000
FXUS65 KGJT 152159
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
359 PM MDT WED MAY 15 2013

.SHORT TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 358 PM MDT WED MAY 15 2013

WIDESPREAD CONVECTION HAS FIRED THIS AFTERNOON...AS EXPECTED...AS
AN APPROACHING DISTURBANCE PROVIDES WIDESCALE LIFT ON A RELATIVELY
MOIST ATMOSPHERE. ATTM...CONVECTION IS A MORE POP AND DROP TYPE
BUT AS THE DISTURBANCE CONTINUES TO GET CLOSER...SOME OF THE
STORMS MAY BECOME A BIT MORE INTENSE. THE MAIN CONCERN WITH THESE
STORMS WILL BE SOME PEA-SIZED HAIL AND ALSO SOME GUSTY OUTFLOW
WINDS POSSIBLY REACHING 40 MPH OR SO. THE STORMS ARE ALSO SLOW
MOVERS SO WILL KEEP AN EYE ON PRECIP AMOUNTS OVER THE MOUNTAINS
AND BURN SCARS WHERE MORE PRECIP WILL BE REACHING THE GROUND. THE
DISTURBANCE WILL MOVE OVER OUR FORECAST AREA FROM 9PM THROUGH 3AM
BEFORE FINALLY EXITING THE AREA. ALL SHORT-TERM MODELS INDICATING
A DOWNTURN IN PRECIP AND STORMS SHORTLY AFTER SUNSET WHICH
INDICATES SUPPORT FOR THE DISTURBANCE WILL WANE AND WEAKEN AS IT
PASSES OVER. FORECAST FOLLOWS SUIT WITH NO PRECIP EXPECTED AFTER
MIDNIGHT.

WESTERLY FLOW ALOFT BECOMES PREDOMINANTLY SOUTHWESTERLY THURSDAY
AHEAD OF A TROUGH THAT WILL COME ASHORE ALONG THE WESTERN COAST. A
110KT JET WILL BE DIGGING THIS TROUGH ON THURSDAY WHILE A WEAKER
JET STREAK WILL BE EXITING THE TROUGH AND MOVING OVER NV AND NRN
UT. THE STREAK WILL PROVIDE JUST ENOUGH SUPPORT...ALONG WITH SOME
OROGRAPHIC LIFT...TO FIRE OFF SOME MORE CONVECTION TOMORROW THOUGH
MODELS HINTING THAT BEST COVERAGE WILL BE NORTHERN THIRD OF THE
FORECAST AREA. SOME CONVECTION IS POSSIBLE BUT WILL BE ON THE WEAK
SIDE...IF IT OCCURS AT ALL...WITH SOME CU BUILDUP AND THE ODD SPOTTY
SHOWER EXPECTED. REMAINING AREAS WILL SEE TIMES OF SUN AND CLOUDS.
SOUTHWESTERLY FLOW WILL KEEP WARM TEMPERATURES IN PLACE CONTINUING
OUR WARM STRETCH. CONVECTION WILL DIE DOWN OVERNIGHT AS DAYTIME
HEATING ENDS LEAVING SOME HIGH LEVEL CLOUDS OVERNIGHT.

MODELS HAVE REALLY PULLED BACK ON PRECIP FOR FRIDAY AHEAD OF THE
TROUGH AS IT APPEARS THE JET DIGGING DOWN INTO THE TROUGH WILL
SLOW THE FORWARD MOVEMENT AND KEEP PRECIP OVER NV AND WRN UT. WENT
AHEAD AND DROPPED POPS IN OUR FORECAST UNTIL THE EVENING HOURS
EXCEPT FOR THE EASTERN UINTAS. EXPECT PRECIP TO START RAMPING UP
SATURDAY MORNING AS THE TROUGH BECOMES NEGATIVELY TILTED AND
BEGINS TO MOVE OVER THE FORECAST AREA.

.LONG TERM...(SATURDAY NIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 358 PM MDT WED MAY 15 2013

THE WESTERN TROF WILL BE TAKING ON SOMEWHAT OF A NEGATIVE TILT AS IT
MOVES INTO THE WESTERN GREAT BASIN SATURDAY AFTERNOON. MOISTURE
TRANSPORT VECTORS NEAR 315K INDICATE A RETURN OF MOISTURE OUT OF THE
BAJA REGION WITH PWATS PUSHING BACK TO NEAR NORMAL AFTER THE DRYING
OUT PERIOD ON FRIDAY. THE EURO/GFS STILL SOMEWHAT SPLIT ON ENERGY
DIVING INTO THE TROF WITH THE GFS CARRYING MORE ENERGY INTO THE BASE
OF THE TROF WITH THE MAIN AREA OF ASCENT MOVING SOUTH OF THE 4
CORNERS. THE EURO ON THE OTHER HAND IS MOVING A SLIGHTLY FLATTER
TROF WITH ASCENT LIFTING ACROSS THE NORTHERN CWA EARLIER IN THE
DAY THEN REFOCUSING IN THE EASTERN PLAINS. CONFIDENCE STILL LESS
THAN STELLAR GOING INTO THIS WEEKEND TO PICK OUT A FAVORED AREA TO
RECEIVE THE BETTER PRECIPITATION...SO ISOLATED TO SCATTERED POPS
WILL REMAIN IN PLACE. COOLING ALOFT ALONG WITH INCREASED CLOUD
COVER WILL BRING A DEFINITE COOL DOWN BUT THE MAIN BOUNDARY
ASSOCIATED WITH THE COLDER AIR DOES NOT LOOK TO PUSH THROUGH THE
CWA UNTIL SATURDAY EVENING. THIS MAY KEEP SOME ISOLATED NOCTURNAL
SHOWERS GOING THROUGH THE EARLY MORNING HOURS ON SUNDAY. SNOW
LEVELS MAY LOWER TO NEAR 9000 FEET ACROSS THE NORTHERN MOUNTAINS
OVERNIGHT BUT WITH LITTLE IMPACT EXPECTED. HIGHS ON SATURDAY WILL
BE KNOCKED DOWN BY 10 DEGREES OR SO ON SATURDAY TO MORE NORMAL
READINGS FOR MID-MAY.

