Hazardous Seas Warning 13, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
243 AM PST TUE MAR 4 2014

.SHORT TERM...A BAND OF SHOWERS THIS MORNING IS SHIFTING SOUTHEAST
OF THE AREA. THIS AREA OF SHOWERS BROUGHT AROUND A QUARTER TO A
HALF AN INCH OF RAIN TO MANY AREAS IN NORTHERN CALIFORNIA AND FROM
THE CASCADES EASTWARDS. BEHIND THIS BAND, WEAK SHORTWAVE RIDGING
WILL BUILDING IN PLACE. HOWEVER MOISTURE IN SOUTHWEST FLOW AND A
WEAK SHORTWAVE MOVING INLAND TODAY IS EXPECTED TO BRING SOME
ISOLATED TO SCATTERED LIGHT SHOWERS, WITH THE BEST CHANCES ALONG
THE COAST, INTO THE UMPQUA AND OVER THE SOUTHERN OREGON CASCADES.

THEN TONIGHT INTO WEDNESDAY A WARM FRONT WILL APPROACH THE COAST
AND SPREAD LIGHT TO MODERATE RAIN INLAND. MODELS HAVE TRENDED
SLOWER WITH THE FRONT BRING RAIN INTO THE AREA TONIGHT AND MODELS
HAVE ALSO BACKED OFF ON PRECIPITATION AMOUNTS. SO HAVE ADJUSTED
THE PRECIPITATION AMOUNTS DOWNWARD FOR THIS PERIOD. ALSO LOWERED
THE CHANCE FOR PRECIPITATION ACROSS THE AREA TUESDAY EVENING,
EXCEPT ALONG THE COAST AND DECREASED THE CHANCE FOR PRECIPITATION
EAST OF THE CASCADES TUESDAY EVENING THROUGH TUESDAY NIGHT.

MODELS THEN SHOW A STRONGER FRONTAL SYSTEM WILL APPROACH THE COAST
FROM THE WEST WEDNESDAY AFTERNOON AND MOVE INLAND WEDNESDAY
EVENING AND NIGHT AS THE SURFACE LOW TRACKS NORTHEAST TOWARDS THE
WASHINGTON COAST. MODELS CONTINUE TO SHOW THAT THIS SECOND FRONT
WILL BRING MODERATE TO HEAVY PRECIPITATION TO AREAS FROM THE
CASCADES WEST WITH LIGHT TO MODERATE PRECIPITATION SPREADING INTO
AREAS EAST OF THE CASCADES.

SNOW LEVELS AROUND 5500 TO 6500 FEET THIS MORNING ARE EXPECTED TO
RISE THROUGH THE DAY AND INTO TONIGHT TO 7000 TO 7500 FEET THEN
8000 FEET OR HIGHER WEDNESDAY. BEHIND THE FRONT EXPECT SNOW LEVELS
TO LOWER TO 5000 TO 6000 FEET  THURSDAY MORNING. DUE TO THE HIGH
SNOW LEVELS, EXPECT MOST THE PRECIPITATION TONIGHT THROUGH WEDNESDAY
NIGHT TO FALL AS RAIN. GREATEST RAINFALL AMOUNTS ARE EXPECTED
ALONG THE COAST AND INTO THE COASTAL MOUNTAINS WITH 1 TO 2.5
INCHES OF RAIN EXPECTED WEDNESDAY AFTERNOON THROUGH WEDNESDAY
NIGHT.

IN ADDITION TO PRECIPITATION, THE INCOMING FRONTS WILL ALSO BRING
GUSTY WINDS TO THE AREA. SOUTH WINDS ARE EXPECTED TO INCREASE
THIS EVENING AND TONIGHT ALONG THE COAST WITH BREEZY AND GUSTY
SOUTH WINDS DEVELOPING. ALSO INLAND AREAS WILL SEE SOME GUSTY
SOUTH TO SOUTHWEST WINDS OVER THE MOUNTAINS AND IN THE SHASTA
VALLEY AND SUMMER LAKE AREAS.

WINDS WILL INCREASE FURTHER WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT AS A STRONG JET ALOFT MOVES OVER THE AREA AHEAD OF THE
SECOND FRONT. MODELS INDICATE 700 MB SOUTHWEST WINDS WILL INCREASE
TO 55 TO 70 KT WEDNESDAY EVENING AND WEDNESDAY NIGHT AS THE FRONT
MOVES INLAND...THEN WIND ALOFT WILL GRADUALLY DECREASE ON
THURSDAY. THESE STRONG WINDS ALOFT COMBINED WITH THE FRONT ARE
EXPECTED TO BRING VERY GUSTY WINDS TO THE COAST, INTO THE
MOUNTAINS, AND FOR THE SHASTA VALLEY AND SUMMER LAKE AREAS. BEST
POTENTIAL FOR HIGH WINDS IS IN THE SUMMER LAKE AREA AND OVER THE
WARNER MOUNTAINS. SO HAVE ADDED A HIGH WIND WATCH FOR THESE
LOCATIONS. MODELS AND GUIDANCE INDICATE WINDS IN THE SHASTA VALLEY
WILL BE GUSTY BUT MAY NOT REACH HIGH WIND CRITERIA. A WIND
ADVISORY MAY BE NEEDED FOR THE SHASTA VALLEY THOUGH WEDNESDAY
AFTERNOON AND WEDNESDAY NIGHT. ALONG THE COAST, EXPECT THE
STRONGEST WINDS TO OCCUR WEDNESDAY EVENING AS A 925 MB SOUTH JET
OF 55 TO 65 KT MOVES TOWARDS THE COAST. THE 925 MB JET DECREASE
OVERNIGHT TO 50 TO 60 KT BUT TAKES ON A MORE SOUTHWESTERLY
COMPONENT. SO HAVE KEPT GUSTY WINDS IN PLACE FOR COASTAL AREAS
WEDNESDAY EVENING AND NIGHT BUT HAVE KEPT WINDS BELOW HIGH WIND
CRITERIA.

