Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 310506
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
905 PM PST FRI JAN 30 2015

.SYNOPSIS...THE UPPER RIDGE ALONG THE WEST COAST OF NORTH AMERICA
WILL HELP THE DRY AND MILD WEATHER LINGER OVER THE REGION THROUGH
SATURDAY. RADIATIONAL COOLING AND LOW LEVEL TEMPERATURE INVERSIONS
WILL SUPPORT AREAS OF FOG OVER MUCH OF THE INTERIOR LOWLANDS TONIGHT
AND SATURDAY MORNING. A SERIES OF WEAK SYSTEMS WILL BRING RAIN BACK
TO THE AREA SUNDAY AND MONDAY. SHOWERS WILL GRADUALLY TAPER OFF
MIDWEEK FOLLOWED BY A TRANSITION BACK TO A MORE ACTIVE PATTERN LATE
NEXT WEEK.

&&

.SHORT TERM...MODELS CONTINUE TO SHOW THE UPPER LEVEL RIDGE
EXTENDING ALONG 130W REBOUNDING INTO BRITISH COLUMBIA AND WESTERN
WASHINGTON SATURDAY MORNING AS THE WEAK SHORTWAVE PASSING THROUGH
BRITISH COLUMBIA EJECTS INTO ALBERTA AND MONTANA. TONIGHT...THE
REBUILDING SURFACE HIGH PRESSURE OVER THE AREA COUPLED WITH
SUBSIDENCE ALOFT AND LITTLE OR NO CLOUD COVER WILL SUPPORT ANOTHER
ROUND OF LOWLAND FOG OVER MUCH OF THE INTERIOR. DESPITE AFTERNOON
CLEARING...LOW LEVEL FOG DID NOT FULLY DISSIPATE ESPECIALLY OVER THE
SOUTH SOUND AND THE SOUTHWEST INTERIOR VALLEYS. EXPECT LOW LEVEL FOG
TO REDEVELOP OVERNIGHT...FILLING IN FROM THE CHEHALIS GAP AND SOUTH
INTERIOR NORTH THROUGH EVERETT AND ARLINGTON. SATELLITE IMAGERY AND
SURFACE OBS SHOWING THIS REDEVELOPMENT ALREADY HAPPENING THROUGH THE
KITSAP PENINSULA INTO SOUTH WHIDBEY ISLAND AS OF 04Z.

FOG AND LOW LEVEL STRATUS WILL LIKELY LIFT MIDDAY SATURDAY INTO THE
EARLY AFTERNOON HOURS. LIKE TODAY...SATURDAYS HIGHS WILL DEPEND
HEAVILY ON FOG BREAKOUT TIME. EARLIER CLEARING MEANS WARMER
TEMPERATURES...EXPECT HIGHS NEAR 50 THROUGH THE INTERIOR LOWLANDS
AND LOWER TO MID 50S ON THE COAST. THE FIRST OF TWO WEAK FRONTAL
SYSTEMS WONT REACH THE INTERIOR VALLEYS UNTIL SUNDAY
AFTERNOON...WHICH MEANS THAT PATCHY FOG WILL LIKELY FORM AGAIN
SATURDAY EVENING AHEAD OF INCREASING CLOUDS LATE SATURDAY NIGHT INTO
SUNDAY MORNING. EXPECT A CHANCE OF RAIN LIKELY CLOSER TO DAYBREAK
SUNDAY MORNING. LIGHT RAIN REMAINS LIKELY OVER THE ENTIRE AREA ON
SUNDAY. THE SECOND FRONT WILL FOLLOW QUICKLY MOVING INTO THE AREA ON
MONDAY...BRINGING SOMEWHAT WETTER AND WINDIER CONDITIONS THAN
SUNDAYS FRONT.

.LONG TERM...MEDIUM RANGE MODELS CONTINUE TO SHOW THE UPPER LEVEL
RIDGE ALONG THE WEST COAST REBUILDING NORTH ALONG 130W TUE HELPING
LINGERING SHOWERS MON NIGHT TAPER OFF TUE AND TUESDAY NIGHT. THE
UPPER LEVEL RIDGE WILL MOVE ONSHORE WED...BRINGING DRIER CONDITIONS
AND LIGHT OFFSHORE FLOW. 00Z GFS IS SLOWER WITH A WEAK WARM FRONT
APPROACHING THE AREA FROM THE SW...KEEPING WEDNESDAY AND WEDNESDAY
NIGHT DRY. THE CURRENT FORECAST PACKAGE IS A BIT MORE PROGRESSIVE
WITH RAIN ON WEDNESDAY WITH CHANCE POPS OVER ALL BUT THE NORTH
INTERIOR. THU THROUGH FRI WILL BE MILD AND WET AS THE FRONTAL SYSTEM
AND ASSOCIATED SURFACE WAVES PASS THROUGH THE REGION. DESPITE
DIFFERENCES IN THE TIMING AND MAGNITUDE OF RAINFALL AMOUNTS...MEDIUM
RANGE MODELS CONTINUE TO HIGHLIGHT THAT THE FRONT WILL BE TAPPED
INTO THE TROPICS MIDWAY BETWEEN SOUTH OF CALIFORNIA AND HAWAII. THE
PASSING WAVES IMPLIES THAT THERE WILL BE SOME BREAKS BETWEEN PERIODS
OF HEAVIER PRECIPITATION...LIMITING THE THREAT FOR FLOODING ON AREA
RIVERS. IN ADDITION TO HEAVIER RAINFALL...SOME SOLUTIONS HAVE SHOWN
SOME WINDY PERIODS WITH THE PASSING WAVES. EXPECT NEAR NORMAL TO
ABOVE NORMAL TEMPERATURES THROUGH THE END OF THE WEEK WITH SNOW
LEVELS AROUND 7000 FEET BY FRIDAY.
&&

.HYDROLOGY...FLOODING IS NOT EXPECTED THROUGH THURSDAY.

A SERIES OF SYSTEMS MOVING BY JUST TO THE WEST OF THE AREA COMBINED
WITH A NEARLY STALLED FRONTAL SYSTEM AROUND WESTERN WASHINGTON MAY
PRODUCE LOCALLY HEAVY RAIN AT TIMES STARTING LATER THURSDAY OR
FRIDAY AND CONTINUING THROUGH NEXT WEEKEND. THIS MAY INCREASE THE
THREAT OF FLOODING ON SOME AREA RIVERS STARTING FRIDAY OR NEXT
WEEKEND. SNOW LEVELS WILL RISE TO AROUND 7000 FEET BY THURSDAY AND
REMAIN HIGH THROUGH NEXT WEEKEND. ALBRECHT


&&

.AVIATION...UPPER RIDGE WITH LIGHT LOW LEVEL OFFSHORE FLOW WITH
AREAS OF FOG THROUGH SATURDAY. A FRONT WILL ARRIVE SUNDAY AND STIR
THINGS UP WITH SOME PRECIP.

KSEA...FOG CONTINUES. AN INCREASE IN OFFSHORE FLOW MAY HELP PUSH IT
OUT OF THE AREA OR DRY IT UP SATURDAY AFTERNOON.

&&

.MARINE...LIGHT FLOW AND AREAS OF FOG. STRONGER OFFSHORE FLOW
SATURDAY AFTERNOON AND NIGHT MAY PUSH THE FOG AWAY...AND THEN
CERTAINLY ON SUNDAY THE FOG WILL BE DONE WITH STRONGER FLOW AND A
FRONT...AND ANOTHER FRONT WILL REACH THE AREA MONDAY.


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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