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000
FXUS65 KGJT 301654
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
954 AM MST SAT NOV 30 2013

.UPDATE...
ISSUED AT 805 AM MST SAT NOV 30 2013

EXPANDED THE DENSE FOG INTO PORTIONS OF NORTHWEST AND CENTRAL
COLORADO.

UPDATE ISSUED AT 448 AM MST SAT NOV 30 2013

DECIDED TO ISSUE A DENSE FOG ADVISORY FOR EXTREME SOUTHWEST CO AND
SOUTHEAST UT UNTIL 10 AM THIS MORNING. AUTOMATED OBSERVATIONS AT
THE CORTEZ AND FARMINGTON, NM AIRPORTS INDICATED 1/4 MI VISIBILITY
IN FOG...AND SATELLITE FOG PRODUCTS SHOWS THAT THIS COULD EXTEND
ACROSS THE FOUR CORNERS INTO SE UT. A CALL TO THE MONTEZUMA
SHERIFF OFFICE CONFIRMED DENSE FOG BETWEEN CORTEZ AND TOWAOC.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 341 AM MST SAT NOV 30 2013

LOW CLOUDS AND SOME FOG PERSISTS ACROSS MUCH OF ERN UT AND PARTS OF
WRN CO EARLY THIS MORNING. EXPECT THIS TO CONTINUE FOR ANOTHER DAY
AND ADJUSTED THE SKY AND TEMP GRIDS ACCORDINGLY.

BUT CHANGE IS NEARING. THE DEFORMATION AREA SHOULD WEAKEN TONIGHT AS
THE UPPER LOW SOUTHWEST OF SRN CA RETREATS FARTHER AWAY FROM LAND
AND THE NORTHERN STREAM BECOMES MORE INFLUENTIAL. A SHORTWAVE
TROUGH ON THE NOSE OF THE PACIFIC JET MOVING INTO WA/OR WILL RACE
ACROSS NW CO NORTH SUNDAY MORNING. 305K/310K ISENTROPIC SURFACES
SHOW MID-LEVEL CLOUDS INCREASING ACROSS THE NORTH LATE TODAY AND
TONIGHT AHEAD OF IT AS PACIFIC MOISTURE GETS TRANSPORTED INLAND.
THE DENDRITIC ZONE SATURATES OVER THE CO NRN MTNS SUNDAY MORNING
FOR EFFICIENT SNOW PRODUCTION AIDED BY STRENGTHENING W-NW
OROGRAPHIC FLOW. IN FACT...IT LOOKS TO BECOME RATHER WINDY ACROSS
THE NRN MTNS SUNDAY. BOOSTED THE CHANCE OF SNOW TO THE LIKELY
CATEGORY FOR THE ELKHEAD/PARK RANGES WHERE A COUPLE INCHES OF SNOW
IS ANTICIPATED. UNFORTUNATELY... MOISTURE DROPS OFF FAIRLY QUICKLY
MOVING SOUTH FOR JUST A SLIGHT CHANCE/CHANCE FOR THE ELK MTNS TO
VAIL.

THIS FAST-MOVING TROUGH FOLLOWED BY COLD ADVECTION MAY BE ENOUGH TO
HELP BREAK UP THE STAGNANT AIR AND LOW CLOUDS NORTH OF INTERSTATE 70
SUNDAY. THE CENTRAL VALLEYS AND THE VALLEYS IN SE UT ARE MORE IFFY
BUT GENERALLY KEPT THE FLAVOR OF LESSER CLOUDS AND FOG IN THE GRIDS
ESTABLISHED BY THE PREVIOUS SHIFT.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 341 AM MST SAT NOV 30 2013

WHILE SMALL DISCREPANCIES REMAIN...THE BIG PICTURE STAYS THE SAME.
AFTER A MODESTLY CALM WEEKEND...NEXT WEEK WILL BRING CONSIDERABLY
COLDER TEMPERATURES AND SNOW TO MUCH OF THE REGION. COME SUNDAY
NIGHT...UPPER LEVEL SUPPORT INCREASES AS THE POLAR JET APPROACHES
FROM THE NW. LITTLE PIECES OF ENERGY EMBEDDED IN THE JET...ALONG
WITH FAVORED OROGRAPHICS...WILL CAUSE SNOW OVER THE NORTHERN MTNS
WITH A FEW INCHES OF SNOW POSSIBLE THROUGH MONDAY. SHOULD MENTION
THAT THE NAM12 IS MORE AGGRESSIVE WITH SNOWFALL FOR THAT AREA
WHILE GFS/EC MUCH LESS SO. AS EC HAS BEEN MOST CONSISTENT...WHICH
ISN/T SAYING MUCH...BELIEVE NAM12 OVERDONE AND WILL GO WITH EC/GFS
AMTS...1 TO MAYBE AS MUCH AS 3 INCHES.

