Gale Watch 7, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
222 PM PST MON JAN 25 2016

.DISCUSSION...MAIN EFFORTS TODAY WERE FOCUSED ON THE UPCOMING
RAIN LATER THIS WEEK. WHILE MODELS ARE IN FAIRLY GOOD AGREEMENT IN
THE SHORT TERM, THERE IS SOME DIVERGENCE IN SOLUTION BEYOND ABOUT
DAY 5. RELIED ON A BLEND OF THE GFS AND ECMWF FOR THE BULK OF THE
FORECAST, WITH SOME NAM IN THE SHORT TERM.

FROM NOW UNTIL THE ARRIVAL OF THE MAIN EVENT THURSDAY MORNING,
HIGH PRESSURE WILL REMAIN IN CONTROL OF MOST OF THE AREA. THERE
WILL BE A FEW WEAK WAVES, THE MORE PROMINENT ONE TUESDAY
AFTERNOON, THAT WILL ATTEMPT TO PUSH ONSHORE AND INTO THE UPPER
LEVEL RIDGE. THESE FEATURES WILL FALTER AND DIE AS THEY MOVE
ONSHORE, AND WILL LIKELY ONLY PRODUCE PERIODS OF LIGHT RAIN,
MAINLY OVER HIGH TERRAIN AND ALONG THE COAST. MEANWHILE, THE AREA
VALLEYS ARE LIKELY TO SEE FOG AND LOW STRATUS OVERNIGHT AND INTO
THE MORNING. THERE IS LOW CONFIDENCE IN DAILY TEMPERATURES DURING
THIS TIME, AS THESE WILL RELY HEAVILY ON CLOUD COVER. SHOULD FOG
OR STRATUS DEVELOP, OVERNIGHT LOWS WILL BE WARMER AND DAYTIME
HIGHS WILL BE COOLER. WHERE NO FOG DEVELOPS, THE OPPOSITE IS
EXPECTED. WHILE VALLEY MOISTURE AND HIGH PRESSURE USUALLY DO LEAD
TO LOW CLOUDS, HIGHER LEVEL CLOUDS ASSOCIATED WITH THE WEAK WAVES
MAY INHIBIT FORMATION.

ON TO THE BIG EVENT THURSDAY. MODELS HAVE TRENDED WETTER WITH
THIS SYSTEM, WITH FORECAST MOISTURE ANOMALIES IN THE 99TH
PERCENTILE,AND THE MAIN PLUME ORIGINATING FROM JUST NORTH OF
HAWAII. ALSO, SOME SOLUTIONS HAVE BROUGHT THE MOISTURE IN ABOUT 6
HOURS SOONER AND SLOWED IT OVERHEAD, PRODUCING A LONGER PERIOD OF
RAIN. WITH THESE FACTORS IN MIND, HAVE OPTED TO INCREASE
PRECIPITATION CHANCES, AS MEASURABLE RAINFALL IS VIRTUALLY
CERTAIN. HAVE ALSO INCREASED PRECIPITATION AMOUNTS SIGNIFICANTLY
ACROSS THE BOARD, BUT EVEN THIS MAY NOT BE ENOUGH. WITH SUCH A
WARM SYSTEM SOURCE, SNOW LEVELS WILL BE VERY HIGH, ON THE ORDER
OF 9000 FEET OR HIGHER. AREA SNOWTEL STATIONS SUGGEST THAT THE
SNOWPACK EXISTS DOWN TO ABOUT 3500 FEET, SO THAT IS A LOT OF AREA
THAT WILL EXPERIENCE HEAVY RAIN ON SNOW. WITH THIS IN MIND, HAVE
ISSUED A HYDROLOGIC OUTLOOK STATING THE CHANCES FOR FLOODING IN
SMALL STREAMS AND RIVERS. WHILE THE MAIN STEM RIVERS ARE NOT
CURRENTLY FORECAST TO FLOOD, PAST EVENTS DO SUGGEST THAT WATER
LEVELS WILL RISE RAPIDLY, AND WILL LIKELY GO WELL ABOVE THE
CURRENT FORECAST LEVELS. WILL NEED TO KEEP THIS IN MIND AS WE GO
THROUGH THE NEXT SEVERAL FORECAST CYCLES.

AT THIS TIME, WE'RE NOT EXPECTING ANY WIND CONCERNS FOR THE NEXT
FEW DAYS. WINDS AT THE SURFACE AND ALOFT SHOULD BE FAIRLY LIGHT
THROUGH TUESDAY. THE UPPER RIDGE WILL SLOWLY BREAK DOWN AND
FLATTEN OUT WEDNESDAY AS AN UPPER TROUGH AND A STRONG JET NEAR 300
MB APPROACHES FROM THE WEST. MODELS SHOW 700MB WINDS INCREASING TO
AROUND 20 KTS WEDNESDAY AFTERNOON. SO THE STRONGEST WINDS SHOULD
BE CONFINED TO THE HIGHER RIDGES EAST OF THE CASCADES. EVEN THEN,
WERE NOT EXPECTING THEM TO REACH ADVISORY LEVELS. 700MB FLOW WILL
INCREASE WEDNESDAY NIGHT WITH WINDS EXPECTED TO BE AROUND 45 KTS
THURSDAY AFTERNOON, SO THERE'S A CHANCE A FEW OF THE HIGHER SPOTS
LIKE SUMMER LAKE COULD REACH ADVISORY CRITERIA.