AS A SHORTWAVE UPPER TROUGH PUSHES INLAND ON THURSDAY EXPECT A
MIX OF RAIN AND SNOW SHOWERS IN THE MOUNTAINS, MAINLY ABOVE 5000
FEET, WITH RAIN SHOWERS IN LOWER ELEVATIONS. THE NAM AND GFS ALSO
SHOW COLD AIR ALOFT AND INSTABILITY MOVING INTO THE COASTAL WATERS
WEDNESDAY NIGHT THEN SPREADING INTO THE, COAST AND WESTERN PORTION
OF THE UMPQUA VALLEY ON THURSDAY. SO HAVE ADDED A SLIGHT CHANCE
FOR THUNDERSTORMS TO THE FORECAST ON THURSDAY. ADDITIONALLY,  WEAK
INSTABILITY COMBINED WITH SHOWERS MAY BRING  GUSTY WINDS DOWN TO
THE SURFACE AT TIMES FOR MOST  AREAS THURSDAY AFTERNOON AND
EVENING.

BY FRIDAY, THERE IS GOOD AGREEMENT WITH MODELS SHOWING A DRYING
TREND WITH DECREASED WINDS AS  AN UPPER RIDGE DEVELOPS OVER THE
AREA. SO HAVE LOWERED THE  CHANCE FOR PRECIPITATION DURING THIS
PERIOD.

THE DRY WEATHER WILL LIKELY BE BRIEF AS MODELS INDICATE ANOTHER
FRONTAL SYSTEM MOVING INTO THE AREA ON THE WEEKEND.

&&

.AVIATION...BASED ON THE 04/06Z TAF CYCLE...
TONIGHT THROUGH TUESDAY MORNING SHOWERS WILL LINGER PRIMARILY FROM
THE OREGON CASCADES NORTHWESTWARD AND ACROSS NORTHEAST CALIFORNIA.
THIS WILL LEAD TO IFR REMAINING ALONG AND NEAR THE COAST THROUGH THE
PERIOD AND MVFR FOR MOST OTHER VALLEY LOCATIONS. MOUNTAINOUS TERRAIN
WILL BE PARTIALLY OBSCURED AS WEST-SOUTHWEST UPSLOPE FLOW CONTINUES
AND BECOMES MORE SOUTHWEST. ON TUESDAY EXPECT IMPROVEMENT TO VFR
FROM MID-MORNING TO EARLY AFTERNOON, LAST ALONG THE COAST AND IN THE
UMPQUA BASIN, AND MOUNTAIN OBSCURATIONS WILL BECOME LIMITED TO THE
COAST RANGE AND UMPQUA DIVIDE NORTHWARD. THE NEXT FRONTAL SYSTEM
WILL BEGIN TO RESULT IN LOWERING CEILINGS AND SHOWERS BEGINNING
AROUND 06Z AND WILL BRING WINDY CONDITIONS AND THE POSSIBILITY OF
MOUNTAIN WAVE TURBULENCE AND LOW LEVEL WIND SHEAR TUESDAY NIGHT. BTL

&&

.MARINE...THE SEAS WILL TRANSITION FROM WIND DRIVEN TO LONG PERIOD
SWELL DOMINATED THIS AFTERNOON INTO TUESDAY. ANOTHER STRONG LOW
PRESSURE SYSTEM AND COLD FRONT WILL BRING STRONG WINDS TUESDAY NIGHT
INTO WEDNESDAY NIGHT. WHILE SOUTHWEST WIND DIRECTIONS ARE NOT AS
FAVORABLE, THERE IS A POSSIBILITY OF GALES AND HEAVY STEEP SEAS
TUESDAY NIGHT THROUGH WEDNESDAY MORNING. ANOTHER PERIOD OF GALES
IS POSSIBLE WEDNESDAY NIGHT INTO THURSDAY MORNING. /FB

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     MORNING FOR ORZ030-031.

CA...HIGH WIND WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
     MORNING FOR CAZ085.

PACIFIC COASTAL WATERS...GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 10 PM THIS EVENING TO 7 AM
     PST WEDNESDAY FOR PZZ350-356-370.
     HAZARDOUS SEAS WARNING FROM 10 PM THIS EVENING TO 10 AM PST
     WEDNESDAY FOR PZZ350-356-370-376.
     GALE WARNING FROM 1 AM TO 7 AM PST WEDNESDAY FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST
     WEDNESDAY FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 7 PM THIS EVENING TO 7 AM
     PST WEDNESDAY FOR PZZ376.

CC