Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 250406
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1006 PM MDT FRI APR 24 2015

.UPDATE...
ISSUED AT 1000 PM MDT FRI APR 24 2015

THE SHORTWAVE RIDGE AXIS OVER FAR WESTERN COLORADO THIS EVENING
HAS DIMINISHED BUT NOT ELIMINATED SHOWERS. THE RIDGE WILL SHIFT
EAST OF THE FORECAST AREA BY MORNING. MOISTURE IS WORKING IN FROM
THE WEST BEHIND THE RIDGE WITH PRECIPITABLE WATER VALUES STILL
PROGGED TO BE MORE THAN 0.5 INCH ACROSS THE REGION. A STRONG VORT
MAX THAT WAS MOVING INTO NW UTAH WILL BRING A BAND OF SHOWERS AND
PERHAPS ISOLATED THUNDERSTORMS INTO NE UTAH BEFORE SUNRISE. THE
REMAINDER OF THE FORECAST AREA WILL SEE THIS STRONGER FORCING
INCREASING THROUGH THE MORNING HOURS.

SNOW LEVELS GENERALLY REMAIN HIGH THROUGH SATURDAY. WET BULB ZERO
LEVELS ARE AROUND 9-10KFT THROUGH SATURDAY THOUGH CONVECTION WILL
DRIVE SNOW BRIEFLY DOWN ANOTHER 1K TO 2KFT. MODELS CONTINUE TO
PRODUCE SIGNIFICANT SNOWFALL ACROSS THE REGION SATURDAY INTO
MONDAY THAT APPEARS TO BE OVERDONE ESPECIALLY FOR ELEVATIONS BELOW
10KFT. WE WILL EVALUATE FURTHER OVERNIGHT.

&&

UPDATE ISSUED AT 722 PM MDT FRI APR 24 2015

MINOR POP ADJUSTMENTS TO GRIDS AS SHOWERS HAVE BEEN MORE ISOLATED
IN NATURE SO FAR THIS EVENING. HRRR HINTING AT AN INCREASE IN
COVERAGE LATE TONIGHT INTO THE EARLY MORNING HOURS...FAVORING
EAST CENTRAL UTAH AS THE NEXT WAVE APPROACHES. ADDITIONAL UPDATES
LIKELY AS THE NIGHT PROGRESSES.

&&

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 359 PM MDT FRI APR 24 2015

NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE LATE
AFTERNOON AS H5 DIFLUENCE KEEPS MOST OF THE ACTIVITY OVER THE
MOUNTAIN TERRAIN OF WESTERN COLORADO. ISOLATED SHOWERS AND A
STRIKE OR TWO OF LIGHTNING CANNOT BE RULED OUT IN EASTERN UTAH AS
WELL...BUT DRIER AIR IS CURRENTLY SEEN ON SATELLITE IN EASTERN
UTAH SO ANYTHING THAT DEVELOPS THIS EVENING THERE WILL BE MAINLY
GUSTY WINDS. THIS SMALL `BREAK` OF DRIER AIR WILL SHIFT INTO
WESTERN COLORADO TONIGHT...SO ACTIVITY IS EXPECTED TO DECREASE
AROUND SUNSET UNTIL JUST BEFORE MIDNIGHT. SHORT TERM MODELS
INDICATE RAIN MOVING INTO SW COLORADO BY 10 OR 11 PM TONIGHT AND
NE UTAH JUST AFTER MIDNIGHT.

CLOUDY AND SHOWERY DAY ON TAP FOR SATURDAY AS A LEAD UPPER TROUGH
MOVES ACROSS NW CO IN THE MORNING. MODELS ARE CONSISTENT WITH A NERN
PACIFIC JET DIGGING THE MAIN BUT SPLITTING TROUGH SOUTH THROUGH THE
GREAT BASIN ON SATURDAY AND EVENTUALLY FORMING A CLOSED LOW OVER
ERN AZ BY MIDDAY SUNDAY. THIS LOW THEN TRACKS ACROSS CENTRAL NM
SUNDAY AFTERNOON/NIGHT. SHOULD SEE PRECIPITATION RAMP UP AGAIN
LATER SAT NIGHT AND SUNDAY MORNING AS THE 700 MB TROUGH AND COLD
FRONT COME THROUGH WITH PRECIPITABLE WATER VALUES OF 0.5 TO 0.7
INCH. FLOW SWITCHES FAIRLY QUICKLY TO EASTERLY SUNDAY AFTERNOON.
NAM AND TO SOME EXTENT THE GFS TRY TO BRIEFLY WRAP SOME DRIER AIR
BACK IN MIDDAY SUNDAY ON THE 305K ISENTROPIC SURFACE (ROUGHLY
700-600 MB) BUT THEN QUICKLY FILLS IT IN AS THE EASTERLY FLOW
PUSHES MOISTURE OVER THE DIVIDE. TEMPS ALOFT NOT OVERLY COLD
HOWEVER...SO SNOW LEVELS SHOULD REMAIN FAIRLY HIGH OUTSIDE OF THE
STRONGER CONVECTIVE SHOWERS/T-STORMS THAT COULD DRIVE IT BELOW
8000 FT AT TIMES. CONFIDENCE NOT HIGH ENOUGH TO ISSUE ANY WINTER
HIGHLIGHTS HOWEVER...BUT THE POSSIBILITY EXISTS WITH MODELS
PUTTING OUT 6+ INCHES BY SUNDAY EVENING OVER THE SAN JUANS AND ELK
MTNS. WILL CONTINUE WITH A SPECIAL WEATHER STATEMENT.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 359 PM MDT FRI APR 24 2015

THE UPPER LOW MOVES INTO THE SOUTHERN PLAINS MONDAY WITH DRIER
AIR PUSHING ACROSS ERN UT INTO WRN CO. SCATTERED SHOWERS WILL
LIKELY PERSIST MAINLY ALONG THE DIVIDE WITH DAYTIME HEATING
WORKING ON THE COOLER AIR. UPPER RIDGE BUILDS OVERHEAD BY MIDWEEK
FOR A DRYING AND WARMING TREND. AFTERNOON TEMPS WILL RISE ABOVE
NORMAL. MAY SEE A CHANCE OF SHOWERS LATE IN THE WEEK AS MODELS
BRING A PACIFIC TROUGH INLAND AND ACROSS THE NORTHERN ROCKIES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING)
ISSUED AT 1000 PM MDT FRI APR 24 2015

ONLY ISOLATED MAINLY MOUNTAIN SHOWERS EXPECTED THROUGH 09Z. THEN A
BROADER AREA OF SHRA/SHSN AND LOW CIGS/VSBY TO IMPACT NE UTAH
FIRST. BETWEEN 12-15Z THIS BAND OF SHOWERS WILL MOVE THROUGH
THE REMINDER OF EASTERN UTAH AND THROUGH WESTERN COLORADO BETWEEN
12Z-18Z. EXPECT WIDESPREAD -SHRA/-SHSN WITH SCT THUNDERSTORMS WITH
THIS BAND...WITH CIGS BLO 050 AND VIS BLO 3SM AT TIMES IN THE
HEAVIEST SHOWERS. MTN TOPS WILL BE OBSCD AT TIMES IN SHSN. SNOW
LEVEL AROUND 10000FT EXCEPT DOWN TO 8000FT IN HEAVIEST STORMS.


&&

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

$$

UPDATE...JOE
SHORT TERM...JAM/JAD
LONG TERM...JAD
AVIATION...JOE


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