Funnel Cloud in Oregon, May 13, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND
207 PM PDT WED MAY 13 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH OF LOW PRES WILL REMAIN OVER THE
PACIFIC NW THROUGH THE REST OF THE WEEK AND INTO NEXT WEEK. SEVERAL
WEAK LOW PRES CENTERS WILL ROTATE THROUGH THE TROUGH...MOVING S OVER
THE E PAC...INLAND OVER NORTHERN CA...AND THEN LIFTING NE TOWARDS
ID. THIS WILL KEEP A CHANCE FOR SHOWERS OFF AND ON THROUGHOUT THE
NEXT WEEK WITH TEMPERATURES CLOSE TO SEASONAL NORMALS.
&&

.SHORT TERM...A LIGHT LOW LEVEL FLOW ACROSS THE N PART OF THE
FORECAST AREA WED AFTERNOON COUPLED WITH MOIST EASTERLY FLOW ALOFT
HAS KEPT SCATTERED SHOWERS GOING ACROSS THE N. THIS EVENING WITH THE
LOSS OF DIURNAL HEATING...THE MID LEVEL MOISTURE LIFTING SLOWLY N...
AND WEAKENING OF THE ONSHORE FLOW SHOWERS EXPECTED TO GENERALLY DIE
OFF. THE BEST THREAT FOR SHOWERS WILL SHIFT TO THE SE PART OF THE
FORECAST AREA AS MOISTURE BEGINS TO LIFT UP WITH A WEAK SHORTWAVE
LATER TONIGHT INTO THU. GFS MODEL SOUNDINGS...AND NOW THE 18Z NAM...
CONTINUED TO SHOW DEEP INSTABILITY THU AFTERNOON OVER INLAND AREAS.
WITH A NEW LOW DIGGING DOWN AND APPROACHING THE N CA COAST TONIGHT
AND THU...THIS LEAVES THE REGION IN A DIFFLUENT FLOW ALOFT IN THE NE
QUADRANT OF THE UPPER LOW WHICH ALSO TENDS TO FAVOR SOME THREAT OF
CONVECTION NOT JUST FOR THE CASCADES...BUT ALSO AS FAR W AS THE
COAST RANGE GIVEN THE SE FLOW ALOFT. FAIRLY DEEP MOISTURE DEPICTED
IN THE SOUNDINGS SUGGESTS QUITE A BIT OF CLOUDINESS ACCOMPANYING THE
SHIFTWAVE THAT LIFTS UP THU...SO IT IS QUESTIONABLE HOW BIG OF AN
IMPACT THE CLOUDS WILL HAVE ON AFTERNOON TEMPS...BUT FOR NOW WILL
STICK WITH TEMPS WARMING INTO THE MID AND UPPER 60S IN THE INLAND
VALLEYS.

THU NIGHT THROUGH FRI NIGHT REGION REMAINS ON THE PERIPHERY OF THE
CLOSED UPPER LOW AS IT SLOWLY ROTATES AROUND THE LARGE SCALE TROUGH
AND OUT INTO NV AND ID. LOW LEVELS EXPECTED TO REMAIN MOIST WITH
ONSHORE FLOW...BUT HIGHER UP MOISTURE MAY BECOME MORE LIMITED IN AN
EASTERLY FLOW WITH THE LOW HAVING MOVED INLAND. BY SAT AN ILL
DEFINED LOW MOVING DOWN OFF THE COAST TURNS THE UPPER LEVEL FLOW
BACK ONSHORE OUT OF THE SW. MODEL SOUNDINGS AT THIS POINT LOOK
RATHER STABLE FRI INTO SAT...WITH MOISTURE PRIMARILY IN THE LOW
LEVELS. GIVEN THE LIMITED STABILITY AND MOISTURE...AND THE LACK OF
AN OBVIOUS LIFTING MECHANISM TO FOCUS ON...WILL TRIM BACK POPS EVEN
MORE FRI AND SAT...WITH THE BEST CHANCES RELATED TO OROGRAPHICALLY
FAVORED AREAS IN ONSHORE FLOW.

