Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 072243
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
443 PM MDT TUE JUL 7 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 247 PM MDT TUE JUL 7 2015

REX BLOCKING OFF THE LEFT COAST AND A STUBBORN DOWNSTREAM TROUGH
OVER THE UPPER MIDWEST IS KEEPING WEAK ENERGY AND MOISTURE TRAPPED
OVER THE ROCKIES AND GREAT BASIN. BOTH OF THESE ARE COMBINING WITH
AFTERNOON INSTABILITY TO CREATE SLOW MOVING STORMS...SOME WITH SMALL
HAIL AND VERY HEAVY RAINFALL THIS AFTERNOON. THE NORTHERN STREAM
TROUGH OVER THE EAST BEGINS TO BREAK DOWN TOMORROW...LEADING TO A
SLOW TRANSFORMATION OF THE FLOW PATTERN GOING INTO THE LATE WEEK
PERIOD. THETA SURFACES NEAR 315K INDICATE THE VERY MOIST CONDITIONS
OVER THE WESTERN DESERTS WILL CONTINUE TO DRAW MOISTURE INTO THE
GREAT BASIN. THE MAIN LOW PRESSURE SYSTEM MOVING ONSHORE IN CENTRAL
CALIFORNIA WILL BE FORCING THE LAST IN A SERIES OF SHORT WAVE
TROUGHS ACROSS EASTERN UTAH LATE TONIGHT AND THEN COLORADO TOMORROW.
SKIES SHOULD REMAIN FAIRLY CLOUDY IN THIS MOIST ATMOSPHERE WITH
CONVECTIVE ACTIVITY WANING BUT NOT SHUTTING OFF OVERNIGHT. THE
SHOWERS SHOULD BE RE-INVIGORATED BY AFTERNOON INSTABILITY FROM
NORTHERN UTAH TO SOUTHEAST COLORADO AS POTENTIAL INSTABILITY
INCREASES. DRIER AIR WILL BE INVADING FORM THE SOUTHWEST BY
WEDNESDAY EVENING AS SHORT WAVE RIDGING BUILDS INTO THE 4 CORNERS
REGION. THIS DRY AIR OVER-RUNNING MOIST PBL CONDITIONS...WITH A
HINT OF A WARM FRONT ARCING FROM NORTHERN NEW MEXICO TO SOUTHERN
UTAH...SHOULD KEEP SOME CONVECTION FIRING INTO THE EVENING ACROSS
OUR WESTERN CWA AS SHOWERS SLOWLY EXIT THE NORTHEAST. CLOUD COVER
AND PRECIPITATION KEPT HIGHS QUITE COOL TODAY AND THIS TREND
CONTINUES FOR WEDNESDAY AND DID TREND BELOW GUIDANCE MOST AREAS.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 247 PM MDT TUE JUL 7 2015

FROM THURSDAY INTO EARLY NEXT WEEK THE DOMINATE FEATURE
IN THE CONUS WILL BE THE SUB-TROPICAL HIGH BUILDING OUT OF THE
SOUTHEAST STATES INTO THE SOUTHERN PLAINS. THE HIGH WILL BE STRONG
ENOUGH TO KEEP THE MAIN AREA OF LOW PRESSURE TO OUR WEST BEFORE IT
LIFTS OUT ACROSS THE NORTHERN ROCKIES BY WEEK/S END. SOUTHWEST FLOW
BETWEEN THESE FEATURES LATE WEEK WILL CAUSE SOME BREEZY AFTERNOON
CONDITIONS WHILE GENERALLY ADVECTING IN DRIER AIR. THE DOWNTURN IN
AFTERNOON CONVECTION WILL BE GRADUAL WITH MODELS CONTINUING TO
FIRE STORMS ACROSS THE WESTERN COLORADO TERRAIN THURSDAY INTO
FRIDAY AFTERNOONS. THIS COVERAGE WILL BE LESS THAN DAYS PAST AND
THE THREAT OF HEAVY RAINFALL DECREASING EACH DAY. MAINLY DRY
CONDITIONS ANTICIPATED BY SATURDAY WITH ONLY A STRAY STORM OR TWO
IN THE AFTERNOON HEATING. AS SUCH TEMPERATURES...THOUGH REMAINING
BELOW NORMAL...WILL GRADUALLY INCREASE EACH DAY THROUGH THE
WEEKEND. THE BIG QUESTION REMAINS...WHEN WILL THE MOISTURE RETURN.
THE IS HIGHLY DEPENDENT ON THE LOCATION WHERE THE SUBTROPICAL HIGH
CENTER SETTLES. THE EURO HAS THIS HIGH FARTHER SOUTH AND WEST
COMPARED TO THE GFS AND KEEPS AN OVERALL DRIER FORECAST INTO EARLY
NEXT WEEK AS THE MONSOON PLUME IS DIRECTED TO OUR WEST. THE GFS
TAPS THE MOISTURE BY SUNDAY AFTERNOON AND THE FORECAST IS
THEREFORE WETTER GOING INTO THE NEW WEEK. CONFIDENCE LOW IN EITHER
SOLUTION AT THIS POINT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 443 PM MDT TUE JUL 7 2015

PASSING SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A THREAT
FOR MOST OF THE NEXT 24 HOURS. THE COVERAGE OF THESE STORMS WILL
DECREASE DURING THE OVERNIGHT HOURS AND INCREASE ONCE AGAIN BY
AFTERNOON ON WEDNESDAY. THE AMOUNT OF MOISTURE IN THE AIR WILL
BE FAVORABLE FOR SOME OF THE RAINFALL TO BE HEAVY AT TIMES. THE
IMPACTS OF THIS WOULD BE LOWERED FLIGHT CRITERIA DUE TO VSBYS
LESS THAN 2 MILES. ERRATIC WIND GUSTS TO 40 MPH THIS EVENING AND
AGAIN WEDNESDAY AFTERNOON COULD ALSO IMPACT FLIGHT OPERATIONS.
OVERALL VFR CONDITIONS WILL PREVAIL BUT DUE TO THE NATURE OF THE
PRECIPITATION...CONFIDENCE IS LOW ON WHEN IMPACTS COULD AFFECT
FORECAST TERMINALS. WILL MONITORING RADAR AND SATELLITE TRENDS
AND AMENDING AS NECESSARY AND INCLUDE TEMPO WORDING IN MANY
AREAS FOR THE 00Z ISSUANCE.

&&

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

$$

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



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