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000
FXUS66 KSEW 192246
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
345 PM PDT SUN MAY 19 2013
.SYNOPSIS...AN UPPER LEVEL RIDGE AXIS WILL CROSS WESTERN WASHINGTON
TONIGHT...BRINGING A RELATIVELY WARM AND DRY DAY ON MONDAY. AN UPPER
TROUGH WILL DEVELOP OFFSHORE ON MONDAY...THEN MOVE EAST ON MONDAY
NIGHT. THIS FEATURE WILL EVOLVE INTO A CUTOFF LOW BY TUESDAY...
BECOMING NEARLY STATIONARY AND PERSISTING OVER THE PACIFIC NORTHWEST
THROUGH THE END OF THIS WEEK. THIS WILL PUSH A STRONG COLD FRONT
ONTO THE COAST ON MONDAY NIGHT...PUSHING QUICKLY INLAND EARLY
TUESDAY MORNING. A COOL AND SHOWERY PATTERN WILL THEN PERSIST FOR
THE REST OF THE WEEK.
&&
.SHORT TERM...AN UPPER RIDGE AXIS WILL CONTINUE TO BUILD INTO WRN WA
TONIGHT. THE RIDGE AXIS SHOULD MOVE ACROSS WRN WA DURING THE
OVERNIGHT HOURS. WITH CLEAR SKIES TONIGHT...EXPECT COOL TEMPS.
SHOULD BE A FEW COLD POCKET LOCATIONS...SUCH AS KOLM...DOWN INTO THE
UPPER 30S LATE TONIGHT.
ON MONDAY...THE RIDGE AXIS WILL BE EAST OF THE CASCADES...AND AN
UPPER TROUGH WILL DIG AND AMPLIFY OUT AROUND 135W-140W. WITH
OFFSHORE LOW PRESSURE EASING THE ONSHORE PRESSURE GRADIENT...AND
LIGHT SOUTHERLY FLOW AT 850 MB...MON SHOULD BE ONE OF THOSE WARM AND
DRY DAYS IN ADVANCE OF TUESDAY`S STRONG COLD FRONT. LOOKING FOR 70+
FROM KSEA ON SOUTH ALONG I-5 MON AFTN.
SPEAKING OF TUE...THE OFFSHORE UPPER TROUGH WILL ADVANCE EAST BTWN
130W AND THE COAST AND THEN BECOME A CUTOFF LOW THAT SINKS SE OFF
THE WA COAST...REACHING NW ORE ON TUE EVNG. AS A RESULT...A STRONG
COLD FRONT WILL PUSH ONSHORE AND INLAND ON TUE MRNG. THE FRONT WILL
BE ACCOMPANIED BY A BAND OF BRIEFLY HEAVY RAIN...FOLLOWED BY
CONVECTIVE SHOWERS ON TUE AFTN AND EVNG GIVEN THE COLD AIR ALOFT. IN
TYPICAL FASHION...SHOWERS WILL FOCUS ON WINDWARD SIDE OF MTNS AND IN
THE PUGET SOUND CONVERGENCE ZONE. AN UNSEASONABLY COOL AIR MASS WILL
FOLLOW THE FRONT...WITH 850 MB TEMPS DOWN IN THE -3C TO 0C RANGE BY
TUE NGT. THIS WILL LOWER SNOW LEVELS AS LOW AS 3000 FEET AT SUNRISE
ON WED MORNING.
