Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 291205
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
405 AM PST THU JAN 29 2015

.DISCUSSION...
WHILE INFRARED SATELLITE IMAGERY INDICATES PLENTY OF CLOUD COVER
OVER THE FORECAST AREA THIS MORNING, THIS CLOUD COVER IS MOSTLY
HIGH AND SEMI-TRANSPARENT. FOG COVERAGE AND DENSITY HAS BEEN MUTED
SOME, HOWEVER, BY THIS HIGH CLOUD COVER, AND SUSPECT THIS MUTING
WILL BE APPARENT THROUGH THIS MORNING. NORMALLY, WITH HIGH CLOUDS
LIMITING COOLING OVERNIGHT, WE WOULD EXPECT WARMER HIGH
TEMPERATURES THIS AFTERNOON. THIS WILL LIKELY OCCUR ACROSS MAINLY
THE WEST SIDE TODAY AS CLOUD COVER SLOWLY GIVES WAY TO
INCREASINGLY LESS FILTERED SUN FROM WEST TO EAST ON THE WEST
SIDE. THIS AFTERNOON TEMPERATURE INCREASE IS STILL LIKELY TO BE
WITHIN 5 DEGREES FAHRENHEIT OF YESTERDAY AFTERNOON`S HIGHS.

THROUGH SATURDAY, THE ONLY APPRECIABLE CHANGE ACROSS THE AREA
WILL BE INCREASING NORTH AND EAST WINDS AT MID TO UPPER ELEVATIONS
THAT WILL BRING WARMER CONDITIONS TO THE SURFACE AT SOME
LOCATIONS. WE SUSPECT THAT BROOKINGS WILL BE BETWEEN 65F AND 70F
SATURDAY AFTERNOON AS A RESULT OF THIS SLIGHT SHIFT IN THE
PRESSURE AND WIND PATTERN.

THE FRONTAL SYSTEM WE`VE BEEN WATCHING FOR SUNDAY INTO MONDAY HAS
TRENDED WEAKER IN THE NUMERICAL MODEL GUIDANCE, SO SOME
ADJUSTMENTS HAVE BEEN MADE TO TREND WEAKER WITH THAT SYSTEM.
TEMPERATURES LOOK WARMER WITH IT THAN THEY DID PREVIOUSLY, AS
WELL. ASIDE FROM IT POSSIBLY BRINGING A LITTLE PRECIPITATION, WE
STILL ANTICIPATE IT WILL AT LEAST TEMPORARILY WEAKEN VALLEY
INVERSIONS.

TUESDAY THROUGH EARLY THURSDAY THERE WILL BE THE POSSIBILITY OF
SOME SHOWERS SKIRTING THE COASTAL WATERS AND, POSSIBLY, THE WEST
SIDE. TEMPERATURES WILL AGAIN WARM ALOFT AS WE END UP IN THE
SOUTHERLY FLOW BETWEEN STRONG HIGH PRESSURE CENTERED OVER THE
INTERIOR WESTERN UNITED STATES AND A DEEPENING TROUGH IN THE
EAST-CENTRAL PACIFIC.

THURSDAY INTO FRIDAY OF NEXT WEEK WE EXPECT THE FIRST IN A SERIES
OF WET AND WARMER THAN NORMAL FRONTAL SYSTEMS TO PUSH INTO THE
AREA. GFS ENSEMBLE MODEL INTEGRATED VAPOR TRANSPORT INDICATES A
MODERATE POSSIBILITY OF A SIGNIFICANTLY WET ATMOSPHERIC RIVER
EVENT ON OR ABOUT FEBRUARY 7TH-8TH. LONGER RANGE ENSEMBLES
INDICATE A WARMER AND WETTER THAN NORMAL PERIOD EXTENDING FROM
THIS LATE WEEK 2 EVENT THROUGH WEEK 3. UNTIL THEN, WE WAIT,
MOSTLY MILD AND DRY. BTL

