Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 221713 AAA
AFDGJT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1113 AM MDT TUE JUL 22 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 352 AM MDT TUE JUL 22 2014

HIGH PRESSURE STRENGTHENS OVER THE FORECAST AREA TODAY AND WILL
LEAD TO HIGHER AFTERNOON TEMPS. STEEP LAPSE RATES BENEATH THE
HIGH WILL RESULT IN A FEW LATE DAY MOUNTAINS STORMS WILL BE OVER
THE ELKS AND SAN JUANS AND POSSIBLY EXTENDING TO THE GORE RANGE.
ENVIRONMENTAL SHEAR PROFILE IS VERY WEAK AND HENCE MOST STORMS
WILL BE SHORT LIVED.

SOUTHERLY WINDS INCREASING AROUND THE HIGH CORE WILL BRING A PLUME
OF MID LEVEL MOISTURE INTO THE REGION ON TUESDAY NIGHT. NOCTURNAL
SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER SW COLORADO AS
AVAILABLE MOISTURE INCREASES FROM THE SOUTH...BUT WOULD BE ISOLATED
TUESDAY NIGHT NEAR THE CO/NM BORDER. WOULD NOT BE SURPRISED TO SEE
SHOWERS MOVING INTO SOUTHWESTERN COLORADO ON WEDNESDAY MORNING AND
EARLY THUNDERSTORM INITIATION WEDNESDAY AS WELL.

ON WEDNESDAY...A SHORTWAVE EMBEDDED IN THE CLOCKWISE FLOW OF HIGH
PRESSURE WILL EVENTUALLY MAKE ITS WAY UP THROUGH THE 4 CORNERS AND
IMPACT OUR CWA REGION. FORECAST PWATS REALLY SKYROCKET ON
WEDNESDAY TO OVER AN INCH SUGGESTING A RATHER CLOUDY AND
POTENTIALLY STORMY DAY. HOWEVER...CONVECTIVE INDICES BY MID
AFTERNOON WEDNESDAY ARE NOT SIGNIFICANT SO DEVELOPMENT WILL BE
DEPENDENT ON WEAK TO MODERATE INSTABILITY THROUGH A WEAK SHEAR
LAYER. AS MENTIONED BY PREVIOUS FORECASTER...THE HINT OF AN
INVERTED V PROFILE REMAINS IN MODELED SOUNDINGS SUGGESTING STORMS
ON WEDNESDAY WILL INITIALLY CONTAIN A WIND THREAT. MODERATE TO
HEAVY RAIN THREAT WILL BE POSSIBLE DURING THE LATE AFTERNOON ON
WEDNESDAY WITH SHOWER AND STORM MOTION FROM SOUTHWEST TO
NORTHEAST...ESPECIALLY FROM THE SOUTHERN SAN JUANS TO THE CO/NM
BORDER. HIGH TEMPERATURES WILL BE HINDERED SLIGHTLY BY CLOUD
COVER ON WEDNESDAY.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 352 AM MDT TUE JUL 22 2014

THURSDAY SHOULD BE ANOTHER ACTIVE DAY WITH STORM INITIATION OVER
HIGHER TERRAIN AND STORM MOVEMENT EASTWARD. THE MAIN THREAT OF
THESE STORMS WILL BE HEAVY RAIN AND FREQUENT LIGHTNING. THE
SOUTHERN EDGE OF A JET STREAK LOOKS TO SLIDE OVER NE UTAH AND NW
COLORADO ON THURSDAY AS THE HIGH PRESSURE OVERHEAD GETS SQUASHED
TO THE SOUTH BY AN APPROACHING PACIFIC NW TROUGH OVER THE NORTHERN
US ROCKIES.

HIGH PRESSURE CONTINUES TO BE QUASI ANCHORED OVER THE FOUR
CORNERS REGION. A PASSING SHORT WAVE FLATTENS THE RIDGE ON FRIDAY
WITH A WEAK MONSOONAL TAP THAT STREAMS INTO WRN COLORADO. AFTER
THE SHORT WAVE MOVES DOWNSTREAM...RIDGE AMPLIFIES AND MODELS
SUGGEST IT WILL BE COVERING THE ENTIRE WRN CONUS BY NEXT MONDAY.
MONSOONAL STREAM GETS PUSHED WESTWARD...BUT SUFFICIENT MOISTURE
REMAINS TRAPPED BENEATH THE HIGH CORE. AFTERNOON INSTABILITY WILL
YIELD DIURNALLY DRIVEN STORMS WITH THE BEST CHANCE OVER THE ELKS
AND SAN JUANS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1109 AM MDT TUE JUL 22 2014

VFR CONDITIONS THROUGH THE TAF PERIOD WITH TYPICAL MID SUMMER DIURNAL
CYCLE OF WINDS AT TAF SITES. ISOLATED CONVECTIVE SHRA/TSRA TODAY
SHOULD BE LIMITED TO THE SAN JUAN MOUNTAINS TO ELK AND SAWATCH
RANGES. A MORE SIGNIFICANT INCREASE IN MOISTURE AND INSTABILITY EXPECTED
ON WEDNESDAY SO WILL LIKELY SEE AN EARLIER AND GREATER COVERAGE OF
SHRA/TSRA. CONFIDENCE NOT GREAT ENOUGH TO MENTION IN TAFS THROUGH
18Z THOUGH.

&&

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

$$

SHORT TERM...PF/JAM
LONG TERM...JAM/PF
AVIATION...BEN



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