ON WED AND THU...THE CENTER OF THE CUTOFF UPPER LOW WILL BE LOCATED
TO OUR SOUTH. WRN WA WILL BE PRONE TO EMBEDDED SHORTWAVES ROTATING
INTO WRN WA FROM THE SOUTHEAST AND EAST. BOTH THE GFS AND ECMWF SHOW
WET PERIODS ON WED. WITH COLD AIR IN PLACE AND SOME WET WX...THE
FCST MAX TEMP OF 54F AT KSEA WOULD TIE THE RECORD LOW MAX TEMP FOR
THE DAY. OF COURSE...THE WET WEATHER WITH SNOW LEVELS OF 3000-4000
FEET WILL PROVIDE SNOW TO THE HIGHER MTN PASSES. SNOQUALMIE PASS IS
UNLIKELY TO GET MORE THAN AN INCH OF ACCUMULATION...BUT THE OFFICIAL
FORECAST SHOWS 30-HOUR SNOWFALL TOTALS FROM TUE EVNG THROUGH WED
EVNG OF 2.5 INCHES AT STEVENS PASS...4 INCHES AT CHINOOK PASS...5
INCHES AT RAINY PASS...6 INCHES AT PARADISE AND 9 INCHES AT HARTS
PASS ALONG THE FAR NORTH CASCADE CREST. THOSE VENTURING INTO HIGHER
ELEVATIONS AND THE BACKCOUNTRY SHOULD BE PREPARED FOR A QUICK CHANGE
TO COLD AND WET OR SNOWY WEATHER EARLY TUE MRNG. WILL ISSUE A
SPECIAL WEATHER STATEMENT TO HIGHLIGHT THIS CONCERN. MAY EVENTUALLY
NEED WINTER WEATHER HIGHLIGHTS FOR THE CASCADES ABOVE 4000 FEET.
HANER
.LONG TERM...THE CUTOFF UPPER LOW WILL MEANDER AROUND THE INLAND
NORTHWEST ON THU AND FRI...THEN START TO FILL AND SLOWLY LIFT OUT
NEXT SAT AND SUN. THIS WILL LEAD TO A SLOW WARMING TREND LATE THIS
WEEK AND NEXT WEEKEND...BUT TEMPS WILL STILL STRUGGLE TO RISE BACK
AS HIGH AS NORMAL. SHOWER COVERAGE WILL ALSO TREND DOWNWARD FROM FRI
THROUGH SUN...BECOMING DRIVEN MORE BY DAYTIME HEATING AND DIURNALLY
DRIVEN CONVECTIVE ELEMENTS. HOWEVER...THERE WILL STILL BE ENOUGH
MOISTURE AND INSTABILITY TO WARRANT A CHANCE OF SHOWERS NEXT SAT AND
SUN. LOOKING OUT TOWARD MEMORIAL DAY...MODELS HINT AT EITHER ZONAL
FLOW OR HEIGHT FALLS SPREADING ONSHORE. AT BEST...THIS WOULD SUGGEST
DEEP MARINE AIR AND CLOUDS. AT WORST...MORE ORGANIZED RAIN. HANER
&&
.AVIATION...LIGHT NW FLOW ALOFT. AIR IS STABLE AND DRYING AS HIGH
PRESSURE BUILDS INTO THE REGION. THE LAYER OF STRATOCU THAT
PERSISTED FOR MUCH OF WESTERN WA THIS AFTERNOON SHOULD CLEAR UP BY
EVENING. MONDAY SHOULD BE SUNNY WITH JUST A LITTLE PATCHY RIVER
VALLEY FOG OR LOW CLOUDS AROUND DAYBREAK.
KSEA...SKIES OUGHT TO BE SCATTERING OUT LATE THIS AFTERNOON. LIGHT
AND VARIABLE WIND EXCEPT NLY TO 10KT AFTERNOON AND EVENING HOURS.
&&
.MARINE...HIGH PRES OVER THE NE PACIFIC WILL MAINTAIN NORTHWESTERLY
FLOW ACROSS WESTERN WA TODAY AND MON. WE PROBABLY WILL SEE SEVERAL
HOURS OF 15-25KT NW WIND COAST AND STRAIT THIS EVENING...ALTHOUGH
THE SEA LEVEL PRESSURE ANALYSIS DOESN`T SHOW A GREAT DEAL OF
GRADIENT THIS AFTERNOON OVER WRN WA. A WEATHER SYSTEM WILL MOVE OVER
THE REGION TUE AND WED...IN FACT AN UPPER LEVEL LOW MAY PERSIST OVER
THE PACNW THROUGH THE END OF THE WEEK. WHAT IS LIKELY TO HAPPEN IS
THAT WESTERN WA WILL HAVE A REGIME OF ONSHORE FLOW AND A LOT OF
SHOWER ACTIVITY...PROBABLY A FEW PERIODS OF RAIN...BUT THE STRONGER
PRESSURE GRADIENT IS LIKELY TO STAY WELL OFFSHORE OR DOWN OVER
OREGON TUE-THU.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COASTAL WATERS AND CENTRAL AND EAST STRAIT
OF JUAN DE FUCA TIL MIDNIGHT.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
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000
FXUS66 KPQR 192222
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
321 PM PDT SUN MAY 19 2013
.SYNOPSIS...HIGH PRESSURE WILL BUILD INTO OREGON THIS EVENING...
