High Surf Advisory 3, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
959 PM PDT FRI SEP 27 2013

.DISCUSSION...THE REMNANTS OF TYPHOON PABUK ARE POISED TO DELIVER
VERY STRONG WINDS AND HEAVY RAIN TO OUR AREA THIS WEEKEND INTO
MONDAY.

GIVEN THE MAGNITUDE OF THE APPROACHING STORM...THE
EVENING UPDATE TO THE FORECAST IS MINOR. I HAVE ADDED A SLIGHT
CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS AND INTO THE COASTAL
AREA SATURDAY AFTERNOON AND EVENING. I ALSO INCREASED THE
PROBABILITY OF PRECIPITATION SUNDAY MORNING IN AREAS THAT DID NOT
ALREADY HAVE A 100% POP.

A MAJORITY OF MY TIME THIS EVENING WAS SPENT EXAMINING THE WIND
FORECAST. THE PREVIOUS DISCUSSION DESCRIBES THE ONE-TWO PUNCH
HEADED OUR WAY WITH STRONG WINDS AND HEAVY RAIN HEADED TO THE
COAST SATURDAY AFTERNOON THROUGH SATURDAY NIGHT THEN AGAIN SUNDAY
AFTERNOON THROUGH SUNDAY NIGHT. THESE TWO FRONTS WILL BE SIMILARLY
STRONG, BUT THERE IS SOME DIFFERENCE IN WIND INTENSITY AND ALSO
STILL UNCERTAINTY ON WHETHER THE SECOND FRONT WILL BE SLIGHTLY
STRONGER (PER THE GFS) OR SLIGHTLY WEAKER THAN THE FIRST (PER THE
NAM). AS SUCH...I HAVE MAINTAINED THE CURRENT SHORT-TERM WIND
FORECAST. THE STRONGEST COASTAL WINDS WILL BE AROUND PORT ORFORD
AND CAPE BLANCO...EXTENDING NORTHWARD. A COUPLE OF QUESTIONS FOR
THE NEXT SHIFT TO ANSWER WITH THE NEXT REGULAR ISSUANCE OF THE
FORECAST ARE WHETHER OR NOT TO EXTEND THE HIGH WIND WARNING TO
THE SOUTH COAST ZONE 22 FOR SATURDAY AFTERNOON AND EVENING AND
WHETHER OR NOT TO ISSUE A HIGH WIND WARNING FOR THE COAST SUNDAY
AFTERNOON AND EVENING.

DURING THE DAY ON SATURDAY...RAIN WILL LIKELY REMAIN CONFINED TO
THE AREA WEST AND NORTH OF JACKSON COUNTY WITH DOWNSLOPE SOUTHERLY
FLOW KEEPING THE SHASTA AND ROGUE VALLEYS DRY. EARLY SUNDAY, THE
FIRST FRONT WILL SPREAD RAIN ACROSS NEARLY ALL OF OUR AREA AND THE
SECOND FRONT WILL BE CLOSE ON ITS HEELS...CONTINUING HEAVY RAIN
INTO MONDAY MORNING.

&&

.AVIATION...VFR CONDITIONS PERSIST TONIGHT INTO SATURDAY FOR MOST
INLAND AREAS SOUTH AND EAST OF THE UMPQUA DIVIDE/CASCADES.
HOWEVER, LOW CLOUDS AND LIGHT RAIN WILL IMPACT THE COAST AND THE
UMPQUA BASIN TO THE CASCADES WITH AREAS OF MVFR CIGS AND PARTIAL
MOUNTAIN OBSCURATIONS. SOUTH WINDS INCREASE AND BECOME VERY STRONG
ALONG THE COAST AND THE EAST SIDE SATURDAY AND THIS MAY LEAD TO
AREAS OF TURBULENCE. SPILDE

&&

.PREV DISCUSSION... /ISSUED 403 PM PDT FRI SEP 27 2013/

SHORT TERM...MODELS ARE COMING IN LINE AND POINTING TO A VERY
RARE LATE SEPTEMBER RAIN/WIND STORM FOR THE AREA BEGINNING
SATURDAY AFTERNOON AND CONTINUING THROUGH SUNDAY NIGHT. MEANTIME,
A WEAK FRONTAL SYSTEM WILL BRING SOME LIGHT RAIN TO AREAS MAINLY
NORTH AND WEST OF THE UMPQUA DIVIDE/CASCADES TONIGHT INTO SATURDAY
MORNING. AS WAS STATED IN THIS MORNINGS AFD, THIS WILL PALE IN
COMPARISON TO WHAT IS SETTING UP FOR THIS WEEKEND.

