Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 061741 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1035 AM PDT FRI MAY 6 2016

.UPDATE...AN UPPER LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA INTO
THE GREAT BASIN AND A HIGH TO THE NORTH OF THE REGION WILL KEEP AN
EAST TO NORTHEAST LOW LEVEL FLOW OVER THE CWA TODAY. THE OVERALL
ATMOSPHERE WILL BE MORE STABLE WITH MUCH LESS SHEAR. HOWEVER
PRECIPITABLE WATER VALUES AND NEGATIVE LI`S ALONG THE SOUTHERN
BORDER OF THE CWA SUGGESTS THAT THERE WILL BE THUNDERSTORMS AGAIN
THIS AFTERNOON AND EVENING ALONG THE SOUTHEAST BORDER REGION OF THE
CWA. THIS MORNING THERE MAY BE A FEW SHOWERS BUT THEY WILL BE LIGHT
AND WITHOUT THUNDER. THE ATMOSPHERE WILL GENERALLY BECOME DRIER OVER
THE NEXT COUPLE DAYS WITH LOCALLY BREEZY CONDITIONS...ESPECIALLY IN
THE AFTERNOON AND EVENING. TEMPERATURES WILL WARM UP TO THE LOWER TO
MID 80S TODAY AND SATURDAY IN THE LOWER ELEVATIONS. 88

.AVIATION...LCL MVFR CONDITIONS COULD OCCUR AT TAF SITE KBDN AND
POSSIBLY KRDM UNTIL 20Z. OTHERWISE MAINLY VFR CONDITIONS WILL
PERSIST ACROSS ALL TAF SITES FOR THE NEXT 24 HOURS. HOWEVER AN ISOLD
TSRA IS POSSIBLE NEAR TAF SITE KRDM AND KBDN BETWEEN 22Z AND 02Z.

&&

.PREV DISCUSSION... /ISSUED 500 AM PDT FRI MAY 6 2016/

SHORT TERM...TODAY THROUGH SUNDAY...AN ELONGATED TROUGH IS LOCATED
OVER THE PACIFIC COAST WITH A CLOSED LOW IN SOUTHERN CALIFORNIA. THE
MOISTURE AND INSTABILITY IS DECREASING TONIGHT AS UPPER LEVEL FLOW
OVER EASTERN OREGON CHANGES FROM SOUTHERLY IN THE TROUGH TO
SOUTHEASTERLY AROUND THE SOUTHERN LOW. AS THIS LOW DRIFTS SOUTHEAST
TODAY AN UPPER LEVEL RIDGE WILL BUILD INTO SOUTHERN CANADA AND
NORTHERN WASHINGTON. THIS RIDGING WILL CREATE A STRONG CAP OVER
WASHINGTON AND PART OF NORTHEASTERN OREGON. THE COMBINATION OF THIS
CAP...DOWN SLOPE EASTERLY FLOW...AND DECREASING MOISTURE WILL KEEP THE
BLUE MOUNTAIN FOOTHILLS AND AREAS TO THE NORTHWEST OF THE FOOTHILLS
DRY TODAY. ALONG THE SOUTHERN BORDER OF THE CWA, ESPECIALLY IN
WALLOWA AND GRANT COUNTIES, THE CAP WILL BE WEAKER AND THERE IS
ENOUGH INSTABILITY TO BREAK IT AND FORM THUNDERSTORMS DURING THE
AFTERNOON AND EVENING. THESE THUNDERSTORMS WILL END WITH THE LOSS OF
DAYTIME HEATING. THE SURFACE GRADIENT BETWEEN THE NORTHERN RIDGE AND
THE LOW TO THE SOUTH WILL CREATE BREEZY NORTH TO NORTHEAST WINDS
OVER THE AREA IN THE AFTERNOON.

THE UPPER LOW WILL CONTINUE TO MOVE EAST SATURDAY AND SUNDAY WHICH
WILL CAUSE A GRADUAL DECREASE IN CONVECTIVE DEVELOPMENT AND
STABILIZATION OF THE ATMOSPHERE. A FEW SHOWERS AND THUNDERSTORMS ARE
STILL POSSIBLE IN EASTERN GRANT COUNTY AND WALLOWA COUNTY SATURDAY.
SUNDAY EASTERN WASHINGTON AND NORTHEASTERN OREGON WILL BE DRY. A
WEAK MARINE PUSH SUNDAY WILL BRING COOLER TEMPERATURES AND BREEZY
WINDS IN THE LOWER COLUMBIA BASIN. COONFIELD

LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...WINDY CONDITIONS WILL
PERSIST INTO SUNDAY EVENING DUE TO THE WEAK MARINE PUSH SUNDAY. A
DISTURBANCE WILL MOVE SOUTHEAST OUT OF BRITISH COLUMBIA AND ACROSS
THE AREA OVERNIGHT SUNDAY INTO MONDAY. THIS SYSTEM WILL KEEP
CONDITIONS LOCALLY BREEZY INTO MONDAY. ALSO THERE WILL BE VARYING
CHANCES OF SHOWERS OVER THE BLUE MOUNTAINS, THE ADJACENT FOOTHILLS
OF THE BLUES, THE GRANDE RONDE VALLEY AND WALLOWA COUNTY, MAINLY ON
MONDAY. FOR THE TUESDAY THROUGH THURSDAY PERIOD, EXPECT DRY AND
WARMING CONDITIONS DUE TO A WEAK UPPER LEVEL RIDGE. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  78  57  81  55 /  10  10  10  10
ALW  80  56  82  56 /  10  10  10  10
PSC  84  58  87  58 /  10  10   0   0
YKM  84  55  87  54 /  10  10   0   0
HRI  82  54  85  56 /  10  10  10  10
ELN  81  51  83  52 /  10  10   0   0
RDM  73  44  79  42 /  10  10  10  10
LGD  72  49  76  48 /  40  20  20  20
GCD  71  50  76  48 /  40  40  20  20
DLS  85  54  86  55 /  10  10   0   0

&&

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

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

$$

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