Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 011137 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PENDLETON OR
437 AM PDT SUN MAY 1 2016

UPDATED FOR AVIATION DISCUSSION

.SHORT TERM...TODAY THROUGH MONDAY NIGHT...AN UPPER LEVEL RIDGE WILL
BUILD OVER THE PACIFIC NORTHWEST AND SOUTHWEST CANADA TODAY. THIS
RIDGE WILL REMAIN OVER THE REGION THROUGH MONDAY, THOUGH THE RIDGE
AXIS WILL BEGIN TO SHIFT EAST MONDAY. AS SUCH WILL SEE FAIR AND DRY
CONDITIONS TODAY THROUGH MONDAY MORNING. TEMPS TODAY WILL BE WARM
WITH HIGHS IN THE 70S AT LOWER ELEVATIONS AND 60S IN THE MOUNTAINS.
THIS HEATING WILL CAUSE SOME WEAK SURFACE BASED INSTABILITY THAT
WILL CAUSE AFTERNOON AND EARLY EVENING CONVECTIVE CLOUDS OVER THE
HIGHER TERRAIN. MEANWHILE STRONG SUBSIDENCE ALOFT WILL KEEP THESE
CLOUDS SHALLOW AND FLAT. WINDS WILL BE GENERALLY FROM THE NORTH AND
NORTHEAST WITH SPEEDS UP TO 15 MPH. WITH THE RIDGE AXIS SHIFTING
EAST MONDAY INTO MONDAY NIGHT, WILL START TO SEE THE DEVELOPMENT OF
A MOIST SOUTHERLY FLOW OVER OUR WESTERN MOST ZONES. AS SUCH WILL SEE
A FEW SHOWERS OVER THE CASCADE EAST SLOPES MONDAY AFTERNOON AND
MONDAY NIGHT. ALSO THERE WILL BE THE POSSIBILITY OF A FEW
THUNDERSTORMS LATE MONDAY AFTERNOON AND MONDAY EVENING OVER THE
OREGON CASCADE EAST SLOPES. ELSEWHERE SUBSIDENCE ALOFT WILL REMAIN
STRONG AND THE AIR MASS WILL STILL BE RELATIVELY DRY. HIGH TEMPS
WILL BE A FEW DEGREES WARMER. 90

.LONG TERM...TUESDAY THROUGH SATURDAY...MODELS ARE IN PRETTY
GOOD AGREEMENT FOR THE NEAR TERM BUT WILL BEGIN TO DIVERGE LATE IN
THE WEEK. HIGH PRESSURE CONTINUES TO SHIFT EAST AS A LOW DEEPENS OFF
THE OR/WA COAST.  MOIST UNSTABLE CONDITIONS CAN BE EXPECTED...ACROSS
CENTRAL OREGON AND THE OR/WA CASCADE EAST SLOPES ON TUESDAY
AFTERNOON. HAVE KEPT A SLIGHT CHANCE OF THUNDERSTORMS ACROSS
NORTHEAST OREGON...BUT MODELS SEEM TO BE HINTING AT A SLOWER
PROGRESSION OF THE MOISTURE...SUGGESTING LOWER PROBABILITIES OF
THUNDERSTORMS ACROSS NORTHEAST OREGON...BUT FOR NOW WILL KEEP IT AS
SLIGHT CHANCE. WEDNESDAY THE LOW IS EXPECTED TO BE JUST OFF THE
SOUTHERN OR/NORTHERN CA COAST. THIS WILL PROVIDE A GOOD UNSTABLE
SETUP FOR MOST OF THE FORECAST AREA...THUSLY THUNDERSTORMS WILL BE
IN THE FORECAST FOR ALL AREAS WEDNESDAY AFTERNOON AND EVENING.

TEMPERATURES WILL COOL OFF A BIT AS WE HEAD TOWARD THE END OF THE
WORK WEEK...BUT ARE STILL EXPECTED TO BE SLIGHTLY ABOVE NORMAL. THE
REST OF THE EXTENDED HAS BEEN LEFT AS IS...WITH MAINLY CHANCE POPS
OVER THE MOUNTAINS AND SLIGHT CHANCE OVER THE LOWER ELEVATIONS. AS
THE LOW CONTINUES TO DIVE SOUTH TOWARDS SOUTHERN NEVADA...MODELS
DIVERGE IN THEIR SOLUTIONS.  SOME MODELS CONTINUE TO SPIN MOISTURE
UP INTO THE DEFORMATION ZONE...MAINLY CENTRAL AND NORTHEAST OREGON.
OTHERS KEEP THE MOISTURE FAR ENOUGH SOUTH TO SUGGEST A DRY END OF
THE WORK WEEK.  WILL HAVE TO FINE TUNE THIS AS THIS SYSTEM
APPROACHES THE NEAR TERM. WEBER

&&

.AVIATION...12Z TAFS...VFR CONDITIONS WITH MOSTLY CLEAR SKIES WILL
PREVAIL FOR THE NEXT 24 HOURS AT ALL TAF SITE. WINDS WILL
GENERALLY BE LESS THAN 10 KTS. WEBER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  75  46  81  48 /   0   0   0  10
ALW  75  50  81  54 /   0   0   0  10
PSC  79  45  84  49 /   0   0   0  10
YKM  80  45  84  48 /   0   0   0  10
HRI  79  42  84  46 /   0   0   0  10
ELN  79  43  84  46 /   0   0   0  10
RDM  73  37  79  42 /   0   0  10  20
LGD  70  40  75  42 /   0   0   0  10
GCD  73  39  79  43 /   0   0   0  10
DLS  81  47  87  52 /   0   0   0  10

&&

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

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

$$

90/89/89



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