209
FXUS66 KSEW 212153
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
253 PM PDT MON APR 21 2025
SYNOPSIS
CONDITIONS WILL CONTINUE TO DRY OUT TODAY. DRY AND
WARMING CONDITIONS ARE EXPECTED THROUGH THURSDAY AS HIGH PRESSURE
MOVES INTO THE REGION. COOLER CONDITIONS AND PRECIPITATION CHANCES
WILL RETURN TO THE FORECAST FRIDAY INTO THE WEEKEND.
SHORT TERM /TONIGHT THROUGH THURSDAY/
WEAK AND SLOW MOVING
SHOWER ACTIVITY CONTINUES ACROSS PORTIONS OF WESTERN WA THIS
AFTERNOON. THIS ACTIVITY WILL CONTINUE TO WANE AS WE GET INTO THE
EVENING HOURS. GENERALLY DECREASING CLOUDS ARE EXPECTED OVERNIGHT.
FOR THE MOST PART LITTLE IMPACT IS EXPECTED. FOR THE SOUTHWEST
INTERIOR, THERE WILL BE A BATTLE BETWEEN AREAS OF FROST AND AREAS
OF FOG BETWEEN ROUGHLY 09-15Z TUESDAY. WITH TEMPERATURES IN THE
MID-30S AND THE FOG POTENTIAL, DECIDED TO HOLD OFF ON ANY FROST
PRODUCTS AS PROBABILITY AND COVERAGE LOOK MARGINAL AT BEST.
FOR THE TUESDAY THROUGH THURSDAY TIMEFRAME, EXPECT DRY CONDITIONS
AND A GRADUAL WARMING TREND. BY THURSDAY, AFTERNOON HIGHS ARE
LIKELY TO REACH THE LOW TO EVEN MID-70S ACROSS MANY AREAS. THAT
SAID, BY THURSDAY AFTERNOON THE RIDGE AXIS WILL SHIFT EAST OF THE
AREA AND WILL OPEN THE DOOR FOR A CHANGE IN THE LONG TERM.
LONG TERM /FRIDAY THROUGH MONDAY/
TROUGHING WILL RETURN FRIDAY
THROUGH THE WEEKEND, BRINGING A RETURN OF COOLER AND SHOWERY
WEATHER. THERE ARE SOME KEY DIFFERENCES WITHIN THE RANGE OF
POSSIBLE OUTCOMES IN TERMS OF THE PATTERN OVER THE WEEKEND WITH
SOME SOLUTIONS KEEPING THE LOW MORE COMPACT AND FURTHER NORTH
IMPACTING WA, WHILE OTHERS RESULT IN CUTOFF LOW THAT BRINGS THE
BULK OF THE ENERGY FURTHER SOUTH. THE MAIN DIFFERENCE FOR WESTERN
WA WOULD BE THE AMOUNT AND COVERAGE OF PRECIPITATION.
BY MONDAY, THERE IS SOME HINT THAT RIDGING MAY TRY TO RETURN TO
THE REGION, STARTING ANOTHER WARMING TREND.
-WOLCOTT-
AVIATION
JUST A FEW SCATTERED SHOWERS MOVING ACROSS THE AREA
THIS AFTERNOON WITH THE PRIMARY CLOUD DECK LIFTING AND SCATTERING
ACROSS WESTERN WASHINGTON. HIGH PRESSURE CONTINUES TO BUILD WITH
CONTINUED SCATTERING OF THE MID-LEVEL CLOUD DECK THROUGH THE
EVENING. THIS WILL INCREASE THE POTENTIAL FOR SOME PATCHES OF LOW
CEILINGS LATE TONIGHT/EARLY TUESDAY MORNING IN SOME OF THE MORE
FAVORED LOCATIONS INCLUDING KOLM AND EXTENDING DOWN INTO LEWIS
COUNTY. WITH STRONGER HIGH PRESSURE TOMORROW, EXPECT BREEZY
NORTHERLY WINDS ACROSS MUCH OF THE AREA LATE TOMORROW MORNING
THROUGH THE DAY. WITH A DRIER FLOW PATTERN AS A RESULT, EXPECT
LESS MID-LEVEL CLOUDS AND CUMULUS BUILD UPS TOMORROW, MAINTAINING
VFR CONDITIONS MOST OF TUESDAY.
KSEA...SOUTHERLY SURFACE WINDS WITH SCATTERED MID-LEVEL CLOUDS
THIS AFTERNOON AND EVENING. EXPECT WINDS TO BECOME LIGHT OVERNIGHT
BEFORE BECOMING PREDOMINANTLY NORTHERLY TUESDAY MORNING. WINDS
SPEEDS INCREASE A BIT MORE INTO THE AFTERNOON HOURS. RISK OF LOW
CEILINGS/FOG OVERNIGHT IS VERY LOW (<10%) FOR THE TERMINAL AREA
WITH MOSTLY CLEAR SKIES EXPECTED BY TUESDAY AFTERNOON.
MARINE
HIGH PRESSURE CONTINUING TO GRADUALLY BUILD OVER THE
COASTAL WATERS THIS AFTERNOON AND THIS HIGH PRESSURE WILL REMAIN
IN PLACE. EXPECT PRIMARILY NORTHERLY WINDS OVER THE COASTAL WATERS
AND PUGET SOUND THE NEXT FEW DAYS, STRONGEST EACH AFTERNOON, AND
WEST WINDS THROUGH THE STRAIT. SEAS WILL GRADUALLY SUBSIDE THROUGH
THE WEEK. WHILE SEAS OVER THE COASTAL WATERS WILL REMAIN
RELATIVELY SHORT PERIOD FOR THE NEXT COUPLE OF DAYS, THEY
SHOULDN'T BE LARGE ENOUGH TO WARRANT AN ADVISORY. THE NEXT FRONTAL
SYSTEM BEGINS TO TAKE APPROACH THE COASTAL WATERS LATE THURSDAY
AND COULD BRING ANOTHER INCREASE IN SEAS AND STRONGER WINDS.
HYDROLOGY
NO RIVER FLOODING IS EXPECTED DURING THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...NONE.
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