000
FXUS65 KGJT 190512
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1112 PM MDT SAT MAY 18 2013

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 314 PM MDT SAT MAY 18 2013

NEGATIVE TILTED UPPER TROUGH AXIS FROM ABOUT THE 4 CORNERS TO ID
WILL CONTINUE LIFTING TO THE NE THROUGH THIS EVENING. SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS PRECEDED THE TROUGH
AXIS IN A MOIST AND UNSTABLE AIRMASS. A FEW SPOTTER REPORTS OF 1/4
TO 1/2 INCH HAIL IN THE GRAND JCT AND MONTROSE AREAS. EXPECT
COVERAGE TO DECREASE BY EARLY TONIGHT WITH THE LOSS OF HEATING BUT
WITH ISOLATED TO SCATTERED SHOWERS PERSISTING ACROSS THE NORTH
THROUGH THE NIGHT IN WEAK COLD ADVECTION AND W-NW FLOW. 700 MB TEMPS
BRIEFLY DROP BELOW ZERO OVER THE FAR NORTH LATE TONIGHT WITH SNOW
LEVELS LOWERING TO 8500-9000 FT THERE.

ANOTHER FAST-MOVING SHORTWAVE WILL RACE FROM WA/OR TO THE GREAT
BASIN BY 12Z SUNDAY AND MAINTAIN BROAD TROUGHING OVER THE WEST AS IT
SLIDES UNDERNEATH TODAY/S DEPARTING SHORTWAVE TROUGH. A RESULTING
EAST-WEST ORIENTED DEFORMATION ZONE/CHANNELIZED VORTICITY AXIS THEN
SINKS SOUTH ACROSS OUR AREA FOR ANOTHER ROUND OF SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS SUNDAY AFTERNOON.

A BETTER PUSH OF COLDER AIR REACHES THE REGION SUNDAY NIGHT AS AN
UPPER LOW DEVELOPS OVER THE CENTRAL PLAINS. 700 MB ZERO TEMP LINE
REACHING AS FAR SOUTH AS THE SAN JUANS. THIS BETTER COLD ADVECTION
IN CONTINUED MOIST N-NW OROGRAPHIC FLOW WILL FAVOR THE NORTH WITH
PRECIPITATION SUNDAY NIGHT. A COUPLE INCHES OF SNOW ARE POSSIBLE IN
THE NORTHERN MTNS AROUND STEAMBOAT SPRINGS BY MON MORNING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 314 PM MDT SAT MAY 18 2013

MONDAY...ON THE BACK SIDE OF THE TROUGH...SUFFICIENT MOISTURE
TRANSPORT AND INSTABILITY KEEP CONVECTIVELY DRIVEN SCATTERED SHOWERS
AND STORMS POSSIBLE THROUGHOUT THE DAY.

TUESDAY AND TUESDAY NIGHT...A RIDGE BEGINS TO SHIFT EASTWARD INTO THE
AREA...ALLOWING DRY AIR TO BEGIN FILTERING INTO THE REGION. AS THIS
RIDGE MOVES EAST TUESDAY...TEMPERATURES WILL TRANSITION BACK TO
NORMAL OVER EASTERN UT/WESTERN CO.

WEDNESDAY-SATURDAY...SOUTHWEST FLOW ON THE BACKSIDE OF THE RIDGE WILL
ALLOW TEMPERATURES 5 TO 10 DEGREES ABOVE NORMAL AND DRIER
CONDITIONS TO RETURN TO THE REGION. A LARGER SYSTEM DROPPING INTO
THE PACIFIC NORTHWEST REGION WILL HELP MAINTAIN THIS SOUTHWEST
FLOW THROUGH THE END OF THE WEEK. THIS SHOULD ALLOW TEMPERATURES
BACK TO AND SLIGHTLY ABOVE NORMAL BY LATE WEEK. THERE IS LITTLE
THREAT OF PRECIPITATION THROUGH LATE WEEK WITH THE EXCEPTION OF
CONVECTIVELY DRIVEN AFTERNOON SHOWERS AT MOUNTAIN ELEVATIONS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1106 PM MDT SAT MAY 18 2013

ISOLATED SHOWERS WILL LINGER ACROSS THE REGION THROUGH
18Z. AFTER 18Z...SHOWERS AND THUNDERSTORMS WILL BE INCREASING
ACROSS THE AREA...WITH LOCALLY HEAVY RAINFALL AND SMALL HAIL WILL
BE POSSIBLE NEAR THE STRONGEST STORMS. SNOW LEVELS WILL BE
RUNNING BETWEEN 8500 AND 9000 FT MSL...WITH MOUNTAINS BECOMING
OBSCURED AT TIMES AS CIGS LOWER IN THE VICINITY OF SHOWERS WITH
AREAS OF MVFR AND EVEN IFR CONDS EXPECTED. AT THE TAF SITES...VFR
CONDITIONS SHOULD BE THE RULE THOUGH A BRIEF PERIOD OF MVFR CIGS
IS POSSIBLE IN A THUNDERSTORM. SHOWERS WILL DISSIPATED AFTER 00Z
MONDAY...BUT WILL BE ON THE INCREASE AGAIN AFTER 06Z SUNDAY AS
ANOTHER STORM DROPS INTO THE REGION FROM THE NORTH.

&&

.FIRE WEATHER...
ISSUED AT 314 PM MDT SAT MAY 18 2013

A COOLER AND MORE MOIST PATTERN WILL LAST THROUGH MONDAY. 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.
&&

$$

SHORT TERM...JAD
LONG TERM...JAM
AVIATION...JDC
FIRE WEATHER...JAM