Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 241917
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
117 PM MDT FRI APR 24 2015

.UPDATE...
ISSUED AT 112 PM MDT FRI APR 24 2015

THUNDERSTORMS BEGAN TO DEVELOP QUICKLY AROUND 11AM THIS
MORNING...AND THEY LOOK IMPRESSIVE ON RADAR FOR A FEW SCANS (10 TO
15 MINS) BEFORE DWINDLING DOWN TO A PASSING SHOWER. THE EXCEPTION
IS OVER THE SAN JUANS AND THE SOUTHERN COLORADO VALLEYS WHERE THE
THUNDERSTORMS ARE SUSTAINING THEMSELVES...AND OVER THE ROAN
CLIFFS/FLATTOPS REGION. EXPECTING THE TSTORM THREAT TO DIMINISH
LATER THIS AFTERNOON AS WEAK RIDGING BUILDS IN FOR A SHORT TIME
LATE THIS AFTERNOON AND EVENING...HOWEVER SHOWERS WILL STICK
AROUND THROUGH SUNSET.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 302 AM MDT FRI APR 24 2015

SPLIT PATTERN OVER THE WEST TO BEGIN THE FORECAST CYCLE THIS
MORNING. A CLOSED LOW WHICH ORIGINATED OVER SOUTHERN CALIFORNIA
HAS OPENED AND WAS TRACKING ACROSS THE DESERT SOUTHWEST EARLY THIS
MORNING. THE BASE OF THE TROUGH NOT QUITE AS FAR SOUTH AS EARLIER
MODEL RUNS HAD INDICATED AND SHOULD BRING ISOLATED TO SCATTERED
SHOWERS TO THE SOUTHWEST SAN JUANS AND POSSIBLY THE LOWER
ELEVATIONS OF LA PLATA AND ARCHULETA COUNTIES BEFORE NOON.
MEANWHILE...A SHORTWAVE TROUGH EJECTED FROM A LOW OVER SOUTHERN
BRITISH COLUMBIA IN THE NORTHERN STREAM WILL CONTINUE TO TRACK
ACROSS THE NORTHERN INTERMOUNTAIN REGION. LIFT ASSOCIATED WITH
THIS FEATURE MAY GENERATE A FEW SHOWERS OVER THE EASTERN UINTA
MOUNTAINS BEFORE NOON. AS HAS BEEN THE CASE OVER THE PAST SEVERAL
DAYS...DAYTIME HEATING AND RESULTANT INSTABILITY WILL BRING
INCREASED SHOWERS ALONG WITH EMBEDDED THUNDERSTORMS DURING THE
AFTERNOON. PRECIPITABLE WATER (PW) VALUES AHEAD OF THE APPROACHING
SHORTWAVE INCREASE TO NEAR 0.40 INCHES WHICH SHOULD YIELD
INCREASED COVERAGE RELATIVE TO YESTERDAY.

MUCH OF THE REGION WILL EXPERIENCE THE USUAL DOWNTURN IN MOIST
CONVECTION THIS EVENING AS THE ATMOSPHERE SETTLES IN RESPONSE TO
DIURNAL COOLING. HOWEVER...EXPECT SHOWERS WILL PERSIST OVER THE
EASTERN UINTA MOUNTAINS AS THE TROUGH IN THE NORTHERN STREAM
DRIVES ITS ASSOCIATED COLD FRONT TO NORTHEAST UTAH DURING THE
NIGHT. SHOWERS INCREASE AND BECOME MORE WIDESPREAD SATURDAY AS A
THE TROUGH CONTINUES TO PUSH EAST AND DEEPENS DURING THE DAY.
MODELS INDICATED AREAS ABOVE 9000 FEET IN THE EASTERN UINTA
MOUNTAINS COULD RECEIVE SNOWFALL AMOUNTS NEAR 6 INCHES TONIGHT
THROUGH SATURDAY. EXPECT IMPACTS FROM SNOWFALL WILL BE MINIMAL
HIGH POINT OF HIGHWAY 191 WELL BELOW THE 9000 FOOT LEVEL.
CONSEQUENTLY...DO NOT PLAN TO HOIST WATCH WITH THIS ISSUANCE.

TEMPERATURES WILL BE NORMAL TODAY OWING LARGELY TO INCREASED CLOUD
AND SHOWER COVERAGE. FOR THE SAME REASON...OVERNIGHT LOWS WILL BE
A LITTLE ABOVE NORMAL DUE TO BLANKETING AFFECT OF CLOUDS. UPTICK
IN ACTIVITY SATURDAY POINTS TO COOLER THAN NORMAL TEMPERATURES BY
THE END OF THE DAY.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 302 AM MDT FRI APR 24 2015

ANOTHER WET AND WARM STORM SYSTEM WILL MOVE THROUGH THE AREA SAT
NIGHT THROUGH SUNDAY NIGHT. THE DIGGING AND SPLITTING TROUGH WILL
REACH THE UT AND AZ BORDER SUNDAY MORNING...AND CLOSE OFF AT 500
MB OVER NE AZ. PRECIPITATION OVER EASTERN UT AND WESTERN CO WILL
BE MOSTLY RAIN AND SHOULD BE WIDESPREAD BY SAT EVENING. THE SNOW
LINE SHOULD REMAIN ABOVE 9000 FEET DURING DAY...DROPPING TO ABOUT
8000 FEET AT NIGHT. A FEW INCHES OF SNOW ACCUMULATION IS EXPECTED
SAT NIGHT THROUGH SUN...BUT THE VAST MAJORITY OF THIS WILL OCCUR
ABOVE 9500 FEET.

THE CLOSED 500 MB LOW CENTER WILL TRAVEL THROUGH NEW MEXICO SUNDAY
NIGHT...WITH SOME MOISTURE WRAPPING AROUND THE NORTH SIDE OF THE
LOW AND INTO NORTHERN AND CENTRAL CO THROUGH SUNDAY NIGHT. THIS
PRECIPITATION WILL MOVE SLOWLY EAST THROUGH MONDAY NIGHT.

TUE THROUGH THU AND RIDGE BUILDS OVER THE AREA ALLOWING FOR DRIER
AND WARMER CONDITIONS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1149 AM MDT FRI APR 24 2015

MINOR SHORTWAVE TROUGH AND QUICKER THAN EXPECTED DESTABILIZATION
TODAY HAS ALREADY YIELDED NUMEROUS SHRA AND TSRA AS OF 18Z. MANY
ALREADY NEAR TAF SITES SO VCTS/VCSH WILL CONTINUE THROUGH MOST OF
THE DAYLIGHT HOURS. DO BELIEVE INTENSITY WILL WANE WEST TO EAST
AFTER 20Z AS SHORTWAVE EXITS TO THE EAST AND A SHORTWAVE RIDGE
BUILDS OVER THE AREA. LOWEST CIGS AND VSBY EXPECTED AT HIGHER
SITES LIKE KASE AND KTEX. AFTER A LULL IN ACTIVITY EARLY
TONIGHT...INCREASINGLY MOIST SOUTHWEST FLOW ALOFT AND APPROACHING
COLD FRONT WILL CAUSE A BROADER AREA OF SHRA AND LOW CIGS/VSBY TO
MOVE WEST TO EAST ACROSS THE AREA AFT 10Z.


&&

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

$$

UPDATE...JAM
SHORT TERM...NL
LONG TERM...CC
AVIATION...BEN


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