Area Forecast Discussion
Issued by NWS Medford, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KMFR 231934
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1235 PM PDT THU OCT 23 2014

.DISCUSSION...THE COLD FRONT HAS MOVED ONSHORE AND EXTENDS FROM
CENTRAL DOUGLAS COUNTY SW TO THE ILLINOIS VALLEY. SOUTH TO NORTH
PRESSURE GRADIENT HAS DECREASES AND WILL BE CANCELING THE WIND
ADVISORY FOR THE SHASTA VALLEY. RAINFALL AT THE COAST RANGE FROM 2
TO 4 INCHES WITH THE HIGHEST AMOUNT SO FAR AROUND 5 INCHES AT RED
MOUND AND 4.5 INCHES NEAR CAPE FERRELO. THE REST OF TODAY WILL BE
CLOUDY WITH RAIN SHOWERS ON AND OFF...FOR SW OREGON UNTIL EARLY
AFTERNOON BUT SHOWERS CONTINUING ALL DAY FOR EAST OF THE CASCADES
AS THE COLD FRONT CONTINUES TO MARCH EAST. THE FRONTAL BOUNDARY IS
EXPECTED TO PUSH EAST AND SOUTH OF OUR FORECAST AREA BY THIS
EVENING. HOWEVER THERE WILL STILL BE PLENTY OF LOW LEVEL MOISTURE.
WITH THE FRONT STALLING JUST EAST OF OUR FORECAST AREA..WE SHOULD
CONTINUE TO SEE SHOWERS INTO THE CASCADES AND SISKIYOUS MTNS, AS
WELL AS MOST OF SISKIYOU COUNTY.

NEXT LOW PRESSURE IS ON TRACK TO MOVE INTO THE COASTAL WATERS LATE
FRIDAY NIGHT AND SATURDAY MORNING. THE TRACK OF THIS LOW IS
IMPORTANT AND WILL DETERMINE WHETHER OR NOT WE WILL SEE VERY
STRONG WINDS IN THE COASTAL WATERS. CONFIDENCE IS HIGH THAT WE
WILL SEE AT LEAST ADVISORY LEVEL WINDS AT THE HIGHER ELEVATION AND
IN THE SHASTA VALLEY. /FB

&&

.AVIATION...BASED ON THE 23/18Z TAF CYCLE...
A FRONTAL BOUNDARY IS CURRENTLY STALLED OVER THE FORECAST AREA,
DRAPED ALONG AND NEAR THE MARBLE MOUNTAINS ACROSS SOUTHERN OREGON
CASCADES. THIS STALLED FRONT IS CAUSING TOTAL MOUNTAIN OBSCURATIONS
ALONG AND NEAR THIS AREAS, AND PARTIAL MOUNTAIN OBSCURATIONS
ELSEWHERE. IN THE VALLEYS IN THIS SAME AREA CONDITIONS ARE A MIX OF
VFR AND IFR WITH GENERALLY LIGHT RAIN, BUT EMBEDDED MODERATE TO
HEAVY SHOWERS. THIS BOUNDARY WILL CONTINUE TO DRIFT EASTWARD THIS
AFTERNOON, AND WILL EVENTUALLY REDEVELOP BACK NORTHWARD AS A WARM
FRONT THIS EVENING THROUGH FRIDAY. THIS MEANS THAT CURRENT REDUCED
CIGS/VIS WITH THE FRONT WILL TRANSLATE EAST TOWARD KLMT THIS
AFTERNOON AND EVENING, WITH SOME IMPROVEMENT AT KMFR BEFORE ALL TAF
LOCATIONS DETERIORATE TO MVFR TO IFR TONIGHT INTO FRIDAY MORNING.
BTL

&&

.MARINE...UPDATED 1200 PM PDT WED 22 OCT 2014...
WINDS HAVE WEAKENED THIS MORNING...BUT SEAS WILL REMAIN ELEVATED AND
HAZARDOUS TO SMALL CRAFT TODAY DUE TO MODERATE WEST SWELL. THERE
WILL BE A LULL IN BOTH WINDS AND SEAS THROUGH MUCH OF FRIDAY. MODELS
ARE COMING INTO BETTER AGREEMENT WITH THE STRONG TO VERY STRONG
FRIDAY NIGHT/SATURDAY SYSTEM. ALL SHOW A DEEPENING SURFACE LOW
MOVING NORTHWARD ALONG THE 130W BENCHMARK FRIDAY NIGHT THEN
NORTHEASTWARD INSIDE 130W SATURDAY. VERY STRONG SOUTH WINDS WILL
DEVELOP AHEAD OF THIS SYSTEM FRIDAY NIGHT WITH HIGH END GALE
CONDITIONS AND POSSIBLE STORM FORCE GUSTS SATURDAY, ALONG WITH 20
FOOT SEAS OR GREATER. STAY TUNED FOR FURTHER UPDATES REGARDING THIS
POTENTIAL BIG WIND AND SEAS MAKER. CONDITIONS WILL IMPROVE THROUGH
THE REMAINDER OF THE WEEKEND, AND AFTER ANOTHER BRIEF ROUND OF
CALMER WINDS AND SEAS, ANOTHER FRONT IS EXPECTED EARLY NEXT WEEK.
BTL/BPN

&&

.PREV DISCUSSION... /ISSUED 100 AM PDT THU OCT 23 2014/

DISCUSSION...23/00Z NAM/GFS IN.

