Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Text Only | 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 041023
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
423 AM MDT MON MAY 4 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 422 AM MDT MON MAY 4 2015

MOISTURE HAS CONTINUED TO INCREASE UNDER A SOUTH/SOUTHWEST FLOW OVER
THE REGION. THE 04/00Z GJT SOUNDING SHOWED 0.55 OF AN INCH OF
PRECIPITABLE WATER...A LITTLE BETTER THAN 150 PERCENT OF NORMAL
FOR EARLY MAY. MODELS INDICATED THAT MOISTURE WILL CONTINUE TO
INCREASE TODAY THROUGH TUESDAY AS THE LOW PRESSURE SYSTEM ALONG
THE SOUTHERN CALIFORNIA/BAJA COAST MOVES ONSHORE AROUND MIDDAY
TODAY...THEN OVER THE FOUR CORNERS EARLY TUE. THE NAM SHOWS PW
WILL REACH 0.6-0.7 OF AN INCH WITH AREAS OF 0.75+ OF AN INCH BY
LATE TODAY THROUGH TUE. ALSO...INSTABILITY ASSOCIATED WITH THIS
APPROACHING LOW PRESSURE TROUGH WILL BOOST THE DIURNALLY DRIVEN
CONVECTION. THEREFORE...WE CAN EXPECT TO SEE AN INCREASE IN
SHOWER AND THUNDERSTORM COVERAGE THIS AFTERNOON AND EVENING. WHILE
ACTIVITY WILL DIMINISH SOMEWHAT BY LATE THIS EVENING...EXPECT
NOCTURNAL SHOWERS AND THUNDERSTORMS TO PERSIST THROUGH THE NIGHT
AS THE DISTURBANCE APPROACHES.

AS THE LOW CENTER TRACKS FROM SOUTHWEST TO NORTHEAST ACROSS OUR
FORECAST AREA ON TUE...CONVECTION WILL AGAIN INCREASE OVER THE
PREVIOUS DAY. BY AFTERNOON...WIDESPREAD SHOWERS AND THUNDERSTORMS
CAN BE EXPECTED...FAVORING THE MOUNTAINS. THE FLOW BECOMES
WESTERLY AND PICKS UP FOR A LITTLE BETTER FOR STORM MOVEMENT
DURING THE AFTERNOON.

TEMPERATURES TODAY WILL BE SIMILAR TO SUNDAY/S...WHICH IS JUST A
TAD ABOVE NORMAL. THE AIR MASS REMAINS WARM BUT CLOUDS AND SHOWERS
WILL AGAIN LIMIT DAYTIME HEATING. ALSO...LITTLE CHANGE IN
OVERNIGHT LOWS EXPECTED TONIGHT. DUE TO INCREASED PRECIPITATION
ON TUE...AND WITH SOME COOLING AS THE LOW TRACKS ACROSS THE
AREA...DAYTIME HIGHS WILL BE NOTICEABLY COOLER THAN ON MON.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 422 AM MDT MON MAY 4 2015

EXPECT SHOWERS AND EMBEDDED THUNDERSTORMS TO CONTINUE TUESDAY
NIGHT IN RESPONSE TO JET LEVEL DIFFLUENCE BETWEEN THE NORTHERN AND
SOUTHERN STREAMS WORKING ON THE UNSEASONABLY MOIST AIRMASS.
DIFFLUENCE COMBINES WITH DAYTIME HEATING AND RESIDUAL MOISTURE TO
BRING ANOTHER ACTIVE DAY ACROSS MUCH OF THE REGION WEDNESDAY WITH
THE BULK OF THE ACTIVITY OCCURRING DURING THE AFTERNOON AND
EVENING. THE FOUR CORNERS AREA LIKELY TO BE QUIETER IN COMPARISON
AS DRIER AIR BEGINS TO FILTER OVER THE AREA FROM THE SOUTHWEST
AHEAD OF A DEEPENING TROUGH OVER THE WEST COAST.

THE DRYING TREND WILL CONTINUE THURSDAY AND FRIDAY AS PRECIPITABLE
WATER LEVELS FALL TO NEAR 0.30 OF AN INCH AS DRY SOUTH/SOUTHWEST
FLOW CONTINUES TO SWEEP OVER THE AREA. HOWEVER...DIFFLUENCE AHEAD
OF THE PACIFIC SYSTEM...WHICH CLOSES OFF OVER THE GREAT BASIN...
COMBINES WITH DIURNAL WARMING TO GENERATE ISOLATED SHOWERS AND
THUNDERSTORMS OVER THE HIGHER TERRAIN EACH AFTERNOON AND EVENING.
THIS ACTIVITY WILL BE LARGELY HIGH BASED SO EXPECT STRONG OUTFLOW
WINDS BUT LITTLE MEASURABLE PRECIPITATION.

LATEST GUIDANCE NOW TAKES THE LOW CENTER DIRECTLY ACROSS THE
FORECAST AREA SATURDAY WITH WRAP-AROUND MOISTURE ON THE BACK SIDE
OF THE SYSTEM IMPACTING THE REGION INTO SUNDAY. THIS SOLUTION IS A
DEPARTURE FROM THE 00Z/SUNDAY SOLUTIONS WHICH CARRIED THE SYSTEM
LARGELY NORTH OF THE FORECAST AREA. GIVEN EVOLVING MODEL SOLUTIONS
SEEMS REASONABLE TO BEGIN TO RAISE POPS...BUT TO KEEP CHANGES
SMALL UNTIL CONFIDENCE LEVEL RISES WITH BETTER RUN-TO-RUN
CONSISTENCY.

CONTINUATION OF UNSETTLED CONDITIONS WILL KEEP TEMPERATURES JUST A
BIT BELOW SEASONAL NORMS THROUGHOUT THE REMAINDER OF THE WEEK...
AND POSSIBLY MARKEDLY SO THIS WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 422 AM MDT MON MAY 4 2015

ISOLATED SHOWERS WILL RESULT IN LOCALIZED OBSCURATION OF MOUNTAIN
TOPS THIS MORNING. DAYTIME WARMING WILL BRING INCREASED SHOWER
COVERAGE AND INTENSITY FROM 18Z TO 03Z ALONG WITH EMBEDDED
THUNDERSTORMS. OUTFLOW WINDS FROM 30 TO 40 MPH ARE POSSIBLE IN THE
VICINITY OF STRONGER STORM CELLS. AIRPORTS ACROSS THE REGION FACE
A 30 TO 40 PERCENT CHANCE OF RAINFALL DURING THE AFTERNOON AND
EARLY EVENING THOUGH ITS LIKELY THAT VFR CONDITIONS WILL PERSIST
REGARDLESS. SHOWERS WILL DECREASE OVERNIGHT WITH MINIMAL IMPACT ON
FLIGHT ACROSS EASTERN UTAH AND WESTERN COLORADO.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

&&

$$

SHORT TERM...EH
LONG TERM...NL
AVIATION...NL



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