Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 021001
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
300 AM PDT THU JUL 2 2015

.SHORT TERM...TODAY THROUGH SATURDAY THE 4TH OF JULY...HIGH PRESSURE
ALOFT WILL CONTINUE TO BUILD OVER THE REGION TODAY. INCREASING
SUBSIDENCE WILL RESULT IN WARMING ALOFT WHICH WILL TRANSLATE TO
HOTTER TEMPERATURES AT THE SURFACE. TODAY`S HIGH TEMPERATURES WILL
RANGE FROM THE LOWER 100S IN THE LOWER ELEVATIONS TO THE MID 80S TO
MID 90S IN THE MOUNTAINOUS AREAS. CONTINUED SUBSIDENCE ON FRIDAY
WILL RESULT IN EVEN SLIGHTLY HOTTER TEMPERATURES ON FRIDAY. EVEN
THOUGH THE UPPER RIDGE IS EXPECTED TO WEAKEN SLIGHTLY ON FRIDAY
MAXIMUM TEMPERATURES ARE STILL EXPECTED TO BE SLIGHTLY WARMER THAN
TODAY IN EASTERN AREAS. THERE MAY BE SOME COOLING ALONG THE CASCADE
EAST SLOPES AS COOLER MARINE AIR BEGINS TO FILTER THROUGH THE GAPS
AND PASSES OF THE CASCADE RANGE FRIDAY AFTERNOON. THE NAM12 MODEL
SHOWS PRESSURE GRADIENTS INCREASING ALONG THE CASCADE EAST SLOPES ON
FRIDAY AFTERNOON AND AGAIN ON SATURDAY (4TH OF JULY HOLIDAY).
TEMPERATURES WILL COOL OFF A FEW DEGREES ON SATURDAY DUE TO THE
INCREASING WEST TO NORTHWEST FLOW AND WEAKENING OF THE UPPER RIDGE
AND THE FLOW BECOMES MORE NORTHWEST. THERE ARE NUMEROUS FIRE WEATHER
WATCHES IN EFFECT THROUGH SATURDAY AND/OR HEAT ADVISORIES IN EFFECT
THROUGH THIS EVENING OR FRIDAY EVENING. THESE LOOK GOOD AS THEY ARE
FOR NOW BUT THEY WILL BE MONITORED IN CASE ANY CHANGES TO TIMING OR
AREA ARE NEEDED. A SLIGHTLY COOLER NORTHWEST FLOW IS EXPECTED GOING
INTO THE EXTENDED FORECAST PERIOD. WINDS WILL BE LIGHT EXCEPT THEY
WILL INCREASE ALONG THE CASCADE EAST SLOPES FRIDAY AND SATURDAY
AFTERNOONS AND EVENINGS. 88

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...FORECAST AREA WILL
BE UNDER A WEAK MID/UPPER LEVEL RIDGE OF HIGH PRESSURE THROUGH THE
PERIOD. THE MODELS INDICATE A STRONGER RIDGE IN THE GULF OF ALASKA
WITH A TROUGH OFFSHORE OF CALIFORNIA AND A TROUGH IN WESTERN CANADA
SATURDAY NIGHT. A WEAKNESS DEVELOPS IN THE RIDGE OVER THE PACIFIC
NORTHWEST AS A RESULT OF THE TROUGH BETWEEN 30N AND 42N AND 125-140W
OFFSHORE OF CALIFORNIA GRADUALLY APPROACHING THE CALIFORNIA COAST.
SUBTLE DIFFERENCES IN HOW EACH MODEL HANDLES AFOREMENTIONED WEAKNESS
IN THE RIDGE. THE ECMWF SHOWS THE TROUGH IN WESTERN CANADA A BIT
STRONGER THAN THE CANADIAN AND GFS MODELS, WHICH YIELDS FLOW ALOFT
OVER REGION FROM THE WEST-NORTHWEST FOR DOWNSLOPE WINDS AND SINKING
MOTION ACROSS FORECAST FOR DRY CONDITIONS. THE CANADIAN AND GFS
MODELS SHOW THE TROUGH WEST OF CALIFORNIA AS THE MORE DOMINANT
FEATURE WITH RESPECT TO FORECAST AREA, WHICH ALLOWS WEAK SOUTHERLY
FLOW ALOFT TO BRING AN INFLUX OF MID LEVEL MOISTURE INTO CENTRAL
OREGON, THUS INTRODUCING THE POTENTIAL FOR A SLIGHT CHANCE OF
AFTERNOON AND EVENING THUNDERSTORMS IN CENTRAL AND EAST CENTRAL
OREGON. I CHOSE TO GO WITH THE LATTER SOLUTION.  POLAN

&&

.AVIATION...12Z TAFS...CLEAR SKIES FOR THE NEXT 24 HOURS EXCEPT SCT
CUMULUS AND CIRRUS AT KRDM AND KBDN TODAY. SURFACE WINDS 5-15 KTS.
POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT 102  66 102  66 /   0   0   0   0
ALW 102  72 104  72 /   0   0   0   0
PSC 104  68 105  68 /   0   0   0   0
YKM 102  69 103  69 /   0   0   0   0
HRI 104  68 104  68 /   0   0   0   0
ELN 103  65 101  65 /   0   0   0   0
RDM  99  58  97  58 /   0   0   0   0
LGD  99  58  97  58 /   0   0   0   0
GCD 102  60 101  60 /   0   0   0   0
DLS 105  68 101  68 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
     EVENING FOR ORZ639.

     HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORZ041-510-511.

     FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
     EVENING FOR ORZ610-640-641.

     HEAT ADVISORY UNTIL 8 PM PDT FRIDAY FOR ORZ044.

     HEAT ADVISORY FROM NOON TODAY TO 8 PM PDT FRIDAY FOR ORZ507.

WA...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
     EVENING FOR WAZ639.

     HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR WAZ024.

     FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
     EVENING FOR WAZ675.

     HEAT ADVISORY UNTIL 8 PM PDT FRIDAY FOR WAZ028.

     HEAT ADVISORY FROM NOON TODAY TO 8 PM PDT FRIDAY FOR WAZ026-027-
     029.

&&

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

$$

88/99/99


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