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

000
FXUS65 KGJT 191155
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
555 AM MDT SAT APR 19 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 428 AM MDT SAT APR 19 2014

H5 HAND ANALYSIS SHOWS SPLIT FLOW IN PLACE ACROSS THE WESTERN CONUS.
WATER VAPOR SHOWING TWO SYSTEMS IN THE FLOW THIS MORNING...ONE
MOVING QUICKLY EASTWARD ACROSS THE NORTHERN PLAINS...AND A SECOND
LAGGING IN THE SOUTHERN STREAM OVER WESTERN ARIZONA. THE DAKOTA
SYSTEM LOOKS TO HAVE PUSHES A WEAK BOUNDARY DOWN INTO NORTHWEST
COLORADO AND NORTHERN UTAH. 300K MOISTURE TRANSPORT VECTORS AND
WATER VAPOR SUGGEST A TAP TO THE SUBTROPICAL FEED OF MOISTURE ACROSS
THE BAJA AND NORTHERN MEXICO. VIRGA FROM LAST EVENING HAS PROBABLY
HELPED SATURATE FROM TOP DOWN IN PLACES...BUT VERY DRY SOUNDING CAME
IN AT 00Z LAST EVENING. QG FIELDS SHOW ONLY WEAK  AND BROAD LARGE
SCALE ASCENT TODAY. HEIGHT FALLS ON THE 00Z CHART INDICATED THE
SYSTEM WOULD DIG SOUTHEAST SOME BEFORE LIFTING AND WATER VAPOR
SUPPORTING THIS ATTM. THEREFORE ASCENT WITH THIS SOUTHERN SYSTEM
ALSO LOOK TO MAINLY BYPASS OUR CWA AND TAKE AIM EAST OF THE DIVIDE.
SO WITH PLENTY OF MOISTURE AND WEAK DYNAMICS FEEL OROGRAPHICS AND
INSTABILITY WILL BE THE DRIVING FORCE FOR PRECIPITATION. THE
BOUNDARY TO THE NORTH APPEARS TO BE WASHING OUT AS WELL WITH LITTLE
SUPPORT FROM ALOFT. ISOLATED THUNDERSTORMS STILL POSSIBLE AND
INTERACTIONS FROM STORMS MAY HAVE SOME IMPACT TO VALLEY WEATHER.
HOWEVER ON THE WHOLE FEEL THE TERRAIN WILL SEE THE BEST CHANCES AND
RAISED POPS SOME IN SOUTH. CONFIDENCE NOT AS HIGH IN THE LOWER
ELEVATIONS AND DID TREND PRECIP CHANCES DOWNWARD. THERE SHOULD BE A
NOTICEABLE DOWNTURN TO THE PRECIPITATION COVERAGE OVERNIGHT.
MOISTURE TRANSPORT VECTORS KEEP A TIGHT GRADIENT TO THE WRAP AROUND
MOISTURE WITH THE SYSTEM IN SOUTHEAST COLORADO BY MORNING. AGAIN THE
MAIN DRIVER FOR SHOWERS ON SUNDAY WILL BE INSTABILITY WITH
STEEPENING AFTERNOON LAPSE RATES. MOISTURE ON THE DECREASE AND
PRECIPITATION COVERAGE WILL FOLLOW SUIT. GOING FORECAST LOOKS ON
TRACK AND ONLY MINOR CHANGES FOR SUNDAY. WARM TEMPERATURES STAY IN
PLACE WITH HIGH AOA NORMAL. SNOW LEVEL WILL BE RISING THROUGH THE
DAY BUT IMPACTS FROM CONVECTION WILL STILL BE PROBLEMATIC. THE
RELATIVE MILD OVERNIGHT TEMPERATURES COMBINED WITH HIGH SNOW LEVELS
AND ADDED PRECIPITATION COULD STILL LEAD TO SOME RUNOFF PROBLEMS FOR
THE SMALLER BASINS AND CREEKS.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 428 AM MDT SAT APR 19 2014

THE PATTERN AMPLIFIES EARLY IN THE PERIOD WITH A WARMING TREND.
STRENGTHENING SOUTHWEST FLOW WILL ADVECT WARM AIR ACROSS THE
ENTIRE FORECAST AREA...PEAKING ON TUESDAY WITH WELL ABOVE
AVERAGE. LATEST GUIDANCE SUGGEST LOWER 80S IN THE DESERT VALLEYS.
AS A BROAD SURFACE LOW DEEPENS THE NRN AND CENTRAL ROCKY MOUNTAIN
STATES...DEEP MIXED LAYER WILL RESULT IN WINDY CONDITIONS. COLD
FRONT SWEEPS ACROSS THE AREA WEDNESDAY EVENING BRINGING COOLER AND
UNSETTLED WEATHER ON WEDNESDAY. THE CORE OF THE UPPER LOW IS
PROJECTED TO TRACK ACROSS MONTANA...THIS LIMITS THE CHANCE OF
SHOWERS ACROSS THE NORTH. AFTER THE TROUGH MOVES DOWNSTREAM ON
THURSDAY...A HIGH PRESSURE RIDGE REACHES WRN COLORADO ON FRIDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 555 AM MDT SAT APR 19 2014

SCATTERED -SHRA WITH NUMEROUS -SHRA OVER THE HIGHER TERRAIN WILL
OCCUR TODAY THROUGH 03Z THIS EVENING. SNOW LEVELS WILL BE BETWEEN
9000 AND 10000 FEET.  ISOLATED THUNDERSTORMS WILL BE POSSIBLE.
CONDITIONS WILL PRIMARILY STAY VFR...HOWEVER LOCAL IFR/MVFR IS
EXPECTED WITH PASSING SHOWERS OVER THE HIGH TERRAIN WITH
OCCASIONAL MOUNTAIN TOP OBSCURATIONS.

CONDITIONS WILL IMPROVE TONIGHT WITH ISOLATED -SHRA AFTER 03Z WITH
VFR BECOMING WIDESPREAD.

&&

.FIRE WEATHER...
ISSUED AT 428 AM MDT FRI APR 18 2014

AS A LARGE LOW PRESSURE TROUGH MOVES ONSHORE OVER THE PACIFIC
NORTHWEST ON TUESDAY...STRONG SOUTHWEST FLOW WILL DEVELOP OVER
EASTERN UTAH AND WESTERN COLORADO. THIS FLOW WILL MIX INTO THE
VALLEYS BY THE AFTERNOON AND INCREASE OVER THE AREA AS A COLD FRONT
ASSOCIATED WITH THE TROUGH APPROACHES FROM THE NORTHWEST. AHEAD OF
THE FRONT CONDITIONS WILL REMAIN DRY...ESPECIALLY OVER SOUTHWEST
COLORADO AND SOUTHEAST UTAH WHERE MINIMUM RELATIVE HUMIDITY VALUES
WILL LIKELY DROP BELOW 15 PERCENT BELOW 8000 FEET. ALSO THE
STRONGEST WINDS ARE EXPECTED ACROSS EASTERN UTAH AND SOUTHWEST
COLORADO. THEREFORE CRITICAL WEATHER CONDITIONS WILL BE POSSIBLE
TUESDAY AFTERNOON IN AREAS WHERE FUELS ARE DRY. MODELS INDICATE THAT
THE BULK OF THE ENERGY AND MOISTURE ASSOCIATED WITH THE TROUGH WILL
REMAIN NORTH OF THE FORECAST AREA. LOW RELATIVE HUMIDITY AND GUSTY
WEST WINDS ARE EXPECTED OVER THE FAR SOUTHERN ZONES WEDNESDAY
AFTERNOON.

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

&&

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

$$

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



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