Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 020420
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
820 PM PST SUN MAR 1 2015

.DISCUSSION...ALREADY MADE A FEW UPDATES THIS EVENING TO RAISE
POPS ALONG THE COAST OVERNIGHT. A SYSTEM IS DROPPING SOUTH ALONG
THE OREGON COAST THIS EVENING, AND WHILE THE COLDEST CLOUD TOPS
ARE MOVING THROUGH RIGHT NOW, THE DEEPER MOISTURE IS EXPECTED
OVERNIGHT. IT HAS NOT YET RAINED AT ANY OF THE UPSTREAM OBS SITES,
BUT RADAR SHOWS RAIN APPROACHING THE NORTH OREGON COAST, AND THIS
WILL SPREAD SOUTH THROUGH THE NIGHT. ALL THE 02/00Z GUIDANCE
SHOWS AT LEAST A FEW HUNDREDTHS OF RAIN ALONG MUCH OF THE COAST BY
MONDAY MORNING WITH THE RAP BEING THE MOST BULLISH IN SHOWING UP
TO 0.10 INCH OVER THE COOS COAST. I DIDN`T GO THAT HIGH WITH
AMOUNTS, BUT I DID RAISE POPS TO CATEGORICAL FOR THE IMMEDIATE
COAST TONIGHT AND BUMPED UP QPF AS WELL. RAIN IS STILL NOT
EXPECTED TO MAKE MUCH PROGRESS INLAND, AND THE REST OF THE
FORECAST FOR TONIGHT REMAINS UNCHANGED. -WRIGHT

&&

.AVIATION...FOR THE 02/00Z TAF CYCLE...VFR CONDITIONS WITH MOSTLY
CLEAR SKIES WILL PREVAIL THROUGH THIS EVENING FOR MOST OF THE
FORECAST AREA. TONIGHT INTO MONDAY MORNING, A WEAK LOW WILL MOVE
SOUTH WITH INCREASING CLOUDS FOR THE AREA FROM NORTH TO SOUTH. SKIES
WILL MAINLY REMAIN VFR BUT ALONG THE COAST AND INTO THE UMPQUA BASIN
EXPECT AREAS OF MVFR CIGS TO DEVELOP BETWEEN 03-10Z AND CONTINUE
INTO MONDAY MORNING WITH A CHANCE OF LIGHT RAIN MAINLY AT THE COAST.
AREAS OF MOUNTAIN OBSCURATION WILL ALSO DEVELOP MONDAY MORNING,
MAINLY FROM THE CASCADES WEST. SK

&&

.MARINE...UPDATED 2 PM PST, SUNDAY, 1 MAR, 2015...HIGH CONFIDENCE
EXISTS THAT AREAS OF MODERATE NORTHERLY WINDS WILL PERSIST THROUGH
WEDNESDAY AND WILL BE STRONGEST DURING THE AFTERNOONS AND EVENINGS
AND IN THE OUTER WATERS AND SOUTH OF CAPE BLANCO. A THERMAL TROUGH
ALONG THE COAST AND HIGH PRESSURE OFFSHORE THIS EVENING WILL BE
FOLLOWED BY A LOW WITH LIGHT RAIN LATE TONIGHT INTO MONDAY MORNING.
THE PATTERN OF A THERMAL TROUGH AT THE COAST AND HIGH PRESSURE
OFFSHORE WILL DEVELOP AGAIN TUESDAY THEN WINDS WEAKEN LATE IN THE
WEEK AS THE HIGH BUILDS EASTWARD. SK

&&

.PREV DISCUSSION... /ISSUED 102 PM PST SUN MAR 1 2015/

DISCUSSION...01/12Z NAM/GFS IN.

MOSTLY CLEAR SKIES PREVAIL ACROSS THE MEDFORD CWA THIS
AFTERNOON...ALTHOUGH SOME CUMULUS IS STARTING TO DEVELOP OVER THE
RIDGES.

IT IS DIFFICULT TO DETERMINE A WAVE NUMBER AROUND THE HEMISPHERE
TODAY BUT IT DOESN`T APPEAR TO BE A FACTOR WITH AN OMEGA BLOCK IN
PLACE OVER THE EASTERN PACIFIC. THE COLDEST AIR REMAINS OVER
NORTHEAST AND FAR NORTHERN CANADA.

A STRONG RIDGE REMAINS IN PLACE ALONG 135W AND IT ISN`T GOING
ANYWHERE ANYTIME SOON. THE ANCHOR LOWS FOR THE BLOCK ARE CURRENTLY
OVER CALIFORNIA AND OUT NEAR 40N 160W. CURRENTLY THERE IS DRY
NORTHEAST FLOW ALOFT OVER THE AREA. ALL OF THIS SUPPORTS THE DRY
OFFSHORE LOW LEVEL FLOW PATTERN.

HOWEVER...A STRONG SHORT WAVE WILL MOVE DOWN THE FRONTSIDE OF THE
RIDGE TONIGHT INTO MONDAY...AND THIS WAVE DOES SPEND SOME TIME
OVER THE WATER...SO IT MAY BRING SOME PRECIPITATION TO THE AREA
ALONG THE COAST AND OVER THE COASTAL WATERS TONIGHT INTO MONDAY.

AFTER THAT...OFFSHORE LOW LEVEL FLOW AND DRY WEATHER WILL RETURN
TO THE AREA MONDAY NIGHT.  THE RIDGE WILL GRADUALLY WEAKEN IN
PLACE THROUGH THURSDAY...SO THE OFFSHORE FLOW WILL WEAKEN AS WELL.
EVENTUALLY SOME HIGH LEVEL MOISTURE WILL MAKE IT OVER THE RIDGE
AND OVER THE CWA AROUND THE MIDDLE OF THE WEEK...BUT NO ADDITIONAL
PRECIPITATION IS EXPECTED.

LONG TERM DISCUSSION...THURSDAY THROUGH SUNDAY. MODELS SHOW GOOD
AGREEMENT THAT THE UPPER LEVEL HIGH PRESSURE RIDGE WILL REMAIN
OVER THE REGION BRINGING WARMING TEMPERATURES AND DRY WEATHER.
SOME AREAS OF LATE NIGHT AND EARLY MORNING VALLEY FOG ARE POSSIBLE
FOR WEST SIDE VALLEYS LATE IN THE WEEK AND PARTLY CLOUDY SKIES ARE
ALSO POSSIBLE WITH A WEAK FRONT MOVING OVER THE RIDGE WELL TO THE
NORTH THURSDAY INTO FRIDAY. OTHERWISE EXPECT MAINLY SUNNY SKIES
OVER THE AREA.

GFS, GFS ENSEMBLES AND ECMWF ARE TRENDING SLOWER WITH THE UPSTREAM
TROUGH AFFECTING THE PACNW AND DO NOT SHOW THE RIDGE SHIFTING EAST
UNTIL AROUND TUESDAY OF NEXT WEEK. /CC

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 AM PST MONDAY FOR PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 7 PM MONDAY TO 1 AM PST
     TUESDAY FOR PZZ356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST MONDAY
     FOR PZZ350-356.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 PM PST MONDAY FOR PZZ370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST TUESDAY
     FOR PZZ370-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 AM PST TUESDAY FOR
     PZZ376.

$$



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