THE LOW IN THE GULF OF ALASKA WILL MOVE TOWARD BRITISH COLUMBIA
AND A FAST 180 KT JET WILL SET UP OVER THE NORTH PACIFIC TAKING
DEAD AIM ON OREGON AND NORTHERN CALIFORNIA. THIS WILL RESULT IN AN
ATMOSPHERIC RIVER WITH ONE FRONTAL SYSTEM MOVING TOWARD THE COAST
SATURDAY AND ONSHORE SATURDAY NIGHT. THEN, ANOTHER FAST-MOVING
DISTURBANCE WILL FOLLOW ON ITS HEELS FOR SUNDAY. THIS ONE-TWO
PUNCH WILL RESULT IN RAIN AMOUNTS ALONG THE COAST OF 3-6 INCHES
WITH LOCAL AMOUNTS TO 10 INCHES OVER SOME OF THE COASTAL
MOUNTAINS. THIS WILL ALSO LEAD TO SIGNIFICANT RISES ON LOCAL
STREAMS, CREEKS AND RIVERS AND WE HAVE OUTLINED THIS IN A FLOOD
POTENTIAL OUTLOOK (ESFMFR). IT SHOULD BE NOTED THAT RIVERS ARE
STARTING OFF AT VERY LOW LEVELS AND SNOW MELT RUNOFF IS A NON-
FACTOR AT THIS TIME OF YEAR. SO, MAIN STEM RIVER FLOODING IS NOT
EXPECTED AT THIS TIME. BUT, IT IS CERTAINLY NOT OUT OF THE REALM
OF POSSIBILITY THAT WE'LL SEE SOME OF THE SMALLER STREAMS AND
CREEKS REACH OR EXCEED THEIR BANKS. WE HAVE ISSUED A FLASH FLOOD
WATCH (FFAMFR) FOR THE WILDFIRE BURN SCAR AREAS (BIG WINDY,
LABRADOR, FORKS, DOUGLAS AND WHISKEY COMPLEXES) TO ACCOUNT FOR THE
POTENTIAL FOR DEBRIS FLOWS/MUDSLIDES AND LOCAL FLASH FLOODING.

THIS SYSTEM WILL ALSO LEAD TO AN EXTENDED PERIOD OF STRONG WINDS
ACROSS THE AREA. MODEL 700MB WINDS HAVE RAMPED UP SIGNIFICANTLY...
INCREASING TO 65-70 KTS SATURDAY NIGHT, THEN PEAKING AT 75-80 KTS
SUNDAY AND SUNDAY NIGHT AS A SUB 975MB LOW MOVES INTO THE NORTH
END OF VANCOUVER ISLAND. THE RESULTING PRESSURE GRADIENT FROM
MFR-RDD IS AROUND -8.0MB. AS A RESULT, WE HAVE INCREASED WINDS
ACROSS THE BOARD DURING THIS TIME FRAME AND A WIDE RANGE OF WIND
HEADLINES (NPWMFR) HAVE BEEN ISSUED.

THE MOISTURE PLUME WILL FINALLY EXIT TO THE SOUTH AND EAST OF THE
AREA DURING THE DAY MONDAY, BUT SOME POST-FRONTAL SHOWERS WILL
LINGER BEHIND IT THROUGH AT LEAST TUESDAY, ESPECIALLY IN THE
MOIST WEST-NORTHWEST ONSHORE FLOW FROM THE CASCADES WESTWARD.
SPILDE

LONG TERM...TUESDAY THROUGH FRIDAY.

THE INDECISIVENESS OF THE MEDIUM-RANGE MODELS CONTINUE TODAY WITH
DIFFERING SOLUTIONS BETWEEN MODELS AND RUN-TO-RUN VARIATIONS WITHIN
THE SAME MODEL.

THE 27/12Z GFS GOES WITH A LOW AMPLITUDE PROGRESSIVE FLOW PATTERN
THROUGH THE EXTENDED PERIOD WITH THE STORM TRACK TO THE NORTH OF THE
MEDFORD CWA.  MEANWHILE...THE EC GOES WITH A HIGH AMPLITUDE PATTERN
WITH A LONG WAVE TROUGH MOVING ONSHORE TUESDAY NIGHT...FOLLOWED BY A
VERY STRONG RIDGE BUILDING OFFSHORE.

WITH THE GFS SCENARIO...THERE WILL BE SOME LINGERING SHOWERS
TUESDAY...MOSTLY OVER THE NORTH COAST...COAST RANGE...AND UMPQUA
BASIN.  THE REST OF THE EXTENDED PERIOD WILL BE DRY EXCEPT POSSIBLY
SOME VERY LIGHT PRECIPITATION ALONG THE NORTH COAST AS THE SOUTHERN
END OF A FRONT MOVES ONSHORE THURSDAY NIGHT INTO FRIDAY.

THE EC SCENARIO STARTS OFF SLIGHT WETTER WITH THE POST-FRONTAL
SHOWERS WITH MORE WIDESPREAD COVERAGE THROUGH TUESDAY EVENING.  THEN
IT GOES DRY FOR THE REST OF THE PERIOD WITH OCCASIONAL OFFSHORE LOW
LEVEL FLOW.