CAUSING SKIES TO CLEAR FOR MUCH OF THE FORECAST AREA. THE HIGH
PRESSURE WILL BE STRONGEST OVER THE AREA MONDAY...LEADING TO A SUNNY
AND WARM DAY. HIGH CLOUDS FROM OUR NEXT SYSTEM WILL BEGIN TO INCREASE
LATER MONDAY AND MONDAY NIGHT EVENTUALLY LEADING TO SOME RAIN BY
TUESDAY. THIS SYSTEM WILL COME WITH A SHARP DROP IN TEMPERATURES AND
SNOW LEVELS...WITH COOL AND UNSETTLED WEATHER THEN LIKELY TO CONTINUE
FOR THE REST OF THE WEEK.
&&
.SHORT TERM...TONIGHT THROUGH WEDNESDAY...SKIES HAVE BEEN SLOW TO
CLEAR FOR MOST OF OUR FORECAST AREA TODAY...AS FLOW HAS REMAINED
RATHER LIGHT AND LOW LEVEL MOISTURE REMAINS PERSISTENT. HIGH PRESSURE
IS STRENGTHENING ACROSS THE REGION SO EXPECT SUBSIDENCE TO EVENTUALLY
TAKE OVER FOR CLEARING SKIES THIS EVENING.
EXPECT PLENTY OF SUNSHINE MONDAY AS HIGH PRESSURE BECOMES MORE
DOMINANT. THE AIR MASS WILL ALSO BE WARMING UP A BIT...WITH 850 MB
TEMPS UP FROM +4 DEG C TODAY TO AROUND +10 DEG C MON AFTERNOON PER
THE 12Z ECMWF. WITH NEAR FULL SUNSHINE THIS SHOULD BE GOOD FOR TEMPS
WELL INTO THE 70S FOR THE INLAND VALLEYS. FLOW WILL STILL BE ONSHORE
SO THE COAST WILL REMAIN COOL WITH HIGHS NOT STRAYING TOO FAR FROM 60
DEGREES.
HIGH CLOUDS WILL BE ON THE INCREASE LATER MONDAY INTO MONDAY NIGHT AS
A SIGNIFICANT COLD FRONT APPROACHES FROM ALASKA. RAIN WILL BECOME
LIKELY FOR MOST OF THE FORECAST AREA BY MIDDAY TUESDAY...WITH A SHARP
DROP IN TEMPERATURES AND SNOW LEVEL ASSOCIATED WITH THE COLD FRONT.
INTERIOR VALLEYS WILL SEE HIGHS 15 TO 25 DEGREES COLDER TUE/WED THAN
THEY DID MONDAY. WITH THE COLDER AIR MASS...SNOW LEVEL WILL DROP
BELOW THE CASCADE PASSES. ACCUMULATING SNOW WILL BE POSSIBLE DOWN AS
LOW AS 2500 TO 3000 FT BY TUE NIGHT AND WED...ESPECIALLY DURING THE
NIGHTTIME HOURS. HIGH TEMPS TUE/WED MAY BE COLD ENOUGH TO SET NEW
RECORD LOW MAXES...FOR PDX THIS WOULD BE 52 ON TUE AND 55 WED. OUR
FORECAST OF 54 DEGREES AT PDX WED WOULD ACHIEVE A RECORD.
WITH SUCH A COLD AND UNSETTLED AIR MASS DURING THE MIDWEEK PERIOD...
