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 262128
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
228 PM PDT THU MAR 26 2015

.SHORT TERM...HIGH PRESSURE IS FIRMLY IN CONTROL OF OUR WEATHER
THIS AFTERNOON. SKIES ARE CLEAR INLAND FROM THE IMMEDIATE COASTAL
STRIP, AND TEMPERATURES ARE WARMING AS EXPECTED. THERE IS SOME LOW
LEVEL INSTABILITY OVER THE MOUNTAINS WHICH MAY RESULT IN BRIEF
CUMULUS BUILDUPS LATER THIS AFTERNOON, BUT LITTLE ELSE IS
EXPECTED. PERSISTENT STRATUS ALONG THE COAST THIS AFTERNOON WILL
SURGE INLAND TONIGHT, LIKELY REACHING INTO THE WESTERN UMPQUA
AGAIN. 24 HOUR TRENDS ELSEWHERE SHOW MUCH WARMER TEMPERATURES,
BUT ALSO HIGHER MOISTURE, WHICH WILL YIELD HIGHER CROSS-OVER
TEMPERATURES AND INCREASE THE POTENTIAL FOR FOG. THE POINT BEING:
WE COULD SEE PATCHY FOG AND STRATUS DEVELOP AGAIN TOMORROW MORNING
IN THE SAME PLACES WE HAD IT THIS MORNING, AND THAT HAS BEEN
ADDED.

WE WILL SEE INCREASING HIGH CLOUD FRIDAY OVER MOST OF OUR AREA AS
A WEAK FRONT APPROACHES THE COAST. THIS WILL RESULT IN A COOL DOWN
COMPARED TO TODAY, BUT IT WILL STILL BE WARMER THAN NORMAL IN MOST
LOCATIONS. INSTABILITY WILL BUILD AGAIN OVER THE MOUNTAINS, AND
THE DIFFERENCE TOMORROW WILL BE A BIT MORE MOISTURE TO WORK WITH.
THUS THERE IS A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS IN
THE AFTERNOON OVER THE CASCADES AS WELL AS THE EAST SIDE LATE
AFTERNOON AND EVENING. LIGHT RAIN IS EXPECTED TO REACH THE COAST
BY LATE AFTERNOON AND THEN SPREAD INLAND TO THE CASCADES THROUGH
THE EVENING. THIS IS NOT A PARTICULARLY WET OR DYNAMIC SYSTEM, SO
THE CONFIDENCE IN RAIN IN THE ROGUE VALLEY IS LOW, BUT SOME RAIN
IS EXPECTED FRIDAY NIGHT.

THE FRONT SWEEPS QUICKLY INLAND FRIDAY NIGHT AND EARLY SATURDAY.
PRECIPITATION CHANCES ARE MUCH LOWER EAST OF THE CASCADES, BUT WE
DO EXPECT AT LEAST A BRIEF PERIOD OF GUSTY WINDS AS THE FRONT GOES
THROUGH. THE BALANCE OF THE WEEKEND (SATURDAY AFTERNOON THROUGH
SUNDAY) LOOKS DRY AND FAIRLY MILD AREA-WIDE. -WRIGHT

.LONG TERM...MONDAY THROUGH THURSDAY...THE EXTENDED FORECAST
FEATURES GENERALLY LOWERING HEIGHTS AND COOLING CONDITIONS AS A
SERIES OF WEAK SHORTWAVE TROUGHS HELP MAINTAIN SLIGHT TROUGHING OR
ZONAL FLOW. THERE IS ABOVE AVERAGE DISAGREEMENT AMONGST GFS
ENSEMBLE MEMBERS BY WEDNESDAY...SO CONFIDENCE IN THE DETAILS OF
THE EXTENDED FORECAST IS LOW.