THE ENSEMBLES START OFF THE EXTENDED PERIOD FAIRLY WELL PACKED...BUT
SIGNIFICANT PHASE SHIFTS BETWEEN SOLUTIONS DEVELOP AS EARLY AS
WEDNESDAY MORNING. HOWEVER...MOST MEMBERS...THE MEANS...AND THE
OPERATIONAL SOLUTIONS ALL SHOW A TRANSITION FROM TROUGHING AT THE
BEGINNING OF THE EXTENDED TO FAIRLY STRONG RIDGING FROM THURSDAY
THROUGH SATURDAY.

SO...MOST SIGNS POINT TOWARD COOL TEMPERATURES WITH SHOWERS TUESDAY
AND DRY WEDNESDAY THROUGH FRIDAY WITH A WARMING TREND. STOCKTON

MARINE...STRONG WINDS AND CHAOTIC SEAS ARE LIKELY TO DEVELOP
OVER THE WATERS THIS WEEKEND. A STRONG FRONTAL BOUNDARY WILL BRING
INCREASING SOUTH WINDS AND STEEP WIND DRIVEN SEAS STARTING LATE
TONIGHT AND LASTING INTO SATURDAY. MODELS SHOW A COASTAL JET
DEVELOPING FROM CAPE BLANCO NORTH WHICH LIKELY WILL RESULT IN GALE
FORCE WINDS LATE SATURDAY MORNING THROUGH SATURDAY EVENING. THE
FRONT LIFTS NORTH SATURDAY NIGHT WITH WINDS TEMPORALLY DECREASING.
THE GFS AND EC ARE IN GOOD AGREEMENT SHOWING A STRONG LOW RAPIDLY
DEVELOPING NEAR 48N/130W AND TRACKING NORTHEAST TOWARDS NORTHERN
VANCOUVER ISLAND. THIS WILL LIKELY BRING HIGH END GALE FORCE WINDS
OVER THE NORTHERN WATERS. THE MODELS SUGGEST STORM FORCE WINDS
SHOULD REMAIN NORTH OF THE WATERS, BUT COULD NOT RULE OUT A 4-6 HOUR
PERIOD IN WHICH OCCASIONAL STORM FORCE WINDS DEVELOP OVER THE
NORTHERN PORTIONS OF PZZ370 AND PZZ350. LATER SHIFTS MAY NEED TO
TAKE ANOTHER LOOK AT THIS. LOW PRESSURE CURRENTLY OVER THE GULF OF
ALASKA WILL BRING A LONG PERIOD HEAVY SWELL INTO THE AREA SATURDAY
NIGHT AND LASTING INTO AT LEAST SUNDAY EVENING. THIS IN COMBINATION
WITH STEEP WIN DRIVEN SEAS WILL LIKELY RESULT IN CHAOTIC SEAS SUNDAY
MORNING THROUGH SUNDAY NIGHT. PETRUCELLI

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ029>031.
     WIND ADVISORY FROM 11 AM SATURDAY TO 11 AM PDT SUNDAY FOR
     ORZ029>031.
     HIGH WIND WARNING FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ024.
     FLASH FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH LATE SUNDAY
     NIGHT FOR ORZ023>025.
     WIND ADVISORY FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ023-025-026.
     HIGH WIND WARNING FROM 8 AM TO 11 PM PDT SUNDAY FOR ORZ027-028.
     HIGH WIND WARNING FROM 2 PM SATURDAY TO 2 AM PDT SUNDAY FOR
     ORZ021.

CA...FLASH FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH LATE SUNDAY
     NIGHT FOR CAZ080.
     HIGH WIND WARNING FROM 11 AM TO 11 PM PDT SUNDAY FOR CAZ081.
     WIND ADVISORY FROM 5 PM SATURDAY TO 11 AM PDT SUNDAY FOR CAZ081.
     WIND ADVISORY FROM 11 AM TO 11 PM PDT SUNDAY FOR CAZ084-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 8 AM TO
     2 PM PDT SATURDAY FOR PZZ356-376.
     HAZARDOUS SEAS WARNING FROM 2 PM SATURDAY TO 11 PM PDT MONDAY
     FOR PZZ356-376.
     GALE WARNING FROM 2 PM SATURDAY TO 11 PM PDT SUNDAY FOR
     PZZ356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 AM TO 2 PM PDT
     SATURDAY FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 AM TO 11 AM PDT SATURDAY
     FOR PZZ350-370.
     HAZARDOUS SEAS WARNING FROM 11 AM SATURDAY TO 11 PM PDT MONDAY
     FOR PZZ350-370.
     GALE WARNING FROM 11 AM SATURDAY TO 11 PM PDT SUNDAY FOR
     PZZ350-370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 AM TO 11 AM PDT
     SATURDAY FOR PZZ350-370.

DW