WE'LL ALSO HAVE TO KEEP AN EYE ON WINDS IN THE SHASTA VALLEY.
THEY ARE EXPECTED TO INCREASE THERE THURSDAY MORNING AND CONTINUE
INTO THURSDAY NIGHT. THE 700MB FLOW IS WEST TO SOUTHWEST, BUT THE
850 MB WINDS SHOW A SOUTHERLY COMPONENT, SO THERE'S A CHANCE SOME
OF THE STRONGER WINDS COULD MIX DOWN LOWER. RIGHT NOW TRENDED
WINDS HIGHER IN THE SHASTA VALLEY, BUT THEY MAY NEED TO BE
ADJUSTED FURTHER HIGHER. CONDITIONS ARE ALSO FAVORABLE FOR GUSTY
WINDS IN THE SOUTHERN PART OF THE ROGUE VALLEY WEDNESDAY NIGHT
INTO THURSDAY AND WILL NEED TO BE MONITORED CLOSELY.

ONCE THE SYSTEM EXITS THE AREA, LONG WAVE TROUGHING IS EXPECTED
TO DIG INTO OUR REGION, WITH TEMPERATURES AND SNOW LEVELS EXPECTED
TO DROP SIGNIFICANTLY. MEANWHILE, ONSHORE FLOW WILL LIKELY
CONTINUE, AND THIS WOULD PRODUCE SOME PRECIPITATION OVER THE AREA
FOR SEVERAL DAYS, ESPECIALLY IF ANY SHORTWAVES ARE TRAVERSING THE
SWIFT FLOW ALOFT. WHILE THERE IS LOW CONFIDENCE IN ANY SPECIFIC
WAVE OR PRECIPITATION EVENT, HAVE KEPT AT LEAST A SLIGHT CHANCE OF
PRECIPITATION IN THE FORECAST THROUGH THE END OF THE TERM, WITH
THE HINT OR PERHAPS SOME LOW ELEVATION SNOW TOWARDS THE BEGINNING
OF NEXT WEEK. -BPN/PETRUCELLI

&&

.AVIATION...FOR THE 25/18Z TAF CYCLE...VFR CONDITIONS WILL BE THE
PREDOMINATE CONDITION AT THE COAST THROUGH THIS EVENING. INLAND,
IFR/LIFR CIGS/VIS WITH MOUNTAIN OBSCURATIONS ARE EXPECTED TO IMPROVE
TO VFR AT 21Z, BUT CONFIDENCE ON THE TIMING IS LOW TO MODERATE AND
THERE'S A CHANCE IT COULD LINGER AN HOUR LONGER IN THE ROGUE VALLEY.
AREAS OF VFR CEILINGS ARE EXPECTED LATER THIS AFTERNOON AND EVENING
AS MID AND HIGH CLOUDS INCREASE AS A WEAK DISTURBANCE BRUSHES PAST
TO THE NORTH. IFR/MVFR IS EXPECTED TO RETURN TONIGHT AT THE COAST,
WEST SIDE VALLEYS AND KLAMATH BASIN. -PETRUCELLI

&&

.MARINE...UPDATED 200 PM PST MONDAY 25 JAN 2016...EXPECT MODERATE
SOUTH WINDS AND SHORT PERIOD WEST SWELL TODAY AS A WARM FRONT LIFTS
NORTH OF THE AREA. LONG PERIOD WEST SWELL WILL BUILD LATE TONIGHT
INTO TUESDAY...PEAKING AT AROUND 14 FEET 17 SECONDS LATE
TUESDAY AFTERNOON.

A HIGH IMPACT MARINE EVENT IS LIKELY WEDNESDAY NIGHT THROUGH
FRIDAY...A STRONG FRONT WILL BRING INCREASING SOUTH WINDS WEDNESDAY
NIGHT THROUGH THURSDAY. GALES ARE LIKELY, ESPECIALLY IN THE NORTHERN
WATERS DURING THIS TIME FRAME AND A GALE WATCH HAS BEEN ISSUED TO
COVER THIS. CURRENTLY IT IS ONLY FOR THE OUTER WATERS. THERE IS SOME
POTENTIAL FOR A COASTAL JET TO SET UP NEAR OR JUST OFF CAPE BLANCO
BY THURSDAY MORNING, BUT WILL LET FUTURE SHIFTS EVALUATE THIS AND
DETERMINE THE NEED FOR A GALE WATCH FOR THE INNER WATERS. IN
ADDITION TO THE GALES, A VERY HIGH AND LONG PERIOD SWELL WILL
ACCOMPANY THIS FRONT. THE SWELL LOOKS TO ARRIVE SOONER THAN THE
PREVIOUS FORECAST...NOW ARRIVING WEDNESDAY AFTERNOON WITH SEAS
EXPECTED TO PEAK AT 20 TO 25 FEET THURSDAY NIGHT.

SEAS WILL THEN LIKELY SUBSIDE BEGINNING FRIDAY BUT WILL REMAIN HIGH
INTO THE WEEKEND AS WEAKER DISTURBANCES FOLLOW. SPILDE/BR-Y

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST THIS
     AFTERNOON FOR PZZ370-376.

BPN/MAP/BR-Y