DRY AND BREEZY CONDITIONS ARE EXPECTED MOST PLACES ON MONDAY AHEAD
OF A COLD FRONT. MONDAY NIGHT INTO TUESDAY MORNING LIGHT RAIN COULD
AFFECT MOSTLY THE COAST...UMPQUA BASIN...AND CASCADES NORTH OF
HIGHWAY 140.  ANOTHER UPPER TROUGH MOVES THROUGH TUESDAY
NIGHT...WITH LITTLE TO NO PRECIPITATION...AND REINFORCES RELATIVELY
COOL TEMPERATURES WHICH SHOULD BE AT OR JUST BELOW NORMAL. BY
WEDNESDAY INTO THURSDAY...THE OPERATIONAL GFS AND EC DIFFER
SIGNIFICANTLY ON THE EXPECTED 500MB PATTERN BUT NEITHER ONE SUGGESTS
A BIG WEATHER-MAKER OR RIDGING...SO WEAK TRANSIENT TROUGHS IS THE
GENERAL CONSENSUS.

PERHAPS THE SINGLE BIGGEST IMPACT IN THE EXTENDED FORECAST COULD BE
NEAR-FREEZING OR FREEZING TEMPERATURES IN WEST SIDE VALLEYS DURING
THE WEDNESDAY/THURSDAY TIMEFRAME. ENSEMBLE MOS GUIDANCE ALREADY
SHOWS LOW POTENTIAL FOR MEDFORD TO BE 35 DEGREES. IF CLEAR SKIES DO
OCCUR AFTER ONE OF THESE UPCOMING TROUGHS...FREEZING TEMPERATURES
WILL BE A GOOD POSSIBILITY IN SUCH A COOL AIR MASS. SK

&&

.AVIATION...FOR THE 26/18Z TAF CYCLE...CONTINUED ONSHORE FLOW
WILL MAINTAIN IFR AND LIFR CONDITIONS AT THE COAST THROUGH FRIDAY
MORNING...WITH PERHAPS A BRIEF BREAK TO VFR CONDITIONS LATE THIS
AFTERNOON. IFR CONDITIONS ARE ALSO EXPECTED TONIGHT IN THE UMPQUA
BASIN AROUND ROSEBURG WHERE HUMIDITIES ARE TRENDING HIGHER THAN
YESTERDAY AND ALL GUIDANCE POINTS TO LOW CEILINGS AND POOR
VISIBILITY BEFORE MIDNIGHT. ELSEWHERE...HUMIDITIES ARE TRENDING
LOWER TODAY...AND ONLY PATCHY FOG IS EXPECTED IN WEST SIDE VALLEYS
TONIGHT. EAST OF THE CASCADES AND IN NORTHERN CALIFORNIA...MAINLY
VFR CONDITIONS ARE EXPECTED THROUGH FRIDAY MORNING.

ON FRIDAY AFTERNOON ENOUGH ENERGY FROM AN APPROACHING
TROUGH...COMBINED WITH SOME WARM SURFACE TEMPERATURES AND
INSTABILITY...COULD PRODUCE ISOLATED THUNDERSTORMS OVER THE
CASCADES...MAINLY ALONG AND NORTH OF CRATER LAKE. SK

&&

.MARINE...UPDATED 2 PM PDT THURSDAY 26 MAR 2015...A WEAK THERMAL
TROUGH HAS INCREASED NORTH WINDS OVER THE SOUTHERN OUTER WATERS, BUT
ARE REMAINING BELOW SMALL CRAFT CRITERIA. A COLD FRONT WILL MOVE
THROUGH THE WATERS FRIDAY AFTERNOON...SHIFTING WINDS TO SOUTH AHEAD
OF THE FRONT, THEN VEERING WEST TO NORTHWEST AFTER THE FRONT MOVES
THROUGH. BEHIND THE FRONT...HIGH PRESSURE BUILDS IN FRIDAY NIGHT
INTO SATURDAY INCREASING NORTHERLY WINDS BY SATURDAY
AFTERNOON...POSSIBLY REACHING LOW END SMALL CRAFT CONDITIONS. THE
STRONGEST WINDS WILL BE SOUTH OF GOLD BEACH AND BEYOND 10 NM FROM
SHORE. WINDS WILL DIMINISH SATURDAY NIGHT INTO SUNDAY.
HOWEVER...MODELS HAVE BEEN CONSISTENT SHOWING A BUILDING WEST SWELL
MOVING INTO THE WATERS SUNDAY THAT MAY PRODUCE WIDESPREAD LOW END
SMALL CRAFT CONDITIONS. A HIGH AND STEEP WEST SWELL MAY CONTINUE
THROUGH EARLY NEXT WEEK. MND

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$



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