Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 281308
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
600 AM PDT FRI AUG 28 2015

UPDATED AVIATION, MARINE AND FIRE DISCUSSIONS.

.DISCUSSION...A VERY UNUSUALLY STRONG WEATHER SYSTEM WILL IMPACT
OUR AREA BEGINNING TONIGHT. OUR FORECAST RAINFALL AMOUNTS AT THE
COAST HAVE NOT BEEN SEEN SINCE APRIL DUE TO THE ONGOING DROUGHT.
THE MODELS ARE IN AGREEMENT THAT A LOW PRESSURE CENTER WILL DEEPEN
RAPIDLY INSIDE OF 130W FRIDAY NIGHT AS IT PASSES OFFSHORE OF THE
SOUTHERN OREGON COAST AS A "SOUWESTER". THE MODELS SHOW ABOUT
10MB OF DEEPENING IN 12 HOURS WHICH IS EXTREMELY IMPRESSIVE FOR
THE END OF AUGUST IN OUR REGION. IN FACT...THIS FORECAST DEEP LOW
PRESSURE CENTER IS OUTSIDE OF THE CLIMATOLOGY (SINCE 1979) FOR
NEARBY LOW PRESSURE IN OUR REGION.

THE LATEST WATER VAPOR LOOP SHOWS AN ENERGETIC SYSTEM WITH DEEPER
MOISTURE EXTENDING SOUTH INTO THE SUBTROPICS. THERE IS A BRIEF
PERIOD OF INTEGRATED WATER VAPOR TRANSPORT GREATER THAN 500
KG/M/S FOR ABOUT 12 HOURS TONIGHT INTO SATURDAY MORNING. THE
MOISTURE TRANSPORT IS ALSO OUTSIDE OF THE CLIMATOLOGY (SINCE
1979) FOR THE END OF AUGUST IN OUR AREA. DESPITE THIS IMPRESSIVE
WATER TRANSPORT I HAVE LOWERED THE QPF A TAD NEAR THE COAST
BECAUSE OF THE DRY ANTECEDENT CONDITIONS AND THE RELATIVE BRIEF
DURATION OF THE PRECIPITATION. ANY RAIN WILL BE WELCOME BUT WILL
ONLY PROVIDE SHORT-TERM DROUGHT RELIEF. HOWEVER...WILDFIRE SMOKE
IMPACTS WILL FINALLY DIMINISH DUE TO THE RAIN...COOLER
TEMPERATURES...HIGHER HUMIDITIES...AND A MORE FAVORABLE WIND
DIRECTION. ROAD CONDITIONS MAY BE QUITE SLICK DUE TO THE OIL
BUILDUP ON THE ROADS AND THE FIRST WIDESPREAD RAIN.

WINDS ALOFT FOR THIS TIME OF YEAR WILL BE VERY UNUSUAL. THE WINDS
AT 700 MB (10,000 FT)ACROSS PARTS OF THE EASTSIDE ARE OUTSIDE OF
THE CLIMATOLOGY (SINCE 1979) FOR THIS TIME OF YEAR AND WILL PEAK
12Z SATURDAY CLOSE TO 65 MPH. HAVE ISSUED A HIGH WIND WATCH FOR
THE SUMMER LAKE AREA AROUND HIGHWAY 31 AS SOUTHWEST WINDS ALOFT
TYPICALLY SURFACE AT LOWER ELEVATIONS THERE. WINDS ELSEWHERE ON
THE EASTSIDE WILL BE GUSTY ESPECIALLY ON THE RIDGES LATE FRIDAY
NIGHT AND SATURDAY MORNING. WIND ADVISORIES MAY BE NEEDED FOR SOME
AREAS. WINDS WILL BE STRONG AT THE COAST BUT DO NOT BELIEVE IT
WILL REACH HIGH WIND WARNING CRITERIA LATE FRIDAY NIGHT/EARLY
SATURDAY MORNING. HOWEVER...THE DROUGHT HAS WEAKENED SOME TREES
AND WIND DAMAGE IS MORE LIKELY WITH THE FIRST STRONG WIND OF THE
SEASON...BUT THE STRONGEST WINDS WILL ONLY LAST A FEW HOURS.
CAPE BLANCO COULD SEE WIND GUSTS EXCEED 60 MPH.

BEHIND THIS STORM THE GENERAL WEATHER PATTERN WILL ANCHOR A TROUGH
OVER THE PACIFIC NORTHWEST. A NUMBER OF WEATHER SYSTEMS IMPACT THE
REGION BUT MAINLY FARTHER NORTH. IT WILL BE A VERY WET UPCOMING
WEAK FOR THE SEATTLE REGION WHILE WE MAY SEE LITTLE RAIN BUT
TEMPERATURES WILL BE COOLER THAN NORMAL NEXT WEEK. DESPITE THE
COOLER ENDING TO SUMMER (JUNE-JULY-AUGUST) WE COULD STILL END UP
WITH THE WARMEST SUMMER ON RECORD IN MEDFORD. IF THE LAST FEW
DAYS OF THE MONTH ARE WELL BELOW NORMAL THEN WE COULD DROP TO THE
2ND OR 3RD WARMEST SUMMER BEHIND 2014 AND 2013.
SANDLER

&&

.AVIATION...FOR THE 28/12Z TAF CYCLE...ALONG THE COAST...EXPECT
ARES OF MVFR CIGS WITH OCCASIONAL LIGHT RAIN AND MVFR VIS THROUGH
THE MORNING...BECOMING VFR IN THE AFTERNOON...THEN MVFR CIGS ARE
EXPECTED TO DEVELOP AGAIN TONIGHT. SOUTHERLY LOW LEVEL WINDS WILL
INCREASE ALONG THE COAST TONIGHT INTO EARLY SATURDAY MORNING.
INLAND...VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING...EXCEPT
FOR AREAS OF MVFR VSBYS IN SMOKE AND HAZE. BREEZY SOUTHWEST WINDS
WILL DEVELOP EAST OF THE CASCADES THIS AFTERNOON AND EVENING. STRONG
SOUTH WINDS WILL ALONG DEVELOP OVER THE MOUNTAINS TONIGHT INTO EARLY
SATURDAY WITH SOME LOWER LEVEL WIND SHEAR IS POSSIBLE OVER THE AREA,
ESPECIALLY ALONG THE COAST AND EAST OF THE CASCADES.


&&

.MARINE...UPDATED 500 AM PDT FRIDAY 28 AUGUST 2015...LIGHT WINDS AND
SEAS ARE EXPECTED TODAY. THEN A SURFACE LOW WILL NEAR THE WATERS
TONIGHT AND TRACK NORTH ALONG THE OREGON COAST SATURDAY. THIS LOW
WILL BRING INCREASED WINDS AND SEAS TONIGHT AND SATURDAY.
CONFIDENCE IS HIGH REGARDING THE DETAILS OF THIS LOW PRESSURE
SYSTEM AS IT NEARS THE COAST TONIGHT AND EARLY SATURDAY. A PERIOD OF
MODERATE TO STRONG SOUTHERLY WINDS IS EXPECTED TO BEGIN TONIGHT WITH
THE STRONGEST WINDS DEVELOPING EARLY SATURDAY MORNING THROUGH AROUND
NOON SATURDAY. THIS WILL CREATE SMALL CRAFT WINDS AND SEAS ACROSS
ALL OF OUR WATERS WITH WINDS INCREASING TO GALES AND VERY STEEP WIND
DRIVEN SEAS BY EARLY SATURDAY, MAINLY FOR THE WATERS NORTH OF GOLD
BEACH. WINDS ARE EXPECTED TO LOWER SOME SATURDAY AFTERNOON BUT AREAS
OF GALES AND VERY STEEP HAZARDOUS MAY CONTINUE INTO THE AFTERNOON,
ESPECIALLY NORTH OF GOLD BEACH.  THIS LOW PRESSURE SYSTEM WILL ALSO
BRING MODERATE RAIN WITH OCCASIONALLY HEAVY RAIN AND LOW
VISIBILITIES POSSIBLE. AS THE SURFACE LOW APPROACHES THE WATERS
TONIGHT INTO EARLY SATURDAY MORNING, THERE IS ALSO A SLIGHT CHANCE
OF THUNDERSTORMS, ESPECIALLY NORTH OF CAPE BLANCO. MULTIPLE LONG
PERIOD SWELLS ARE ALSO EXPECTED THIS WEEKEND WITH  INCREASED SNEAKER
WAVE ACTIVITY POSSIBLE. CONDITIONS WILL IMPROVE SOME ON MONDAY, BUT
MODERATE LONG PERIOD NORTHWEST SWELL WILL DEVELOP OVER THE WATERS
AND CONTINUE THROUGH WEDNESDAY.