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...THE GENERAL PATTERN
FOR THE FIRST HALF OF NEXT WEEK LOOKS TO REMAIN A CONTINUATION TO
THE END OF THIS WEEK WITH BROAD LOW PRESSURE REMAINING OVER THE EAST
PACIFIC AND WESTERN UNITED STATES UNDER A LARGE RIDGE OVER WESTERN
CANADA. FLOW AROUND THIS BROAD LOW PRESSURE ALONG WITH WEAK ONSHORE
LOW-LEVEL FLOW AT TIMES WILL MAINTAIN SOME MOISTURE/CLOUD COVER AND
POTENTIAL FOR SHOWERS THROUGH THE PERIOD. WHILE SOME DRY PERIODS ARE
QUITE POSSIBLE...PINPOINTING THE TIMING OF THESE AT THIS RANGE IS
DIFFICULT AT BEST...SO MAINTAINED SLIGHT CHANCE TO LOW END CHANCE
POPS THROUGH THE EXTENDED. BEST CHANCES OF SEEING PRECIPITATION WILL
BE IN THE CASCADES. ONE EXCEPTION IS FOR MONDAY WHEN THE UPPER LOW
PRESSURE SWINGS INLAND THROUGH CENTRAL CALIFORNIA AND INTO THE GREAT
BASIN. EAST-SOUTHEAST FLOW ALOFT WITH WEAK ONSHORE FLOW AND CORE OF
COOL TEMPERATURES ALOFT LOOK TO PROVIDE THE BEST CHANCE FOR
CONVECTION...WITH NEGATIVE LI VALUES ALONG WITH DECENT INSTABILITY
EXTENDING FROM THE CASCADES INTO THE EASTERN HALF OF THE WILLAMETTE
VALLEY. OBVIOUSLY MUCH CAN CHANGE BY THEN AND WITH LOWER CONFIDENCE
AT THIS RANGE WILL HOLD SHORT OF INTRODUCING THUNDER CHANCES TO
GRIDS BUT SOMETHING TO MONITOR. HIGH TEMPERATURES WILL REMAIN NEAR
OR A FEW DEGREES BELOW NORMALS FOR THE FIRST HALF OF NEXT WEEK.
CULLEN
&&

.AVIATION...CIGS HAVE IMPROVED TO VFR ACROSS MOST OF THE
AREA...WITH SOME LOWER SCATTERED CLOUDS STILL HANGING AROUND. SHOWERS
ARE DEVELOPING ALONG THE COAST RANGE AND WILL PUSH INLAND...AND
START AFFECTING TAF SITES OVER THE NEXT COUPLE HOURS. HEAVIER
SHOWERS COULD LOWER CIGS AND/OR REDUCE VIS TO MVFR FOR BRIEF
PERIODS. SHOWERS SHOULD START TO COME TO AN END AROUND 14/06Z
THIS EVENING. THERE IS A GOOD CHANCE CIGS WILL DROP TO MVFR
AT ALL INLAND TAF SITES AGAIN TONIGHT AROUND 10-12Z. ALONG THE
NORTH COAST...EXPECT CIGS AT KAST TO REMAIN PRIMARILY MVFR THROUGH
TONIGHT. FURTHER SOUTH AT KONP CIGS SHOULD REMAIN VFR THROUGH
THIS EVENING...BUT WITH CONTINUED ONSHORE FLOW MARINE LOW STRATUS
WILL PUSH ONSHORE BRINGING CIGS DOWN TO MVFR AND POSSIBLY IFR
AFTER 14/09Z.

KPDX AND APPROACHES...PRIMARILY VFR CIGS AND VIS THROUGH THIS
EVENING...WITH SOME SCATTERED LOWER CLOUDS. SCATTERED SHOWERS
COULD BRING CIGS AND/OR VIS DOWN TO MVFR FOR BRIEF PERIODS AFTER
22Z. CIGS MAY DROP TO MVFR EARLY THURSDAY AROUND 10-12Z...WITH
IMPROVEMENT BACK TO VFR BY 18Z. -MCCOY

&&

.MARINE...SEAS CURRENTLY AROUND 5 FT MAY BUILD TO AROUND 7 FT THIS
EVENING AS THE LOW OFF THE COAST BRINGS IN SLIGHTLY LARGER SWELL.
SEAS SHOULD DROP BACK DOWN TO 4 TO 6 FT FOR THE WEEKEND INTO EARLY
NEXT WEEK. AS HIGH PRESSURE BUILDS BACK OVER THE WATERS THURSDAY
WITH A THERMAL LOW ONSHORE...WINDS WILL START TO INCREASE OUT OF
THE NORTHWEST. GUSTS MAY FLIRT WITH SMALL CRAFT CRITERIA THURSDAY
EVENING...BUT SHOULD DROP BACK DOWN WELL BELOW 20 KT FRIDAY AND
STAY BELOW CRITERIA THROUGH THE WEEKEND INTO EARLY NEXT WEEK.
-MCCOY

&&

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

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
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.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PORTLAND OR
1248 PM PDT WED MAY 13 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     FUNNEL CLOUD     3 N DALLAS              44.96N 123.31W
05/12/2015                   POLK               OR   PUBLIC

            A FUNNEL CLOUD WAS SIGHTED NEAR THE INTERSECTION OF
            HIGHWAY 22 AND HIGHWAY 223, NORTH OF DALLAS, OR.

&&

TW