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000
FXUS65 KGJT 162156
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
356 PM MDT THU MAY 16 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 355 PM MDT THU MAY 16 2013

SOME ISOLATED SHOWERS AND STORMS HAVE FORMED THIS AFTERNOON MAINLY
OVER THE BOOKCLIFFS AND ROAN/TAVAPUT PLATEAUS. THIS FOLLOWS SINCE
PWATS ARE HIGHER OVER THIS AREA AS IS THE AVAILABLE ENERGY FOR ANY
STORMS THAT FORM. AN ISOLD SHOWER/STORM IS ALSO POSSIBLE OVER THE SAN
JUANS THROUGH THIS EVENING BUT AS OF NOW...RADAR MOSAIC NOT
PICKING UP ON ANY STORMS. ONCE DAYTIME HEATING ENDS...CONVECTION
WILL QUICKLY DIE DOWN GIVING WAY TO CLEARING SKIES OVERNIGHT.

THE POLAR JET WILL CONTINUE TO DIG OFF THE PACIFIC COAST CAUSING
HGT FALLS ACROSS THE INTERMOUNTAIN WEST. AS PIECES OF ENERGY ROUND
THE BASE OF THE TROUGH...UPPER LEVEL SUPPORT WILL FAVOR PRECIP
OVER NRN NV/UT WHILE KEEPING OUR FORECAST AREA DRY. AS THE TROUGH
APPROACHES...THE PRESSURE GRADIENT WILL TIGHTEN CAUSING SOME
GUSTY SURFACE WINDS OF 25 TO 30 MPH AT TIMES. THESE WINDS...ALONG
WITH DRY CONDITIONS...WILL CREATE RED FLAG CONDITIONS AS DESCRIBED
IN THE FIRE WEATHER SECTION BELOW. ASIDE FROM THE GUSTY
WINDS...PLENTY OF SUN EXPECTED WITH ABOVE AVERAGE TEMPERATURES CONTINUING.

GFS/NAM/EC CONTINUE TO DELAY THE ONSET OF PRECIP WITH THE ASSOD
TROUGH/FRONT SATURDAY WITH SOME LGT PRECIP EXPECTED IN THE MORNING
BEFORE MORE WIDESPREAD PRECIP KICKS IN FROM NOON ONWARDS. COLD
FRONT LOOKS TO BE JUST WEST OF THE UT/CO BORDER NOON
SATURDAY...CROSSING THE GRAND VALLEY MIDAFTERNOON AND ACROSS THE
REST OF WESTERN COLORADO BY THE EVENING HOURS. SOME INTERESTING
ASPECTS TO THIS SYSTEM...THE H5 TROUGH WILL BE NEGATIVELY TILTED
WHICH INDICATES THE POSSIBILITY FOR STRONGER...MORE INTENSE
CONVECTION. SFC CAPE NOT FOLLOWING THIS THINKING THOUGH AS VALUES
TOP OUT AROUND 500 J/KG WITH MOST VALUES BETWEEN 200 TO 300
J/KG...FAIRLY WEAK. QG FORCING ALSO REACHES A MAXIMUM TO OUR
SOUTH. ALL OF THE INGREDIENTS ARE IN PLACE FOR SOME ACTIVE
WX...JUST NOT LINED UP AS WELL AS THEY COULD BE.
REGARDLESS...PLENTY OF WEATHER TO BE HAD SATURDAY WITH
SHOWERS/STORMS INCREASING DURING THE DAY AS THE FRONT MOVES
THROUGH.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 355 PM
MDT THU MAY 16 2013

THE STRONGEST PART OF THE ASCENT WITH THIS NEGATIVELY TILTED TROF
WILL BE RE-FOCUSING ON THE PLAINS SATURDAY EVENING. THIS SHOULD
ALLOW FOR A NOTICEABLE DOWNTURN TO THE CONVECTION AFTER SUNSET WITH
ISOLATED TO WIDELY SCATTERED STORMS LINGERING THROUGH THE MORNING
HOURS MAINLY OVER THE TERRAIN. THE STRONG RIDGING AHEAD OF THIS TROF
AND HIGH PRESSURE TO THE NORTH WILL ALLOW THE NEXT UPSTREAM SYSTEM
TO DIG INTO THE REAR OF THE LEAD TROF SUNDAY...EVENTUALLY FORMING A
REX LOW OVER THE UPPER MISSOURI VALLEY BY SUNDAY NIGHT. THIS
NORTHERN PLAINS LOW WILL BE SLOW TO MOVE EASTWARD AND WILL KEEP A
THREAT OF UNSETTLED WEATHER ACROSS THE EASTERN 2/3 OF OUR CWA GOING
INTO THE EARLY WEEK PERIOD.

