Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 290508
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1108 PM MDT SAT MAR 28 2015

.UPDATE...
ISSUED AT 1105 PM MDT SAT MAR 28 2015

THE FRONT HAD SAGGED SOUTH OF THE I-70 CORRIDOR AT 11PM AND THE
BEST FORCING WAS MOVING EAST OF VAIL PASS. ASPEN AIRPORT RECEIVED
A LIGHT SHOWER WITH FRONTAL PASSAGE BUT VALLEYS WERE MOSTLY DRY.
THIS MILD FRONT WILL DROP TEMPERATURES A FEW DEGREES FOR ALL BUT
THE SOUTHERN MOST ZONES. FORECAST REMAINS ON TRACK WITH MARGINAL
MOISTURE AND THE STALLED FRONTAL BOUNDARY PRODUCING LIGHT
ISOLATED-SCATTERED SHOWERS OVER THE SAN JUAN MOUNTAINS SUNDAY
AFTERNOON. THESE SHOULD BE RAIN AT ALL ELEVATIONS. LIGHTNING IS
NOT EXPECTED WITH MEAGER INSTABILITY.

&&

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 317 PM MDT SAT MAR 28 2015

THE TAIL END OF AN UPPER LEVEL SHORTWAVE MOVING ACROSS MONTANA
THIS AFTERNOON AND INTO THE DAKOTAS THIS EVENING...WILL BRUSH THE
NORTHERN PORTION OF OUR FORECAST AREA. AN ASSOCIATED COLD FRONT
WILL DROP IN FROM NORTH THIS EVENING AND MAKE IT TO THE I-70
CORRIDOR BY AROUND MIDNIGHT. SATELLITE IMAGES INDICATE THAT THE
SOUTHERN EXTENT OF THIS SYSTEM IS MOISTURE STARVED AS IT
APPROACHES THE CENTRAL ROCKIES. BUT GUSTY WINDS HAVE ALREADY BEGUN
TO DEVELOP IN THE PREFRONTAL ENVIRONMENT. THESE SHOULD PERSIST
THROUGH THE DAYLIGHT HOURS...AND POSSIBLY LONGER IN CLOSE
PROXIMITY TO THE FRONT. ALSO IN SPITE OF THE WEAK FORCING AND
MARGINAL MOISTURE EXPECT THAT ISOLATED TO LOW SCATTERED SHOWERS
WILL DEVELOP BY LATE THIS AFTERNOON OVER THE NORTHERN
MOUNTAINS...THEN QUICKLY SPREADING INTO THE CENTRAL COLORADO
MOUNTAINS. EXPECT THIS ACTIVITY WILL PEAK BETWEEN 00Z AND 04Z
...6PM-10PM MDT. ANY SHOWERS OR EVEN VIRGA THAT DEVELOP WILL
PRODUCE ERRATIC WIND GUSTS.

ON SUNDAY MODELS HINT THAT A SLIGHT INCREASE IN MOISTURE WILL SPREAD
NORTHWARD INTO THE SOUTHERN CWA. THIS WILL COMBINE WITH THE STALLED
FRONT...AND DIURNAL HEATING TO PRODUCE ISOLATED TO SCATTERED SHOWERS
OVER THE SOUTHERN MOUNTAINS...SOUTH OF THE LEFT OVER FRONTAL
BOUNDARY. AN ISOLATED THUNDERSTORMS WILL BE POSSIBLE AS WELL.

