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000
FXUS65 KGJT 231705
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1105 AM MDT THU MAY 23 2013

.UPDATE...
ISSUED AT 941 AM MDT THU MAY 23 2013

LOOKING AT OBSERVATIONS FROM YESTERDAY MANY SITES GUSTED WELL INTO
THE 30S ACROSS SOUTHEAST UTAH TO NORTHWEST COLORADO. KGJT RAOB
THIS MORNING SHOWS MUCH STRONG WINDS IN THE 600-500MB LAYER AS
WELL AS UPSTREAM AT KSLC. WITH MIXING EXPECTED TO REACH THIS HIGH
WIND GUSTS IN THE 45 TO 50 MPH ARE NOT OUT OF THE QUESTION SO HAVE
ADDED A WIND ADVISORY TO PORTIONS OF OUR EASTERN CWA. THE STRONGER
WINDS SHOULD COMMENCE ONCE TEMPERATURES BEGIN TO PUSH INTO THE
LOWER TO MID 80S.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 400 AM MDT THU MAY 23 2013

WINDY AND WARMER TODAY AS A LARGE UPPER LOW PARKED OVER WA/OR
MAINTAINS DRY SOUTHWEST FLOW ALOFT ACROSS THE AREA. SEE THE FIRE
WEATHER SECTION BELOW FOR IMPACTS. A COLD FRONT WAS BUTTED UP
AGAINST THE WESTERN SIDE OF THE UTAH MTNS EARLIER AND SHOULD
REMAIN TO OUR NORTHWEST TODAY AS THE SOUTHWEST FLOW WILL PROVIDE
LITTLE EASTWARD PUSH.

AN UPPER JET MAX ROTATING AROUND THE UPPER LOW WILL MOVE ACROSS NWRN
UT TODAY AND ENHANCE WINDS ALOFT OVER ERN UT/WRN CO. LAST EVENING/S
SOUNDING AT GRAND JCT SHOWED DEEP MIXING UP TO 500 MB AND SEE NO
REASON WHY DEEP MIXING WON/T OCCUR AGAIN TODAY WITH STRONG SURFACE
HEATING...RESULTING IN GUSTY WINDS AGAIN THIS AFTERNOON AND A BIT
STRONGER THAN YESTERDAY. WIND GUSTS OF 35-40 MPH WILL BECOME COMMON
ACROSS ERN UT AND MUCH OF WRN CO THIS AFTERNOON...AND SOME ISOLATED
LOCATIONS IN ERN UT AND NW CO COULD FLIRT WITH GUSTS UP TO 45 MPH.

GUSTY WINDS WILL PERSIST UNTIL AROUND MIDNIGHT AS THE UPPER JET MAX MOVES
INTO SOUTHEAST IDAHO...THOUGH ONCE THE DIURNAL INPUT SUBSIDES
AROUND SUNSET...WIND STRENGTH WILL BEGIN TO DIMINISH. HOWEVER
SOME GUSTINESS WILL PERSIST UNTIL AROUND MIDNIGHT AS AN ASSOCIATED
COLD FRONT MOVES WEST-EAST ACROSS WY AND BRUSHES OUR NORTHERN
BORDER. THE AREA WILL SEE ANOTHER WARM NIGHT MOST LOCATIONS WITH
LOWS 0-2 DEGREES COOLER THAN WED NIGHT`S.

THE GRADIENT RELAXES A LITTLE ON FRIDAY. HOWEVER THE LARGE-SCALE
PATTERN REMAINS IN PLACE AS THE FORECAST AREA SITS BETWEEN THE
NORTHWEST LOW AND HIGH PRESSURE OVER THE PLAINS STATES. THEREFORE
GUSTY WINDS ARE AGAIN EXPECTED TO MIX TO THE SURFACE BY THE
AFTERNOON. WITHOUT THE SHORTWAVE ENERGY OF THE PREVIOUS
DAY...WINDS ARE NOT EXPECTED TO BE QUITE AS STRONG. BUT THE
POTENTIAL WILL AGAIN DEVELOP FOR CRITICAL FIRE WEATHER CONCERNS
WHERE FUELS ARE DRY. TEMPERATURES REMAIN A FEW DEGREES LOWER THAN
THOSE ON THU.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 400 AM MDT THU MAY 23 2013

LITTLE CHANGE TO THE DRY...WARM AND GUSTY CONDITIONS AS STRONG
SOUTHWEST FLOW REMAINS ENTRENCHED OVER THE FORECAST AREA THROUGH
SATURDAY. THE LARGE SCALE PATTERN ONLY GRADUALLY EVOLVES AS THE
LOW PRESSURE TROUGH REMAINS OVER THE WEST COAST AND HIGH PRESSURE
SITS TO OUR EAST. AGAIN GUSTY WINDS WILL MIX TO THE SURFACE BY
SATURDAY AFTERNOON. TEMPERATURES WILL REMAIN WARM WITH HIGHS 7-10
DEGREES ABOVE NORMAL...AND LOWS CLOSER TO NORMAL VALUES.