ALONG WITH LOW FREEZING LEVELS...IT IS LIKELY HEAVIER SHOWERS WILL
COME WITH SMALL HAIL. THERE IS ALSO THE POSSIBILITY FOR THUNDER
DEPENDING ON THE EXACT TRACK OF THE COLD POOL ALOFT. SOME MODEST
DIRECTIONAL SHEAR WEDNESDAY MAY AID THUNDERSTORM DEVELOPMENT...BUT
AGAIN THIS DEPENDS ON THE TIMING OF INDIVIDUAL SHORTWAVES ROTATING
AROUND THE BROADER UPPER LEVEL LOW. WILL HOLD OFF ON ADDING THUNDER
MENTION FOR NOW SINCE THERE IS STILL A LOT OF UNCERTAINTY AS TO HOW
THESE EXACTLY THESE ELEMENTS WILL COME TOGETHER. WEAGLE
.LONG TERM...WEDNESDAY EVENING THROUGH SUNDAY...A LINGERING CLOSED
LOW PRESSURE SYSTEM WILL KEEP THE AREA SHOWERY AND COOL THROUGH THE
WEEK. WITH THE COLD NATURE OF THE LOW...EXPECT SNOW DOWN TO PASS
LEVEL IN THE CASCADES WEDNESDAY NIGHT....WITH SNOW LEVELS RISING
ABOVE THE PASSES THURSDAY AFTERNOON. MODELS HAVE COME INTO BETTER
AGREEMENT FOR THE LONG TERM AND TAKE THE LOW NORTHEAST ON
SATURDAY...WITH A FEW SHOWERS POSSIBLE AS MOISTURE WRAPS AROUND THE
WEST SIDE OF THE LOW. AT THIS TIME SUNDAY LOOKS DRY BUT
CLOUDY...WITH MODEL DISCREPANCIES EMERGING IN REGARD TO THE NEXT
SYSTEM THAT MAY IMPACT THE AREA LATE SUNDAY. BURGESS
&&
.AVIATION...HIGH PRESSURE WILL CONTINUE TO STRENGTHEN OVERNIGHT
INTO MONDAY ALLOWING VFR CONDITIONS TO PREVAIL FOR THE NEXT 24
HRS. CEILINGS AROUND 5K FT WILL CONTINUE THROUGH THIS AFTERNOON
AND EVENING... GRADUALLY DISSIPATING OVERNIGHT. SOME LOW
STRATUS/PATCHY FOG MAY ATTEMPT TO FILL BACK IN AT SITES THAT SAW
SOME LOW CLOUDS THIS MORNING...SUCH AS KSLE IN PARTICULAR. /27
KPDX AND APPROACHES...VFR CONDITIONS THROUGH THE NEXT 24 HRS. BKN
CLOUD DECK AROUND 5K FT WILL GRADUALLY LIFT LATER TONIGHT.
&&
.MARINE...HIGH PRES OVER THE NE PAC WILL STRENGTHEN OVERNIGHT...WITH
N TO NW WINDS. THE SMALL CRAFT ADVISORY FOR WINDS OVER THE CENTRAL
OREGON COASTAL WATERS IS STAYING STRONG AS PRESSURE GRADIENTS
TIGHTEN THROUGH MONDAY... ALLOWING GUSTS TO 25 KT FROM NEWPORT
SOUTH. A FEW GUSTS 20-25 KT ARE POSSIBLE OVER THE NORTHERN
WATERS...BUT OVERALL WINDS SHOULD STAY BELOW CRITERIA. SEAS HOLDING
AT 4 TO 6 FT THROUGH TUE...THOUGH MAY GET BIT CHOPPY WITH BRISK NW
WINDS AT TIMES...MAINLY S OF CASCADE HEAD.
MODELS ARE HINTING AT A LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING
BY MID WEEK. SINCE SOLUTIONS HAVE BEEN RATHER CONSISTENT IN
INDICATING SOME HIGH SWELL BY WED AND THU...WENT AHEAD AND UPPED
SEAS CLOSER TO THE 10 TO 11 FT RANGE. WOULD LIKE A FEW MORE MODEL
RUNS TO DECIDE ON FORECASTING ANY HIGHER SWELL THOUGH.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 PM PDT MONDAY FOR
COASTAL WATERS FROM CASCADE HEAD TO FLORENCE OUT 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
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000
FXUS66 KOTX 192137
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
237 PM PDT Sun May 19 2013
.SYNOPSIS...
