Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 122120
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
320 PM MDT SAT JUL 12 2014

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 319 PM MDT SAT JUL 12 2014

THE UPPER RIDGE AMPLIFIES AND SHIFTS SLIGHTLY WEST TONIGHT SO ITS
AXIS IS OVER THE GREAT BASIN. MODELS INDICATE DRIER NW FLOW
PUSHING INTO THE REGION SUNDAY...HOWEVER THERE IS STILL PLENTY OF
AVAILABLE MOISTURE FOR DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS
OVER THE HIGHER TERRAIN. THE BEST CHANCE OF THUNDERSTORMS SUNDAY
WILL BE OVER THE CENTRAL CONTINENTAL DIVIDE AND SAN JUAN
MOUNTAINS. LITTLE CHANGE SUNDAY NIGHT...JUST THE USUAL SHOWERS
DISSIPATING AFTER SUNSET.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 319 PM MDT SAT JUL 12 2014

WITH THE HIGH PRESSURE CENTERED OVER THE GREAT BASIN ON
MONDAY...THE FLOW WILL REMAIN LESS FAVORABLE FOR CARRYING
ADDITIONAL MOISTURE ACROSS THE AREA. HOWEVER TRAPPED MOISTURE
UNDER THE RIDGE WILL CONTINUE TO RECIRCULATE ACROSS THE
REGION...AND WITH DAYTIME HEATING WILL PRODUCE ANOTHER ROUND OF
AFTERNOON SHOWERS AND THUNDERSTORMS. BUT ACTIVITY WILL BE
TEMPERED SOMEWHAT DUE TO THE LESS AVAILABLE MOISTURE.

A SHORTWAVE DISTURBANCE ROTATING AROUND THE TOP OF THE RIDGE WILL
MOVE INTO THE PACIFIC NORTHWEST EARLY MONDAY...THEN BY MON NIGHT
IT WILL GET PICKED UP BY THE LARGE LOW PRESSURE CENTER OVER THE
GREAT LAKES...THEN DROP SOUTHEAST-WARD. THIS WAVE...AND THE
TIGHTENED GRADIENT BETWEEN A LARGE GREAT LAKES LOW AND THE
SUPPRESSED WESTERN HIGH...WILL HAVE THE POTENTIAL TO MAKE THINGS
INTERESTING THROUGH TUE. THE FLOW WILL BEGIN TO INCREASE OVER THE
AREA MON EVENING AS A LOCAL JET MAXIMA PASSES OVER NORTHEAST CO.
THE FLOW WILL INCREASE OVERNIGHT WITH SURFACE WINDS INCREASING BY
THE AFTERNOON AND BETTER SHEAR DEVELOPING. ALSO THE BRIEF
SOUTHWEST FLOW AHEAD OF THE WAVE WILL BE MORE FAVORABLE FOR
BRINGING ADDITIONAL MOISTURE INTO THE AREA. THESE INGREDIENTS
COMBINED WITH EXCELLENT DAYTIME HEATING MAY PRODUCE SOME VIGOROUS
THUNDERSTORMS WITH GUSTY WINDS AND HAIL POSSIBLE. THE SITUATION
WILL CONTINUED TO BE MONITORED TO SEE IF MODELS CONTINUE TO
ADVERTISE THESE ELEMENTS.

THE DRIER NORTHWEST FLOW THEN BECOMES MORE PERSISTENT. HOWEVER
MOISTURE WILL LINGER OVER THE SOUTH WHERE THE FLOW WILL BE
LIGHTER. ALSO SOME MOISTURE ROTATING AROUND THE WESTERN HIGH WILL
CONTINUE TO REACH INTO SOUTHWEST COLORADO. THEREFORE DIURNAL AND
TERRAIN ENHANCED SHOWERS AND THUNDERSTORMS WILL PERSIST IN AND
AROUND THE SAN JUAN MOUNTAINS AND WESTWARD INTO SOUTHEAST
UT...WITH LESS ACTIVITY ELSEWHERE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 319 PM MDT SAT JUL 12 2014

STORMS AND SHOWERS HAVE JUST STARTED FIRING ACROSS MOUNTAINOUS
TERRAIN THIS MORNING WITH COVERAGE INCREASING THROUGH THE DAY. MTN
TAF SITES HAVE THE BEST CHANCES FOR VCTS AND TS THOUGH SOME
DRIFTING STORMS LATER IN THE DAY MAY BRING SOME CONVECTION TO
VALLEY LOCATIONS. SOME HEAVY RAIN WILL DROP VIS BRIEFLY UNDER
STRONGER STORMS THOUGH FLT CONDITIONS WILL GENERALLY REMAIN VFR
FOR THE NEXT 24 HOURS. AFTER 03Z...MOST CONVECTION WILL DIE DOWN
THOUGH SOME ISOLD SHOWERS/STORMS MAY PERSIST OVERNIGHT.

&&

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

$$

SHORT TERM...JAM
LONG TERM...EH
AVIATION...TGR



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