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000
FXUS65 KGJT 191701
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1101 AM MDT SUN MAY 19 2013

.UPDATE...
ISSUED AT 1100 AM MDT SUN MAY 19 2013

VISIBLE SATELLITE IMAGES SHOWED CONVECTIVE CLOUDS BEGINNING TO BUILD
IN AREAS THAT SAW SOME SUNSHINE THIS MORNING. SHOWERS AND THUNDER-
STORMS WILL BE INCREASE ACROSS MUCH OF THE FORECAST AREA THIS
AFTERNOON...AND CURRENT FORECAST LOOKS REASONABLE. SMALL HAIL WILL
AGAIN BE POSSIBLE NEAR THE STRONGER STORMS.

FORECAST CHALLENGE TONIGHT AND MONDAY IS SNOW ACROSS THE NORTHERN
AND CENTRAL MTNS AS AN UPPER LOW FORMING OVER NEBRASKA RESULTS IN
MOIST NW OROGRAPHIC FLOW AND COLD ADVECTION. 12Z NAM THE MOST
AGGRESSIVE WITH THE 12Z GFS A TAD WARMER AND SLOWER TO DEVELOP. SNOW
LEVEL COULD DROP AS LOW AS 8000-8500 FT WHICH WOULD AFFECT RABBIT
EARS/GORE/VAIL PASSES...AND MAY HAVE TO CONSIDER A LATE-SEASON WINTER
WEATHER ADVISORY FOR AT LEAST ZONE 4 (PARK MTNS) WHERE SOME DECENT
ACCUMULATIONS LOOK POSSIBLE.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 309 AM MDT SUN MAY 19 2013

ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
MORNING AHEAD OF NEXT INCOMING SHRTWV. CONVECTION WILL BE ON THE
INCREASE BY MID MORNING WITH FAIRLY WIDESPREAD ACTIVITY
ANTICIPATED FOR THE HIGH COUNTRY. VALLEY SHOWERS DO NOT APPEAR AS
ROBUST IN COVERAGE TODAY...BUT A FEW WILL SNEAK IN THIS AFTERNOON
AND EARLY EVENING. WILL KEEP ACTIVITY MORE IN THE SCATTERED RANGE
FOR TODAY...WITH LOCALLY HEAVY RAINFALL POSSIBLE. SNOW LEVELS WILL
BE RUNNING NEAR 9000 FT TODAY...WITH CONVECTION DRIVING SOME SNOW
DOWN LOWER. HOWEVER...NO SIGNIFICANT ACCUMULATIONS EXPECTED DURING
THE DAYTIME HOURS. TEMPS WILL BE RUNNING A GOOD 10 DEGREES BELOW
NORMAL TODAY WITH GUIDANCE VALUES IN THE BALLPARK.

THE MUCH ADVERTISED REINFORCING WAVE DROPS INTO THE AREA TONIGHT
INTO EARLY MON. MOISTURE DEEPENS OVERNIGHT UNDER A NORTH-NORTHWEST
FLOW WRAPPING AROUND THE LOW THAT WILL HAVE STRENGTHENED OVER WESTERN
NE/SD. THIS FLOW AND THE DEEP MOISTURE WILL RESULT IN FAVORABLE
OROGRAPHICS FOR THE NORTHERN PORTION OF THE FORECAST AREA. SO EXPECT
AN UPTICK IN SHOWER ACTIVITY OVERNIGHT...ESPECIALLY NORTH. 700MB
TEMPERATURES WILL DROP BELOW ZERO C BY MIDNIGHT ACROSS ALL BUT THE
FAR SOUTH. THEREFORE SNOW WILL BE POSSIBLE ABOVE 8500-9000 FT.
ACCUMULATIONS WILL MAINLY OCCUR ABOVE 9500 FT WITH 1-2 INCHES
POSSIBLE BY LATE MON MORNING. BY MON AFTERNOON...ANY ASSOCIATED
DYNAMICS WILL HAVE ALREADY PEAKED AS THE WAVE EXITS THE AREA.
DAYTIME HEATING WILL TAKE OVER FOR A MORE CONVECTIVE ENVIRONMENT.
THEREFORE GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE...DIMINISHING AFTER MAX HEATING.

TEMPERATURES WILL REMAIN COOLER THAN NORMAL WITH HIGHS 8-10 DEGREES
BELOW SEASONAL NORMS. LOWS WILL ONLY DEVIATE FROM NORMAL A COUPLE
DEGREES MOST LOCATIONS.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 309 AM MDT SUN MAY 19 2013

MONDAY NIGHT-TUESDAY...SHOWERS WILL DIMINISH THROUGH MON EVENING
AND OVERNIGHT AS A RIDGE APPROACHES FROM THE WEST. THE RIDGE WILL
USHER IN A DRYING AND WARMING TREND AS THE RIDGE AXIS REACHES
CENTRAL UT BY TUE AFTERNOON. A FEW CONVECTIVE SHOWERS WILL REMAIN
POSSIBLE THROUGH THE DAY OVER THE HIGHER TERRAIN.

TUESDAY NIGHT THROUGH SATURDAY...DRY SOUTHWEST FLOW WILL BE IN
PLACE THROUGH THE PERIOD WITH TEMPERATURES CLIMBING TO WELL ABOVE
SEASONAL NORMS. A FEW DIURNALLY DRIVEN STORMS WILL BE POSSIBLE
NEAR THE DIVIDE WEDNESDAY AFTERNOON AND EVENING...OTHERWISE THE
FORECAST WILL LEAN TOWARD ZERO POPS THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1100 AM MDT SUN MAY 19 2013

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP FROM THE SAN JUAN
MTNS NORTHWARD THIS AFTERNOON...WITH NUMEROUS SHOWERS AT TIMES OVER
THE CENTRAL MTNS. AT THE TAF SITES...VFR CONDITIONS SHOULD BE THE
RULE THOUGH A BRIEF PERIOD OF MVFR VIS/CIGS IS POSSIBLE IN A SHOWER
OR THUNDERSTORM. EXPECT MOUNTAIN OBSCURATIONS AS CIGS LOWER IN THE
VICINITY OF SHOWERS. SMALL HAIL...GUSTY WINDS...AND A BRIEF PERIOD
OF MODERATE TO HEAVY RAIN ARE POSSIBLE FROM SOME THUNDERSTORMS. SNOW
LEVEL AS LOW AS 8500 TO 9000 FT MSL IN CONVECTIVE SHOWERS.

AFTER 03Z TONIGHT...SNOW WILL BECOME WIDESPREAD OVER THE NORTHERN
MTNS FROM VAIL/KCCU NORTHWARD TO K3MW OBSCURING MOUNTAINS. PERIODS
OF MVFR CIGS IN -RA ARE LIKELY AT KSBS...KHDN...AND KCAG AFTER 09Z.

&&

.FIRE WEATHER...
ISSUED AT 309 AM MDT SUN MAY 19 2013

A COOLER AND MORE MOIST PATTERN WILL LAST THROUGH MONDAY WITH
NUMEROUS SHOWERS AND AFTERNOON THUNDERSTORMS...ESPECIALLY OVER THE
HIGH COUNTRY. SOUTHWEST FLOW WILL THEN BRING VERY DRY AIR BACK INTO
EASTERN UTAH AND WESTERN COLORADO BY MIDWEEK...BUT WINDS AT THIS
TIME DO NOT APPEAR TO BE STRONG ENOUGH FOR CONCERN.

&&

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

$$

UPDATE...JAD
SHORT TERM...JDC/EH
LONG TERM...EH/JDC
AVIATION...JAD
FIRE WEATHER...JAM/JDC