Evening showers will begin to wind down as the sun sets and a
ridge heads into the region. By Monday the ridge will become
firmly established over much of the region providing a dry and
warm day before a strong storm system enters the region on
Tuesday. Tuesday`s weather system will bring a good threat of showers
and thunderstorms followed by significantly cooler temperatures.
cool and showery weather will envelop the region from mid- week
into the holiday weekend.
&&
.DISCUSSION...
.Tonight and Monday...Elongated upper level trough remains fixed
over the eastern half of the forecast area late this afternoon
per the latest water vapor loops. The best moisture per satellite
looks like it extends east of a line from Omak to the Moses Lake.
This region correlates fairly well with the best region of
instability per the Rapid Refresh model which shows MLCape values
between 100-300 j/kg mainly over the NE corner of Washington and
extending across most of the Idaho Panhandle. Showers and even a
thunderstorm or two will likely continue into the early
evening...especially over the NE quarter of Washington and the
northern half of the Panhandle...however since there is very
little if any trigger in the mid/upper atmosphere evident on
satellite things should taper off rapidly during the evening.
After the threat wanes...the focus will turn to an upper level
ridge axis meandering into the region from the SW. Plenty of dry
air is evident across of much of Oregon and western Washington and
this will track into the region later tonight and Monday. The
decreasing moisture will contribute to a drier forecast while
increasing stability will also work against any convection. The
one exception could occur tomorrow afternoon near the
Montana/Idaho border where residual instability and moisture could
trigger a shower during the afternoon. Model soundings also
suggest a small possibility of thunderstorms...but better chances
will likely occur east of the border as the ridge works into Idaho
during the day. fx
Monday night through Wednesday: We will transition from a dry and
above average temperature regime to a very wet and below average
temperature regime.
Monday night through Tuesday morning: A very strong closed upper level
low pressure system will move south down the coast line out of the
Gulf of Alaska. This will put the Inland Northwest under southerly
flow ahead of the cold front. The forecast will remain dry with
the exception of the cascade crest where starting Tuesday
morning they may start to see rain. Temperatures will remain at or
above average.
Tuesday afternoon through Wednesday: The low will push inland and
the chances of widespread rain will spread from west to east
starting Tuesday afternoon. Tuesday afternoon there may be enough
instability for an isolated thunderstorm ahead of the front across
extreme eastern WA and north ID. The front will push through early
Wednesday morning. Widespread rain can be expected everywhere. Have
increased chance of precipitation as well as how much liquid
precipitation we are expecting. Temperatures will plummet from
Tuesday to Wednesday. A 10 degree drop in temps across the
Cascades and a 20 to 25 degree drop in temps across Eastern WA and
north ID can be anticipated. Winds will be breezy from the
southwest 10 to 15 mph with gusts around 20 mph. Snow levels will
lower to about 4k ft by Wed with snow expected in the mountains. /nisbet
Wednesday night through Sunday...Confidence is high that the region
will be under a very slow moving upper level low pressure center
that will bring an abundance of clouds, unseasonably cool daytime
temperatures along with a good chance of precipitation for the
Inland Northwest during the extended forecast period. If there were
to be any breaks in the overcast during daytime heating, and this is
fraught with uncertainty, some convection would be possible. For
now, confidence is too low to add thunder to the weather grids.
/Kelch
&&
.AVIATION...
18z TAFS: VFR conditions expected to affect all TAF sites through
the period...although brief MVFR cigs will be possible through 20z
at COE due to the presence of convective cloud bases just below
030. There will be a threat of -shra at PUW...COE...GEG...and SFF
however the limited coverage suggests that if an airport is hit
the wet weather would be brief. Do not believe there will be any
thunder at any of the sites as best instability will remain over
NE WA. Skies will clear overnight at all sites with the upper
level ridge moving overhead. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 46 72 51 76 44 51 / 10 0 0 20 90 90
Coeur d`Alene 45 71 46 76 45 49 / 10 0 0 10 60 90
Pullman 42 71 48 75 42 50 / 10 0 0 10 70 60
Lewiston 48 79 52 81 49 57 / 0 0 0 10 60 60
Colville 44 78 45 77 46 55 / 20 0 0 40 90 80
Sandpoint 42 72 44 76 45 52 / 20 10 0 20 70 80
Kellogg 41 69 50 76 45 47 / 20 10 0 10 60 90
Moses Lake 48 80 51 73 47 60 / 0 0 0 40 50 30
Wenatchee 49 78 53 67 46 57 / 0 0 0 50 50 30
Omak 43 78 47 70 46 58 / 0 0 0 70 90 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KOTX 191908
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1208 PM PDT Sun May 19 2013
.SYNOPSIS...
