Flash Flood and Hail in Washington, July 31, 2010

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
1055 AM PDT SAT JUL 31 2010

UPDATED AVIATION AND FIRE WEATHER DISCUSSION.

.SHORT TERM...SATELLITE SHOWS UPPER LOW IS MOVING INTO THE PACIFIC
NORTHWEST TODAY. A BAND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
THIS FEATURE IS SLOWLY MOVING ACROSS THE COLUMBIA BASIN THIS
MORNING. BASED ON INSTABILITY EXPECT TO SEE SHOWERS AND
THUNDERSTORMS THROUGH THE DAY...WITH MOST OF THE ACTIVITY ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. THE OTHER ITEM FOR TODAY IS THE
INCREASING WESTERLY WINDS AS THE LOW MOVES INLAND. PLENTY OF COOL
AIR AND STRATUS WEST OF THE CASCADES SO SHOULD SEE BREEZY WINDS FROM
THE CASCADE EAST SLOPES OUT INTO THE BASIN TODAY. ALL LOCATIONS WILL
SEE COOLER TEMPERATURES TODAY. WINDS AND PRECIPITATION WILL DIMINISH
LATER THIS EVENING.  94

&&

.AVIATION...18Z TAFS...SHOWERS AND THUNDERSTORMS WILL CONTINUE FROM
KPSC NORTHWARD FOR THE NEXT HOUR OR TWO WITH FURTHER DEVELOPMENT
EXPECTED FROM 20Z TO 06Z OVER THE NORTHERN AND EASTERN PORTIONS OF
THE AREA AFFECTING ALL TAF LOCATIONS EXCEPT KRDM AND KDLS. SKIES
WILL BE SCT-BKN ABOVE 8000 FT AGL TODAY BECOMING MAINLY CLEAR BY 10Z
TONIGHT. SURFACE WINDS WILL REACH 15 TO 25 KTS WITH GUSTS TO 35 KT
AT KDLS THROUGH 05Z THIS EVENING WITH 10 TO 20 KTS WITH GUSTS TO 25
KTS AT KRDM AND KPDT. OTHERWISE WINDS WILL GENERALLY REMAIN UNDER 15
KTS THROUGH THE NEXT 24 HOURS. LOCALLY STRONGER WINDS TO 30 KTS ARE
POSSIBLE NEAR THE STRONGER THUNDERSTORMS. PERRY

&&

.FIRE WEATHER...RED FLAG WARNINGS WERE CANCELLED OR ALLOWED TO
EXPIRE.  MOST OF THE T-STORMS HAVE MOVED TO THE NORTHEAST...AND
CENTRAL OREGON AND THE COLUMBIA BASIN WILL SEE ONLY ISOLATED
THUNDERSTORMS TODAY.  BELIEVE THAT THE JOHN DAY-OCHOCO HIGHLANDS AND
MOST OF BAKER WILL ALSO SEE ISOLATED CONVECTION.  ALTHOUGH THE BLUE
MTNS EASTWARD ARE NOT OBSERVING ANY T-STORMS AT THIS TIME...THE
UPPER LOW WILL TRIGGER CONVECTION IN THIS AREA AS IT MOVES INTO
IDAHO.  DECIDED NOT TO ISSUE A RED FLAG FOR THESE AREAS AS LIGHTNING
ACTIVITY LEVEL MAY NOT BE EXTENSIVE TO EXTEND THE RED FLAG WARNING.
JOHNSON

&&

.PREV DISCUSSION... /ISSUED 430 AM PDT SAT JUL 31 2010/

SHORT TERM...TODAY THROUGH TUESDAY...AN UPPER LOW CONTINUES TO MOVE
INTO NORTHWEST OREGON AT THE MOMENT. THIS SYSTEM WILL CONTINUE TO
MOVE NORTHEAST DURING THE NEXT 24 HOURS...REACHING THE TOP OF THE
IDAHO PANHANDLE BY THIS TIME TOMORROW (SUNDAY) MORNING. THIS SYSTEM
HAS INSTIGATED A BAND OF STRONG THUNDERSTORMS THAT IS LIFTING NORTH
OUT OF OUR AREA INTO NORTH-CENTRAL WASHINGTON. SOUTH OF THIS BAND...
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE AFFECTING
SOUTH-CENTRAL WASHINGTON...AND NORTH-CENTRAL AND CENTRAL OREGON. AS
TODAY PROGRESSES SHOULD SEE THIS NORTH-SOUTH AREA OF ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS SHIFT GRADUALLY EAST ACROSS THE
REMAINDER OF THE AREA. MEANWHILE WILL ALSO SEE A GRADUAL DECREASE OF
AND END TO THE SHOWERS AND STORMS OVER OUR WESTERN ZONES...STARTING
WITH CENTRAL OREGON BY EITHER MID OR LATE MORNING. THUNDERSTORMS
HAVE BEEN PRODUCING LOCALLY HEAVY RAIN...FREQUENT LIGHTNING AND WIND
GUSTS OF 30 TO 50 MPH. SMALL HAIL IS ALSO POSSIBLE. SPEED SHEAR OVER
EXTREME NORTHEAST OREGON AND EXTREME SOUTHEAST WASHINGTON STILL
LOOKS TO BE FAVORABLE FOR THE POTENTIAL DEVELOPMENT OF A STRAY
SEVERE THUNDERSTORM THIS AFTERNOON AND EARLY EVENING. THE STORM
PREDICTION CENTER CONTINUES TO HAVE WALLOWA AND UNION COUNTIES IN
OREGON AND SOUTHERN COLUMBIA COUNTY IN WASHINGTON WITHIN A SLIGHT
RISK OF SEVERE STORMS AREA. THE GRADUAL DECREASE AND ENDING OF THE
SHOWERS AND STORMS WILL CONTINUE FROM THE SOUTHWEST...WITH ALL
SHOWERS AND THUNDERSTORMS BEING EAST OF OUR AREA OR DISSIPATED BY
LATE EVENING.

