Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 011814
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1214 PM MDT WED APR 1 2015

.UPDATE...
ISSUED AT 1210 PM MDT WED APR 1 2015

THE FIRST OF TWO COLD FRONT WAS ALONG A LINE FROM HAYDEN SE TO
GRAND JUNCTION AND INTO SOUTHERN CANYONLANDS NP AT NOON TODAY. THE
FRONT WILL CONTINUE TO PROGRESS TO THE EAST SETTLING SOMEWHERE
NEAR THE HIGHWAY 50 CORRIDOR BY LATE AFTERNOON. THE 12Z GUIDANCE
INDICATES THIS FRONT WILL RETREAT NORTHWARD INTO THE ROAN-
TAVAPUTS-FLAT TOPS BY THURSDAY MORNING. THEN THE SECOND STRONGER
FRONT WILL SWEEP THROUGH THE ENTIRE REGION THURSDAY AFTERNOON.

SHOWERS STILL LOOK LIGHT ALONG THE FRONTAL BANDS FAVORING THE
MOUNTAINS MAINLY DUE TO MEAGER MOISTURE. RED FLAG WARNINGS LOOK ON
TRACK FOR THE SW COLORADO VALLEYS. THE OTHER MAIN IMPACT IS
WIDESPREAD FREEZING TEMPERATURES THURSDAY NIGHT AND FRIDAY NIGHT.
THE LATEST GUIDANCE HAS TRENDED DOWNWARD FOR THURSDAY NIGHT LOWS.
700MB/10000FT TEMPERATURES DROP TO -10C/12F BY FRIDAY MORNING SO
COLD AIR WILL BE DEEP.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 302 AM MDT WED APR 1 2015

A VORTICITY CENTER OVER UT WAS HELPING DRIVE A BAND OF MID/HIGH
LEVEL CLOUDS EAST ACROSS THE FORECAST AREA EARLY THIS MORNING AND
AHEAD OF A LARGER UPPER TROUGH MAKING LANDFALL IN THE PACIFIC
NORTHWEST. THIS BAND SHOULD BE EXITING TO THE EAST BY SUNRISE. A
SURFACE COLD FRONT MEANDERED FROM SW WY TO SRN NV.

THE SURFACE FRONT BECOMES MORE DIFFICULT TO DISTINGUISH IN THE
MODELS WITH TIME BUT NOT THE 700 MB BAROCLINIC BAND...WHICH PUSHES
OVER NE UT/NW CO TODAY AND THEN STALLS AS THE PACNW TROUGH LIFTS
ACROSS THE NRN ROCKIES INTO CANADA. THIS BOUNDARY LIKELY TO BE THE
FOCUS FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THIS
AFTERNOON WITH DAYTIME INSTABILITY AND WEAK LIFT FROM AN UPPER JET
CUTTING ACROSS SRN UT TO THE FOUR CORNERS. BUT WITH MOISTURE QUITE
LACKING...EXPECT ONLY LIGHT PRECIPITATION AT THE SURFACE FROM THE
HIGH-BASED CONVECTION WITH GUSTY OUTFLOW WINDS THE BIGGER THREAT.
PLAN ON ANOTHER DAY OF GUSTY AFTERNOON WINDS AS THE FRONT TIGHTENS
THE GRADIENT AND WITH DEEP MIXING BRINGING DOWN STRONGER WINDS
ALOFT. GUSTY WINDS WITH LOW HUMIDITY ELEVATES FIRE WEATHER CONCERNS.

A STRONGER SHORTWAVE ARRIVES ON THU THAT WILL BEGIN TO PUSH THE 700
MB FRONTAL BOUNDARY SOUTHEAST ACROSS THE REMAINDER OF THE FORECAST
AREA. MODELS SHOW A WEAK 700 LOW TRACKING ACROSS NE UT/NW CO LATE
TONIGHT AND THU MORNING. Q-G VERTICAL VELOCITY DIAGNOSTICS INDICATE
A DECENT SHOT OF DYNAMICS...BUT THE Q-G BULLSEYE CROSSES THU MORNING
AT A LESS FAVORABLE TIME FOR CONVECTION AND BEFORE MAX HEATING.
STILL... WITH THE DYNAMICS ALSO ENERGIZING THE FRONT WILL EXPECT
SCATTERED SHOWERS AND ISOLATED T-STORMS ACROSS THE CENTRAL AND
NORTHERN MTNS DESPITE THE DEARTH OF MOISTURE. WITH 700 MB TEMPS
FORECAST BELOW ZERO CELSIUS ACROSS THE NORTH...LOOK FOR LOCAL
LIGHT SNOW ACCUMULATIONS IN THE NRN MOUNTAINS. GUSTY WINDS WILL
CONTINUE THU...MAINLY ACROSS THE SOUTH. TEMPS CONTINUE TO COOL.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 302 AM MDT WED APR 1 2015