Another day of seasonably mild conditions are expected today with a
few mountain showers and possible thunderstorms. Monday will
provide a dry and mild break period before a strong storm system
enters the region on Tuesday with a chance of showers and
thunderstorms. Showery and unseasonably cool conditions will
envelop the region from mid-week onward.
&&
.DISCUSSION...
.rest of today...Elongated upper level trough will remain over the
Inland NW again this afternoon. The trough and its associated
upper level cold pool will result in another day of potentially
unstable conditions. While the potential instability values will
be on par with what the region saw yesterday...there is one key
difference...ample diurnal heating. As of 1130am...much of the
region was devoid of clouds...save extreme NE and SE WA as well as
the ID Panhandle. This heating has resulted in significantly
warmer surface temps compared to 24 hrs ago...which will likely
result in better chances of tapping into the potential
instability. Showers will likely develop fairly rapidly early this
afternoon with little if any convective inhibition to overcome.The
best instability will occur over the northeastern half of the forecast
area. Thunderstorms are a distinct possibility but should not be
widespread given the lack of a significant upper level trigger. Farther
southwest...the influence of an incoming shortwave ridge and upper
level sw jet will tend to cap the depth of the convection and
hence the chance of showers. The threat of showers should rapidly
decrease with the setting sun and the growing influence of the
upper level ridge. fx
&&
.AVIATION...
18z TAFS: VFR conditions expected to affect all TAF sites through
the period...although brief MVFR cigs will be possible through 20z
at COE due to the presence of convective cloud bases just below
030. There will be a threat of -shra at PUW...COE...GEG...and SFF
however the limited coverage suggests that if an airport is hit
the wet weather would be brief. Do not believe there will be any
thunder at any of the sites as best instability will remain over
NE WA. Skies will clear overnight at all sites with the upper
level ridge moving overhead. fx
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 66 46 72 52 76 42 / 20 10 0 0 20 90
Coeur d`Alene 64 44 71 47 77 42 / 20 20 0 0 10 60
Pullman 63 42 71 47 77 40 / 20 10 0 0 10 70
Lewiston 68 49 78 53 83 47 / 20 10 0 0 10 60
Colville 72 43 77 45 80 43 / 20 20 10 0 40 90
Sandpoint 63 42 72 44 77 41 / 30 30 10 0 20 70
Kellogg 60 46 70 50 76 41 / 30 30 10 0 10 60
Moses Lake 75 46 80 50 78 44 / 10 0 0 0 40 50
Wenatchee 73 49 78 53 72 44 / 0 0 0 0 50 50
Omak 72 43 78 46 76 44 / 10 10 0 0 70 90
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 191638
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
938 AM PDT SUN MAY 19 2013
.SYNOPSIS...AN UPPER RIDGE WILL BUILD INTO THE REGION TODAY...THEN
CROSS THE AREA ON MONDAY MORNING...FOR WARMER AND DRIER WEATHER. A
LARGE UPPER LOW WILL DROP INTO THE AREA ON TUESDAY AND REMAIN OVER
THE REGION THROUGH THE REMAINDER OF THE WEEK FOR SHOWERY WEATHER AND
BELOW NORMAL TEMPERATURES.
&&
.SHORT TERM...HAVE ALREADY UPDATE THE FIRST PERIOD FORECAST TO ADD
20-40 POPS TO THE PUGET SOUND LOWLANDS DUE TO ONGOING LIGHT SHOWERS
AND SPRINKLES MOVING SOUTH FROM ADMIRALTY INLET. WITH A NORTHERLY
SFC BREEZE AND A SUBSIDENCE INVERSION ARND 8000 FEET TODAY...EXPECT
THE LOWLAND SHOWERS TO DISSIPATE THIS AFTN. LOOKING FOR CLEARING TO
DEVELOP OVER THE INLAND WATERS THIS AFTN...WITH SUNNIER SKIES
SPREADING OUT OVER LAND AREAS THIS AFTN. WITH ONSHORE FLOW AND
SHALLOW INSTABILITY BENEATH THE SUBSIDENCE INVERSION...WOULD EXPECT
SHOWERS OR SPRINKLES TO CONTINUE THROUGH THIS AFTN OVER THE
CASCADES...FOOTHILLS...AND AROUND THE PERIMETER OF THE OLYMPICS.
