840 
FXUS66 KPDT 191725 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PENDLETON OR
1025 AM PDT TUE MAR 19 2013

UPDATED FOR AVIATION DISCUSSION

.UPDATE...TODAY THROUGH WEDNESDAY NIGHT...HAVE LOWERED POPS FOR
TODAY BASED UPON LATEST RADAR...SATELLITE...AND MODEL OUTPUT.
PRECIPITATION AHEAD OF WARM FRONT TO MOVE ACROSS CASCADES THIS
AFTERNOON AND SPREAD ACROSS REST OF THE AREA OVERNIGHT. REST OF
FORECAST LOOKS GOOD FOR NOW. 

&&

.AVIATION...18Z TAFS...ANOTHER WEATEHR SYSTEM WILL MAKE ITS WAY 
ACROSS THE AREA TODAY THROUGH TOMORROW.  HIGH CLOUDS WILL START OFF 
THE TAF PERIOD...WITH CIGS QUICKLY DECREASING OVER THE NEXT 6 TO 12 
HOURS AT ALL TAF SITES.  EXPECT SHOWERS AT ALL TAF SITES BY 03Z THIS 
EVENING.  ON AND OFF RAIN SHOWERS WILL LIKELY CONTINUE THROUGH THE 
REMAINDER OF THE TAF PERIOD.  VISIBILITIES HAVE BEEN REDUCED TO 
FACTOR IN SOME POTENTIAL MODERATE RAIN SHOWERS.  WINDS MAY START TO 
PICK UP ABOVE 10KTS AFTER 15Z TOMORROW AS THE NEXT FRONTAL SYSTEM 
APPROACHES.  WEBER   

&&


.PREV DISCUSSION... /ISSUED 344 AM PDT TUE MAR 19 2013/ 

SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...A WARM FRONT WILL MOVE 
INTO CENTRAL OREGON TODAY AND SPREAD PRECIPITATION NORTH AND EAST 
ACROSS THE CWA THIS AFTERNOON. THE PRECIPITATION WILL BE PRIMARILY 
RAIN AS SNOW LEVELS WILL RISE TO 5000-6000 FEET BY THIS EVENING. 
BREEZY SOUTHERLY WINDS WILL DEVELOP TONIGHT, PARTICULARLY IN THE 
SOUTHERN GRANDE RONDE VALLEY. A STRONG COLD FRONT WILL MOVE THROUGH 
THE AREA WEDNESDAY AFTERNOON AND EVENING. THIS WILL KEEP 
PRECIPITATION OVER THE AREA. RAIN SHADOWING WILL DEVELOP OVER THE 
LOWER COLUMBIA BASIN AND DESCHUTES PLATEAU, BUT OROGRAPHIC EFFECTS 
WILL KEEP POPS HIGH IN THE MOUNTAINS. WINDS WILL BE WINDY TO LOCALLY 
VERY WINDY BEHIND THE COLD FRONT...ESPECIALLY IN THE COLUMBIA BASIN 
AND THE FOOTHILLS OF THE BLUE MOUNTAINS. THE UPPER TROUGH SUPPORTING 
THE FRONT WILL MOVE EAST WEDNESDAY NIGHT WITH DECREASING 
PRECIPITATION.  COONFIELD

LONG TERM...THURSDAY THROUGH MONDAY NIGHT...MODELS ARE BEGINNING TO 
AGREE WITH A TROUGH OF LOW PRESSURE DROPPING ACROSS THE PACIFIC 
NORTHWEST FROM THE NORTH THURSDAY INTO FRIDAY. THIS WILL KEEP 
TEMPERATURES BELOW NORMAL AND SNOW LEVELS WILL REMAIN AROUND 
2000-3000 FEET. WITH SOME MOISTURE AND AN UPSLOPE FLOW...THERE WILL 
REMAIN A CHANCE OF PRECIPITATION IN THE AREA MOUNTAINS THROUGH 
FRIDAY. MODELS BEGIN TO DIVERGE SATURDAY INTO NEXT WEEK WITH THE GFS 
SHIFTING THE TROUGH OVER THE ROCKY MOUNTAINS AND LEAVING THE PACIFIC 
NORTHWEST IN A NORTH FLOW. THE EUROPEAN MODEL MOVES THE TROUGH 
EASTWARD WITH A RIDGE BUILDING INTO THE REGION. HAVE LEANED TOWARD 
THE GFS AS IT HAS HAD THE BETTER CONSISTENCY OVER THE LAST FEW DAYS. 
WITH THE NORTHERLY FLOW...SOME DISTURBANCES MOVING THROUGH IT WILL 
KEEP A CHANCE OF PRECIPITATION OVER THE AREA THROUGH SUNDAY. SUNDAY 
NIGHT INTO MONDAY...THE GFS BUILDS THE RIDGE OF HIGH PRESSURE OFF 
SHORE...PUSHING THE TROUGH FURTHER EAST AND LEADING TO A DRYING AND 
WARMING TREND. DMH

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  58  42  60  36 /  10  60  60  30 
ALW  59  45  60  39 /  10  60  60  30 
PSC  57  43  63  42 /   0  60  40  20 
YKM  54  35  58  32 /  10  70  50  20 
HRI  58  41  62  36 /   0  60  40  20 
ELN  55  35  56  32 /  10  70  50  20 
RDM  61  37  54  24 /  20  60  50  20 
LGD  50  44  55  34 /  10  70  70  30 
GCD  59  38  53  28 /  10  70  60  30 
DLS  55  40  56  36 /  20  80  50  20 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

THREAT INDEX
TODAY : GREEN
WEDNESDAY : YELLOW
THURSDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

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