AN UPPER LEVEL TROUGH WILL CONTINUE TO MOVE ACROSS THE REGION
THURSDAY NIGHT THROUGH FRIDAY MORNING BUT AS HAS BEEN THE CASE AS
OF LATE...THE TROUGH HAS VERY LITTLE MOISTURE TO WORK WITH. SOME
SNOW AND RAIN SHOWERS POSSIBLE THROUGH THIS TIME PERIOD WITH SOME
CONVECTION ALSO POSSIBLE THURSDAY EVENING AS THE COLD AIR FILTERS
INTO THE AREA. LOWS ON FRIDAY MORNING WILL BE BELOW FREEZING FOR
ALMOST THE ENTIRE CWA EXCEPT FOR PORTIONS OF SOUTHEASTERN UTAH.

PRECIP COMES TO AN END FRIDAY AS WEAK...LOW AMPLITUDE RIDGING
BUILDS IN. HI TEMPS WILL REMAIN COOL ON FRIDAY BUT WILL WARM UP
INTO THE WEEKEND. THE NEXT CHANCE FOR PRECIP LOOKS TO BE TUESDAY
BUT SIGNIFICANT DIFFERENCES BETWEEN MIDRANGE MODELS MAKING IT
DIFFICULT TO DISCERN EXACTLY HOW THIS SYSTEM WILL PLAY OUT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY NOON)
ISSUED AT 1210 PM MDT WED APR 1 2015

A COLD FRONT WILL SETTLE NEAR THE I-70 CORRIDOR THIS AFTERNOON.
ISOLD TO SCT SHOWERS ARE EXPECTED WITH SOME STORMS ALSO POSSIBLE
ESPECIALLY OVER THE NRN AND CENTRAL MTNS THIS AFTERNOON. VCSH
LOOKS GOOD FOR KASE AND KEGE FOR NOW. DO NOT EXPECT FLIGHT
CONDITIONS TO DROP BELOW VFR THOUGH SOME MIDLEVEL CLOUDS WILL
OCCUR IN THE AFTERNOON. GUSTY OUTFLOW WINDS FROM SHOWERS AND
STORMS ARE POSSIBLE REACHING 35KTS OR SO THIS AFTERNOON. SOME
CONVECTION ALSO POSSIBLE OVER THE SAN JUANS BUT NO EXPECTING TAF
SITES TO BE AFFECTED. DOWNTURN IN SHOWERS AND WINDS EXPECTED
TONIGHT. CONVECTIVE MAINLY MTN SHOWERS EXPECTED AGAIN THURSDAY
BEGINNING AFTER 16Z.


&&

.FIRE WEATHER...
ISSUED AT 1210 PM MDT WED APR 1 2015

GUSTY WINDS OF 25MPH OR GREATER HAVE BEGUN ACROSS SW COLORADO AND
THE RH VALUES ARE EXPECTED TO DROP BELOW 15 PERCENT THROUGH THE
AFTERNOON CREATING 3-5 HOURS OF RED FLAG CONDITIONS FOR FIRE
WEATHER ZONES 207 AND 290....WHERE LAND MANAGEMENT AGENCIES HAVE
DETERMINED THAT FUELS ARE ALSO CRITICALLY DRY BELOW 8000 FT. THE
FIRST COLD FRONT STALLS ACROSS WEST CENTRAL COLORADO THIS
AFTERNOON WITH A SECOND STRONGER FRONT EXPECTED THURSDAY
AFTERNOON. RED FLAG CONDITIONS ARE POSSIBLE AGAIN THURSDAY
AFTERNOON DUE TO GUSTY WINDS AND LOW HUMIDITY.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ207-290.

     FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY
     EVENING FOR COZ207-290.

UT...NONE.
&&

$$

UPDATE...JOE
SHORT TERM...JAD
LONG TERM...TGR
AVIATION...JOE
FIRE WEATHER...JOE



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