AN UPPER RIDGE AXIS WILL CONTINUE TO BUILD INTO WRN WA TONIGHT. THE
RIDGE AXIS SHOULD MOVE ACROSS WRN WA DURING THE OVERNIGHT HOURS.
WITH CLEAR SKIES TONIGHT...EXPECT COOL TEMPS. SHOULD BE A FEW COLD
POCKET LOCATIONS...SUCH AS KOLM...DOWN INTO THE UPPER 30S TONIGHT.
ON MONDAY...THE RIDGE AXIS WILL BE EAST OF THE CASCADES...AND AN
UPPER TROUGH WILL DIG AND AMPLIFY OUT AROUND 135W-140W. WITH
OFFSHORE LOW PRESSURE EASING THE ONSHORE PRESSURE GRADIENT...AND
LIGHT SOUTHERLY FLOW AT 850 MB...MON SHOULD BE ONE OF THOSE WARM AND
DRY DAY IN ADVANCE OF TUESDAY`S STRONG COLD FRONT.
SPEAKING OF TUE...THE OFFSHORE UPPER TROUGH WILL ADVANCE EAST BTWN
130W AND THE COAST AND THEN BECOME A CUTOFF LOW THAT SINKS SE OFF
THE WA AND ORE COASTS. A STRONG COLD FRONT WILL PUSH ONSHORE AND
INLAND ON TUE MRNG. THE FRONT WILL BE ACCOMPANIED BY A BAND OF
RAIN...THEN FOLLOWED BY CONVECTIVE SHOWERS ON TUE AFTN AND EVNG. IN
TYPICAL FASHION...SHOWERS WILL FOCUS ON WINDWARD SIDE OF MTNS AND IN
THE PUGET SOUND CONVERGENCE ZONE. AN UNSEASONABLY COOL AIR MASS WILL
FOLLOW THE FRONT...WITH 850 MB TEMPS DOWN IN THE -1C TO +1C RANGE BY
TUE EVNG. THIS WILL LOWER SNOW LEVELS AS LOW AS 3000 FEET AT SUNRISE
ON WED MORNING. A FEW INCHES OF SNOW ARE EXPECTED AT THE HIGHER
HIGHWAY PASSES WHICH HAVE ALREADY OPENED FOR THE SUMMER...INCLUDING
CHINOOK PASS. HANER
.LONG TERM...FROM PREVIOUS DISCUSSION...AS THE CASE HAS BEEN FOR
SOME TIME NOW...THE MODELS CONTINUE TO BE AT ODDS WITH THE EVOLUTION
OF THE TROUGH FROM THURSDAY ON THROUGH THE HOLIDAY WEEKEND. THERE
ARE LIKELY TO BE SOME DRY PERIODS AT TIMES...BUT A SERIES OF
DISTURBANCES ROTATING THROUGH THE TROUGH WILL BRINGS SHOWERS OR
PERHAPS A STEADY LIGHT RAIN. HEIGHTS DO RECOVER SOME...SO
TEMPERATURES SHOULD MODERATE WITH TIME. THE 00Z RUN OF THE GFS TAKES
MUCH OF THE TROUGHS ENERGY AND PRECIP INTO THE CANADIAN ROCKIES BY
NEXT WEEKEND...WHILE THE 00Z EURO KEEPS THE TROUGH CENTERED RIGHT
OVER WASHINGTON STATE WITH AREAS OF PRECIP SPREADING INTO THE REGION
FROM THE EAST AT TIMES. DETAILS ARE NEARLY IMPOSSIBLE TO PUT ANY
REAL CONFIDENCE IN FOR THE HOLIDAY WEEKEND...BUT THE TREND OF COOLER
THAN NORMAL TEMPERATURES AND A CHANCE OF SHOWERS AT TIMES LOOKS LIKE
A GOOD FORECAST. 27
&&
.AVIATION...THE FLOW ALOFT WILL REMAIN NORTHWESTERLY TODAY WITH HIGH
PRESSURE OFFSHORE. THERE WERE SCATTERED SHOWERS POPPING UP IN THE
EASTERN STRAIT OF JUAN DE FUCA AREA DRIFTING SSE ACROSS PORT
TOWNSEND AND DOWN ADMIRALTY INLET...BUT THE SHOWERS SHOULD END LATER
THIS MORNING WITH MORE CLEARING INTO THE AFTERNOON. AREAS OF MORNING
CLOUDS SHOULD LIFT TO MAINLY SCATTERED CU THIS AFTERNOON...ALTHOUGH
A FEW AREAS OF BROKEN CLOUDS MAY PERSIST NEAR THE MOUNTAINS. SKIES
SHOULD BE MOSTLY CLEAR TONIGHT.
