Gale Warning 6, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
930 PM PDT TUE MAR 19 2013

.DISCUSSION...EVENING UPDATE. LATEST MODEL DATA IS INDICATING
MOMENTUM TRANSFER OF WINDS AHEAD OF THE FRONT BRINGING DOWN WINDS
GUSTS TO 55 KT IN THE COASTAL WATERS. THE 850 WINDS OF 65 KT FROM
THE SW WITH A ACV-OTH GRADIENT OF 8MB ARE ALSO HINTING AT A COASTAL
BARRIER JET FORMING WITH 925 MB WINDS OF 75 KT ALSO HELPING THE
DECISION. WITH THIS HAVE UPDATED THE GALE WARNING TO STORM AND FEEL
HIGHER CONFIDENCE WITH THE REMAINING WIND WARNINGS/ADVISORIES.

.SHORT TERM...VISIBLE IMAGERY IS SHOWING THICKENING CLOUD COVER
ACROSS THE CWA THIS AFTERNOON AHEAD OF A BROAD AREA OF LOW
PRESSURE THAT IS CURRENTLY CENTERED NEAR 45N AND 135W. KMAX RADAR
IS SHOWING PRECIPITATION EXPANDING OVER THE AREA AS WELL WITH THE
FIRST DROPS IN THE LAST HOUR OR SO IN BROOKINGS. CIRA LAYERED
TOTAL PRECIPITABLE WATER IMAGERY SHOWING A FINGER OF DEEP MOISTURE
WITH PWS IN THE 1.00-1.50 RANGE, WHICH EQUATES TO ABOUT 150-200%
OF NORMAL, EXTENDING FROM THE TROPICS NORTHEASTWARD INTO THE
SYSTEM ALONG 130W. A QUICK GLANCE AT THE ESRL AUTOMATED
ATMOSPHERIC RIVER DETECTION SITE SHOWS HEALTHY INTEGRATED WATER
VAPOR TRANSPORT INTO THE REGION TONIGHT. WHAT THIS ALL MEANS IS
THAT THIS SHOULD RESULT IN A PERIOD OF MODERATE TO HEAVY RAINFALL
ALONG THE COAST AND INTO PORTIONS OF WESTERN SISKIYOU COUNTY
TONIGHT INTO WEDNESDAY MORNING. WE ARE EXPECTING A GENERAL 1 TO 3
INCHES OF RAINFALL IN THOSE AREAS WITH THE COASTAL CURRY MOUNTAINS
LIKELY SEEING THE HIGHEST AMOUNTS. RAINFALL WILL OVERSPREAD THE
REST OF THE AREA TONIGHT. SNOW LEVELS WILL BE VERY HIGH
TONIGHT...BETWEEN 6500 AND 7000 FEET.

PRESSURE GRADIENTS ALSO CONTINUE TO STRENGTHEN ACROSS THE AREA AND
THIS IS RESULTING IN INCREASING SOUTH WINDS ALONG THE COAST, THE
SHASTA VALLEY AND THE EAST SIDE. WINDS WILL BECOME QUITE STRONG
TONIGHT INTO WEDNESDAY ALONG AND AHEAD OF A SHARP COLD FRONT.
GRADIENTS FROM MFR-RDD PEAK AROUND -8.0MB AND AND WITH 700MB WINDS
OF 55-65 KT, HAVE OPTED TO GO WITH A HIGH WIND WARNING. IN FACT,
HIGH WIND WARNINGS AND WIND ADVISORIES HAVE BEEN ISSUED FOR MANY
AREAS AND DETAILS CAN BE SEEN AT NPWMFR. SNOW LEVELS WILL DROP
SHARPLY ALONG/BEHIND THE FRONT WEDNESDAY AND THERE CAN BE SEVERAL
INCHES OF SNOW AT THE HIGHER ELEVATIONS OF THE CASCADES,
INCLUDING CRATER AND DIAMOND LAKE. A SPECIAL WEATHER STATEMENT
(SPSMFR) REMAINS IN EFFECT FOR THIS.

THE FRONT WILL EXIT TO THE EAST OF THE AREA WEDNESDAY EVENING AND
WINDS WILL SUBSIDE. A POST-FRONTAL SHOWERY PATTERN IS EXPECTED
TO PERSIST WEDNESDAY NIGHT INTO THURSDAY, ESPECIALLY ALONG AND
WEST OF THE CASCADES. SPILDE

.LONG TERM...(FRIDAY THROUGH TUESDAY)...I DIDN'T HAVE TO MAKE MANY
CHANGES TO THE EXTENDED FORECAST TODAY. WHILE THE OPERATIONAL MODEL
RUNS MADE SOME FAIRLY LARGE ADJUSTMENTS OVER THE LAST FEW RUNS (ESP
REGARDING THE UPCOMING WEEKEND), THEIR ENSEMBLES STAYED THE COURSE,
AND AS OF 19/12Z THE OPERATIONAL RUNS ARE BACK IN GENERAL AGREEMENT.

