Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 271649
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1049 AM MDT WED MAY 27 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 352 AM MDT WED MAY 27 2015

THE SOUTHERN TROUGH WILL WORK INTO AZ TODAY AND WHILE REMAINING
SLIGHTLY AHEAD...IT WILL PHASE WITH THE IDAHO LOW FOR A BROAD TROUGH
OVER THE GREAT BASIN. WHILE IT APPEARS THAT MOISTURE WILL DECREASE A
LITTLE...SLIGHTLY LOWER PRECIPITABLE WATER AND DEW POINTS...WE WILL
STILL SEE ANOTHER ROUND OF AFTERNOON CONVECTION. HOWEVER COVERAGE
WILL PROBABLY BE A LITTLE LESS. THEN THE REMNANTS OF THE SOUTHERN
LOW...IN THE FORM OF A WEAK SHORTWAVE EJECTING FROM THE BASE OF THE
TROUGH...WILL PASS OVER OUR FORECAST AREA LATE TONIGHT. IN ADDITION
A WEAK COOL FRONT WILL WORK THROUGH THE FORECAST AREA FROM THE
NORTHWEST. THIS COMBINATION...ALONG WITH A STILL MOIST AIR MASS WILL
ALLOW SOME SHOWERS AND STORMS TO PERSIST BEYOND MIDNIGHT.

THE GREAT BASIN TROUGH...DOMINATED BY THE NORTHERN BRANCH LOW...WILL
APPROACH ON THU WITH THE TROUGH AXIS REACHING OUR NORTHWEST CORNER
LATE THU AFTERNOON/EARLY EVENING. A WEAK-MODERATE UPPER LEVEL JET
CORE ALSO APPROACHES DURING THE AFTERNOON PROVIDING SOME SUPPORT.
MOISTURE REMAINS DEEP FOR LATE MAY...AROUND 0.5 INCH PRECIPITABLE
WATER. THURSDAY AFTERNOON WILL HAVE SLIGHTLY INCREASED INSTABILITY
WITH SUBTLE COOL ADVECTION ALOFT...ESPECIALLY NORTH OF I-70.
THEREFORE LOOK FOR CONTINUED SHOWERS AND THUNDERSTORMS...
INCREASING AND STRENGTHENING IN THE AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 352 AM MDT WED MAY 27 2015

THE TROUGH OVER THE GREAT BASIN AND NORTHERN ROCKIES WILL MOVE
THROUGH THE FORECAST AREA THU NIGHT THRU FRI. DYNAMIC SUPPORT FOR
DEEP CONVECTION WILL SLIDE EAST OF THE AREA EARLY THU EVENING...
THEN DRIER AIR WILL BEGIN BUILDING INTO THE AREA FROM THE SW.
BELIEVE CLOUDS AND SHOWERS WILL REMAIN OVER THE NORTHERN CO MTS
THRU THE NIGHT AND THROUGHOUT FRIDAY AS ANOTHER SECONDARY
SHORTWAVE SLIPS IN BEHIND THE MAIN TROUGH. THE SURFACE COLD FRONT
SHOULD BACK UP ALONG THE FRONT RANGE AND PUSH A LITTLE WEST SUCH
THAT SHOWERS WILL REMAIN POSSIBLE ALONG THE CONTINENTAL DIVIDE
THRU FRI NIGHT. SOME RETURN FLOW FROM THE SE MAY KEEP CLOUDS AND
PRECIP OVER THE EASTERN PORTIONS OF THE SAN JUANS AND THE LOWER
ELEVATIONS OVER ARCHULETA COUNTY SAT AND SAT NIGHT. MONDAY AND
TUESDAY BOTH LOOK DRY AND WARMER WITH THE EXCEPTION OF A CHC OF
AFTERNOON AND EVENING SHOWERS/TSTMS IN THE RESIDUAL MOISTURE ALONG
THE CONTINENTAL DIVIDE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1049 AM MDT WED MAY 27 2015

A SHORT BREAK IN THE SHOWER AND THUNDERSTORM ACTIVITY THIS MORNING
IS LEAVING VFR CONDITIONS ACROSS THE FORECAST TERMINALS. HOWEVER
SOME CLOUD COVER HUGGING THE DIVIDE PEAKS ARE LEADING TO AREAS OF
TERRAIN OBSCURATION. AFTERNOON HEATING AND PLENTY OF REMAINING
MOISTURE WILL AGAIN LEAD TO SCATTERED AFTERNOON SHOWERS WITH
EMBEDDED THUNDERSTORMS. EXACT TIMING IS DIFFICULT BUT 27/20Z TO
28/04Z WILL BE THE PERIOD OF THE MOST ACTIVITY. THE MAIN THREATS
WILL BE GUSTY...ERRATIC WINDS AND LIGHTNING. FLIGHT CRITERIA COULD
BE TEMPORARILY DECREASED BY SHOWERS PASSING OVER THE FLIGHT
TERMINALS. SHOWERS WILL REMAIN OVER NORTHERN UTAH AND COLORADO
OVERNIGHT...OTHERWISE CLEARING IS EXPECTED ELSEWHERE.

&&

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

$$

SHORT TERM...EH
LONG TERM...CC
AVIATION...TGJT


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