Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 032342
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
440 PM PDT WED JUN 3 2015

UPDATED AVIATION SECTION

.SHORT TERM...THIS AFTERNOON THROUGH SATURDAY...VISIBLE SATELLITE
SHOWING PLENTY OF CUMULUS OUT THERE THIS AFTERNOON. AN UPPER LEVEL
TROUGH DIGGING SOUTHEASTWARD OFFSHORE IS BRINGING ADEQUATE MID-
LEVEL MOISTURE AND INSTABILITY AHEAD OF THIS SYSTEM FOR SOME
SHOWERS TO DEVELOP OVER THE HIGHER TERRAIN OF THE CASCADES, THE
FREMONT RANGE AND THE TRINITY ALPS/MARBLE MTNS TO NEAR MEDICINE
LAKE EARLY THIS AFTERNOON. EXPECT SHOWERS TO PERSIST IN THESE
LOCATIONS LATE THIS AFTERNOON/EVENING ALONG WITH ISOLATED
THUNDERSTORMS.

THE UPPER TROUGH WILL CLOSE OFF INTO AN UPPER LOW NEAR CAPE
MENDOCINO TONIGHT AND THIS WILL KEEP A SLIGHT CHANCE OF SHOWERS
IN THE FORECAST, ESPECIALLY FROM THE CASCADES AND SISKIYOUS SOUTH
AND EAST. IN THIS TYPE OF PATTERN, AS THE LOW-LEVEL FLOW TURNS
INTO THE NORTH OVER THE EAST SIDE, WE OBSERVE A PERIOD OF GUSTY
WINDS THAT DEVELOP AT NIGHT, ESPECIALLY NEAR LAKEVIEW. THIS IS
EXPECTED TONIGHT, WHICH SHOULD HOLD TEMPERATURES UP A BIT THERE.

ON THURSDAY, THE UPPER LOW WILL GRADUALLY SETTLE SOUTHWARD ALONG
THE CALIFORNIA COAST WITH THE MID TO UPPER LEVEL FLOW BACKING FROM
THE SOUTH TO THE EAST. A SHORT WAVE ARRIVING FROM THE SOUTHEAST
ALONG WITH A SURGE OF MOISTURE FROM NORTHWEST NEVADA WILL INCREASE
COVERAGE OF SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN AND EASTERN
SECTIONS OF OUR FORECAST AREA, ESPECIALLY DURING THE AFTERNOON.
HIGHEST PROBABILITIES OF RAINFALL WILL BE OVER NORTHERN
CALIFORNIA AND EAST-FACING TERRAIN. THURSDAY MORNING WEST OF THE
CASCADES THERE WILL LIKELY BE SOME CLOUDS IN THE UMPQUA BASIN AND
PERHAPS BANKED UP AGAINST THE SISKIYOUS. EXPECT THESE TO THIN OUT
BY AFTERNOON WITH JUST SOME LEFTOVER CUMULUS AND MID-LEVEL CLOUD
FROM THE UPPER LOW TO THE SOUTH. TEMPERATURES SHOULD BE ABOUT 5-10
DEGREES HIGHER THAN THEY ARE TODAY.

THURSDAY NIGHT INTO FRIDAY...THE UPPER LOW WILL CONTINUE SOUTHWARD
INTO SOUTHERN CALIFORNIA WITH AN INVERTED TROUGH EXTENDING
NORTHWARD INTO THE SOUTHEASTERN PART OF OUR CWA. A RIDGE BUILDING
OFFSHORE WILL BEGIN TO NOSE INTO THE WASHINGTON/OREGON COAST.
INCREASING OFFSHORE FLOW SHOULD RESULT IN MUCH WARMER CONDITIONS
WEST OF THE CASCADES WITH HIGHS AT LEAST IN THE MID TO UPPER 80S
IN THE VALLEYS. BROOKINGS WILL START TO WARM UP TOO WITH HIGHS IN
THE UPPER 70S. ENOUGH MOISTURE AND INSTABILITY WILL STILL BRING A
CHANCE OF SHOWERS AND THUNDERSTORMS TO FAR SOUTHERN AND EASTERN
SECTIONS.

