Hazardous Seas Warning 2, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
256 PM PST MON JAN 4 2016

.SHORT TERM...

A MINI SHORTWAVE WILL EJECT AHEAD OF A CUTOFF LOW AND MOVE OVER
THE REGION LATER THIS EVENING INTO TUESDAY MORNING. AN OCCLUDED
FRONT WILL FOLLOW THIS SHORT WAVE INTO THE CWA TUESDAY MORNING.
ANOTHER LARGER SHORT WAVE WILL FOLLOW IT DURING TUESDAY AFTERNOON
AND EVENING. EVENTUALLY A CUTOFF LOW WILL PROGRESS OVER THE CWA
THURSDAY. PRIMARY FOCUS OF THE SHORT TERM FORECAST PERIOD WAS FOR
THE SNOW IN SISKIYOU COUNTY AT HIGHER ELEVATIONS.

ALL THE MODELS ARE HIGHLIGHTING A PRECIPITATION MAXIMA OF ROUGHLY
.5 INCHES FROM 6Z TO 12Z TUESDAY. EVEN THE HUMBLE SREF. WITH A
FORECAST 10-13:1 SNOW RATIO, WE SHOULD SEE 4 TO 7 INCHES NEAR THE
MT SHASTA REGION ABOVE 3500 FEET. PRIMARY CONCERN WITH THIS
SNOWFALL WILL BE THAT RATES MAY APPROACH 1 INCH PER HOUR.

WE ALSO BUMPED UP THE WINDS AND GUSTS IN THE SHASTA VALLEY FROM
10 PM MONDAY UNTIL 10 AM TUESDAY. LOOKING AT THE MHS BUFR
SOUNDING, THE 850 TO 750 MB WINDS AHEAD OF THE OCCLUDED FRONT ARE
AROUND 40 TO 50 KTS. SO EXPECTING SOME OF THESE GUSTS TO HIT AREAS
SOUTH OF GAZELLE AND NORTH OF WEED. TYPICAL SHASTA VALLEY WIND
ADVISORY.

ALTHOUGH IT IS NOT MENTIONED IN OUR WINTER WEATHER PRODUCT AT THE
MOMENT, MORE SNOW IS PROBABLE WHEN THE CUTOFF LOW MOVES OVER LAND
THURSDAY. GOOD 40-45 KT 700MB FLOW SHOULD PUSH MOIST AIR UP
AGAINST THE TRINITY MOUNTAINS. RIGHT NOW WITH 3000 FOOT SNOW
LEVELS AND SNOW RATIOS AROUND 10:1 WERE EXPECTING 4-7 INCHES FROM
4AM UNTIL 10 PM WEDNESDAY

-SMITH

.EXTENDED...(THURSDAY THROUGH MONDAY)...THE SPLIT JET STREAM WILL
CARRY THE LOW PRESSURE THURSDAY AND THE WEATHER SYSTEM INTO NORTHERN
CALIFORNIA WITH MAINLY LIGHTER SHOWERS IN SOUTHERN OREGON. DRYING
TREND IS EXPECTED FROM THURSDAY NIGHT INTO FRIDAY AS A RIDGE SETS UP
NEAR 140W ALLOWING NORTHERLY FLOW TO BRING COLDER AND DRIER AIR TO
THE FORECAST AREA. THIS TREND IS CONSISTENT WITH THE PREVIOUS DAY'S
FORECAST. THE DIFFERENCE IS THE SHORT WAVE TROUGH COMING DOWN THE
EAST SIDE OF THE RIDGE ON SATURDAY IS NOW VERY WEAK. AS A RESULT
WE ARE TRENDING TOWARD A DRIER FORECAST FOR SOUTHERN OREGON AND
KEEPING HIGHER POPS IN NORTHERN CALIFORNIA.

THIS PATTERN HOWEVER FAVORS COLD TEMPERATURES FOR THE KLAMATH
TULELAKE AND GOOSE LAKE BASINS, ESPECIALLY AT NIGHT, AND GUIDANCE
MAY NOT CAPTURE THE COLD TEMPERATURES WELL. AS A RESULT WE ARE
FORECAST MUCH LOWER HIGH AND LOW TEMPERATURES FOR THE EAST
SIDE.

BOTH THE GFS AND THE ECMWF SHOW THE RIDGE BREAKING DOWN A BIT ON
SUNDAY AND MONDAY AND BRING ANOTHER PACIFIC WEATHER SYSTEM INLAND.
BOTH ARE ABOUT 12 HOURS OFF ON THE TIMING WITH THE GFS BEING FASTER.
HOWEVER BOTH MODELS ARE SHOWING THE TREND OF PATTERN CHANGING BACK
TO A MORE WESTERLY FLOW WITH A SERIES OF FRONTS AND PRECIPITATION
MOST OF NEXT WEEK. /FB

&&

.AVIATION...FOR THE 04/18Z TAF CYCLE...A FRONT APPROACHING FROM THE
SOUTHWEST WILL BRING LIGHT PRECIPITATION ALONG WITH MVFR CIGS THIS
AFTERNOON. MVFR CIGS/VIS ARE EXPECTED TO BECOME WIDESPREAD OVERNIGHT
AND LCL IFR CIGS ESPECIALLY NEAR KRBG. MOUNTAINS WILL ALSO BE
OBSCURED. /FB

&&

.MARINE...UPDATED 830 AM PST MONDAY 4 JAN 2016...A COMBINATION OF
WESTERLY AND SOUTHERLY SWELL WILL MAKE FOR STEEP AND CHAOTIC SEAS
TODAY. A FRONT WILL MOVE ONSHORE TONIGHT...FOLLOWED BY A STRONGER
FRONT WEDNESDAY. EACH OF THESE FRONTS WILL BRING SMALL CRAFT
ADVISORY WINDS AND CHOPPY SEAS TO MUCH OF THE AREA. HEAVY LONG
PERIOD WEST SWELL WILL ARRIVE TUESDAY AND REMAIN THROUGH
WEDNESDAY...WITH HAZARDOUS SEAS PEAKING AROUND 20 FEET TUESDAY
EVENING. ANOTHER ROUND OF HEAVY LONG PERIOD SWELL WILL MOVE IN
WEDNESDAY NIGHT AND LAST THROUGH THURSDAY. YET ANOTHER FRONT WILL
APPROACH THE COASTAL WATERS FRIDAY NIGHT. /FB

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 4 AM TUESDAY TO 4 AM PST WEDNESDAY FOR
     ORZ021-022.

CA...WIND ADVISORY FROM 10 PM THIS EVENING TO 7 AM PST TUESDAY FOR
     CAZ081.
     WINTER STORM WARNING FROM 10 PM THIS EVENING TO 10 AM PST
     TUESDAY ABOVE 3500 FEET FOR FOR CAZ082.
     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
     TUESDAY ABOVE 4000 FEET FOR FOR CAZ080.
     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
     TUESDAY ABOVE 4000 FEET FOR FOR CAZ083.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM PST TUESDAY
     FOR PZZ350-356-370-376.
     HAZARDOUS SEAS WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY
     NIGHT FOR PZZ350-356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST TUESDAY
     FOR PZZ350-356.
     HAZARDOUS SEAS WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
     NIGHT FOR PZZ370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST TUESDAY
     FOR PZZ370-376.

CZS/FJB/BTL