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000
FXUS66 KPDT 250351
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
850 PM PDT FRI MAY 24 2013

.UPDATE...SHOWERS FROM EARLIER WERE DECREASING WITH THE LOSS OF
DAYTIME HEATING. OTHERWISE A DISTURBANCE WILL TRACK ACROSS OUR
SOUTHERN PORTIONS OF THE REGION TONIGHT. THIS WILL INCREASE MID/HIGH
LEVEL CLOUDS AND A FEW SHOWERS ARE POSSIBLE OVER THE JOHN DAY
HIGHLANDS/OCHOCOS OVERNIGHT. THUS THE ZONES WERE UPDATED TO REFLECT
THIS AND THE REMAINDER OF THE FORECAST APPEARS ON TRACK FOR NOW.

&&

.PREV DISCUSSION... /ISSUED 138 PM PDT FRI MAY 24 2013/

SHORT TERM...TONIGHT THROUGH MEMORIAL DAY...THE LARGE LOW PRESSURE
SYSTEM IS CURRENTLY ELONGATING AND SHIFTING NORTHWARD AND IS
CURRENTLY OVER WASHINGTON. ISOLATED TO SCATTERED SHOWERS ARE ACROSS
MUCH OF WASHINGTON WITH A BAND OF SHOWERS MOVING EAST IN THE
FOOTHILLS AND THE BLUE MOUNTAINS OF OREGON. EXPECT SHOWERS TO
GRADUALLY TAPER OFF TONIGHT. SOME INSTABILITY THIS AFTERNOON AND
EVENING MAY LEAD TO A THUNDERSTORM OR TWO. THE BEST SHEAR FOR STORM
DEVELOPMENT IS IN CENTRAL AND NORTHEAST OREGON. CENTRAL OREGON
HOWEVER WILL LACK UPPER LEVEL SUPPORT DUE TO THE LOW MOVING FURTHER
AWAY BUT WILL KEEP AN EYE ON NORTHEAST OREGON. DON`T ANTICIPATE
SEVERE...BUT CAN NOT RULE OUT A STRONG STORM IF ENOUGH CLEARING
HAPPENS THIS AFTERNOON AND EVENING.

THE LOW WILL MOVE OUT OF THE AREA WITH SOME DRYING AND WARMING
EXPECTED ON SATURDAY. THE OVERALL PATTERN WILL REMAIN A TROUGH
THROUGH THE WEEKEND WITH INDIVIDUAL DISTURBANCES ROTATING THROUGH.
THE NEXT ONE IS EXPECTED TO MOVE INTO THE OREGON PORTION OF THE
REGION SATURDAY NIGHT INTO SUNDAY. THE SECOND SYSTEM LOOKS TO IMPACT
THE REGION ON MEMORIAL DAY...THOUGH MODELS ARE DISAGREEING ON THE
EXACT TIMING OF THE SYSTEM. BOTH SYSTEMS WILL BRING A CHANCE OF RAIN
AND SOME INSTABILITY FOR THE POTENTIAL OF AFTERNOON THUNDERSTORMS
OVER NORTHEAST OREGON AND SOUTHEAST WASHINGTON. SNOW LEVELS WILL
RISE THROUGH THE WEEKEND SO PRECIPITATION WILL BE IN THE FORM OF
RAIN EXCEPT FOR THE HIGHEST OF PEAKS. DMH

LONG TERM...MONDAY NIGHT THROUGH FRIDAY...MODELS IN GOOD AGREEMENT
IN CONTINUING PERSISTENT UNSETTLED WEATHER PATTERN THROUGH THE
PERIOD.  WITH SOME DIFFERENCES IN TIMING AND STRENGTH OF EACH
DISTURBANCE...WILL KEEP SLIGHT CHANCE OF SHOWERS IN THE BASIN WITH
HIGHER POPS OVER THE MOUNTAINS THROUGH WEDNESDAY.  BY
THURSDAY...MODELS BEGIN TO DIFFER QUITE SIGNIFICANTLY AS GFS KEEPS A
BROAD UPPER TROUGH CENTERED OVER THE FORECAST AREA.  MEANWHILE...
ECMWF DEVELOPS AN UPPER LOW OVER WASHINGTON AND MOVES IT SOUTHEAST
INTO IDAHO FRIDAY.  AT THIS TIME...WILL STICK CLOSER TO THE GFS/S
DRIER FORECAST AS IT HAS BEEN A LITTLE MORE CONSISTENT.  IN
FACT...ECMWF INDICATED THE AFOREMENTIONED LOW DEVELOPING OVER IDAHO
THE PREVIOUS  RUN.  TEMPERATURES WILL GENERALLY BE BELOW NORMAL BUT
GRADUALLY WARMING TO NEAR NORMAL LATE IN THE PERIOD.  EARLE

AVIATION...00Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE
FORECAST PERIOD. ISOLATED EVENING SHOWERS WILL DISSIPATE BY 25/04Z.
SHOWERS WILL ONCE AGAIN DEVELOP MAINLY OVER THE MOUNTAINS TOMORROW
AFTERNOON. WINDS 8-15 KTS WILL DIMINISH TO LESS THAN 10 KTS
OVERNIGHT THEN INCREASE TO 8-15 KTS WITH HIGHER GUSTS AFTER 25/18Z.
EARLE

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  66  46  68 /  20  10  10  30
ALW  44  68  50  71 /  20  10  10  20
PSC  42  71  47  74 /  20  10  10  10
YKM  43  66  46  70 /  20  10  10  10
HRI  42  70  47  73 /  10  10  10  20
ELN  42  64  44  68 /  20  10  10  10
RDM  34  66  39  64 /  10  20  30  40
LGD  36  64  40  67 /  20  20  20  40
GCD  35  64  42  65 /  10  20  20  40
DLS  45  69  49  71 /  10  10  20  30

&&

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

THREAT INDEX
SATURDAY : GREEN
SUNDAY : GREEN
MONDAY : 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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