MOIST NORTHWEST FLOW WILL CONTINUE OVER THE PACNW FRIDAY AS A RIDGE
BUILDS OFFSHORE. THIS FAVORS AT LEAST SOME CHANCE OF PRECIPITATION
IN THE MOUNTAINS, ALONG THE COAST, AND NORTH OF THE UMPQUA, BUT MUCH
OF THE REST OF THE AREA SHOULD BE DRY AND COOL. HAVE LOWERED POPS A
BIT OVER THE WEEKEND AS MODELS ALL NOW SHOW A FAIRLY WEAK WAVE
MOVING THROUGH THE NW FLOW OVER THE WEEKEND WHICH DOESN'T
NECESSITATE MUCH CHANGE IN POPS COMPARED TO FRIDAY. DID CONTINUE THE
DOWNWARD TREND OF TEMPERATURE AS THIS FLOW PATTERN SHOULD BE COOL.

THE RIDGE MOVES OVER THE PACNW ON MONDAY WHICH LOOKS LIKE THE DRIEST
AND WARMEST DAY OF THE EXTENDED PERIOD. BEHIND THAT RIDGE LURKS THE
NEXT TROUGH WHICH THE MODELS NOW WANT TO BRING THROUGH IN SOME FORM
LATER NEXT WEEK. THE POPS ARE ALREADY TRENDED MORE TOWARD CLIMO
TUESDAY AND BEYOND AND THAT LOOKS REASONABLE AT THIS TIME. -WRIGHT

&&

.AVIATION...BASED ON THE 19/18Z TAF CYCLE.

VFR CIGS AND VIS ARE EXPECTED TO CONTINUE THROUGH THIS EVENING FOR
MOST AREAS. HOWEVER, A STRONG FRONTAL SYSTEM IS APPROACHING THE
COAST AND WILL BRING LIGHT RAIN AND MVFR CIGS TO THE COAST THIS
EVENING WHICH WILL SPREAD INLAND OVERNIGHT. STRONG SOUTH WINDS ALOFT
WILL RESULT IN INCREASING MOUNTAIN OBSCURATIONS AND WAVE TURBULENCE
THROUGH THE NIGHT. THESE WINDS WILL AFFECT THE COAST AND EAST SIDE
VALLEYS OVERNIGHT AND WILL GRADUALLY SURFACE IN THE WEST SIDE
VALLEYS AS WELL BY MORNING. PRIOR TO THE SURFACING OF STRONG SOUTH
WINDS AT ALL TERMINALS, LOW LEVEL WIND SHEAR WILL BE POSSIBLE. THERE
WILL BE A PERIOD OF VERY WINDY CONDITIONS WITH IFR CIGS AND VIS AT
MOST LOCATIONS AS THE FRONT GOES THROUGH TOMORROW MORNING.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 8 PM THIS EVENING TO 8 AM PDT WEDNESDAY
     FOR ORZ021-022.
     HIGH WIND WARNING FROM 8 PM THIS EVENING TO 8 PM PDT WEDNESDAY
     FOR ORZ030-031.
     WIND ADVISORY FROM 8 AM TO 8 PM PDT WEDNESDAY FOR ORZ029.

CA...HIGH WIND WARNING FROM 2 AM TO 2 PM PDT WEDNESDAY FOR CAZ081.
     WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 2 AM PDT WEDNESDAY
FOR
     CAZ081.
     WIND ADVISORY FROM 8 AM TO 8 PM PDT WEDNESDAY FOR CAZ084-085.

PACIFIC COASTAL WATERS...GALE WARNING UNTIL 8 AM PDT WEDNESDAY FOR
     PZZ370-376.
     HAZARDOUS SEAS WARNING UNTIL 11 PM PDT WEDNESDAY FOR
PZZ370-376.
     GALE WARNING UNTIL 8 AM PDT WEDNESDAY FOR PZZ350-356.
     HAZARDOUS SEAS WARNING UNTIL 11 PM PDT WEDNESDAY FOR
PZZ350-356.

MAS/MAS/TRW