Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 261013
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
413 AM MDT SUN JUL 26 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 412 AM MDT SUN JUL 26 2015

THE MONSOONAL MOISTURE STREAM REMAINED MOSTLY SOUTH AND EAST OF
THE FORECAST AREA ON SATURDAY. BUT AN INVERTED TROUGH IN SONORA
TODAY WILL HELP TO PULL THE MOISTURE STREAM BACK INTO THE FOUR
CORNERS THIS MORNING AND INTO THE CENTRAL ZONES THROUGH THE
AFTERNOON. PRECIP WATER VALUES CLIMB TO NEAR 1.1 INCH SOUTH OF
I-70. STORM MOTION WILL BE TO THE NE AT AROUND 20 MPH SO ONLY
LOCALIZED HEAVY SHOWERS ARE EXPECTED FAVORING THE SW SAN JUANS.
DRIER AIR REMAINS IN PLACE OVER THE NORTH RAISING FIRE WEATHER
CONDITIONS. ISOLATED HIGH-BASED STORMS MAY FORM NORTH OF I-70.
THESE STORMS IN AN INVERTED V ENVIRONMENT ARE EXPECTED TO PRODUCE
MORE GUSTY WIND AND LIGHTNING THAN RAIN.

TONIGHT THE NE PACIFIC TROUGH WORKS INTO THE NORTHERN GREAT BASIN.
SW GRADIENT WINDS ALOFT CONTINUE TO INCREASE. THIS WILL ERODE
MOISTURE FROM WEST TO EAST THROUGH THE NIGHT BUT A FEW STORMS
CONTINUING PAST MIDNIGHT. MIN TEMPERATURES EXPECTED TO STAY ON THE
MILD SIDE OF NORMAL.

MONDAY THE TROUGH/S ASSOCIATED 90KT JET NOSES ACROSS NW UTAH THEN
LIFTS INTO WYOMING. AN ASSOCIATED DRY COOL FRONT PUSHES ACROSS NE
UT AND NW CO THROUGH THE AFTERNOON. SW GRADIENT WINDS INCREASE TO
40KTS AHEAD OF THE FRONT. THIS SW FLOW IS ALSO QUITE DRY SO ANY
SHOWER OR STORM ACTIVITY WILL BE IN THE EASTERN MOST MOUNTAINS.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 412 AM MDT SUN JUL 26 2015

A SUBTLE CHANGE IN THE PATTERN ACROSS THE CONUS WILL BE SEEN BEHIND
THE PASSAGE OF THE NORTHERN STREAM SYSTEM CROSSING THE NORTHERN
STATES THROUGH MIDWEEK. THE PATTERN OF A PERSISTENT TROUGH OVER THE
NORTHWEST STATES WILL BE RELAXING WHILE LOW PRESSURE SETTLES MORE
OVER EASTERN CANADA. AS THIS HAPPENS DURING THE MIDDLE TO LATE WEEK
PERIOD...SUBTROPICAL HIGH PRESSURE WILL BE BULGING WESTWARD OUT
OF THE SOUTHERN PLAINS TO THE 4 CORNERS REGION. THE AXIS OF THIS
HIGH APPEARS TO BE THE DELINEATION FOR DRY AIR TO THE NORTH AND
MOIST AIR TO THE SOUTH. FOR THE MOST PART THIS AXIS OF MOSITURE
WILL BE ALONG AND SOUTH AND WEST OF OUR SOUTHERN CWA BORDER
THROUGH THE WEEK. EVENTUALLY THE MOISTURE RECIRCULATES INTO THE
RIDGE BY NEXT WEEKEND BUT CURRENTLY ANOTHER PUSH OF DIRECT
MONSOONAL MOISTURE IS NOT WELL DEFINED BY THE MED RANGE MODELS.
THIS SHOULD EQUATE TO TEMPERATURES STAYING NEAR TO ABOVE NORMAL
WHILE THE BEST PRECIPITATION CHANCES STAY TO OUR WEST. THE
SOUTHERN COLORADO MOUNTAINS IN PROXIMITY THE BETTER MOISTURE
SOURCE STAND THE BETTER CHANCE FOR ISOLATED TO SCATTERED SHOWERS
AND STORMS BUT THIS CHANCE IS SMALL LIKE POPS FOR NOW. THE BIGGEST
CHALLENGE THROUGH THIS PERIOD WILL BE TEMPERATURES ON TUESDAY
BEHIND A COOL FRONT PUSHED INTO THE CWA BEHIND THE PASSING SYSTEM
TO THE NORTH. ALL MODELS SUGGEST COOL ADVECTION IN OUR NORTHERN
CWA ON TUESDAY WITH THIS BOUNDARY IN THE PROXIMITY OF INTERSTATE
70. BASICALLY USED A BLEND TO ARRIVE AT THE TEMPERATURE FORECAST
WITH A SLIGHT TURN DOWNWARD IN GOING FORECAST. SHOULD SEE MAINLY
DRY CONDITIONS WITH SUBSIDENCE IN PLACE BUT STRONG UPSLOPE TO OUR
EAST MAY ALLOW SOME STORMS TO FIRE ALONG THE DIVIDE MOUNTAINS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 412 AM MDT SUN JUL 26 2015

MID TO HIGH LEVEL CLOUDS AR MOVING INTO THE 4 CORNERS THIS MORNING
AS A PUSH OF MONSOONAL MOISTURE ARRIVES. HOWEVER VFR CONDITIONS
WILL PREVAIL AT THE AREA FORECAST TERMINALS OVER THE NEXT 24
HOURS. THE MORE NOTICEABLE CHANGE WILL BE THE INCREASE IN COVERAGE
OF SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. THE MAIN
THREAT FROM THESE SHOWERS/STORMS WILL BE ERRATIC AND GUSTY OUTFLOW
WINDS IMPACTING FLIGHT OPERATIONS. LOWERED FLIGHT CRITERIA
PROBABILITY IS QUITE LOW ATTM BUT PASSING STORMS MY IMPACT ILS
BREAK POINTS AT KEGE...KASE AND KRIL TEMPORARILY AFTER 26/20Z.

&&

.FIRE WEATHER...
ISSUED AT 412 AM MDT SUN JUL 26 2015

A RED FLAG WARNING IS IN EFFECT FOR COLORADO ZONE 200 DUE TO LOW
AFTERNOON HUMIDITY...GUSTY WINDS...AND HAINES INDEX OF 6.
ISOLATED AFTERNOON THUNDERSTORMS ARE POSSIBLE THAT WOULD PRODUCE
GUSTY OUTFLOW WINDS AND LIGHTNING BUT LITTLE RAIN. WINDS ARE
EXPECTED TO DIMINISH AFTER 8 PM.

ALSO THE WATCH FOR MONDAY FOR FIRE ZONES 200 201 202 AND 203
REMAINS IN EFFECT WITH INCREASING CONFIDENCE FOR STRONG SOUTHWEST
WINDS AND LOW RH FOR MONDAY AS A DRY COLD FRONT PUSHES ACROSS
NORTHWEST COLORADO. WILL LET THE SUNDAY DAY SHIFT LOOK AT THIS
PERIOD IN DETAIL AND MAKE THE WARNING DECISION.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
     FOR COZ200>203.

     RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM MDT THIS
     EVENING FOR COZ200.

UT...NONE.
&&

$$

SHORT TERM...JOE
LONG TERM...15
AVIATION...TGJT
FIRE WEATHER...TGJT


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