Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 241148
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
548 AM MDT SUN MAY 24 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 350 AM MDT SUN MAY 24 2015

SATELLITE IMAGERY AND RADAR MOSAIC CLEARLY SHOWS AREA OF LOW
PRESSURE SPINNING OVER WESTERN COLORADO THIS MORNING AS IT LIFTS
TO THE NORTHEAST. SHOWERS WILL CONTINUE OVERNIGHT...MAYBE A FEW
RUMBLES OF THUNDER BUT BY AND LARGE MOST PRECIP WILL HAVE ENDED
EXCEPT FOR AREAS SOUTH. A STRONG VORT MAX IS ROTATING AROUND THE
LOW PRESSURE AND WILL MOVE ACROSS SOUTHERN LOCALES THIS MORNING
AFFECTING SOUTHERN VALLEYS AND ALSO THE SAN JUANS. AS THIS
OCCURS...COLD AIR IS ALSO MOVING OVER THE SAME AREA THANKS TO THE
COLD CORE NATURE OF THIS LOW PRESSURE. THE END RESULT...SNOW...1
TO 3 INCHES ABOVE TIMBERLINE. ONLY CONCERN ARE THE SHORT RANGE
MODELS...HRRR AND RAP...THAT WANT TO SHIFT THIS PRECIP A LITTLE
FURTHER SOUTH.

FOR MONDAY...THE LOW WILL HAVE DRIFTED TO THE NORTHEAST BUT WE`RE
STILL NOT OUT OF THE WOODS YET. WRAPAROUND FLOW WILL MOVE IN
BRINGING MORE UNSETTLED WX. AT DAYBREAK...FAR NRN AND SRN AREAS
WILL SEE BEST CHANCES FOR PRECIP. AS THE DAY PROGRESSES...THE REST
OF THE CWA WILL SEE SHOWERS AND STORMS FIRING FIRST OVER THE
HIGHEST TERRAIN BEFORE DROPPING INTO THE VALLEYS. LIKE SATURDAY
EVENING...MOST PRECIP WILL END BY 9PM THOUGH SOME ISOLATED SHOWERS
WILL CONTINUE. NEXT CONCERN SHIFTS TO THE PARK AND GORE RANGES AS
THE NAM...AND TO A LESSER EXTENT THE GFS...HIGHLIGHT THE
POSSIBILITY FOR SOME SNOW ABOVE 9500 FEET. ADVISORIES CERTAINLY
POSSIBLE AND MAY BE NEEDED BUT TO AVOID CONFUSION WITH GOING
HIGHLIGHTS...WILL HOLD OFF FOR NOW. TEMPS WILL CONTINUE TO BE WELL
BELOW NORMAL THOUGH A WARMUP IS IN STORE.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 350 AM MDT SUN MAY 24 2015

THE ACTIVE MAY PATTERN CONTINUES INTO THE LONG TERM PERIOD...BUT
THERE IS ONE SUBTLE CHANGE. THE DEEP CLOSED LOW CIRCULATION THAT
HAS IMPACTED THE CENTRAL ROCKIES REGION FOR THE PAST FEW DAYS WILL
HAVE MOVED DOWNSTREAM. THE ELONGATED OVAL SHAPED CIRCULATION
ALONG THE BRITISH COLUMBIA COAST DIGS INTO WASHINGTON STATE WITH A
TROUGH THAT EXTENDS INTO THE GREAT BASIN. DECENT MOISTURE TRANSPORT
WILL EXIST ACROSS UTAH INTO THE WRN SLOPE ON TUESDAY...YIELDING
ANOTHER ROUND OF CONVECTIVE SHOWERS/STORMS. THE UPSTREAM TROUGH
OVER THE PACIFIC NORTHWEST SAGS INTO NRN UTAH AND PHASES WITH A
SRN BRANCH CIRCULATION (CURRENTLY AROUND 31N/145W) BY THURSDAY.
FROM A DYNAMICAL POINT OF VIEW...THESE MID LEVEL CIRCULATIONS DO
NOT GENERATE MUCH IN THE WAY FOR QG ASCENT...THEREFORE CONDITIONAL
INSTABILITY AND CONVECTIVE POTENTIAL WILL BE THE PRIMARY DRIVERS
THAT GENERATE SHOWERS. MUCH THE PCPN WILL OCCUR DURING THE
AFTERNOON HOURS...ALTHOUGH SOME SHOWERS WILL LINGER THROUGH THE
NIGHT GIVEN RELATIVELY MOIST CONDITIONS AND THE CLOSE PROXIMITY
OF THE TROUGH.

BY SATURDAY...THIS TROUGH MOVES DOWNSTREAM AND MUCH OF THE REGION
MAY BE DRY WITH ABOVE NORMAL TEMPS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 548 AM MDT SUN MAY 24 2015

EXTENSIVE CLOUD COVER WILL COVER OR OBSCURE MOUNTAIN TOPS. A
REGION OF -SHRA/-RA OVER NE UTAH/NW COLORADO WILL REACH THE I70
CORRIDOR BETWEEN 16Z-20Z. EMBEDDED THUNDERSTORMS WITH SMALL HAIL
WILL BE POSSIBLE. CIGS BELOW ILS BREAKPOINTS WILL BE COMMON...
ESPECIALLY FOR THE MOUNTAIN TAF SITES.

SLOW IMPROVEMENT IS EXPECTED AFTER 02Z THIS EVENING BUT ILS CIGS
MAY PERSIST THROUGH THE FORECAST PERIOD.

&&

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

$$

SHORT TERM...TGR
LONG TERM...PF
AVIATION...PF



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