BY SATURDAY, WE`LL BE AT THE BEGINNING OF A HEAT WAVE FOR THE WEST
SIDE. THE RIDGE OFFSHORE WILL CONTINUE TO PUSH INTO WASHINGTON
AND NORTHWEST OREGON WITH THE UPPER LOW OVER SOCAL/SRN NEVADA. WITH
MODEL 850 TEMPS IN THE LOWER 20S, EXPECT HIGHS IN THE LOW TO MID
90S FOR THE WEST SIDE VALLEYS. THE THERMAL TROUGH ALONG THE COAST
SHOULD PUSH JUST FAR ENOUGH OFFSHORE TO BRING VERY WARM TEMPS TO
BROOKINGS AS WELL. IT ISN`T A SLAM DUNK FOR A FULL-FLEDGED
BROOKINGS EFFECT, SINCE THE THERMAL TROUGH DOESN`T PUSH VERY FAR
OFFSHORE, BUT FOR RIGHT NOW, WE HAVE GONE WITH LOW 80S THERE.
THUNDERSTORM CHANCES STILL EXIST ACROSS THE FAR SOUTH AND EAST
PORTIONS OF THE FORECAST AREA. SPILDE

.LONG TERM...SUNDAY THROUGH WEDNESDAY...THE MODELS REMAIN IN GOOD
AGREEMENT REGARDING THE EXTENDED PERIOD, AND THUS CONFIDENCE REMAINS
HIGH. ON SUNDAY, AN UPPER LOW WILL EJECT NORTHEAST INTO THE GREAT
BASIN AND A SECONDARY LOW WILL FORM WELL OFF THE SOCAL COAST.
THIS HAS THE EFFECT OF STRETCHING THE LOW INTO A BROAD TROUGH TO
OUR SOUTH. AT THE SAME TIME, A POSITIVELY TILTED UPPER RIDGE LEANS
IN OVER THE PACNW TO OUR NORTH, AND THE DEEP OFFSHORE FLOW BETWEEN
THE TWO WILL RESULT IN A HOT DAY OVER MUCH OF OUR AREA (15-20F
ABOVE NORMAL). THE SURFACE THERMAL TROUGH WILL BE RIGHT ALONG THE
COAST, WHICH MAKES FOR A TRICKY TEMPERATURE FORECAST AT THE COAST
SUNDAY. A TINY DIFFERENCE IN THE POSITION OF THE THERMAL TROUGH
COULD MEAN THE DIFFERENCE BETWEEN HOT, DRY OFFSHORE FLOW AT THE
COAST AND CHILLY, MOIST ONSHORE FLOW. WE DECIDED TO SPLIT THE
DIFFERENCE AND RAISE TEMPERATURES AT THE SOUTH COAST, BUT KEEP
THEM FAIRLY COOL NORTH OF CAPE BLANCO. WE`LL KEEP AN EYE ON THIS,
BUT SUNDAY COULD BE MUCH WARMER AT THE COAST THAN WE HAVE IN THE
FORECAST.

ON MONDAY, THE NORTHERN PORTION OF THE TROUGH WEAKENS AND MOVES EAST
WHICH ALLOWS THE UPPER RIDGE TO BUILD RIGHT OVER US. THIS WILL YIELD
ANOTHER HOT DAY INLAND FROM THE COAST MONDAY, BUT THE MODELS ARE
HINTING AT SOME MONSOON-LIKE RETURN FLOW AROUND THE HIGH, WHICH MAY
PRODUCE SOME STORMS OVER NORCAL. THE RIDGE EDGES OFF TO THE EAST
MONDAY NIGHT AND TUESDAY, AND WHILE IT STILL LOOKS HOT, THE MOISTURE
CONTINUES TO INCREASE. ALL THE MODELS TO SOME EXTENT, BUT THE GFS
IN PARTICULAR, ARE HINTING AT THE POTENTIAL FOR NOCTURNAL
CONVECTION TUESDAY NIGHT. THEN ON WEDNESDAY, THE RIDGE MOVES WELL
EAST, AND A PACIFIC TROUGH APPROACHES. THIS TURNS THE FLOW ONSHORE
AND BRINGS A COOL DOWN TO THE WEST SIDE. IT WILL STILL BE WARMER
THAN NORMAL WEDNESDAY, BUT THE EXTREME HEAT SHOULD BE OVER.
-WRIGHT

