Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 041720 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1020 AM PDT SAT JUL 4 2015

.SHORT TERM... FORECAST REMAINS ON TRACK WITH ONLY MINOR CHANGES TO
MAINLY SKY COVER...TEMPERATURES AND WINDS. THERE ARE SOME SCT TO BKN
HIGH CLOUDS ACROSS MUCH OF NORTH-CENTRAL OREGON THIS MORNING WHICH
ARE FORECAST TO REMAIN GENERALLY IN PLACE THROUGH TODAY AND TONIGHT
BEFORE SHIFTING SOUTH BY SUNDAY. THE CLOUDS THIN OUT AND ALLOW FOR
MOSTLY SUNNY/CLEAR CONDITIONS TO PREVAIL HEADING NORTH TOWARD THE
BLUE MOUNTAIN FOOTHILLS...COLUMBIA BASIN AND INTO
WASHINGTON...OVERALL DID RAISE SKY COVER SLIGHTLY OVER MUCH OF
OREGON TO ACCOUNT FOR THESE CLOUDS. OTHERWISE IT WILL BE ANOTHER HOT
AFTERNOON ACROSS THE FORECAST AREA...AFTERNOON HIGHS WERE RAISED A
DEGREE OR TWO WITH HIGHS EXPECTED TO RANGE FROM 98 TO 105 IN THE
LOWER ELEVATIONS/BASINS AND IN THE 80S TO MID-90S FOR THE MOUNTAINS.
IT WILL STAY DRY AND VERY MILD THIS EVENING INTO THE OVERNIGHT HOURS
WITH LOW TEMPERATURES ONLY DIPPING DOWN INTO THE MID TO UPPER 60S IN
THE COLUMBIA BASIN AND SURROUNDING VALLEYS WITH 50S IN THE
MOUNTAINS. SUNDAY WILL REMAIN VERY WARM BUT LIKELY A FEW DEGREES
COOLER THAN THIS AFTERNOON...WITH HIGH TEMPERATURES IN THE MID-90S
TO AROUND 100 FOR THE LOWER ELEVATIONS. KEPT CONDITIONS DRY FOR NOW
BUT WILL MAY NEED TO REEVALUATE THE THREAT FOR AT LEAST SOME
ISOLATED PM THUNDERSTORMS ACROSS PARTS OF OUR OREGON MOUNTAIN ZONES
WITH THE AFTERNOON GUIDANCE. 77

&&

.FIRE WEATHER...THE RED FLAG WARNINGS FOR WIND AND LOW RELATIVE
HUMIDITY FOR PORTIONS OF THE COLUMBIA BASIN...EASTERN COLUMBIA RIVER
GORGE...AND NORTH CENTRAL AND CENTRAL OREGON WILL CONTINUE TODAY.
RH`S WILL BE SIMILAR TO YESTERDAY...I.E. 8 TO 15 PERCENT FOR MOST OF
THE REGION.  WINDS MAY BE LESS THAN YESTERDAY BUT WILL STILL BRING
THE POSSIBILITY OF RAPID FIRE SPREAD IN SOME AREAS WHERE WINDS WILL
INCREASE TO AROUND 10-20 MPH THIS AFTERNOON AND EVENING.  THE
WARNING FOR THE HANFORD DISTRICT AND THE YAKIMA VALLEY IS IN EFFECT
THROUGH SUNDAY MORNING. NORTHERLY WINDS WILL INCREASE THERE TONIGHT
AND GUSTS TO 30-35 MPH ARE POSSIBLE...MAINLY ALONG RATTLESNAKE
RIDGE.  THE FIRE WEATHER CONCERNS WILL SHIFT TO THE THUNDERSTORM
POTENTIAL LATER THIS WEEK...AND THIS WILL BE ADDRESSED IN FUTURE
DISCUSSIONS.  WISTER

