000
FXUS65 KGJT 180437
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1037 PM MDT FRI MAY 17 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 356 PM MDT FRI MAY 17 2013

WATER VAPOR IMAGERY SHOWING A GOOD FETCH OF MOISTURE INTO THE
EASTERN GREAT BASIN WITH PWATS RUNNING OVER 150 PERCENT. THIS
MOISTURE IS SEEN WELL NEAR THE 315K THETA SURFACES AND WILL BE
PUSHED INTO OUR CWA LATE THIS EVENING INTO THE OVERNIGHT HOURS. VERY
DRY ATMOSPHERE IS PLACE AHEAD OF THIS MOISTURE AS 12Z KGJT RAOB
SHOWED .20 PWAT WHICH IS HALF OF NORMAL. THIS HAS PROBABLY MOISTENED
SLIGHTLY AS EVIDENCED BY THE HIGH CLOUDS MOVING OVERHEAD BUT THERE
WILL NEED TO BE SOME PROLONGED LIFT TO WORK THIS MOISTURE DOWNWARD.
LARGE SCALE ASCENT WILL BEGIN THIS TASK DURING THE OVERNIGHT HOURS
BUT IT APPEARS THE ENERGY WILL BE SPLITTING AS IT APPROACHES WESTERN
COLORADO AND THEN REFORMING ON THE EASTERN PLAINS SATURDAY
AFTERNOON. THE ATMOSPHERE WILL NEED THE CONVECTIVE BOOST FROM
HEATING TOMORROW TO BRING THE MORE WIDESPREAD SHOWER AND
THUNDERSTORM ACTIVITY. 18Z HAND ANALYSIS SHOWS A SURFACE BOUNDARY
DRAPED ACROSS CENTRAL UTAH TO A LOW ACROSS WESTERN WYOMING. THIS
FRONT LOOKS TO BE FORCED EASTWARD THROUGH OUR CWA LATE THIS EVENING
AND TO THE DIVIDE OR BEYOND BY SUNRISE ON SATURDAY. THE DYNAMICS AND
MOISTURE DO NOT SEEM TO LINK UP VERY GOOD WITH THE LOW LEVEL LIFT
AND EXPECT MAINLY A WIND SHIFT WITH THE FRONT. THE COOLER AIR MOVING
IN BEHIND THE FRONT HOWEVER WILL BE FELT WITH HIGHS DROPPING SOME 10
TO 15 DEGREES OVER THOSE FOUND TODAY. THIS SHOULD HELP ALLEVIATE THE
THREAT OF CRITICAL FIRE WEATHER OVER MOST OF THE REGION ON SATURDAY
WITH THE ADDED MOISTURE ALSO BOOSTING UP AFTERNOON RH VALUES. AS
STORMS DO FIRE THROUGH THE DAY SOME OF THE STRONGER STORMS MAY
PRODUCE SMALL HAIL AND SOME GUSTY WINDS BUT OVERALL SHEAR PROFILES
LOOK TO BE WEAKENING THROUGH THE DAY SO THE THREAT OF SEVERE LOOKS
LIMITED. EXPECT A DECENT DOWNTURN IN THE PRECIPITATION SATURDAY
EVENING BUT WEAK ASCENT AND MODERATE LAPSE RATES AS COOLER AIR
FILTERS IN ALOFT WILL KEEP SOME SHOWERS ACROSS THE CENTRAL AND
NORTHERN MOUNTAINS...POSSIBLY DRIFTING ACROSS THE NORTHERN VALLEYS
THROUGH SUNRISE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 356 PM MDT FRI MAY 17 2013

SUNDAY NIGHT A SECOND LOW DROPS DOWN INTO THE HIGH DESERT
REGION...ALLOWING BELOW NORMAL TEMPERATURES TO PERSIST THROUGH THE
START OF THE WORK WEEK. MARGINAL MOISTURE AND INSTABILITY KEEP
CONVECTIVELY DRIVEN SCATTERED SHOWERS AND STORMS POSSIBLE THROUGH
THE DAY MONDAY. SNOW LEVELS ARE PROGGED TO LOWER TO 7000FT FEET
SUNDAY NIGHT IN THE VERY EASTERN SECTION OF THE CWA NEAR VAIL...BUT
IS NOT ANTICIPATED TO GREATLY IMPACT THE PASSES AS PRECIPITATION
AMOUNTS WILL BE SMALL.

MONDAY 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...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 ABOVE
NORMAL BY LATE WEEK. THERE IS LITTLE THREAT OF PRECIPITATION THROUGH
LATE WEEK WITH THE EXCEPTION OF CONVECTIVELY DRIVEN SHOWERS AND
THUNDERSTORMS IN THE CENTRAL MOUNTAINS BEGINNING MID-WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 356 PM MDT FRI MAY 17 2013

SOME MID TO HIGH LEVEL CLOUDS ARE CROSSING THE FORECAST THIS
EVENING WITH VARYING COVERAGE FROM SCT TO OVC. THIS WILL CONTINUE
BUT FLIGHT CONDITIONS WILL REMAIN VFR. IN FACT...VFR WILL CONTINUE
THROUGH TOMORROW AFTERNOON UNTIL AN UPPER LEVEL TROUGH AND ASSOD
COLD FRONT MOVES THROUGH. WIDESPREAD CONVECTION IS EXPECTED WITH
HIGHER TERRAIN BEING FAVORED THOUGH SOME STORMS WILL MOST LIKELY
DRIFT INTO THE VALLEYS. FEEL CONFIDENT IN VCTS FOR ALL TAF SITES
THOUGH WILL HOLD OFF ON ANY TEMPO GROUPS AS FROPA IS SO FAR OUT.
EXPECT MVFR NEAR AND UNDER THE STRONGER STORMS WITH GUSTY SURFACE
WINDS AND BRIEF HEAVY RAIN DROPPING CONDITIONS TO MVFR...POSSIBLY
EVEN IFR AT TIMES...BEFORE QUICKLY RETURNING TO VFR.

&&

.FIRE WEATHER...(TODAY THROUGH WEDNESDAY)
ISSUED AT 1036 PM MDT FRI MAY 17 2013

SOUTHWEST WINDS WITH GUSTS IN THE 25 TO 35 MPH RANGE ALONG WITH
HUMIDITY VALUES IN THE SINGLE DIGITS AND TEENS WILL CONTINUE
TO BRING CRITICAL FIRE WEATHER CONDITIONS TO MANY LOWER ELEVATIONS
IN SOUTHWEST COLORADO THROUGH SUNSET WHERE FUELS ARE DRY. THE
SYSTEM RESPONSIBLE FOR THE WARM AND DRY...AND WINDY CONDITIONS
WILL BE SHIFTING OVER EASTERN UTAH AND WESTERN COLORADO OVER THE
NEXT 24 HOURS. THIS WILL BRING COOLER TEMPERATURES AND A CHANCE OF
PRECIPITATION TO THE REGION AND LOWER CRITICAL FIRE WEATHER
CONCERNS. MANY ELEVATIONS OVER 8000 FEET MAY RECEIVE WETTING
RAINS...BUT LOWER ELEVATIONS THIS WILL BE MORE SPOTTY.

&&

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

&&

$$

SHORT TERM...15
LONG TERM...JAM
AVIATION...TGR
FIRE WEATHER...15