&&

.AVIATION...FOR THE 04/00Z TAF CYCLE...SHOWERS AND ISOLATED
THUNDERSTORMS WILL CONTINUE ALONG AND EAST OF THE CASCADES AND
SISKIYOUS THIS AFTERNOON WHICH COULD BRING BRIEF MVFR CIGS OR VIS,
BUT THEY WILL DISSIPATE AFTER SUNSET. STRATUS WITH MVFR CIGS IS
EXPECTED AGAIN TONIGHT ALONG THE UMPQUA BASIN. FOR THE COAST,
STRATUS WITH IFR/MVFR CIGS ARE EXPECTED TONIGHT BEFORE LIFTING
TOMORROW. IN ADDITION STRONG NORTHERLY WINDS ARE EXPECTED ALONG THE
COAST AND IMMEDIATELY OFFSHORE. ELSEWHERE, VFR CONDITIONS ARE
EXPECTED THROUGH THE REST OF THE TAF PERIOD.  -SCHAAF/SVEN

&&

.MARINE...UPDATED 345 PM PDT, WEDNESDAY, 3 JUNE 2015...WINDS AND
SEAS WILL REMAIN LIGHT THIS AFTERNOON BEFORE BEGINNING TO INCREASE
THIS EVENING. HIGH PRESSURE WILL BEGIN BUILDING OFFSHORE...AND WILL
COUPLE WITH LOW PRESSURE INLAND TO ALLOW NORTHERLY WINDS AND STEEP
CHOPPY SEAS TO REACH ADVISORY LEVELS THIS AFTERNOON THROUGH THURSDAY
MORNING FOR THE WATERS SOUTH OF CAPE BLANCO. THEN AS A THERMAL
TROUGH DEVELOPS ALONG THE COAST AND THE PRESSURE GRADIENT INCREASES,
EXPECT WINDS TO INCREASE FURTHER ON THURSDAY AND FRIDAY. CONFIDENCE
IS HIGH THAT THIS WILL BRING SMALL CRAFT WINDS AND STEEP SEAS ACROSS
MOST THE COASTAL WATERS BY LATE THURSDAY AFTERNOON AND THURSDAY
EVENING. ADDITIONALLY, MODELS CONTINUE TO SHOW THAT AREAS OF GALES
AND HAZARDOUS SEAS WILL DEVELOP FOR AREAS SOUTH OF CAPE BLANCO.
THESE STRONG WINDS AND STEEP TO VERY STEEP SEAS ARE FORECAST TO
PERSIST INTO FRIDAY...THEN DECREASING SLIGHTLY ON SATURDAY...BUT
REMAINING NEAR ADVISORY LEVELS THROUGH AT LEAST NEXT WEEK.
CONFIDENCE IS INCREASING FOR THE DETAILS OF THE WIND AND SEA
FORECAST LATE IN THE FORECAST PERIOD SINCE MODELS ARE REMAINING
CONSISTENT OR HAVE TRENDED SLIGHTLY HIGHER WITH WINDS. -SCHAAF/SVEN

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM THURSDAY MORNING THROUGH FRIDAY
     EVENING FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT THURSDAY FOR
     PZZ356-376.
     HAZARDOUS SEAS WATCH FROM THURSDAY MORNING THROUGH FRIDAY
     EVENING FOR PZZ356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT THURSDAY
     FOR PZZ356-376.
     HAZARDOUS SEAS WATCH FROM THURSDAY MORNING THROUGH SATURDAY
     AFTERNOON FOR PZZ376.

$$

MAS/TRW/SBN/BMS


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