000
FXUS65 KGJT 191658
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1058 AM MDT FRI MAR 19 2010
.1050 AM UPDATE...STORM IS GENERALLY EVOLVING AS PROGGED. THE COLD
FRONT IS PASSING SOUTH OF THE FOUR-CORNERS THIS LATE MORNING. SOME
SIGNIFICANT SNOW REPORTS THIS MORNING INCLUDE 2-11 INCHES ON THE
NORTH SIDE OF UINTA MTNS...6-8 VAIL...3.5 AT GOTHIC...AND 4 INCHES AT
STEAMBOAT MTN THAT HAS BLOWN AWAY. THE 700MB LOW IS OVER GLENWOOD
CANYON. THE RESULTANT EAST WINDS OVER THE PARK RANGE HAVE BEEN 30-
40MPH...BUT SKI PATROL HAS REPORTED 70-75MPH MID MTN. THESE WINDS
WILL LIKELY DIMINISH THE AFTERNOON AS THE SFC PRESSURE GRADIENT
RELAXES A BIT AND THE 700MB LOW DROPS SOUTH ALONG THE WESTERN EDGE OF
THE CONTINENTAL DIVIDE.
OTHERWISE STRONG COLD ADVECTION OCCURS TODAY AND TONIGHT WITH
500/700MB -32C/-14C COLD CORE NESTLED OVER THE PARK RANGE BY SUNRISE
SATURDAY. RADAR IS ALREADY SHOWING A POPCORN EFFECT OF THE
CONVECTION. MOST SITES WILL SEE GUSTY NW-NE WINDS THROUGH THE DAY. A
SLIVER OF CAPE ACROSS THE NORTH-CENTRAL HOLDS THE POTENTIAL FOR HEAVY
SHOWERS AND EVEN AN ISOLATED LIGHTNING STRIKE. THE 12Z NAM AND RUC
BOTH PRODUCE ANOTHER 6 INCHES OF SNOWFALL TODAY IN THE ELKS-WEST ELKS
WHERE WARNINGS ARE VALID. NE FLOW THIS EVENING MAY LIMIT SNOWFALL IN
THE HWY 550 GORGE IN THE NW SAN JUANS. STILL EXPECT SOME SIGNIFICANT
SNOWFALL FOR CERRO SUMMIT SW TO TELLURIDE.
A COLD NIGHT TONIGHT UNDER PARTIALLY CLEARING SKIES AND DIMINISHING
WINDS...WITH MORNING FOG WHERE SIGNIFICANT SHOWERS OCCUR TODAY.
&&
.PREVIOUS DISCUSSION... /ISSUED 420 AM MDT FRI MAR 19 2010/
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...
FAIRLY COMPLICATED PATTERN UNFOLDING THIS MORNING THROUGH THIS
AFTERNOON. FIRST THE LEADING COLD FRONT ASSOCIATED WITH THE PRESENT
SYSTEM HAS MOVED OVER THE FORECAST AREA AND AT 3 AM MDT WAS STRETCHED
FROM THE NORTHEAST CORNER TO THE SOUTHWEST CORNER. PRECIPITATION HAS
INCREASED OVER THE AREA EARLY THIS MORNING AS A RESULT OF THIS
FRONT...AND OF A LEADING SHORTWAVE IN A DEEPENING LOW PRESSURE
TROUGH. A COUPLE OTHER SHORTWAVES WILL TO AFFECT THE REGION THROUGH
THE DAY AND INTO TONIGHT. THESE FEATURES SHOW UP WELL ON IR SATELLITE
LOOPS. ONE HAS MOVED OVER THE AZ/NV/UT TRIPLE POINT AND WILL CONTINUE
SOUTHEAST THROUGH THE MORNING. THE MAIN ENERGY ASSOCIATED WITH THIS
IMPULSE WILL GO TO OUR SOUTH...BUT GENERAL TROUGHINESS WILL KEEP THE
AIR MASS UNSETTLED OVER THE SOUTHERN PORTION. THE OTHER MORE
NORTHERLY DISTURBANCE MOVED SOUTHEAST ACROSS WESTERN MT AND IS
DROPPING INTO NORTHWEST WY AT THIS TIME. THIS IMPULSE WILL DROP
ACROSS WY AND INTO OUR FORECAST AREA BY MIDDAY. IT WILL THEN WORK ITS
WAY SOUTH-SOUTHEAST REACHING OUR SOUTHERN BORDER LATE THIS EVENING.
THEREFORE PRECIPITATION WILL BE FAIRLY WIDESPREAD THROUGHOUT MOST OF
THE DAY...DIMINISHING FROM THE WEST THIS EVENING. THE MAIN CAVEAT TO
THIS SCENARIO...IS THE EASTERLY FLOW THAT WILL DEVELOP BEHIND AN
INITIAL 700MB LOW AS IT TRACKS FROM NORTH TO SOUTH ALONG OUR EASTERN
EDGE. THIS EASTERLY FLOW WILL DEVELOP FIRST OVER THE PARK RANGE THIS
MORNING THEN SPREAD SOUTHWARD THROUGH THE DAY.
