Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 220524
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1124 PM MDT TUE APR 21 2015

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 327 PM MDT TUE APR 21 2015

A CLOSED LOW AT H7 OVER SOCAL WILL SPIN SOME ENERGY TOWARD THE 4
CORNERS TONIGHT. ISOLATED SHOWERS AND THUNDERSTORMS OVER THE
MOUNTAINS THIS EVENING WILL TAPER OFF AROUND SUNSET AS DIURNAL
HEATING CEASES...BUT A FEW SHOWERS MAY PERSIST OVER THE HIGHER
TERRAIN OF SOUTHEAST UTAH THROUGH THE NIGHT.

SHORT WAVE ROTATING NORTHWARD AHEAD OF SRN CALIF CLOSED LOW
CIRCULATION GETS STRETCHED. MODEL DATA SHOWING SHOWERS WITH
ISOLATED THUNDERSTORMS WILL FORM IN THE AREA OF DIVERGENCE...WITH
THE HIGHEST CHANCE OVER THE SAN JUAN MOUNTAINS. THESE SHOWERS WILL
MOVE NNE AND SPREAD INTO THE NRN HALF AS THE DAY PROGRESSES.
THE MAJORITY OF THE SCATTERED EVENING SHOWERS ARE EXPECTED TO BE
ALONG AND NORTH OF I70 BY EVENING BEFORE DIMINISHING OVERNIGHT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 327 PM MDT TUE APR 21 2015

DRIER AIR IS EXPECTED TO SPREAD ACROSS THE FORECAST AREA ON
THURSDAY...BUT SURFACE HEATING AND CONDITIONAL AFTERNOON INSTABILITY
SHOULD RESULT IN SCATTERED SHOWERS/ISOLATED STORMS. THE SAN
JUAN/ELK MOUNTAINS STAND THE BEST CHANCE OF SHOWERS GIVEN THE
PROXIMITY OF UPPER LEVEL JET AND BETTER GRADIENT FLOW FOR
OROGRAPHIC LIFT. LESS CONVECTIVE ACTIVITY IS EXPECTED WEST OF THE
COLORADO HIGH COUNTRY (WITH THE EXCEPTION OF THE ERN UINTA
MOUNTAINS).

CLOSED LOW EJECTS MAINLY EASTWARD AND BECOMES AN OPEN WAVE IN THE
PROCESS THURSDAY NIGHT AND FRIDAY. WINDS ALOFT VEER AND BECOME
NWLY. ANOTHER ROUND OF DIURNALLY DRIVEN AFTERNOON
SHOWERS/ISOLATED STORMS ARE EXPECTED AGAIN ACROSS THE ENTIRE
FORECAST AREA. THIS SCENARIO REPEATS ITSELF ON SATURDAY AS A
TROUGH AXIS CROSSES THE CENTRAL ROCKIES.

A DRYING TREND BEGINS ON SUNDAY AS RIDGE BUILDS ACROSS THE
INTERIOR WEST...ALTHOUGH THE THREAT OF DIURNAL SHOWERS/STORMS
CONTINUES OVER THE COLORADO HIGH COUNTRY. BY MONDAY AND
TUESDAY...WARMING TREND WITH CLEARER CONDITIONS ARE EXPECTED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1119 PM MDT TUE APR 21 2015

SOME HIGH CLOUDS MOVING OVERHEAD TONIGHT POSING NO THREAT TO
AVIATION. A DISTURBANCE IS MOVING UP FROM THE SOUTH THOUGH WHICH
WILL INCREASE CLOUD COVER DOWN SOUTH IN THE NEXT FEW HOURS. THIS
DISTURBANCE WILL ALSO AID IN CONVECTIVE DEVELOPMENT THIS AFTERNOON
STARTING FROM 18Z ONWARDS WITH BEST CHANCES AFTER 21Z. INCLUDED
VCSH AND VCTS TO A FEW TAF SITES FOR THIS AFTERNOON THROUGH THE
EVENING HOURS WITH MOST DEVELOPMENT DYING DOWN QUICKLY AFTER
SUNSET. NO MENTION OF FLIGHT CONDITIONS BELOW VFR IN TAFS THOUGH
POSSIBILITY DOES EXIST IF ANY AERODROMES GET A STORM OR SHOWER
OVERHEAD. CONFIDENCE NOT HIGH ATTM SO LEFT OUT OF TAFS FOR NOW.
SOME GUSTY WINDS OF 35 MPH ALSO POSSIBLE UNDER THE STRONGER
STORMS/SHOWERS.

&&

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

$$

SHORT TERM...JAM/PF
LONG TERM...PF
AVIATION...TGR


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