Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 282131
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
331 PM MDT SUN SEP 28 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 331 PM MDT SUN SEP 28 2014

FORECAST AREA IN A BIT OF A LULL THIS AFTERNOON WITH JUST A FEW
SCATTERED THUNDERSTORMS CONTINUING ALONG THE BORDER AREA BETWEEN
UTAH AND COLORADO AND THE NORTHERN MOUNTAINS OF COLORADO. MODELS
INDICATED MID-LEVEL DRYING WORKING ACROSS THE AREA WHICH HAS
LIMITED CONVECTION ALONG WITH SUBSIDENCE ON THE BACKSIDE OF THE
SHORTWAVE WHICH PUSHED ACROSS THE REGION EARLIER IN THE DAY.
MEANWHILE...THOUGH MOISTURE HAS DECREASED...MODELS CONTINUED TO
INSIST THAT STORMS WILL REDEVELOP OVER SOUTHWEST COLORADO DURING
THE LATE AFTERNOON SO WILL CONTINUE FLASH FLOOD WATCH FOR THE
SOUTHWEST SAN JUAN MOUNTAINS IN ADDITION TO THE LOWER ELEVATIONS
OF LA PLATA AND ARCHULETA COUNTIES THROUGH 6 PM.

ANOTHER LOBE OF ENERGY MOVING DOWN THE BACKSIDE OF THE UPPER LOW
WILL CAUSE THE CIRCULATION TO SHIFT OVER WESTERN UTAH DURING THE
NIGHT. AS THE LOW SHIFTS...A DRY SLOT WILL WORK OVER SOUTHEAST
UTAH PRETTY MUCH ENDING PRECIPITATION CHANCES. DIVERGENCE OVER
THE NORTHERN PORTION OF THE FORECAST AREA SHOULD LEAD TO INCREASED
COVERAGE THIS EVENING. MEANWHILE...OROGRAPHIC LIFT AND INSTABILITY
WILL CONTINUE TO GENERATE SHOWERS AND A FEW EMBEDDED THUNDERSTORMS
OVER THE SAN JUANS AND ADJACENT VALLEYS. CONTINUED DRYING AND
DIURNAL COOLING WILL RESULT IN A DECREASE IN ACTIVITY LATER
TONIGHT...THOUGH A FEW SHOWERS WILL LINGER MAINLY OVER THE
NORTHERN AND SOUTHERN REACHES OF THE FORECAST AREA.

SHOWERS AND THUNDERSTORMS WILL INCREASE AGAIN MONDAY AS A STRONG
VORT LOBE ROTATES THROUGH THE BASE OF THE TROUGH AND ON TO THE
NORTHEAST CROSSING THE FORECAST AREA. PRECIPITABLE WATER
UNIFORMLY NEAR 0.5 INCHES WHILE INSTABILITY MARGINAL AND MUCAPE
UNIMPRESSIVE. CONSEQUENTLY...EXPECT DEVELOPING STORMS WILL BE
RELATIVELY WEAK AND UNLIKELY TO GENERATE EXCESSIVE RAINFALL.
DRYING COMES MONDAY NIGHT...THOUGH SHOWERS MAY LINGER OVER THE
NORTHERN MOUNTAINS. SNOW LEVELS LOW ENOUGH FOR LIGHT ACCUMULATIONS
ABOVE 10000 FEET DURING THE NEXT 36 HOURS. IN FACT ...STRONGER
CONVECTIVE CELLS COULD BRING SNOW LOWER AS EVIDENCED BY PICTURE
RECEIVED OF LONE CONE IN THE SAN JUAN MOUNTAINS WHICH INDICATED
SNOW ACCUMULATIONS DOWN TO...OR PERHAPS A BIT BELOW 9000 FEET.

TEMPERATURES TONIGHT WILL BE CHILLY AND COLDER YET MONDAY NIGHT...
THOUGH STILL ABOVE FREEZING FOR THE VALLEYS. MONDAY/S HIGHS WILL
BE SIMILAR TO THOSE EXPERIENCED TODAY...OR ROUGHLY 10 DEGREES
BELOW NORMAL.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 331 PM MDT SUN SEP 28 2014

A LARGE-SCALE TROUGH WILL REMAIN OVER THE ROCKIES THROUGH MIDWEEK
BEFORE SHIFTING OVER THE EASTERN STATES BY NEXT WEEKEND. TUESDAY
LOOKS LIKE AN IN-BETWEEN DAY WITH WESTERLY OROGRAPHIC FLOW KEEPING
SOME SCATTERED SHOWERS AND HIGH ELEVATION SNOW AROUND FOR THE NRN
MTNS. AN EMBEDDED DISTURBANCE IN THE NW FLOW WILL BRING AN INCREASE
IN SHOWER COVERAGE ON WED AS IT BRINGS A REINFORCING PUSH OF COOLER
AIR WED-WED NIGHT. ISOLATED THUNDERSTORMS MAY ALSO BE POSSIBLE.
MODELS WERE IN REASONABLE AGREEMENT SO BLENDED IN THE LATEST
CONSENSUS MODEL POPS FOR WED. CLEARING SKIES LATE WED NIGHT TO
FREEZING TEMPS THU MORNING IN SOME VALLEYS.

A PACIFIC RIDGE OF HIGH PRESSURE WILL BEGIN TO PUSH INLAND LATE THIS
WEEK BRINGING DRY WEATHER THU-SUN. TEMPERATURES...WHICH WILL AVERAGE
NEAR TO COOLER THAN NORMAL FOR MUCH OF THIS WEEK...WILL BEGIN A
WARMING TREND FRI.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1049 AM MDT SUN SEP 28 2014

WIDESPREAD RAIN SHOWERS WILL PERSIST OVER THE AREA INTO THIS
EVENING...THEN BECOME MORE LOCALIZED OVERNIGHT. THUNDERSTORMS
EMBEDDED IN THE SHOWERS WILL ALSO INCREASE FROM THE SOUTH AND
WEST EARLY THIS AFTERNOON...WITH PEAK THUNDERSTORM ACTIVITY
EXPECTED DURING THE LATE AFTERNOON TO EARLY EVENING PERIOD. AT
AREA AIRPORTS VFR WILL BE THE PREDOMINANT FLIGHT CATEGORY...
HOWEVER BRIEF PERIODS OF MVFR OR EVEN IFR WILL BE POSSIBLE IN THE
HEAVIER SHOWERS. WIDESPREAD MOUNTAIN OBSCURATIONS ARE EXPECTED.
THE STRONGEST THUNDERSTORMS MAY PRODUCE STRONG GUSTY OUTFLOW
WINDS IN EXCESS OF 45 KTS AND/OR SMALL HAIL UP TO ONE HALF INCH.
SHOWERS AND ESPECIALLY THUNDERSTORMS WILL DIMINISH OVERNIGHT.
WHILE ACTIVITY WILL BE LESS ON MONDAY THE CHANCE OF SHOWERS AND
THUNDERSTORMS WILL CONTINUE. MORNING FOG WILL BE POSSIBLE IN MOST
VALLEY AREAS.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...FLASH FLOOD WATCH UNTIL 6 PM MDT THIS EVENING FOR COZ019-022-023.

UT...NONE.

&&

$$

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



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