A FRONT IS NOW PUSHING THROUGH THE MEDFORD CWA. LIGHT TO MODERATE
RAIN IS OCCURRING WITH THE WEAKENING FRONTAL BOUNDARY.
MEANWHILE...BEHIND THE FRONT...THERE IS LOTS OF SHOWER ACTIVITY. A
FEW THUNDERSTORMS MAY MOVE INTO THE COASTAL WATERS LATER THIS
MORNING.

THE LONG WAVE TROUGH REMAINS OFFSHORE WITH STRONG SOUTHWEST FLOW
ALOFT. SHORT WAVES EJECTING FROM THE TROUGH WILL BRING ROUNDS OF
SHOWERS TO THE AREA THURSDAY...BUT MOST OF THE ENERGY IN THE
SHORT WAVES WILL BE DIRECTED TO THE NORTH OF THE CWA. THE SURFACE
FRONT WILL STALL OVER THE SOUTHERN AND EASTERN PORTIONS OF THE
MEDFORD CWA THURSDAY.

RAINFALL AMOUNTS FOR THIS CURRENT STORM SYSTEM HAVE BEEN ADJUSTED
DOWN SOME THROUGH THURSDAY EVENING FOR AREAS INLAND FROM THE
COAST...BUT HAVE LEFT 3 TO 5 INCH AMOUNTS INTACT FOR THE COAST
AND COASTAL MOUNTAIN AREAS...WITH MOST OF THE RAIN THERE EXPECTED
THROUGH 5AM PDT THURSDAY. OTHER AMOUNTS WILL BE 1.3 TO 2.3 INCHES
IN DOUGLAS COUNTY...1-3 INCHES IN JOSEPHINE COUNTY, AND 0.50" TO
1.5" IN JACKSON COUNTY. 0.10" TO 0.50" INCHES WILL FALL IN THE
EAST SIDE VALLEYS...DECREASING FROM WEST TO EAST.

THE OFFSHORE UPPER TROUGH WILL DEEPEN AND START TO SHEAR FRIDAY.
IN RESPONSE A LONG WAVE RIDGE WILL PUMP UP OVER THE INTERMOUNTAIN
STATES...AND THIS WILL LIFT THE FRONT BACK NORTH AS A WARM FRONT
FRIDAY. EXPECT WIDESPREAD LIGHT PRECIPITATION WITH THE FRONT AS IT
MOVES THROUGH THE AREA.

THERE WILL BE A BREAK IN THE PRECIPITATION FRIDAY NIGHT AS THE
WARM FRONT CLEARS TO THE NORTH. CONDITIONS WILL THEN GET QUITE
INTERESTING OFFSHORE AS A LOW WINDS UP UNDER THE SOUTHERN PORTION
OF THE SHEARING TROUGH. THIS LOW WILL DEEPEN AS IT TRACKS NORTH
NORTHEAST INSIDE 130W. THE TRACK AND DEEPENING OF THE LOW WILL BE
CRITICAL AS FAR AS HIGH WINDS AT THE COAST ARE CONCERNED. AT THIS
TIME IT LOOKS LIKE THE LOW WILL TRACK FAR ENOUGH OFFSHORE AND WILL
NOT BE STRONG ENOUGH...AROUND 990 MB...FOR A WARNING ALONG THE
COAST...WHERE THERE WILL BE A SIGNIFICANT OFFSHORE COMPONENT TO
THE WIND. HOWEVER...STORM FORCE WINDS MAY DEVELOP OVER THE OUTER
COASTAL WATERS. WINDS ALOFT COMBINED WITH STRONG SOUTHERLY GRADIENTS
MAY PROVIDE ENOUGH SUPPORT FOR HIGH WINDS IN THE SHASTA VALLEY AND
EAST OF THE CASCADES AROUND SUMMER LAKE.

WIDESPREAD MODERATE PRECIPITATION WILL MOVE ONSHORE SATURDAY
AFTERNOON AND EVENING. SATURDAY NIGHT WILL BE QUITE WET FROM THE
CASCADES WEST WITH LIGHTER PRECIPITATION EAST OF THE CASCADES.

THE SOUTHERN BRANCH SYSTEM WILL MOVE ONSHORE TO THE NORTH
SATURDAY NIGHT AND WHAT`S LEFT OF THE LONG WAVE TROUGH WILL MOVE
ONSHORE SATURDAY NIGHT AND THROUGH THE MEDFORD CWA SUNDAY. EXPECT
SHOWERS TO CONTINUE THROUGH SUNDAY...BUT THEY WILL BE DIMINISHING
WITH TIME.

EXTENDED DISCUSSION FROM THE WEDNESDAY AFTERNOON AFD...MONDAY
THROUGH WEDNESDAY. NUMERICAL MODELS INDICATE ABOUT TWO FRONTAL
SYSTEMS NEXT WEEK WITH MONDAY BEING DRY FOR MOST LOCATIONS AWAY
FROM THE COAST. TIMING OF THE FRONTS NEXT WEEK IS A BIT IN
QUESTION...BUT SUFFICE IT TO SAY THAT THE WEATHER PATTERN DOES
LOOK TO REMAIN ACTIVE WITH A FRONTAL SYSTEM EVERY 2-3 DAYS. THE
OVERALL PARENT TROUGH OVER THE AREA SINKS SOUTHWARD NEXT WEEK...SO
EXPECT SNOW LEVELS WILL LIKELY COME DOWN TO THE 5000 TO 7000 FOOT
RANGE. BTL

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY UNTIL 11 AM PDT THIS MORNING FOR ORZ031.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS
UNTIL 8 AM PDT FRIDAY FOR PZZ350-356-370-376.

$$

FJB/BTL/BPN









USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.