A WEAK...BAGGY UPPER TROUGH LOOKS TO REMAIN OVER THE REGION SUNDAY
THROUGH TUESDAY. THE EXACT DEPTH AND STRENGTH OF THIS UPPER TROUGH
IS STILL UNCERTAIN...BUT IN GENERAL EXPECT A MOSTLY DRY
WEST-SOUTHWEST TO WEST FLOW TO BE OVER SOUTHEAST WASHINGTON...AND
NORTHEAST AND CENTRAL OREGON. THUS WILL CONTINUE THE CURRENT MOSTLY
DRY FORECAST SUNDAY THROUGH TUESDAY. THERE MAY BE ENOUGH INSTABILITY
NEAR THE CENTRAL WASHINGTON CASCADE CREST FOR A STRAY AFTERNOON AND
EVENING SHOWER OR THUNDERSTORM SUNDAY AND TUESDAY. 90

LONG TERM...TUESDAY NIGHT THROUGH FRIDAY...FORECAST UNCERTAINTY
REMAINS HIGH FOR THIS PERIOD. SOME SORT OF WEAK UPPER TROUGH MAY
LINGER OVER THE PACIFIC NORTHWEST TUESDAY NIGHT THROUGH THURSDAY.
SOME PREVIOUS MODEL RUNS HAVE FAVORED A FLATTER ZONAL FLOW BY THE
MIDDLE OF NEXT WEEK...THOUGH THE MOST RECENT RUNS PUSH THIS PATTERN
INTO FRIDAY. CURRENT FORECASTS ARE MOSTLY DRY WITH NEAR TO SLIGHTLY
ABOVE SEASONAL TEMPERATURES. THERE IS ALSO THE OCCASIONAL INCLUSION
OF A FEW AFTERNOON AND EVENING THUNDERSTORMS OVER SOME MOUNTAIN
RANGES AT TIMES. FOR NOW WILL CONTINUE THE CURRENT EXTENDED
FORECASTS DUE TO THE CONTINUED UNCERTAINTY. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  86  54  86  54 /  30  20   0   0
ALW  88  59  87  60 /  30  20   0   0
PSC  90  58  89  56 /  30  20   0   0
YKM  87  52  87  53 /  20  20   0   0
HRI  88  56  88  55 /  30  10   0   0
ELN  85  57  86  56 /  30  30   0   0
RDM  84  41  85  44 /  20   0   0   0
LGD  84  49  84  47 /  30  30  10  10
GCD  85  50  85  50 /  20  20  10   0
DLS  82  59  85  58 /  10  10   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 10 AM PDT THIS MORNING
     ORZ041>044-049-501>506.

WA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING WAZ026-027-501.

     RED FLAG WARNING UNTIL 10 AM PDT THIS MORNING WAZ024-028>030-502.

&&

THREAT INDEX
TODAY : YELLOW
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

94/83/90/85

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
953 AM PDT SAT JUL 31 2010

UPDATED TO REMOVE RED FLAG WARNING INFORMATION

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-011515-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS OF WASHINGTON-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
953 AM PDT SAT JUL 31 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, LOWER
     COLUMBIA BASIN OF WASHINGTON, FOOTHILLS OF THE BLUE MOUNTAINS
     OF WASHINGTON, NORTHWEST BLUE MOUNTAINS OF WASHINGTON, EASTERN
     COLUMBIA RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, CENTRAL
     OREGON, LOWER COLUMBIA BASIN OF OREGON, GRANDE RONDE VALLEY,
     WALLOWA COUNTY, FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON,
     NORTHERN BLUE MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF
     OREGON, NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES, JOHN
     DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS

A SMALL COMPACT WEATHER SYSTEM WILL MOVE FROM NORTHWEST OREGON TO
EXTREME NORTHERN IDAHO OVER THE NEXT 24 HOURS. THIS SYSTEM WILL
CONTINUE TO CAUSE ISOLATED TO SCATTERED THUNDERSTORMS. THUNDERSTORMS
WILL GRADUALLY DECREASE AND END FROM THE SOUTHWEST THROUGH THE
DAY. THE STRONGEST THUNDERSTORMS MAY OCCUR OVER WALLOWA COUNTY IN
THE AFTERNOON AND EVENING. THE STORM PREDICTION CENTER CURRENTLY
HAS PLACED WALLOWA... UNION AND SOUTHERN COLUMBIA COUNTIES WITHIN
A SLIGHT RISK OF SEVERE THUNDERSTORMS AREA.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THUNDERSTORMS SUNDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON

A MOSTLY DRY WEST-SOUTHWEST TO WEST FLOW WILL PERSIST OVER THE AREA
SUNDAY THROUGH THURSDAY. INSTABILITY MAY BECOME SUFFICIENT FOR THE
DEVELOPMENT OF STRAY AFTERNOON AND EVENING THUNDERSTORMS OVER SOME
OF THE MOUNTAIN RANGES AT TIMES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED DUE TO THUNDERSTORMS THROUGH
THIS EVENING.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE.