Lightning Strike in Oregon, September 15, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
851 AM PDT SUN SEP 15 2013

.SYNOPSIS...A TROUGH OF LOW PRESSURE WILL MOVE OVER THE PACIFIC NW
TODAY THROUGH TUESDAY...RESULTING IN COOLER AND SHOWERY WEATHER.
THERE MAY BE SOME ISOLATED THUNDERSTORMS EMBEDDED WITHIN THE SHOWERS
TODAY. THE TROUGH WILL DEPART WEDNESDAY AND AN UPPER RIDGE WILL BRING
DRY AND WARMER WEATHER FOR THURSDAY. ANOTHER TROUGH WILL BRING A
RETURN OF RAIN AND COOLER TEMPERATURES FRIDAY.

&&

.SHORT TERM...SATELLITE RADAR AND LIGHTNING DATA SHOWED MAIN
CONVECTIVE THREAT N OF A LINE FROM KAST TO KSLE TO SISTERS THIS
MORNING...WHICH FIT WELL WITH THE IDEA OF THE INSTABILITY ALOFT
RUNNING WELL AHEAD OF THE UPPER LOW. THIS AREAS OF SHOWERS AND
THUNDERSTORMS WILL LIFT NE TODAY...LEAVING THE MAIN THREAT OF
THUNDERSTORMS W OF THE CASCADES THIS MORNING. MODELS INDICATE SOME
INSTABILITY REMAINS ALONG THE CASCADES THIS AFTERNOON. NEXT MAIN
THREAT OF SHOWERS COMES TOWARDS THE END OF THE DAY AS THE VORT MAX
SEEN OFF THE N CA COAST THIS MORNING BEGINS TO LIFT UP THROUGH THE
FORECAST AREA.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...
OTHERWISE COOLER TEMPERATURES CAN BE EXPECTED TODAY AND CONTINUING
THROUGH TUESDAY AS THE UPPER TROUGH LINGERS OVER THE AREA. A WEAK
COLD FRONT WILL MOVE ACROSS THE AREA LATE TONIGHT AND MONDAY AND
CONTINUE THE CHANCES FOR RAIN. THERE MAY BE A BRIEF BREAK IN THE RAIN
MONDAY NIGHT BEFORE A SHORTWAVE TROUGH BRINGS ADDITIONAL SHOWERS TO
THE AREA TUESDAY. THE TROUGH AXIS SHOULD PUSH EAST OF THE AREA
TUESDAY NIGHT.

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS.
WEDNESDAY THROUGH SATURDAY NIGHT...AN UPPER RIDGE WILL BUILD
WEDNESDAY BEHIND THE DEPARTING TROUGH. THE RIDGE WILL AMPLIFY
THURSDAY AS ANOTHER UPPER LEVEL LOW DEVELOPS OFFSHORE...RESULTING IN
DRY AND WARMER CONDITIONS. MODELS ARE IN FAIRLY GOOD AGREEMENT THAT
THE LOW WILL SWING A COLD FRONT THROUGH THE REGION FRIDAY. THIS LOW
WILL LINGER OVER THE AREA SATURDAY...FOR SLIGHTLY BELOW NORMAL
TEMPERATURES AND A CONTINUING CHANCE FOR RAIN. TH/BURGESS
&&

.AVIATION...EXPECT PREDOMINANTLY A MIX OF IFR AND MVFR CONDITIONS
ACROSS THE ENTIRE AREA THROUGH 18Z MONDAY. CONDITIONS MAY IMPROVE A
BIT THIS AFTERNOON AND/OR WITH ANY PASSING HEAVIER SHOWER...BUT
SHOULD DETERIORATE ONCE AGAIN WITH TIME TONIGHT. THERE IS ALSO A
CHANCE FOR THUNDERSTORMS PRIMARILY NORTH OF KSLE TODAY. EXPECT IT TO
LAST PRIMARILY THROUGH 18Z SUNDAY FOR KSLE AND THEN THROUGH
APPROXIMATELY 21Z SUNDAY FOR KAST AND THE PORTLAND TAF SITES.

KPDX AND APPROACHES...EXPECT IFR CONDITIONS THIS MORNING TO SLOWLY
TO IMPROVE TO MVFR TODAY. THERE WILL BE A GOOD CHANCE FOR
THUNDERSTORMS THIS MORNING. CONDITIONS SHOULD DETERIORATE INTO
HIGH END IFR OR LOW END MVFR OVERNIGHT. /NEUMAN

&&

.MARINE...FLOW WILL TURN SW THIS MORNING OVER THE WATERS AS A LOW
PRESSURE SYSTEM APPROACHES THE COAST. THIS LOW WILL BRING THE
CHANCE FOR SOME SCATTERED THUNDERSTORM ACTIVITY TODAY. OTHERWISE
EXPECT LITTLE IMPACT FROM THE SYSTEM. CONDITIONS SHOULD REMAIN
RATHER BENIGN FOR THE NEXT SEVERAL DAYS...WITH WINDS GENERALLY
BELOW 20 KT AND SEAS BELOW 6 FT.

ANOTHER WEAK SYSTEM WILL ARRIVE ON TUE...WITH LITTLE IMPACT OTHER
THAN AGAIN TURNING THE WINDS BRIEFLY TO THE SW. THE NEXT
POTENTIALLY SIGNIFICANT MARINE IMPACTS LOOK TO ARRIVE LATE NEXT
WEEK INTO NEXT WEEKEND. A MORE ACTIVE WEATHER PATTERN WILL
ARRIVE AS A SHARP UPPER LEVEL TROUGH APPROACHES THE PAC NW. SMALL
CRAFT ADVISORIES WILL LIKELY BE NECESSARY WITH A CHANCE FOR GALES
AND SEAS OVER 10 FT AT SOME POINT. CONFIDENCE ON TIMING REMAINS
LOW THIS FAR OUT...BUT CONFIDENCE IS INCREASING ON THE OVERALL
PATTERN. PYLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&

MORE WEATHER INFORMATION ONLINE AT...
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.