Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 301618
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
918 AM PDT TUE SEP 30 2014

.DISCUSSION...LOW STRATUS CONTINUES TO LINGER IN PARTS OF THE UMPQUA
BASIN AND NORTH COAST THIS MORNING. THE LOW CLOUDS WILL LIFT LATER
THIS MORNING, BUT WE`LL CONTINUE TO HAVE PLENTY OF CLOUD COVER
FORMING MAINLY ALONG AND NORTH OF THE UMPQUA THE REST OF TODAY. MADE
SOME UPDATES TO REFLECT THIS THINKING. A FEW SPRINKLES ARE
POSSIBLE NORTH OF CRATER LAKE THIS MORNING, BUT I DON`T THINK
WE`LL GET ANYTHING MEASURABLE AND HAVE REDUCED POPS FOR THIS
MORNING AND AFTERNOON. TEMPERATURES EAST OF THE CASCADES WILL
LIKELY DROP WELL BELOW FREEZING IN THE TYPICAL COLD SPOTS AND
WE`LL LIKELY ISSUE A FREEZE WATCH FOR WEDNESDAY NIGHT/EARLY
THURSDAY MORNING. REST OF THE FORECAST IS STILL ON TRACK. SEE
PREVIOUS DISCUSSION FOR DETAILS. - PETRUCELLI


&&

.AVIATION...FOR THE 30/12Z TAF CYCLE...
CONDITIONS ARE MAINLY VFR BUT AREAS OF IFR CIGS AREA EXPECTED EARLY
THIS MORNING ALONG THE COAST AND INTO VALLEYS WEST OF THE CASCADES.
INLAND, THE IFR CIGS WILL MAINLY AFFECT THE UMPQUA VALLEY BUT
ISOLATED IFR IS POSSIBLE IN OTHER WEST SIDE VALLEYS. THE COAST AND
INLAND TERMINALS SHOULD IMPROVE TO VFR AROUND MID TO LATE MORNING.
THEN EXPECT VFR AREAWIDE THIS AFTERNOON INTO THIS EVENING. /CC


&&

.MARINE...UPDATED 3 AM PDT MON 29 SEP 2014... HIGH PRESSURE
BUILDING INTO THE WATERS WILL CAUSE WINDS AND SEAS TO INCREASE
TODAY AND MORE SO ON WEDNESDAY. HAZARDOUS SEAS ARE POSSIBLE SOUTH
OF CAPE BLANCO WEDNESDAY AFTERNOON AND EVENING WITH GALE FORCE
GUSTS POSSIBLE AS WELL. GUSTY SMALL CRAFT ADVISORY LEVEL NORTH
WINDS WILL CONTINUE INTO THURSDAY MORNING THEN GRADUALLY DECREASE
LATE THURSDAY. ON FRIDAY HIGH PRESSURE WILL WEAKEN AS A COLD FRONT
PASSES TO THE NORTH. THIS WILL CAUSE WINDS AND SEAS TO DIMINISH
SOME FRIDAY. THEN SEAS INCREASE DUE TO BUILDING WESTERLY SWELL
FRIDAY NIGHT. ON THE WEEKEND, STEEP SEAS AND GUSTY NORTH WINDS ARE
POSSIBLE ONCE MORE FOR THE WATERS SOUTH OF CAPE BLANCO AS HIGH
PRESSURE BUILDS OFFSHORE. /CC


&&

.PREV DISCUSSION... /ISSUED 301 AM PDT TUE SEP 30 2014/

DISCUSSION...A WEAK FRONT MOVED ACROSS THE CWA LAST EVENING AND
BROUGHT MEASURABLE RAINFALL TO MANY AREAS ALONG AND WEST OF THE
CASCADES. THERE WASN`T A LOT OF RAINFALL, GENERALLY TWO-TENTHS OF
AN INCH OR LESS...BUT THE FRONT DID MANAGE TO BRING A COUPLE OF
HUNDREDTHS TO THE MEDFORD AIRPORT RAIN GAUGE JUST BEFORE MIDNIGHT.
MOIST ONSHORE FLOW WILL KEEP AREAS OF CLOUDINESS AND ISOLATED
SHOWERS NEAR THE CASCADES AND THE NORTH COAST THIS MORNING. CLOUDS
ELSEWHERE SHOULD THIN OUT BY LATER THIS MORNING AS DRIER AIR WORKS
IN ALOFT...THOUGH PORTIONS OF THE UMPQUA AND COAST MAY HOLD ONTO
SOME CLOUDS INTO THE AFTERNOON. OVERALL, IT WILL BE COOL BY LATE
SEPTEMBER STANDARDS WITH HIGH TEMPERATURES ONLY AROUND 70 DEGREES
OVER THE WEST SIDE VALLEYS AND NO BETTER THAN THE LOW 60S OVER
THE EAST SIDE.