&&

.PREV DISCUSSION... /ISSUED 420 AM PDT SAT JUL 4 2015/

SHORT TERM...TODAY THROUGH MONDAY...AN UPPER RIDGE WILL CONTINUE
TODAY SOUTHEAST OF THE FORECAST AREA OVER THE GREAT BASIN AND THERE
WILL BE A NORTHWEST FLOW OVER THE CWA NORTH OF THE RIDGE. THIS WILL
KEEP HIGH HEIGHTS AND VERY WARM 850 MB TEMPERATURES OVER THE REGION
TODAY AND WILL RESULT IN ANOTHER HOT DAY FOR THE FORECAST AREA WITH
HIGHS AROUND 100 IN THE LOWER ELEVATIONS AND 80S TO LOWER 90S IN THE
MOUNTAINS. THESE TEMPERATURES HOWEVER DO NOT MEET HEAT ADVISORY
CRITERIA. SURFACE PRESSURE GRADIENTS WILL TIGHTEN UP ALONG THE
CASCADE EAST SLOPES THIS AFTERNOON. THIS WILL CAUSE INCREASING WINDS
ALONG THE CASCADE EAST SLOPES AND ADJACENT VALLEYS AND PLATEAUS.
THIS COMBINED WITH LOW RELATIVE HUMIDITY AND HOT TEMPERATURES WILL
CONTINUE TO WARRANT RED FLAG WARNINGS FOR CRITICAL FIRE WEATHER
CONDITIONS IN THE FIRE WEATHER ZONES JUST EAST OF THE CASCADES.
ELSEWHERE WINDS WILL BE MOSTLY LIGHT TODAY. ON SUNDAY WINDS WILL
REMAIN LIGHT IN ALL AREAS WHICH WILL REDUCE THE THREAT OF CRITICAL
FIRE WEATHER CONDITIONS. RED FLAG WARNINGS WILL REMAIN IN EFFECT
UNTIL 9 AM SUNDAY MORNING FOR PORTIONS OF THE WASHINGTON YAKIMA AND
KITTITAS VALLEYS AND A PORTION OF THE LOWER COLUMBIA BASIN ADJACENT
TO THESE VALLEYS. TEMPERATURES WILL BE ANOTHER COUPLE DEGREES COOLER
ON SUNDAY. THE UPPER RIDGE SOUTHEAST OF THE CWA WILL NUDGE BACK TO
THE NORTHWEST ON MONDAY RESULTING IN WARMING TEMPERATURES BY A
DEGREE OR TWO...BUT NOT ENOUGH FOR A HEAT ADVISORY ANYWHERE IN THE
CWA. TEMPERATURES WILL THEN REMAIN NEARLY STEADY GOING INTO THE
EXTENDED FORECAST PERIOD. 88

LONG TERM...MONDAY NIGHT THROUGH FRIDAY NIGHT...UPPER LEVEL LOW OFF
THE CALIFORNIA COAST WILL SLOWLY PROGRESS EASTWARD THROUGH THE LONG
TERM PERIOD. AN UPPER LEVEL RIDGE WILL PERSIST TO THE SOUTHEAST. THE
LOW WILL BRING MID LEVEL MOISTURE AND INSTABILITY TO SOUTHEASTERN
OREGON. THIS MOISTURE AND INSTABILITY MAY BRING AFTERNOON AND
EVENING THUNDERSTORMS TO THE SOUTHERN BORDER OF THE CWA FROM CENTRAL
OREGON TO GRANT COUNTY. DRY WEST TO NORTHWEST FLOW WILL KEEP DRY
CONDITIONS WITH MOSTLY CLEAR SKIES IN OTHER AREAS. BY THURSDAY
COVERAGE WILL SPREAD TO NORTHEAST OREGON AS THE LOW MOVES INLAND AND
UPPER LEVEL FLOW CHANGES TO SOUTHERLY OVER THE REST OF EASTERN
OREGON AND WASHINGTON. AS THE LOW EXITS THE AREA FRIDAY
NIGHT...EXPECT DRY WESTERLY FLOW TO SET IN AND PERHAPS AN INCREASE
IN WINDS. GFS INDICATES MUCH COOLER AIR AND HIGHER SURFACE
HUMIDITIES POSSIBLE WITH THIS WESTERLY FLOW.  COONFIELD

AVIATION...18Z TAFS...VFR CONDITIONS WILL OCCUR OVER THE NEXT 24
HOURS.  UPPER LEVEL MOISTURE IS SPREADING FROM THUNDERSTORMS OVER
NEVADA WITH SCT CIRRUS OVER SOUTHERN OREGON. LOOK FOR INCREASING
NORTHERLY WINDS 10 TO 20 KTS AFTER 21Z WITH THE WIND CONTINUING
OVERNIGHT. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT 100  65  97  64 /   0   0   0   0
ALW 101  71  96  69 /   0   0   0   0
PSC 104  68 100  66 /   0   0   0   0
YKM 105  68  96  66 /   0   0   0   0
HRI 103  66 100  65 /   0   0   0   0
ELN 102  65  98  62 /   0   0   0   0
RDM  97  57  95  57 /   0   0   0   0
LGD  94  59  91  57 /   0   0   0   0
GCD  99  59  97  57 /   0  10   0   0
DLS 101  69 101  69 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 8 PM PDT THIS EVENING FOR ORZ610-639>641.

WA...RED FLAG WARNING UNTIL 8 PM PDT THIS EVENING FOR WAZ639.

     RED FLAG WARNING UNTIL 9 AM PDT SUNDAY FOR WAZ675.

&&

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

$$

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