National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KGJT 280322
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
922 PM MDT SUN JUL 27 2014

.UPDATE...
ISSUED AT 910 PM MDT SUN JUL 27 2014

LATEST GUIDANCE CONTINUES TO SHOW INCREASING PRECIP ACROSS THE
CWA MONDAY...REACHING A MAXIMUM TUESDAY...BEFORE SLOWLY DROPPING
DOWN ON WEDNESDAY. AS FAR AS MOISTURE GOES...FORECAST PWATS RANGE
FROM 1 TO 1.3 INCHES MONDAY DUE TO CONTINUED MONSOONAL FLOW.  A
WEAK DISTURBANCE IS PROGGED TO MOVE OVER THE AREA AND WILL BE THE
FOCUS OF CONVECTION. AS THIS OCCURS...FAIRLY WEAK STEERING FLOW
ALOFT WILL ALLOW ANY STORMS AND SHOWERS THAT FORM TO BE SLOW
MOVERS. THESE INGREDIENTS LEND THEMSELVES TO INCREASED FLASH
FLOODING RISKS SO A FLASH FLOOD WATCH HAS BEEN ISSUED FROM NOON
THROUGH MIDNIGHT. AS IS THE CASE WITH THESE SITUATIONS...SOME
AREAS UNDER THE WATCH WILL SEE LITTLE TO NO RAIN WHILE OTHERS WILL
SEE PLENTY DEPENDING ON WHERE THE STRONGEST CELLS SET UP. TUESDAY
LOOKS TO HAVE WIDER COVERAGE SO FLASH FLOODING REMAINS POSSIBLE
THEN AND AGAIN INTO WEDNESDAY.

&&

.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 350 PM MDT SUN JUL 27 2014

AN AREA OF CLOUDS AND GENERALLY LIGHT SHOWERS THIS MORNING ALONG
AND NORTH OF THE TAVAPUTS TO FLATTOPS...HAS ACTED TO SUPPRESS
THUNDERSTORM ACTIVITY IN THE NORTH SO FAR THIS AFTERNOON. WHILE
THIS ACTIVITY HAS DIMINISHED...SOME SHOWERS LINGER. EXPECT BY
LATER THIS AFTERNOON A FEW THUNDERSTORMS WILL DEVELOP OVER THOSE
MOUNTAINS AS MORE SUNSHINE REACHES THE GROUND THERE. OTHERWISE
CONVECTION THROUGH EARLY THIS AFTERNOON HAS BEEN CONFINED MOSTLY
TO THE SOUTHERN PORTION OF THE FORECAST AREA...FOCUSED MAINLY ON
THE SAN JUAN...ABAJO AND LA SAL MOUNTAINS. THUNDERSTORMS HAVE
BEGUN TO SHIFT NORTH ALONG THE UNCOMPAHGRE PLATEAU. EXPECT STORMS
WILL ALSO BEGIN TO DEVELOP OVER OTHER MOUNTAIN AREAS DURING THE
NEXT COUPLE HOURS...WITH ISOLATED STORMS MOVING INTO THE VALLEYS.
OVERALL HOWEVER ACTIVITY HAS BEEN A LITTLE LESS THAN YESTERDAY.
THAT SAID...STORMS ARE SLOW MOVING AND WITH LOCALIZED HEAVY RAIN
POSSIBLE INTO THE EVENING HOURS.

THE SOUTHERLY FLOW WILL BECOME MORE PRONOUNCED ACROSS THE ENTIRE
FORECAST AREA TONIGHT WITH A SERIES OF EMBEDDED DISTURBANCES
PASSING ACROSS THE REGION DURING THE NEXT COUPLE OF DAYS. THIS
SOUTHERLY FLOW WILL ALSO BRING A DEEP SURGE OF MONSOONAL MOISTURE
TO THE AREA BEGINNING TONIGHT. THEREFORE EXPECT THAT WE WILL SEE
BETTER COVERAGE OF NOCTURNAL SHOWERS AND THUNDERSTORMS OVERNIGHT.

THE NAM SHOWS PRECIPITABLE WATER VALUES INCREASING TO 1.30 INCHES
IN THE FOUR CORNERS BY EARLY MONDAY...AND AROUND 1.25 INCHES IN
NORTHEAST UT BY MON AFTERNOON. MODELS ALSO SHOW THE FIRST...BUT
WEAKER...WAVE MOVING NORTHWARD INTO THE AREA ON MON...AFFECTING
MAINLY THE SOUTHERN HALF. WE SHOULD SEE AN UPTICK IN SHOWERS AND
THUNDERSTORMS DUE TO THE COMBINATION OF DAYTIME HEATING...
INSTABILITY SUPPLIED BY THE DISTURBANCE...AND THE DEEP AVAILABLE
MOISTURE. HEAVY RAIN WILL BE POSSIBLE WITH A FEW STORMS...
AGGRAVATED BY SLOW STORM MOVEMENT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 350 PM MDT SUN JUL 27 2014