THE MUCH TOUTED CLOSED LOW WILL BE OVER THE PACNW MONDAY MORNING
AND WILL SWING DOWN TO THE ID/UT BORDER BY TUESDAY. EXPECT WINDS
TO PICK UP TUESDAY AS THE LOW APPROACHES. A STRONG SFC COLD FRONT
WILL ACCOMPANY THIS LOW AND WILL BE JUST ENTERING THE CWA TUESDAY
EVENING. QG FORCING CORROBORATES THIS SOLN AS PLENTY OF LARGE
SCALE ASCENT IS ASSOD WITH THE LOW AND FRONT. THOUGH SOME SMALL
TIMING DIFFERENCES REMAIN AS TO WHEN FRONT WILL MOVE THROUGH...TUE
EVENING THROUGH WED MORNING LOOKS ABOUT RIGHT. MODELS DEPICT
PRECIP MOVING THROUGH WITH THE FRONT SO ANY PRECIP THAT STARTS AS
RAIN WILL VERY QUICKLY SWITCH TO SNOW. THIS IS BORNE OUT AS THE
THICKNESS GRADIENT IS EXCEEDINGLY TIGHT ALONG AND BEHIND THE FRONT
INDICATING VERY COLD AIR. SO...PRECIP SHOULD START LATE
TUESDAY/EARLY WEDNESDAY AND CONTINUE THROUGH WED EVENING WITH
ACCUMULATING SNOW LIKELY FOR MANY AREAS INCLUDING VALLEY
LOCATIONS. AT THIS TIME THE NRN AND CENTRAL MTNS LOOK
FAVORED...ESPECIALLY NW FACING SLOPES...AS DO THE CENTRAL AND NRN
VALLEYS THOUGH SOME SNOW FOR THE SAN JUANS IS NOT OUT OF THE
QUESTION. SNOWFALL AMOUNTS ARE A LITTLE IFFY ATTM BUT DO EXPECT
HIGHLIGHTS WITH THIS SYSTEM.

ONCE THE FRONT MOVES THROUGH...THE NORTHERLY AND SOUTHERLY
PORTIONS OF THE JET STREAM WILL MERGE INTO ONE PIECE STRETCHING
FROM OLD MEXICO UP TO NY STATE. AS THE JET LIFTS OUT...A DEEP
TROUGH WILL STRETCH FROM THE UP OF MICHIGAN ALL THE WAY TO THE
PACIFIC WITH SEVERE WEATHER LOOKING INCREASINGLY LIKELY FROM OK
AND TX EWRD THURSDAY. FOR OUR CWA...BITTERLY COLD ARCTIC AIR WILL
FILTER DOWN FROM THE NORTH CAUSING HIGHS TO BE ABOUT 10 DEGREES
BELOW NORMAL WHILE LOWS WILL BE ANYWHERE FROM 10 TO 15 DEGREES
BELOW NORMAL FRIDAY AND AGAIN SATURDAY MORNING. ANOTHER CONCERN
WILL BE FOG AND LOW STRATUS THAT MAY STAY CONFINED TO THE VALLEYS AS
SEEN THIS PAST WEEK DUE TO RESIDUAL MOISTURE FROM THE SNOWFALL.

A VERY BUSY WEEK IN STORE WITH SOME BIG CHANGES TOWARDS THE END OF
THE WEEK. PLEASE KEEP AN EYE ON YOUR FAVORITE WEATHER SOURCE AS
THE FINER DETAILS OF THIS STORM BECOME MORE APPARENT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 954 AM MST SAT NOV 30 2013

LOW STRATUS AND FOG MAINTAINED ITS GRIP ACROSS THE LOWER VALLEYS
WEST OF OF A KDWX-KCAG-KEGE-KMTJ-KAIB-KCEZ LINE THIS MORNING.
EXPECT THERE WILL BE EROSION DUE TO CONVECTIVE CURRENTS ALONG THE
EDGES OF THE STRATUS FIELD DURING THE AFTERNOON. HOWEVER...THE
STAGNANT...INVERTED AIRMASS IS UNLIKELY TO BE ALTERED BY THE
PERSISTENT WEAK WESTERLY FLOW ALOFT. THEREFORE...STRATUS AND LIGHT
FOG WILL CONTINUE THROUGH THE DAY FOLLOWED BY AN EXPANSION
EASTWARD TONIGHT. FALLING TEMPERATURES WILL CAUSE FOG TO SPREAD
AND BECOME MORE DENSE OVERNIGHT AND INTO SUNDAY MORNING. THE ONLY
EXCEPTION TO THIS RULE WILL BE ACROSS THE NORTH...WHERE AN UPPER
LEVEL DISTURBANCE MAY WEAKEN INVERSIONS CAUSING CLOUDS TO LIFT
WHILE FOG DECREASES IN COVERAGE AND INTENSITY. IFR CIGS AND VSBY
WILL LINGER IN SOME OF THE HIGHER VALLEYS THROUGH 1300 BEFORE
GIVING WAY TO MVFR CIGS. MEANWHILE...THE LOWER VALLEYS WILL CONTINUE
TO EXPERIENCE MVFR CIGS THROUGHOUT THE DAY AND INTO SUNDAY
MORNING. AREAS WEST OF THE LINE DESCRIBED ABOVE WILL HAVE VFR
CONDITIONS THROUGHOUT THE NEXT 24 HOURS. THE ONLY EXCEPTION BEING
THE NORTHERN COLORADO MOUNTAINS WHERE THE DISTURBANCE MENTIONED
PREVIOUSLY WILL BRING SCATTERED TO NUMEROUS SNOW SHOWERS RESULTING
IN MOUNTAIN OBSCURATION OF THE ELKHEAD AND PARK RANGES.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR COZ002-008-
     021.

UT...DENSE FOG ADVISORY UNTIL 10 AM MST THIS MORNING FOR UTZ022.

&&

$$

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