST THOUGH MUCH OF THIS MAY TURN OUT TO BE ACCAS.
HEATING WILL INCREASE IN THE DRIER AIRMASS ON TUESDAY AND HIGHS
SHOULD PUSH BACK TO NORMAL. EXPECT ANY RESIDUAL MOISTURE TO BE
LIFTED BY THE TERRAIN WINDS TO PRODUCE SOME RIDGETOP BUILDUPS.
ONLY ISOLATED STORMS ARE EXPECTED FROM THIS ACTIVITY AND FOCUSED
OVER OUR EASTERN MOUNTAINS. A QUICK DOWNTURN BY EVENING WILL LEAVE
A MAINLY CLEAR NIGHT IN PLACE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 359 PM MDT MON AUG 3 2015

THE ANOMALOUSLY STRONG LOW DOMINATING THE HUDSON BAY AREA
WILL BE EJECTED DOWNSTREAM BY ANOTHER STRONG SYSTEM DROPPING OUT
OF THE ARCTIC REGION DURING THE MID TO LATE WEEK PERIOD. THIS WILL
ALLOW THE DOWNSTREAM PATTERN OVER THE REMAINING PORTION OF NOAM TO
BECOME A BIT MORE PROGRESSIVE. IN THE BIG PICTURE THE SUB-TROPICAL
HIGH WILL BECOME RE-ESTABLISHED OVER THE SOUTHERN PLAINS BY WEEK/S
END WHERE IT WILL REMAIN THROUGH THIS FORECAST PERIOD. A QUICK
MOVING SYSTEM TO OUR NORTH WILL DRAG A BIT OF MOISTURE TO OUR
NORTHERN BORDER AND MAY LEAD TO A SLIGHT UPTICK IN THUNDERSTORM
ACTIVITY THURSDAY AFTERNOON BUT CONFIDENCE LOW ATTM. MORE CERTAIN
IS THE INFLUX OF MONSOON MOISTURE EARLY FRIDAY AS THE RIDGE AXIS
ALOFT SHIFTS EAST OF THE ROCKIES. A SIMILAR PATTERN TO WHAT IS
CURRENTLY HAPPENING IS THEN FORECAST TO OCCUR LATE SATURDAY WITH A
SYSTEM LIFTING NORTHWARD ACROSS THE GREAT BASIN. THIS LEAVES
SATURDAY SATURDAY AFTERNOON AS THE PERIOD MOST LIKELY FOR HEAVY
RAIN AND THUNDERSTORMS WITH THE ACTIVITY RAMPING UP FRIDAY
AFTERNOON AND DECREASING SUNDAY AS DRIER AIR SWEEPS IN.
TEMPERATURES LOOK TO COOL BELOW NORMAL WHEN THIS MOISTURE ARRIVES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1153 PM MDT MON AUG 3 2015

AN AREA OF SHOWERS AND THUNDERSTORMS STRETCHING FROM THE GRAND
MESA SOUTH-SOUTHWESTWARD TO NEAR MEXICAN HAT IN SOUTHEAST UTAH WILL
CONTINUE TO SWEEP EASTWARD AT 25 MPH THROUGH 10Z. THE MAIN THREAT
IS OUTFLOW WINDS TO 40 MPH ALONG WITH FREQUENT LIGHTNING. LIGHT TO
MODERATE RAINFALL MAY IMPACT KTEX...KMTJ AND KGUC DURING THIS
PERIOD. VFR AND MOSTLY SUNNY SKIES DOMINATE THE FORECAST FOR
TUESDAY.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

&&

$$

UPDATE...JAM
SHORT TERM...15
LONG TERM...15
AVIATION...NL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.