&&

.CLIMATE...
AS FOLLOW-UP TO YESTERDAY MORNING`S CLIMATE DISCUSSION, WHICH
NOTED THAT THE JANUARIES OF 1983, 1984, AND 1985 WERE
COLLECTIVELY DRIER THAN THE COMBINED JANUARIES OF 2013, 2014, AND
2015 AT THE MEDFORD AIRPORT, WE HAVE SOME RELATED TEMPERATURE AND
SNOWFALL STATISTICS TO RELAY. 1983, 1984, AND 1985 WERE NOT IN THE
TOP 30 WARMEST JANUARIES ON RECORD FOR MEDFORD, WHEREAS JANUARY
2015 IS LIKELY TO RANK 12TH WARMEST. ADDITIONALLY, SNOW DEPTH AT
CRATER LAKE NATIONAL PARK HEADQUARTERS IN THOSE YEARS IN THE 1980S
WAS BETWEEN 90 AND 105 INCHES, COMPARED TO THIS YEAR`S 28-36 INCH
VALUES, JANUARY 2014`S 4-32 INCH DEPTHS, AND 2013`S NEAR 80 INCH
DEPTH. THUS, THE DIFFERENCE BETWEEN THIS JANUARY AND THOSE DRY
JANUARIES OF THE 1980S HAS BEEN AVERAGE TEMPERATURE AND ITS
RESULTANT EFFECTS ON SNOW PACK. OF COURSE, CONDITIONS FROM OCTOBER
THROUGH DECEMBER ARE ALSO CRITICAL ELEMENTS FOR JANUARY SNOW
PACK. BTL

&&

.AVIATION...BASED ON THE 29/12Z TAF CYCLE...IFR CIGS/VIS ARE IN THE
INLAND WEST SIDE VALLEYS. THESE AREA WILL SEE CONDITIONS LIFT TO MFR
LATE THIS MORNING.

THE REMAINDER OF THE AREA WILL REMAIN VFR WITH MID LEVEL CLOUDS
BASED AROUND 12K FT MSL DISSIPATING AFTER 18Z THIS MORNING.
/SVEN

&&

.MARINE...UPDATED AT 345 AM WEDNESDAY 29 JANUARY 2015...A TROUGH
ALONG THE COAST WILL MOVE INTO NORTHERN OREGON ON TODAY WITH HIGH
PRESSURE BUILDING OFFSHORE. THIS WILL LEAD TO MODERATE NORTHERLY
WINDS THAT WILL INCREASE INTO FRIDAY AFTERNOON. THE INCREASED CHOP
WILL BE HIGHEST IN THE OUTER WATERS SOUTH OF CAPE BLANCO. SMALL
CRAFT CONDITIONS DEVELOP THERE THIS AFTERNOON AND CONTINUE INTO
FRIDAY NIGHT. THE HIGH PRESSURE WILL WEAKEN SATURDAY NIGHT AS THE
NEXT FRONT APPROACHES. THE FRONT WILL PRODUCE WEAK SOUTH WIND AND
MODERATE WEST SWELL WITH LIGHT TO MODERATE RAIN ON SUNDAY. IT WILL
THEN MOVE ONSHORE LATE SUNDAY NIGHT WITH A CHANCE OF SHOWERS INTO
MONDAY AS THE MODERATE WEST SWELL BUILDS TO A PEAK.
/SVEN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 1 PM PST SATURDAY FOR
     ORZ023-024-026-616-620-622.
     AIR STAGNATION ADVISORY UNTIL 1 PM PST SATURDAY FOR
     ORZ029>031-623>625.

CA...NONE.

PACIFIC COASTAL WATERS...
- SMALL CRAFT ADVISORY FOR WINDS FROM 4 PM THIS AFTERNOON TO 10
  PM PST FRIDAY FOR PZZ376.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 4 PM THIS
  AFTERNOON TO 3 AM PST SATURDAY FOR PZZ370-376.

$$

BTL/SVEN



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