THE CLOSED LOW OVER THE PAC NW LIFTS INTO WRN CANADA SAT NIGHT AND
SUNDAY...BUT UPSTREAM PACIFIC ENERGY LOOKS TO MAINTAIN AN UPPER
TROUGH OVER THE WEST THROUGH THE FIRST HALF OF NEXT WEEK. MODEL
DIFFERENCES GROW...HOWEVER. THE ECMWF KEEPS THE TROUGH CLOSER TO
THE WEST COAST AND IS SLOWER TO PROGRESS IT EASTWARD FOR MOSTLY
DRY WEATHER...WHILE THE GFS LIFTS A SHORTWAVE TROUGH ACROSS THE 4
CORNERS BY WED FOR A BIT BETTER CHANCE OF SHOWERS BY MIDWEEK.
WARMER THAN NORMAL TEMPERATURES SHOULD CONTINUE THROUGH THE FIRST
PART OF NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1105 AM MDT THU MAY 23 2013

DRY...WARM AND WINDY CONDITIONS WILL BE IN PLACE OVER THE NEXT
24 HOURS. WITH ONLY HIGH TO MID LEVEL CLOUDS EXPECTED VFR
CONDITIONS ARE EXPECTED TO PREVAIL. SOUTH TO SOUTHWEST WINDS MAY
BE AN ISSUE TO FLIGHT OPERATIONS AS GUSTS OF 40 TO 50 MPH ARE
EXPECTED THROUGH THIS AFTERNOON AND MAY PERSIST ACROSS THE
RIDGE TOPS OF HIGHER TERRAIN THROUGH THE OVERNIGHT HOURS...WHERE
MECHANICAL TURBULENCE COULD BE AN ISSUE. WIND GUSTS DO NOT LOOK AS
STRONG FRIDAY AFTERNOON BUT COULD STILL BE IN THE 25 TO 35 MPH
RANGE IN THE LATE AFTERNOON OVER THE LOWER VALLEY REGIONS OF
WESTERN COLORADO AND EASTERN UTAH.

&&

.FIRE WEATHER...
ISSUED AT 400 AM MDT THU MAY 23 2013

SOUTHWEST FLOW WILL STRENGTHEN TODAY AS THE AREA SITS BETWEEN A HIGH
PRESSURE RIDGE TO OUR EAST...AND A STRONG LOW PRESSURE SYSTEM OVER
THE PACIFIC NORTHWEST. A DISTURBANCE ROTATING AROUND THE PACIFIC
NORTHWEST LOW WILL BRUSH THE FORECAST AREA THIS AFTERNOON AND ENHANCE THE
ALREADY STRONG FLOW. DEEP MIXING IN THE AFTERNOON WILL ALLOW THE
STRONG SOUTHWEST WINDS TO MIX TO THE SURFACE. RELATIVE HUMIDITY
VALUES WILL DROP INTO THE SINGLE DIGITS ACROSS THE LOWER SOUTHWEST
AND WEST CENTRAL VALLEYS. WHERE FUELS ARE DRY...WIND GUSTS 25-40 MPH
IN THE LOWER ELEVATIONS WILL COMBINE WITH THE DRY CONDITIONS TO
PRODUCE CRITICAL FIRE WEATHER CONDITIONS THIS AFTERNOON AND EVENING.
THEREFORE A RED FLAG WARNING WILL CONTINUE TO BE IN EFFECT FOR THE
LOWER ELEVATIONS OF CO FIRE ZONES 207...290 AND 292 WHERE FUELS ARE
CRITICALLY DRY.

THE STRONG FLOW ALOFT WILL CONTINUE INTO EARLY NEXT WEEK WITH ONLY A
GRADUAL MODIFICATION TO THE LARGE SCALE PATTERN. THEREFORE THE
POTENTIAL WILL CONTINUE FOR CRITICAL FIRE WEATHER CONDITIONS TO
DEVELOP EACH AFTERNOON AS THESE WINDS ALOFT MIX TO THE SURFACE. IN
ADDITION...THE WARM AND DRY CONDITIONS WILL PERSIST. A FIRE WEATHER
WATCH FOR FRIDAY AFTERNOON AND EVENING WILL REMAIN IN EFFECT FOR THE
ABOVE MENTIONED ZONES.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR COZ207-290-292.

     FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY EVENING
     FOR COZ207-290-292.

     WIND ADVISORY UNTIL 9 PM MDT THIS EVENING FOR COZ001.

UT...WIND ADVISORY UNTIL 9 PM MDT THIS EVENING FOR UTZ022-027-029.

&&

$$

UPDATE...15
SHORT TERM...EH/JAD
LONG TERM...EH/JAD
AVIATION...15
FIRE WEATHER...EH