BOTH MODELS SHOW A SECONDARY WAVE ROTATING IN THE BACK OF THE TROF
ON SUNDAY WITH THE COOLER AIR ALOFT LEADING TO UNSTABLE CONDITIONS
IN THE AFTERNOON. WITH DRIER AIR FILTERING IN MUCH OF THE FOCUS
SHOULD MAINLY BE ACROSS THE HIGHER TERRAIN OF THE CENTRAL AND
NORTHERN MOUNTAINS DUE TO JET DYNAMICS LIFTING NORTHWARD ACROSS THIS
REGION. BEYOND THIS PERIOD THE GFS AND EURO ARE KEEPING THEIR
STUBBORN SOLUTIONS GOING INTO THE EARLY WEEK PERIOD WITH THE EURO
WETTER ACROSS OUR NORTHERN MOUNTAINS AND SLOWER TO PUSH OUT THE TROF
UNTIL MID WEEK AND SEEMS THE WAY TO LEAN WITH THE NEGATIVE TILT TO
THIS SYSTEM. THIS WILL KEEP BELOW NORMAL TEMPERATURES IN PLACE
MONDAY WITH SOME SLOW WARMING GOING INTO THE MID WEEK PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 358 PM MDT WED MAY 15 2013

WIDESPREAD CONVECTION WILL CONTINUE THROUGH 03Z AND THEN DIE DOWN
AS DAYTIME HEATING ENDS. ALL TAF SITES WILL SEE VCTS WITH KASE AND
KEGE SEEING TSTORMS THIS AFTN. GUSTY SFC WINDS WILL BE BIGGEST
CONCERN WITH SOME BRIEF MVFR ALSO POSSIBLE UNDER THE HEAVIER
SHOWERS. REMAINING AREAS SHOULD SEE PLENTY OF VFR WITH SCT TO BKN
SKIES BEING COMMON. AFTER 03Z...VFR WILL BE THE RULE AS A FEW HIGH
CLOUDS PERSIST OVERNIGHT AND INTO TOMORROW. EXPECT CLOUDS ON THE
INCREASE STARTING AROUND 17Z WITH MORE AFTERNOON CONVECTION
POSSIBLE FOR AREAS MOSTLY NORTH OF I-70.

&&

.FIRE WEATHER...(TONIGHT THROUGH TUESDAY)
ISSUED AT 358 PM MDT WED MAY 15 2013

THE UPPER RIDGE WILL BE BREAKING DOWN OVER THE NEXT FEW DAYS AS A
STRONGER PACIFIC TROF PROGRESSES INLAND INTO THE GREAT BASIN. UPPER
LEVEL WINDS WILL TURN MORE SOUTHERLY AND INCREASE THROUGH THE
REMAINDER OF THE WEEK. AS TEMPERATURES WARM INTO THE MID 80S
TOMORROW INTO FRIDAY AFTERNOON...WIND GUSTS IN THE 30 TO 40 MPH
RANGE WILL BE POSSIBLE OVER MUCH OF WESTERN COLORADO. FUELS REMAIN
CRITICAL ALONG THE THE GRAND VALLEY EASTWARD ALONG THE I-70
CORRIDOR BELOW 8000 FEET WHICH WILL COMBINE WITH RELATIVE HUMIDITY
READINGS IN THE LOWER TEENS AND GUSTY WINDS TO CREATE CRITICAL
FIRE WEATHER CONDITIONS. SOME RECOVERY OF THE HUMIDITY IS EXPECTED
THURSDAY NIGHT...WITH DRY AND WINDY CONDITIONS REDEVELOPING BY
FRIDAY AFTERNOON LEADING TO ANOTHER ROUND OF CRITICAL FIRE WEATHER
CONDITIONS. THE MAIN TROF WILL PUSH ACROSS THE REGION SATURDAY
INTO SUNDAY WITH SOME SHOWERS LINGERING ACROSS THE HIGHER TERRAIN
OF NORTHERN COLORADO INTO EARLY NEXT WEEK. A COOL DOWN WITH THE
TROF SHOULD EASE THE CRITICAL FIRE WEATHER CONDITIONS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...RED FLAG WARNING FROM 2 PM TO 9 PM MDT THURSDAY FOR COZ203.

UT...NONE.
&&

$$

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