Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 032159
AFDGJT

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

.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 MOSITURE 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 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 359 PM MDT MON AUG 3 2015

KTEX...KASE AND KEGE HAVE THE MOST LIKELY CHANCE TO BE IMPACTED BY
PASSING THUNDERSTORMS FROM 03/22Z TO 04/02Z. ERRATIC AND GUSTY
OUTFLOW WINDS APPEAR THE BE THE MAIN THREAT TO AVIATION BUT SMALL
HAIL AND LIMITED VISIBILITY DUE TO PASSING RAIN SHOWERS CAN NOT BE
RULED OUT. AFTER SUNSET IMPROVEMENT SHOULD OCCUR RAPIDLY AS THE
STORMS WEAKEN AND DISSIPATE. DO NOT ANTICIPATE LOWER FLIGHT
CRITERIA OVERNIGHT BUT HEAVY RAINFALL NEAR THE TERMINALS COMBINED
WITH CLEARING SKIES TONIGHT MAY PRODUCE SOME LIGHT FOG BY
SUNRISE...HOWEVER CONFIDENCE EXTREMELY LOW. VFR AND MOSTLY SUNNY
SKIES DOMINATE THE FORECAST FOR TUESDAY.

&&

$$

SHORT TERM...15
LONG TERM...15
AVIATION...TGJT


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