Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KGJT 261650
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1050 AM MDT FRI SEP 26 2014

.UPDATE...
ISSUED AT 1047 AM MDT FRI SEP 26 2014

SUNNY SKIES PREVAILED THIS MORNING THOUGH VISIBLE SATELLITE
IMAGES SHOWED SOME CUMULUS CLOUDS WERE BEGINNING TO DEVELOP OVER
THE SAN JUANS. PRECIPITABLE WATER WAS A LITTLE HIGHER THIS MORNING
THAN YESTERDAY SO A FEW MORE STORMS ARE POSSIBLE OVER THE SAN
JUANS AND UP THE CENTRAL DIVIDE TODAY COMPARED TO YESTERDAY.
OTHERWISE...THIS AFTERNOON SHOULD BE QUITE SIMILAR. NO UPDATE IS
PLANNED TO THE FORECAST FOR THIS AFTERNOON.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 244 AM MDT FRI SEP 26 2014

ANOTHER NICE DAY IN STORE AS HIGH PRESSURE REMAINS OVERHEAD
BRINGING PLENTY OF SUNNY SKIES TO THE REGION. LIKE YESTERDAY...MODELS
PICKING UP ON DAYTIME HEATING ALLOWING SOME AFTERNOON CONVECTION
TO FIRE OVER THE SAN JUANS AND CENTRAL MTNS THIS AFTN AND EVENING.
ASIDE FROM THAT...WARM TEMPERATURES CONTINUE BEFORE BIG CHANGES
COMMENCE FOR THE WEEKEND.

TONIGHT AND SATURDAY...A STRONG BLOCKING RIDGE TO THE EAST WILL
FORCE THE WESTERN ENERGY COMING ASHORE IN THE TROUGH TO DIG THROUGH
THE GREAT BASIN RATHER THAN PROGRESS INLAND. SOUTHERLY WINDS WILL BE
INCREASING ALOFT THROUGH THIS 24 HOUR PERIOD AS THE CENTER OF THE
LOW CIRCULATION MOVES INTO SOUTHERN NEVADA. SUB TROPICAL MOISTURE
WILL BE ADVECTED NORTHWARD IN THIS FLOW BUT THROUGH SATURDAY
SOUNDING SUGGEST THIS WILL BE MAINLY HIGH LEVEL MOISTURE. ORGANIZED
LARGE SCALE ASCENT TO BEGIN TOP DOWN SATURATION WILL BE MAINLY WEST
OF OUR CWA UNTIL LATE IN THE DAY WHEN THE UPPER JET BEGINS TO REFORM
ON THE DOWNSTREAM SIDE OF WESTERN LOW. THEREFORE SHOWERS SHOULD
GENERALLY SHOW A DISSIPATING TREND TONIGHT THEN REFORM OVER THE
HIGHER TERRAIN THROUGH SATURDAY AFTERNOON AS OROGRAPHICS
CIRCULATIONS BEGIN TO TAP INTO THE MOISTURE ALOFT. RAISED
TEMPERATURES A TAD AS THE SLOWER PUSH OF MOISTURE AND LIFT SHOULD
ALLOW FOR SOME BETTER HEATING. THE COOLER NAM GUIDANCE FROM THE
PAST FEW RUNS HAS NOW WARMED TOWARD THE HIGHER MAV NUMBERS AS
WELL.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 244 AM MDT FRI SEP 26 2014

SATURDAY NIGHT INTO SUNDAY...THE UPPER LOW WILL BE FULLY CUTOFF FROM
THE FLOW TO THE NORTH AND ENERGY WILL BE ROTATING AROUND THE LOW
REMAINS NEARLY STATIONARY OVER SOUTHERN NEVADA. LARGE SCALE ASCENT
INCREASES OVER OUR CWA SATURDAY EVENING AND THROUGH WEAKENING WILL
BE IN PLACE THROUGH SUNDAY AS JET ENERGY ROTATES THROUGH AS WELL.
THE BIGGER DIFFERENCE WILL BE AVAILABLE MOISTURE AS 315K THETA
SURFACES SHOW THE MOISTURE ADVECTION PUSHING ACROSS THE UTAH/CO
BORDER. HAVE CONTINUED TO TREND POPS UPWARD AS PWATS REACH OVER
AN INCH WHICH IS WELL ABOVE NORMAL FOR EARLY FALL IN THIS REGION.
TEMPERATURES WILL BE IMPACTED BY THE PCPN AND CLOUD COVER AND LOOK
TO BE COOLING BY SOME 7 TO 12 DEGREES.

EXAMINATION OF THICKNESS VALUES SHOWS PUSH OF COLDER AIR MOVING
IN SUNDAY EVENING WITH PRECIP OVERSPREADING MUCH OF THE AREA. NAM
IS A BIT MORE AGGRESSIVE WITH PRECIP AMTS COMPARED TO EC AND GFS
THOUGH THEY ALSO SHOW SOME AREAS OF HEAVIER RAINFALL. QUESTION IS
WHETHER RAINFALL WILL BE CONVECTIVE OR STRATIFORM IN
NATURE. IF CONVECTIVE...LOCALIZED FLASH FLOODING CONCERNS INCREASE
WHILE A STEADY SOAKING RAIN WILL NOT BRING AS MANY PROBLEMS. WILL
PROBABLY BE A MIX OF THE TWO.  UNSETTLED WX CONTINUES INTO MONDAY
AS STORM SYSTEM MOVES OVER COLORADO THOUGH PRECIP WILL LIKELY
BECOME MORE SHOWERY IN NATURE. BY TUESDAY MORNING...ANY
SIGNIFICANT RAINFALL WILL BE JUST ABOUT OVER AS ANOTHER WEAK
TROUGH APPROACHES FROM THE NW. THIS TROUGH WILL MOVE OVER THE AREA
WED BUT MODELS HAVE REALLY LET UP ON PRECIP AMTS. HAVING SAID
THAT...SNOW LEVELS WILL DROP TO 9K TO 10K FEET SO SOME LIGHT SNOW
ACCUMULATIONS IS IN THE REALM OF POSSIBILITY FOR THE NRN MTNS WED.
ONCE THE TROUGH MOVES OUT...NW FLOW SETS UP KEEPING COOLER AIR IN
THE PICTURE WITH HIGHS SEVERAL DEGREES BELOW NORMAL.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1047 AM MDT FRI SEP 26 2014

HIGH PRESSURE WILL CONTINUE TO DOMINATE ERN UT AND WRN CO THROUGH
THIS EVENING FOR WIDESPREAD VFR CONDITIONS. DAYTIME HEATING AND
RESIDUAL MOISTURE COULD LEAD TO ISOLD TO SCT -SHRA/-TSRA OVER THE
SAN JUAN MOUNTAINS AND THE CENTRAL CO MOUNTAINS NEARER THE DIVIDE
UNTIL 03Z. GUSTY OUTFLOW WINDS WILL BE THE MAIN THREAT. CLOUDS WILL
BE ON THE INCREASE SAT AS THE NEXT STORM APPROACHES.


&&

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

$$

UPDATE...JAD
SHORT TERM...TGR/15
LONG TERM...15/TGR
AVIATION...JAD


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.