STRONG SUBSIDENCE AND RADIATIONAL COOLING WILL ALLOW TEMPERATURES
TO FALL SIGNIFICANTLY TONIGHT INTO WEDNESDAY MORNING...ESPECIALLY
EAST OF THE CASCADES. EXPECT LOW TEMPERATURES IN THE UPPER TEENS
IN THE COLDEST SPOTS NEAR KLAMATH MARSH WITH READINGS DOWN NEAR OR
JUST BELOW FREEZING IN KLAMATH FALLS, LAKEVIEW AND ALTURAS. AS A
RESULT, WE HAVE ISSUED A FREEZE WARNING FOR THOSE AREAS, DETAILS
OF WHICH CAN BE VIEWED AT NPWMFR. IN ADDITION, IT WILL GET QUITE
COLD IN THE SHASTA VALLEY. SOME LOCATIONS LIKE WEED AND MONTAGUE
MAY HAVE TEMPERATURES IN THE LOW TO MID 30S AND A FROST ADVISORY
IS IN EFFECT THERE. WEST OF THE CASCADES, IT WILL BE COOL IN THE
ROGUE AND ILLINOIS VALLEYS, BUT LOW TEMPERATURES SHOULD BOTTOM OUT
IN THE UPPER 30S TO LOWER 40S. A FEW OUTLYING AREAS MAY REACH THE
MID 30S LIKE NEAR CAVE JUNCTION AND THE APPLEGATE, BUT PROBABLY
NOT LONG ENOUGH FOR FROST IMPACTS.

HIGH PRESSURE ALOFT WILL BUILD IN FIRMLY OVER THE AREA WEDNESDAY.
EXPECT ABOUT 4 TO 8 DEGREES OF WARMING WEDNESDAY AFTERNOON...WITH
TEMPERATURES TOPPING OUT IN THE MID TO UPPER 70S OVER THE WEST
SIDE VALLEYS WITH GENERALLY MID 60S EAST SIDE. WITH OFFSHORE FLOW
DEVELOPING EXPECT A BIT OF A CHETCO EFFECT WITH HIGHS IN THE
UPPER 70S AND LOW 80S NEAR BROOKINGS. ANOTHER COLD NIGHT IS
EXPECTED WEDNESDAY NIGHT INTO THURSDAY MORNING WITH ADDITIONAL
FROST/FREEZE IMPACTS POSSIBLE. A CLEAR SKY AND CALM WINDS WILL
MAXIMIZE RADIATIONAL COOLING AND RESULT IN A VERY STRONG
TEMPERATURE INVERSION. TEMPERATURES IN THE VALLEYS WILL LIKELY BE
VERY SIMILAR TO OR EVEN SLIGHTLY COLDER THAN THE PREVIOUS
NIGHT...WHILE SURROUNDING HILLS AND RIDGES WILL BE COMPARATIVELY
MILDER. FOR THIS REASON, HAVE ADJUSTED MIN TEMPERATURES DOWNWARD
IN THE VALLEYS, BUT SLIGHTLY UPWARD FOR THE MID SLOPES AND RIDGES.

NOT MUCH HAS CHANGED IN THE FORECAST THURSDAY THROUGH EARLY NEXT
WEEK. EXPECT A BROAD RIDGE ALOFT TO BE ALONG THE WEST COAST DURING
THIS TIME. THE GFS FLATTENS THE RIDGE A BIT SATURDAY INTO SUNDAY
AS A SHORTWAVE SCOOTS ACROSS BRITISH COLUMBIA, WHILE THE ECMWF
KEEPS THIS FEATURE FAR ENOUGH NORTH TO HAVE LITTLE EFFECT ON OUR
WEATHER. OVERALL, THE EXPECTATION IS THAT WE`LL HAVE PERSISTENT
WARM, DRY WEATHER WITH TEMPERATURES ABOUT 5 TO 10 DEGREES ABOVE
AVERAGE. FOR THIS TIME OF YEAR, THIS TRANSLATES TO HIGHS IN THE
MID TO UPPER 80S IN MEDFORD AND IN THE MID TO UPPER 70S IN THE
KLAMATH FALLS. SPILDE



&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FROST ADVISORY FROM 1 AM TO 8 AM PDT WEDNESDAY FOR ORZ029>031.
     FREEZE WARNING FROM 1 AM TO 8 AM PDT WEDNESDAY FOR ORZ029>031.

CA...FROST ADVISORY FROM 1 AM TO 8 AM PDT WEDNESDAY FOR
     CAZ081-082-084-085.
     FREEZE WARNING FROM 1 AM TO 8 AM PDT WEDNESDAY FOR
     CAZ082-084-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM TO 11 PM PDT
     WEDNESDAY FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 PM THIS AFTERNOON
     TO 11 AM PDT THURSDAY FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11 PM
     PDT WEDNESDAY FOR PZZ356.
     HAZARDOUS SEAS WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
     EVENING FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM THIS AFTERNOON
     TO 11 AM PDT THURSDAY FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11 AM
     PDT THURSDAY FOR PZZ376.

$$





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