WHILE OVERNIGHT LOWS WILL CONTINUE TO BE MILD DUE TO THE STILL
SOMEWHAT UNSETTLED AIR MASS. THE FRONT WILL BRING A FEW DEGREES OF
COOLING TO SUNDAY`S HIGHS...ESPECIALLY OVER THE NORTH. THAT
SAID...TEMPERATURES WILL STILL REMAIN WELL ABOVE NORMAL FOR THE END
OF MARCH. SUNDAY NIGHT LOWS WILL BE A TAD COOLER THAN TONIGHT`S.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 317 PM MDT SAT MAR 28 2015

IT APPEARS THERE ARE TWO MAIN CIRCULATIONS ACROSS NOAM THAT WILL BE
FEEDING ENERGY INTO THE LOWER LATITUDES...THE NORTH PACIFIC REGION
INCLUDING THE GULF OF ALASKA AND THE POLAR VORTEX IN THE VICINITY OF
HUDSON BAY. INITIALLY THROUGH MID WEEK WE WILL BE MAINLY INFLUENCED
BY THE PACIFIC FEED OF MOISTURE AND ENERGY WHICH WILL LEAD TO A
SLIGHT COOL DOWN AS THIS DOMINANT RIDGE IS FLATTENED. BY LATE IN THE
WEEK THE TWO FEEDS APPEAR TO PHASE AND THIS WILL PUSH A MORE
SIGNIFICANT FRONT THROUGH THE REGION AND TEMPERATURES MAY END UP ON
THE LOW SIDE OF GUIDANCE BY FRIDAY INTO THE EARLY WEEKEND PERIOD.
OTHERWISE TEMPERATURES WILL START OUT WELL ABOVE NORMAL MONDAY INTO
TUESDAY...THEN SLOWLY TREND DOWNWARD AS A MORE SIGNIFICANT SYSTEM
TRACKS ACROSS THE NORTHERN STATES AND PUSHES SOME COOLER AIR
SOUTHWARD. PWATS LOOKS TO STALL AT AROUND A THIRD OF AN INCH THROUGH
MID WEEK THEN SLOWLY FALL OFF AS THE COOLER AIR DROPS IN. WITH NO
SIGNIFICANT FORCING THROUGH MID WEEK...INSTABILITY WILL BE THE MAIN
FORCING MECHANISM SO ISOLATED SHOWERS OR A THUNDERSTORMS WILL POP
OVER THE CENTRAL AND SOUTHERN MOUNTAINS EACH AFTERNOON THROUGH
TUESDAY. A WEAK FRONTAL BOUNDARY WILL SETTLE OVER THE CENTRAL CWA
COME WEDNESDAY AND RE-FOCUS ADDITIONAL CONVECTION TO THE NORTH
WEDNESDAY AND THURSDAY. A MORE ORGANIZED SYSTEM MOVED ACROSS WYOMING
ON THURSDAY NIGHT. WITH A COLD AIR SOURCE BEHIND THIS SYSTEM
TEMPERATURES LOOK TO DROP ANOTHER 5 TO 8 DEGREES COME FRIDAY AND END
UP BELOW NORMAL. A QUICK REBOUND IS THEN EXPECTED SATURDAY AS
RIDGING REBUILDS ALOFT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1105 PM MDT SAT MAR 28 2015

THE COLD FRONT WAS SOUTH OF I-70 CORRIDOR PRODUCING SHOWERS FROM
KASE EASTWARD WITH MTN TOPS POSSIBLY OBSCURED AT TIMES. AFTER 09Z
VFR RETURNS TO ALL SITES

SHOWERS ARE EXPECTED TO REDEVELOP OVER THE CENTRAL AND SOUTHERN
COLORADO MOUNTAINS AFTER 18Z SUNDAY WITH OUTFLOW WIND GUSTS TO 30
MPH LIKELY. SUSTAINED WINDS WILL BE LIGHTER.

DESPITE THE SHOWER ACTIVITY DESCRIBED TAF SITES AND OTHER AREA
AIRPORTS ARE NOT EXPECTED TO SEE FLIGHT CATEGORIES REDUCED BELOW
VISUAL RULES THROUGH THE NEXT 24 HOURS THOUGH AN ISOLATED SHOWER
AND LOWERED CIGS ARE POSSIBLE MAINLY AT KTEX.


&&

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

$$

UPDATE...JOE
SHORT TERM...EH
LONG TERM...15
AVIATION...JOE


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