Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 312055
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
255 PM MDT MON AUG 31 2015

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 254 PM MDT MON AUG 31 2015

FAIRLY IMPRESSIVE AMOUNT OF WATER OVER OUR REGION ON THE 12Z KGJT
RAOB...WITH A PWAT OF 1.03...WETTER THAN ALL BUT 5 PERCENT OF PAST
DAYS ON THIS DATE. THIS MORNING/S SHORT WAVE IS EXITING OUR EASTERN
CWA VIA THE CENTRAL DIVIDE THIS AFTERNOON. MEANWHILE OUT
WEST...UPPER LEVEL WIND SUPPORT COMBINED WITH LOW AND MID LEVEL
INSTABILITY IS STARTING TO ACT ON THE MOISTURE PLUME TO PRODUCE
SOME RATHER ROBUST CONVECTION. STORM STRUCTURE WILL MAINLY BE
MULTI CELLULAR BUT RADAR TRENDS APPEAR TO SHOW THAT A FEW STORMS
MAY BE CAPABLE OF PRODUCING SOME HAIL AND HEAVY RAINFALL RATES.
WILL HAVE TO WATCH ANY TRAINING OF ECHOS FOR THE FLOODING
POTENTIAL. POTENTIAL VORT FIELDS WOULD INDICATE A LOT OF THE
SUPPORT LIFTING NORTH BY MID EVENING WITH A DOWNTURN OF CONVECTION
EXPECTED. THIS 1.5 PVU FIELD ALSO SHOWS A WEAK LATE NIGHT WAVE
MOVING INTO OUR SOUTHWEST CWA AND SOME MODELS SUGGEST SOME
ISOLATED CONVECTION SURVIVING INTO THE EARLY MORNING HOURS.

TUE AND TUE NIGHT THE TROUGH MOVING INTO THE PACNW STRENGTHENS AND
DIGS SOUTH A BIT...TIGHTENING THE GRADIENT FOR SLIGHTLY STRONGER
WINDS OVER NW CO AND NE UT. THIS ALSO BRINGS IN A BIT OF SPEED
SHEAR ALOFT AND A MINOR VORT MAX TRAVELING ACROSS THE AREA FROM SW
TO NE. ALL THIS SHOULD ENHANCE THUNDERSTORM DEVELOPMENT A BIT
THROUGH EARLY EVENING. TUE NIGHT THE MOISTURE PLUME FROM THE
SOUTH IS FORCED TO THE EAST WITH THE MAIN BAND OF MOISTURE OVER SE
CO AND NRN NM AND BARELY CLIPPING THE SAN JUAN MTS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 254 PM MDT MON AUG 31 2015

WEDNESDAY APPEARS TO BE THE DRIEST DAY AS THE SOUTHERN MOISTURE
SHOULD REMAIN SOUTH AND EAST OF THE AREA...AND A DRY SLOT OVER THE
FORECAST AREA AHEAD OF A DEVELOPING LOW IN THE NW.

THURSDAY THROUGH MONDAY SHOW A LARGE DIVERGENCE OF SOLUTIONS IN
THE MIDRANGE MODELS. THE GFS...FOR EXAMPLE...BEGINS TO DRAW
MOISTURE INTO THE AREA FROM THE SOUTH AS IT STRENGTHENS THE LOW
OVER THE NW U.S. BY FRIDAY MORNING. IT PRODUCES A STRONG CLOSED
LOW OVER THE PACNW AND A SIGNIFICANT MONSOONAL MOISTURE PLUME OVER
MUCH OF THE FORECAST AREA...WHICH ALSO INCLUDES THE REMNANTS OF A
TROPICAL DEPRESSION. FRI AND FRI NGT IN THE GFS APPEAR
PARTICULARLY WET ACROSS THE AREA. THE ECMWF SHOWS THE SAME GENERAL
FLOW PATTERN BUT FEEDS MUCH LESS MOISTURE INTO THE PLUME AND
MOISTURE FROM THE TROPICAL DEPRESSION ADDED TO THE FLOW UNTIL
FRIDAY NIGHT. WHILE THE GFS SHOWS DRYING SATURDAY WITH A DRY SLOT
ASSOCIATED WITH THE NORTHERN TROUGH PUSHING ACROSS THE AREA...THE
EC SHOWS SATURDAY AND SATURDAY NIGHT AS ITS WETTEST PERIOD FOR OUR
AREA.

SUNDAY AND MONDAY SHOWS MODERATE SW FLOW ALOFT OVER THE CENTRAL
ROCKIES AND SWRN U.S. THE GFS IS MUCH QUICKER IN MOVING THE
NORTHWEST LOW EAST WHILE THE EC HAS A DEEPER AND SLOWER MOVING
FEATURE. ALL MEANS A GOOD DEAL OF UNCERTAINTY IN THE FORECAST FROM
THURSDAY THROUGH MONDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 254 PM MDT MON AUG 31 2015

MOIST AND UNSTABLE ATMOSPHERE WILL KEEP SHOWERS AND THUNDERSTORMS
ACROSS MUCH OF THE AREA THROUGH THIS EVENING. SOME STORMS WILL BE
STRONG WITH SMALL HAIL...HEAVY RAIN AND WIND GUSTS TO 35 MPH. THE
STRONGEST CELLS WILL BE OVER NE UT AND NW CO NORTH OF THE
BOOKCLIFFS WITH AREAS OF MOUNTAIN OBSCURATION. KVEL IS MOST
LIKELY TO SEE CIGS AND VSBYS DEGRADED FROM STRONGER STORMS...
BRIEFLY DOWN TO MVFR THROUGH ABOUT 03Z. ALL OTHER TAF SITES HAVE
ABOUT 10 TO 20 PERCENT RISK OF BEING AFFECTED BY A STORM WITH
FLIGHT CONDITIONS DOWN TO ILS CUTOFFS.

SHOWERS AND THUNDERSTORMS SHOULD DECREASE AFTER 03Z BUT NOT
ENTIRELY DISSIPATE. EXPECT LOCAL MOUNTAIN TOP OBSCURATIONS.
SIMILAR THUNDERSTORM DEVELOPMENT IS EXPECTED TUE AFTERNOON THOUGH
SHIFTED EAST AND SOUTH.

&&

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

$$

SHORT TERM...15/CC
LONG TERM...CC
AVIATION...CC


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