Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 232145
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
345 PM MDT SAT MAY 23 2015

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 344 PM MDT SAT MAY 23 2015

THE UPPER LOW CENTER WILL SLOWLY TRACK FROM WEST TO EAST ACROSS
THE CENTRAL PORTION OF THE FORECAST AREA LATE THIS AFTERNOON
THROUGH TONIGHT. AS A RESULT...MOISTURE AND DYNAMICS WILL BE
PLENTIFUL THROUGHOUT THE NIGHT FOR CONTINUED PRECIPITATION. EXPECT
GOOD THUNDERSTORM COVERAGE DURING THE EVENING...THEN SHOWERS WILL
BECOME LESS CONVECTIVE LATE TONIGHT. MODELS AGREE THAT THE
SOUTHERN PORTION WILL BE FAVORED THROUGH TONIGHT WHILE WE STILL
HAVE A SOUTHERLY COMPONENT TO THE FLOW. AND THE COLDER AIR WILL
BE IN CLOSE PROXIMITY...AND JUST SOUTH OF THE LOW. THAT SAID ALL
AREAS WILL SEE AT LEAST SCATTERED SHOWERS/EVENING THUNDERSTORMS
AS WELL. EXPECT ACCUMULATING SNOW ABOVE 9000 FT...ESPECIALLY OVER
THE SAN JUAN MOUNTAINS WHERE A SNOW ADVISORY HAS BEEN HOISTED FOR
DIFFICULT OVERNIGHT TRAVEL ACROSS THE PASSES. PASSES OVER OTHER
MOUNTAINS MAY ALSO SEE SOME SNOW...BUT SO NOT EXPECT THIS TO
IMPACT TRAVEL EXCEPT POSSIBLY FOR SHORTER TIME PERIODS LATE
TONIGHT.

THE 300-305K THETA SURFACES SHOW A CONTINUAL FEED OF WRAP AROUND
MOISTURE BETWEEN THE TWO CIRCULATIONS OVER THE SOUTHEAST WYOMING
AND WESTERN COLORADO. QG FORCING AND INSTABILITY IS ON THE DOWNTURN
BY SUNRISE ON SUNDAY...AND THE NORTHWEST OROGRAPHICS ARE NOT
PARTICULARLY STRONG. THERMAL PROFILES SUGGEST SNOW WILL BE THE
PRIMARY PTYPE ABOVE 9500 FEET BUT CAN NOT SEE HOW THIS WILL BE AN
IMPACT ONCE THE SUN COMES OUT. HEATING OF THE DAY WILL LIKELY
INITIATE CONVECTION IN THE AFTERNOON BUT MODELS ARE SUGGESTING THIS
WILL BE MORE FOCUSED ON THE TERRAIN. RESIDUAL MOISTURE PROMISES SOME
OF THESE SHOWERS WORKING DOWN TO THE VALLEYS BUT POPS WILL REMAIN
HIGHEST ON THE HILLS. TEMPERATURES WILL MAKE A PUSH UPWARD BUT STILL
REMAIN AROUND 10 DEGREES BELOW NORMAL FOR LATE MAY. AN UPSTREAM WAVE
MAKING IT/S WAY FROM DOWN FROM THE NORTHERN ROCKIES WILL ADD SOME
ASCENT TO OUR NORTHERN CWA TOWARD SUNRISE ON MONDAY. WILL KEEP SOME
HIGHER POPS THERE BUT OTHERWISE THERE WILL BE A NOTICEABLE DOWNTURN
TO THE PRECIPITATION SUNDAY NIGHT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 344 PM MDT SAT MAY 23 2015

A KICKER SYSTEM WILL ARRIVE TO THE PACIFIC NORTHWEST ON MONDAY AND
FORCE THIS SYSTEM OUT ONTO THE NORTHERN PLAINS. THE TRANSITORY WAVE
ENTERING OUR CWA IN THE MORNING WILL PROVIDE THE SPARK NEEDED FOR
ANOTHER DECENT COVERAGE OF SHOWERS AND THUNDERSTORMS MONDAY
AFTERNOON THOUGH INSTABILITY IS ONLY MARGINAL. BRIEF SHORT WAVE
RIDGING THEN MOVES ACROSS OUR CWA TUESDAY AND BRING WHAT APPEARS TO
BE THE DRIEST DAY IN THE PAST WEEK. THE KICKER WAVE OVER THE
NORTHWEST WILL BE JOINED BY EASTERN PACIFIC ENERGY AND CARVE OUT A
MORE DEFINED TROUGH OVER THE WESTERN STATES. THE ONLY DIFFERENCE
FROM THE PAST FEW WEEKS IS THERE IS NOT A WELL DEFINED LOW
DEVELOPING IN THIS TROUGH. RATHER OUR CWA WILL BE UNDER A PROLONGED
PERIOD OF MOIST SOUTHWEST FLOW ALLOWING MAINLY DIURNAL SHOWERS AND
STORMS TO FORM AND FAVOR THE HIGHER TERRAIN. TEMPERATURES WILL
RESPOND ACCORDINGLY AND WE SHOULD BACK TOWARD NORMAL READINGS BY
WEEK/S END. THE MODELS ARE STILL TRYING TO PROMISE A RIDGE ACROSS
THE WEST BY NEXT WEEKEND WHICH WOULD BRING A DRIER AND WARMER CLOSE
TO MAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1057 AM MDT SAT MAY 23 2015

SHOWERS AND THUNDERSTORMS WILL BECOME WIDESPREAD THIS AFTERNOON AS
AN UPPER LEVEL DISTURBANCE MOVES DIRECTLY OVERHEAD. PASSING
SHOWERS/THUNDERSTORMS WILL LOWER CIGS TO BELOW ILS BREAKPOINTS
FOR THE MOUNTAIN SKI COUNTRY TAF SITES. EVEN AT VALLEY TAF SITES
LOCALIZED AND BRIEF +TSRA COULD LOWER VIS INTO THE 3-5SM RANGE.
MOUNTAIN TOPS WILL BE OBSCURED AT TIMES. SHOWERS/THUNDERSTORMS
WILL DECREASE IN AREAL COVERAGE AFTER 03Z...BUT EXPECT SCATTERED
COVERAGE TO PERSIST THROUGH SUNDAY MORNING.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM MDT
     SUNDAY FOR COZ018-019.

UT...NONE.
&&

$$

SHORT TERM...EH/15
LONG TERM...15
AVIATION...EH



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