AN ACTIVE MONSOONAL DAY IS ANTICIPATED FOR TUESDAY WITH HEAVY RAIN
POSSIBLE AS AN UPPER LOW CIRCULATION CURRENTLY ALONG THE BAJA COAST
ROTATES ACROSS OUR AREA DURING THE AFTERNOON AND EVENING HOURS.
MODELS HAVE BEEN SHOWING THIS WAVE AFFECTING OUR AREA ON TUESDAY FOR
THE PAST SEVERAL DAYS...GIVING CONFIDENCE TO THE FORECAST.
PRECIPITABLE WATER VALUES PEAK AROUND 1.30 INCHES OR LOCALLY MORE
DEPENDING ON THE MODEL FOR THE POSSIBILITY OF HEAVY RAIN AND THE
ASSOCIATED THREATS OF FLASH FLOODING AND MUD/DEBRIS FLOWS. NAM12
SHOWED POCKETS OF K-INDEX > 40 WHICH CAN ALSO BE AN INDICATOR OF
HEAVY RAIN AND FLASH FLOODING. BEST DYNAMIC FORCING PER 300 MB UPPER
DIVERGENCE AND DEEP-LAYER OMEGA APPEARS TO BE ACROSS THE NORTH
HALF OF THE FORECAST AREA AS THE CENTER OF THE WAVE EVENTUALLY
TRACKS ALONG THE WY/CO BORDER TUE EVENING...BUT WILL NOT DISCOUNT
THE MOIST S-SW FLOW INTO THE SRN MTNS EITHER. WHILE INSTABILITY IS
PRESENT IN THE MODELS...EXTENSIVE MORNING CLOUD COVER MAY LIMIT
THUNDERSTORM DEVELOPMENT SO THAT RAIN SHOWERS/HEAVY RAIN MAY BE
THE PREDOMINANT WEATHER TYPE TUESDAY AFTERNOON AND EVENING. RIGHT
NOW...WILL ISSUE A SPECIAL WEATHER STATEMENT...AND ALSO A MULTIMEDIA
WEATHER BRIEFING ON OUR YOUTUBE AND FACEBOOK SITES...ADDRESSING
THIS ANTICIPATED MONSOONAL SURGE. LATER SHIFTS CAN ADDRESS THE
FLASH FLOOD WATCH QUESTION. KNOCKED DOWN HIGH TEMPS A BIT MORE FOR
TUE DUE TO CLOUDS AND RAIN.

MODELS SHOW SOME DRYING BEHIND THIS WAVE FOR THE LAST HALF OF NEXT
WEEK. SHOULD TRANSITION BACK TO A MORE TYPICAL PATTERN OF ISOLATED
TO SCATTERED MAINLY AFTERNOON/EVENING THUNDERSTORMS THU-SUN AS
LINGERING MOISTURE GETS RECYCLED UNDERNEATH AN UPPER RIDGE ALOFT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 518 PM MDT SUN JUL 27 2014

GUSTY WINDS BEING REPORTED ACROSS THE AREA AND SOME HEAVY RAIN IS
DROPPING VIS UNDER THE STRONGER STORMS AND SHOWERS THIS EVENING. MOST
CONVECTION WILL DIE DOWN BY 03Z WITH AN OCCNL SHOWER/STORM
CONTINUING OVERNIGHT. KDRO AND KTEX MAY SEE SOME OF THIS OVERNIGHT
PRECIP BUT MEDIUM TO LOW CONFIDENCE KEEPS VFR GOING IN THE TAFS.
TOMORROW IS A DIFFERENT STORY AS A WAVE MOVES ACROSS THE AREA WITH
PLENTY OF MOISTURE TO WORK WITH. HEAVY RAIN IS EXPECTED FOR MUCH
OF THE FORECAST AREA AND ALSO MUCH OF THE DAY WITH STRONG STORMS
AND SHOWERS BEING COMMON. ALL TAF SITES HAVE A CHANCE TO SEE TS ON
STATION WITH MVFR...TO POSSIBLY IFR...CONDITIONS POSSIBLE AS VIS
DROPS UNDER HEAVIER SHOWERS. NO TEMPO GROUPS YET WITH CONVECTION
SO FAR OUT.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FLASH FLOOD WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR COZ009-011-012-014-017>023.

UT...FLASH FLOOD WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
     FOR UTZ022-028-029.

&&

$$

UPDATE...TGR
SHORT TERM...EH
LONG TERM...JAD
AVIATION...TGR