&&

.FIRE WEATHER...UPDATED 500 AM PDT FRIDAY 28 AUGUST 2015...A LARGE
UPPER TROUGH OFF THE COAST THIS TODAY AND ITS ASSOCIATED FRONTAL
SYSTEM WILL MOVE INLAND OVER THE AREA SATURDAY. THIS WILL BRING A
WETTING RAIN TO MUCH OF THE AREA FROM THE CASCADES WESTWARD. ON THE
EAST SIDE, LESS RAIN IS EXPECTED WITH THE FRONT. THE BIGGER CONCERN
EAST OF THE CASCADES WILL BE THE DRY CONDITIONS AND GUSTY SOUTHWEST
WINDS THAT WE`LL GET THIS AFTERNOON BRINGING NEAR CRITICAL
CONDITIONS. OVERALL, EXPECT HUMIDITIES TO REMAIN ABOVE CRITICAL
LEVELS THOUGH.

TONIGHT A STRONG SURFACE LOW IS EXPECTED TO FORM ALONG THE FRONT
OFFSHORE  AND TRACK NORTH ALONG THE SOUTHERN AND CENTRAL OREGON COAST
SATURDAY. THIS WILL BRING STRONG WINDS TO THE COAST, MOUNTAINS, AND
THE SUMMER LAKE AREA SATURDAY MORNING. WHILE HUMIDITIES WILL BE
INCREASING (ESPECIALLY WHERE IT RAINS), A NEGATIVELY TILTED UPPER
TROUGH IS A POTENTIAL HIGH WIND MAKER ON THE EAST SIDE. WE HAVE
INCREASED WINDS ON THE EAST SIDE, ESPECIALLY NEAR THE SUMMER LAKE
AREA WHERE STRONG GUSTY WINDS ARE POSSIBLE SATURDAY MORNING.

WHILE WE WILL GET RAIN OVER MANY OF OUR ONGOING FIRES, THERE ARE
SPECIFIC CONCERNS ABOUT THIS STORM WITH RESPECT TO THOSE FIRES AND
THE PERSONNEL MANNING THEM. THERE IS THE POTENTIAL FOR MODERATE TO
HEAVY RAIN OVER ALL FIRE AREAS FROM THE CASCADES WEST. THIS IS
EXPECTED TO BE A GENTLE SOAKING RAIN RATHER THAN CONVECTIVE, HIGH
INTENSITY RAIN, SO BURN SCAR FLOODING AND DEBRIS FLOWS ARE NOT A
HUGE CONCERN. BUT IT IS SOMETHING TO THINK ABOUT. ALSO, SNAGS,
BURNED TREES, AND OTHER MATERIAL THAT HAVE BEEN WEAKENED OVER THE
SUMMER HAVE THE POTENTIAL TO COME DOWN FROM WIND, THE ADDED WEIGHT
OF RAINFALL, OR A COMBINATION OF BOTH. FIREFIGHTERS SHOULD REMAIN
VERY AWARE OF THEIR SURROUNDINGS THIS WEEKEND, ESPECIALLY ON OR
AROUND EXISTING FIRES AND BURN SCARS. -WRIGHT/CC


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR
     ORZ030-031.

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM LATE TONIGHT THROUGH SATURDAY AFTERNOON FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 AM TO 5 PM PDT SATURDAY
     FOR PZZ356-376.
     HAZARDOUS SEAS WATCH FROM LATE TONIGHT THROUGH SATURDAY
     AFTERNOON FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 AM TO 5 PM PDT
     SATURDAY FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 AM TO 5 AM PDT SATURDAY
     FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 AM TO 5 AM PDT
     SATURDAY FOR PZZ350-370.

$$


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