BY TONIGHT ACTIVITY WILL BEGIN TO WIND DOWN AS THE MAIN TROUGH TRACKS
TO THE SOUTHEAST. HOWEVER A -32C COLD CORE AT 500MB FOLLOWING THE
NORTHERN SHORTWAVE WILL MOVE ACROSS THE NORTH THIS EVENING. THIS WILL
RESULT IN LOW LEVEL INSTABILITY IN THE COLD AIR...EVEN AS 700 MB
TEMPS DROP TO -12C. THE LIMITING FACTOR WILL BE MOISTURE AS DRIER AIR
MOVES OVER FROM THE WEST-NORTHWEST. FOG POSSIBLE IN MANY VALLEY
LOCATIONS IN THE WAKE OF THE STORM LATE TONIGHT AND EARLY SATURDAY
MORNING.
THE SYSTEM CONTINUES TO MOVE EAST ON SATURDAY AS A RIDGE OF HIGH
PRESSURE DEVELOPS OVER THE GREAT BASIN. LINGERING SHOWERS WILL BE
POSSIBLE ALONG THE DIVIDE...ESPECIALLY OVER THE NORTHERN HALF. BY
SATURDAY NIGHT STABILITY WILL INCREASE...AND THE NORTH FLOW RELAXES
AS THE RIDGE APPROACHES FROM THE WEST.
AFTER A RECENT TASTE OF SPRING...TEMPERATURES WILL FALL BELOW NORMAL
VALUES DURING THIS PERIOD.
.LONG TERM...SUNDAY THROUGH FRIDAY...
A STRONG RIDGE WILL CONTINUE MIGRATING OVER THE AREA AND THE
RIDGELINE WILL PAST OVERHEAD SUNDAY AFTERNOON. SUNDAY NIGHT...THE
FLOW ALOFT BECOMES MORE ZONAL WITH MID AND HIGH LEVEL MOISTURE
ADVECTING INTO THE AREA FROM THE WEST. MODEL DIFFERENCES BECOME
NOTICEABLE BEGINNING MONDAY...IN THE DEVELOPMENT OF THE NEXT TROUGH.
THE GFS IS INITIALLY MORE PROGRESSIVE WITH THIS TROUGH. IT CLOSES OFF
THE 500 MB LOW FURTHER EAST /OVER SLC/ MONDAY NIGHT...THEN DIGS THE
TROUGH SSE THROUGH EASTERN UT TO THE FOUR CORNERS TUE THROUGH TUE
NIGHT. THE ECMWF CLOSES OFF THE 500 MB LOW FURTHER NORTHWEST /OVER
SOUTHERN IDAHO/ THEN TRACKS IT SOUTH OVER CENTRAL AND WESTERN UT
BEFORE TURNING IT TO THE EAST.
BOTH MODELS PLACE THE LOW CENTER OVER THE FOUR CORNERS ABOUT 12Z WED.
THE GFS CONTINUES TO DIG THE TROUGH TO THE SOUTH THROUGH EASTERN
AZ...BEFORE FINALLY TURNING IT TO THE EAST WED EVENING. THE ECMWF
PRESENTS THE MORE PROGRESSIVE SOLUTION ON WED AS IT MOVES THE TROUGH
EAST ALONG THE CO/NM BORDER TO THE PANHANDLES BY 00Z THU. RIDGING
SHOULD BRING DRIER CONDITIONS FRIDAY.
HAVE INCREASED CLOUDS...PRECIP...AND WINDS MON NIGHT AND TUE AS THE
NEXT SYSTEM APPROACHES...AND BLENDED THE MIDRANGE MODEL SOLUTIONS.
&&
.AVIATION...
AS THE COLD FRONT PASSES THROUGH THE AREA FROM WEST TO EAST...EXPECT
WIDESPREAD MVFR CIGS AND VSBYS IN RAIN AND SNOW SHOWERS...WITH
EMBEDDED IFR CONDITIONS...ACROSS THE AREA. SOME IMPROVEMENT WILL MOVE
IN FROM THE WEST THIS AFTERNOON AND TONIGHT.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING THROUGH 6 AM SATURDAY MORNING FOR
ZONE 10/12.
WINTER WEATHER ADVISORY THROUGH 6 AM SATURDAY MORNING FOR
ZONES 4/13/18
WINTER WEATHER ADVISORY THROUGH 6 PM FRIDAY FOR ZONES
3/9/17.
UT...WINTER STORM WARNING THROUGH MIDNIGHT FRIDAY FOR ZONE 23.
&&
$$
UPDATE.......JOE
SHORT TERM...EH
LONG TERM....CJC
AVIATION.....CJC