COOLER AIR FILTERING INTO THE TROF SUNDAY WILL ALLOW FAIRLY
WIDESPREAD CONVECTION TO FORM OVER THE NORTHERN AND CENTRAL
MOUNTAINS SUNDAY AS THE ATMOSPHERE DESTABILIZES. QG FIELDS INDICATE
THE BETTER FORCING DROPPING INTO NORTHERN UTAH LATE IN THE DAY WHICH
WILL BE SWEEPING ACROSS COLORADO THROUGH THE EVENING. SUPPORTING
THIS WAVE WILL RIGHT EXIT REGION OF THE CYCLONIC JET WHICH SHOULD
KEEP SOME SHOWER ACTIVITY GOING ACROSS THE NORTHERN MOUNTAIN THROUGH
THE EARLY MORNING HOURS EVEN AS DRIER AIR BEGINS TO FILTER IN.
TEMPERATURES WILL COOLING OFF QUITE A BIT GOING INTO SUNDAY WITH
HIGHS RUNNING SOME 10 DEGREES OR SO BELOW NORMAL. H7 TEMPERATURES
LOWER TO NEAR FREEZING OVERNIGHT ACROSS THE NORTHERN COLORADO
MOUNTAIN WHICH MAY LEAVE SOME LIGHT SNOW ACCUMULATION ACROSS THE
HIGHER PEAKS...WITH LITTLE IMPACT TO THE PASSES EXPECTED.
CONVECTIVELY DRIVEN SHOWERS WILL PERSIST INTO MONDAY IN NORTHWEST
FLOW WITH COOL ADVECTION THROUGH THE DAY. TEMPERATURES WILL REMAIN
BELOW NORMAL UNDER THIS FLOW WITH WAA NOT MOVING UNTIL THE OVERNIGHT
HOURS.

TUESDAY SHOULD BE THE TRANSITION DAY BEFORE MUCH WARMER TEMPERATURES
AND DRIER CONDITIONS MOVE INTO THE REGION. A LARGER SYSTEM DROPPING
INTO THE PACIFIC NORTHWEST REGION WILL HELP PUSH A RIDGE BACK INTO
THE ROCKIES BY MID-WEEK BEFORE THE SOUTHWEST FLOW AHEAD OF THIS
FEATURE BUILDS IN BY THE LATE WEEK PERIOD. THIS SHOULD PUSH
TEMPERATURES BACK TO AND ABOVE NORMAL BY LATE WEEK. A TIGHTENING
PRESSURE GRADIENT AND STRONG MIXING MAY ONCE AGAIN BRING FIRE
WEATHER CONCERNS TO THE FOREFRONT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 355 PM MDT THU MAY 16 2013

VFR CONTINUES FOR MOST AREAS THOUGH A LINE OF STORMS AND SHOWERS
HAS FORMED JUST NORTH OF THE BOOKCLIFFS/TAVAPUTS FROM RANGELY
THROUGH MEEKER...INTO STEAMBOAT SPRINGS. ATTM...CIGS HOVER AROUND
7K TO 10K FEET WITH HEAVIER SHOWERS DROPPING VIS TO 3SM OR MVFR.
OUTFLOW WINDS UP TO 45 MPH HAVE ALSO BEEN REPORTED OVER KEEO SO
AREAS NEAR THIS LINE ALSO HAVE THE CHANCE FOR SEEING THESE GUSTY
WINDS. VFR WILL BECOME PREDOMINANT AFTER 03Z AND CONTINUE THROUGH
FRIDAY WITH SOME HIGH CLOUDS EXPECTED OVERNIGHT AND INTO TOMORROW
THOUGH SOME SCT CU CLOUDS ARE POSSIBLE OVER HIGHER TERRAIN.

&&

.FIRE WEATHER...(TODAY THROUGH WEDNESDAY)
ISSUED AT 355 PM MDT THU MAY 16 2013

STRONG HEATING THE NEXT FEW DAYS WILL COMBINE WITH STRONGER WINDS
ALOFT TO PRODUCE EFFICIENT MIXING PRODUCING GUSTY AFTERNOON WINDS.
RELATIVE HUMIDITY VALUES IN THE LOWER TEENS AND DRY FUELS WILL
COMBINE WITH THE STRONGER WINDS TO PRODUCE CRITICAL FIRE WEATHER
CONDITIONS DURING THE AFTERNOON AND EARLY EVENING HOURS TODAY AND
AGAIN ON FRIDAY. ISOLATED TO SCATTERED THUNDERSTORMS THIS AFTERNOON
WILL ALSO BE CAPABLE OF PRODUCING STRONG OUTFLOW WINDS. THE DRIER
ATMOSPHERE ON FRIDAY SHOULD PROHIBIT THE THUNDERSTORM ACTIVITY. THE
WESTERN TROF WILL ARRIVE ON SATURDAY AND PRODUCE ACTIVE WEATHER
THROUGH EARLY NEXT WEEK BEFORE UPPER RIDGING MOVE BACK INTO THE
ROCKIES. COOLER WEATHER THIS WEEKEND WILL THEN GRADUALLY WARM THROUGH
NEXT WEEK WITH MAINLY DRY CONDITIONS EXPECTED.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...RED FLAG WARNING FROM NOON TO 8 PM MDT FRIDAY FOR COZ203-207-290-
     292-293.

     RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR COZ203-207-290-
     292.

UT...NONE.
&&

$$

SHORT TERM...TGR
LONG TERM...15
AVIATION...TGR
FIRE WX...15