Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 241026
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
326 AM MST SAT JAN 24 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 326 AM MST SAT JAN 24 2015

THE FAMILIAR PATTERN OF A WESTERN RIDGE AND EASTERN TROUGH THIS
WINTER REMAINS IN PLACE THE 00Z HAND ANALYSIS CHART. THIS TROUGH
GETS RE-ENFORCED BY ANOTHER STRONG PACIFIC TROUGH TOPPING THE RIDGE
AND DROPPING INTO THE MIDWEST. THE OTHER PERSISTENT FEATURE OF LATE
HAS BEEN A WEAK CYCLONIC CIRCULATION STUCK OVER THE BAJA REGION. THE
JET TRANSLATING EASTWARD WILL PULL THE TOP OF THE RIDGE OUT OF THE
EASTERN PACIFIC...CREATING A REX BLOCK OVER THE WESTERN STATES BY
SUNDAY. THIS DOES NOT BODE WELL FOR BRING PRECIPITATION TO THE GREAT
BASIN AND CENTRAL ROCKIES AND THE DRY MONTH OF JANUARY CONTINUES.
DERIVED SATELLITE IMAGERY SHOWS PACIFIC MOISTURE SLAMMING INTO THE
NORTHWEST COASTLINE...WHERE PWATS ARE RUNNING OVER 200 PERCENT.
HOWEVER THE UPSTREAM MOUNTAINS SEEM TO BE ABSORBING MOST OF THIS
MOSITURE AS OBSERVATIONS SHOW LITTLE TO NO MOISTURE FALLING
UNDERNEATH THE APPROACHING MID AND HIGH CLOUDINESS. THE BULK OF THE
FORCING WILL TRACK WELL TO THE NORTH OF OUR CWA. CROSS SECTIONS SHOW
THE BEST WE CAN REALLY DO IS FORCE SOME OROGRAPHIC SHOWERS ALONG THE
NORTHERN DIVIDE MOUNTAINS...AND CONFIDENCE HERE IS MINUSCULE.
HAVE SOME ISOLATED POPS ALONG THE TOP OF THE PARK AND GORE RANGE
THIS AFTERNOON AND EVENING...BUT 300K TRANSPORT VECTORS AND OMEGA
FIELDS INDICATE SLIGHTLY BETTER CHANCES JUST A MOUNTAIN RANGE TO
OUR EAST. THEREFORE THE REAL CHALLENGE WILL BE TEMPERATURES THE
NEXT FEW DAYS. MID LEVEL TEMPERATURES WILL CONTINUE TO RISE AS THE
WESTERN RIDGE BUILDS FARTHER INLAND. THIS WILL STRENGTHEN THE
INVERSIONS WITH MID MOUNTAIN TEMPERATURES WARMING NICELY WHILE
VALLEYS MAY STRUGGLE TO WARM...ESPECIALLY THE SNOW COVERED AREAS.
THIS IS MAINLY LIMITED TO THE MOUNTAIN VALLEYS AND GUNNISON BASIN
WHERE HIGHS WILL BE FORECAST TO LAG BEHIND THE COLDEST GUIDANCE.
FOG HAS NOT SHOWN ITSELF OVER THE GUNNISON AND UINTA BASINS WITH
DRIER AIR MIXING IN IT APPEARS. GUIDANCE SUGGEST THIS TREND MAY
CONTINUE THE NEXT FEW NIGHTS AS WELL.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 AM MST SAT JAN 24 2015

ACTIVE SOUTHERN STREAM THROUGH THE LONG TERM PERIOD. A CLOSED LOW
SITUATED NEAR BAJA CALIFORNIA WILL DRIFT NORTHWARD...BUT ENCOUNTERS
THE STRONG RIDGE AXIS THAT COVERS UTAH AND COLORADO.  THERE IS
PLENTY OF MOISTURE WITH THIS FEATURE...AND DYNAMICAL FORCING IS
QUITE WEAK. RIDGE AXIS SHOULD SUPPRESS PRECIPITATION AND ANY QPF
WILL BE LIGHT. SNOW LEVELS WILL BE HIGH (POSSIBLY AROUND 8-9K
FEET) GIVEN THE RELATIVE WARMTH OF THIS SYSTEM.

MODEL DISCREPANCY OCCURS ON WEDNESDAY BUT THE BLENDED APPROACH YIELDS
LOW POP VALUES OVER THE NRN MOUNTAINS. GFS AND ECMWF INDICATE
THAT THE REMNANTS OF THE CLOSED LOW GETS ENTRAINED INTO THE
WESTERLIES AND SKIRTS NRN COLORADO.

FRIDAY...ANOTHER CLOSED LOW WILL BE NEAR BAJA CALIFORNIA THAT
SENDS MORE MOISTURE OVER THE DESERT SOUTHWEST. UNCLEAR AT THIS
TIME HOW MUCH OF THIS MOISTURE REACHES UTAH AND COLORADO.

WHAT IS CLEAR IS THAT MILD CONDITIONS WILL PREVAIL NEXT WEEK.
RIGHT NOW...WINTER IS MISSING IN ACTION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 326 AM MST SAT JAN 24 2015

VFR WILL PREVAIL AT ALL TAF SITES THROUGH THE FORECAST PERIOD.
LIGHT SNOW OR FLURRIES MAY EXIST NORTH AND EAST OF KSBS WITH
PARTIAL MOUNTAIN OBSCURATION.

&&

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

$$

SHORT TERM...15
LONG TERM...PF
AVIATION...PF


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