Area Forecast Discussion
Issued by NWS Grand Junction, CO

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KGJT 220430
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1030 PM MDT MON JUL 21 2014

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 333 PM MDT MON JUL 21 2014

PASSING SHORT WAVES TO OUR NORTH HAS SHUNTED THE STRONG HIGH
PRESSURE CORE A BIT SOUTHWARD. THIS HAS ALLOWED DRIER AIR TO
ADVECT ACROSS ERN UTAH INTO NW COLORADO TODAY. THIS HAS REDUCED
THE CONVECTIVE POTENTIAL THIS AFTERNOON...LIMITING ANY
THUNDERSTORM THREAT TO THE ERN SAN JUAN MOUNTAINS. GRADIENT FLOW
OVER NW COLORADO HAS TIGHTENED FOR AFTERNOON BREEZES IN THE 20-25
MPH RANGE.

AMPLIFICATION OF THE PACIFIC NORTHWEST COAST TROUGH LEADS TO THE
SUBTROPICAL HIGH CORE TO BUILD BACK INTO COLORADO. THIS STRONG
HIGH WILL LEAD TO A HOT DAY ACROSS MUCH OF THE FORECAST AREA.
STEEP LAPSE RATES BENEATH THE HIGH WILL RESULT IN A BETTER CHANCE
OF MOUNTAIN THUNDERSTORMS FROM THE SAN JUANS...ELKS AND SAWATCH
RANGE...POSSIBLY AS FAR NORTH AS THE GORE RANGE. STEERING FLOW
WILL BE WEAK...THEREFORE THESE CELLS WILL BE THE POP AND DROP
VARIETY.

CIRCULATION AROUND THE HIGH CORE LEADS TO AN EXPANSION OF MID
LEVEL MOISTURE ON TUESDAY NIGHT. AIR MASS WILL HAVE SUFFICIENT
MOISTURE TO SUPPORT NOCTURNAL THUNDER OVER SW COLORADO...WITH THE
REMAINDER OF THE FORECAST AREA STAYING DRY. WITH NO OBVIOUS MID
LEVEL SHORT WAVE AND ABSENT OF A DEEP MONSOONAL SURGE...AREAL
COVERAGE OF ANY NOCTURNAL STORMS APPEARS ISOLATED.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 333 PM MDT MON JUL 21 2014

WATER VAPOR IMAGERY SHOWING A FAIRLY ACTIVE EASTERLY WAVE OVER THE
NORTH-CENTRAL STATES OF MEXICO THIS AFTERNOON. THIS WAVE IS ROTATING
AROUND THE CENTER OF THE RIDGE LOCATED NEAR THE TEXAS PANHANDLE.
WITH THE HIGH WOBBLING OVER OR EAST OF THE SOUTHERN ROCKIES OVER THE
NEXT 36 HOURS...MONSOON MOISTURE AND THIS WAVE WILL EVENTUALLY BE
DRAWN UP THROUGH THE 4 CORNERS AND IMPACT OUR CWA GOING INTO
WEDNESDAY. MODEL PWATS GENERALLY APPROACH 1.1 INCHES BY WEDNESDAY
AFTERNOON AS THIS WAVE APPROACHES...PRODUCING WEAK TO MODERATE
INSTABILITY THROUGH A WEAK SHEAR LAYER. THE MIXED LAYER LOOKS TO BE
REDUCED BY THE ADDED MOISTURE THOUGH SOME HINT OF AN INVERTED V
PROFILE REMAINS. INITIAL STORMS WILL SHOW A THREAT OF STRONGER WINDS
FROM THE OUTFLOWS BUT MAY TRANSITION TO A MODERATE TO HEAVY RAIN
THREAT WHERE BOUNDARIES COLLIDE. HIGHS ALSO WILL BE IMPACTED BY
THE MOISTURE AS CLOUD COVER WILL BE MORE ROBUST...HOWEVER IT LOOKS
TO REMAIN NEAR NORMAL FOR LATE JULY.

HIGH PRESSURE IS TRAPPED OVER THE  ROCKIES HIGH PLAINS BY LOW
PRESSURE OFF EACH OF THE NORTHERN COASTS OF NOAM. THE WESTERN
TROUGH WILL BE BREAKING FREE AND TRAVERSING THE NORTHERN ROCKIES
AND SOUTHERN CANADIAN PRAIRIES AT THE END OF THE WEEK. MOISTURE
ADVECTION IS ENOUGH TO BOOST CAPE VALUES A TAD AND THE PASSAGE OF
THE WAVE TO THE NORTH INCREASES SHEAR. AS A RESULT STORMS MAY BE A
BIT MORE ORGANIZED GOING INTO THURSDAY AFTERNOON. WITH MOSITURE
REMAINING OVERHEAD ISOLATED TO WIDELY SCATTERED CONVECTION APPEARS
TO SURVIVE DURING THE OVERNIGHT HOURS AS WELL. THE NORTHERN SYSTEM
WILL CONTINUE TREK EASTWARD UNTIL PLOWING INTO THE WELL DEFINED
EASTERN TROF BY EARLY WEEKEND. AT THIS POINT MODELS DIVERGE ON
WHETHER THIS LOW REMAINS IN THE HIGHER LATITUDES (EURO)...OR DIVES
INTO THE GREAT LAKES REGION (GFS). THIS HAS A DIRECT IMPACT TO
WHERE THE SUB TROP RIDGE SETTLES AND WHETHER MONSOON MOSITURE OR
RECIRCULATED MOISTURE IMPACTS THE REGION. FOR NOW THE TREND OF
DECLINING POPS CONTINUES GOING INTO THE LATTER PART OF THE
FORECAST WITH HIGHS REMAINING AT OR ABOVE NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1025 PM MDT MON JUL 21 2014

NO AVIATION HAZARDS ARE EXPECTED THROUGH 18Z TUESDAY
AFTERNOON. ISOLATED -TSRA/-SHRA WILL DEVELOP AFTER 18Z...MAINLY
ACROSS THE SAN JUAN MOUNTAINS WITH ISOLATED MVFR VSBY DUE TO HEAVY
RAIN AND WIND GUSTS TO 40 MPH POSSIBLE NEAR STORMS.

&&

.FIRE WEATHER...
ISSUED AT 803 PM MDT MON JUL 21 2014

RED FLAG WARNING EXPIRED AT 0800 PM.

DRY AIR REMAINS IN PLACE ON TUESDAY AS MONSOON MOISTURE SHIFTS
EASTWARD. WINDS ALOFT WILL WEAKEN SUBSTANTIALLY AS HIGH PRESSURE
CENTERS ON COLORADO WHICH WILL LIMIT CRITICAL FIRE WEATHER
CONDITIONS. MOISTURE RETURNS TO THE MIX MID WEEK AS IT ROTATES
BACK AROUND THE CENTER OF HIGH PRESSURE...WHICH WILL ALLOW FOR AN
UPTICK IN THUNDERSTORM COVERAGE WEDNESDAY AND THURSDAY AFTERNOON.
GUSTY OUTFLOW WINDS AND THE POTENTIAL FOR FIRE STARTS WILL BE THE
MAIN CONCERN WITH THESE STORMS.

&&

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

$$

SHORT TERM...PF
LONG TERM...15
AVIATION...MPM
FIRE WEATHER...MPM



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.