KSEA...MORNING CLOUDS THEN INCREASING SUN IN THE AFTERNOON. A FEW OF
THE SHOWERS COMING DOWN ADMIRALTY INLET MAY WORK INTO THE METRO AREA
THIS MORNING. NLY BREEZE.
&&
.MARINE...HIGH PRES OVER THE NE PACIFIC WILL MAINTAIN NORTHWESTERLY
FLOW ACROSS WESTERN WA TODAY AND MON. A SMALL CRAFT ADVISORY IS IN
EFFECT FOR THE CENTRAL AND EAST STRAIT OF JUAN DE FUCA THROUGH
TONIGHT AND I HAVE ADDED ONE FOR THE TWO NORTHERNMOST OUTER COASTAL
ZONES SINCE THERE IS A SHIP REPORT OUT THERE WITH NW 25KT WIND. THE
NW WIND MAY INCREASE AND WORK TOWARD THE COASTLINE LATER TODAY AND I
WOULD NOT BE SURPRISED TO HAVE TO PUT UP AN ADVISORY FOR ALL OF THE
COASTAL WATERS WITH THE AFTERNOON FORECAST PACKAGE.
A FRONTAL SYSTEM WILL TRACK OVER THE OFFSHORE WATERS MON
NIGHT...THEN SHIFT SOUTH AND MOVE INLAND OVER OREGON OR NORTHERN CA
TUE MORNING. MODELS SHOW A SOUTHWEST PUSH TUE NIGHT AS THIS SYSTEM
MOVES FARTHER INLAND AND WEAKENS. THE FLOW WILL REMAIN ONSHORE
THROUGH AT LEAST MIDWEEK.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY OUTER COASTAL WATERS FROM CAPE FLATTERY TO
POINT GRENVILLE...AND THE CENTRAL AND EAST STRAIT OF JUAN DE FUCA.
&&
$$
000
FXUS66 KPQR 191615
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
914 AM PDT SUN MAY 19 2013
.SYNOPSIS...CLOUDS AND SCATTERED SHOWERS WILL GRADUALLY DECREASE
TODAY AS HIGH PRESSURE BUILDS INTO THE PACIFIC NORTHWEST. MORE
SUNBREAKS THIS AFTERNOON SHOULD LEAD TO MORE SEASONABLE TEMPERATURES
ESPECIALLY FOR THE LOWLANDS. THE HIGH PRESSURE WILL BE STRONGEST OVER
THE AREA MONDAY...LEADING TO A SUNNY AND WARM DAY. HIGH CLOUDS FROM
OUR NEXT SYSTEM WILL BEGIN TO INCREASE LATER MONDAY AND MONDAY NIGHT
EVENTUALLY LEADING TO SOME RAIN BY TUESDAY. THIS SYSTEM WILL COME
WITH A SHARP DROP IN TEMPERATURES AND SNOW LEVELS...WITH COOL AND
UNSETTLED WEATHER THEN LIKELY TO CONTINUE FOR THE REST OF THE WEEK.
&&
.SHORT TERM...TODAY THROUGH WEDNESDAY...OBSERVATIONS AND RADAR
IMAGERY STILL INDICATE A FEW SHOWERS DOTTING THE FORECAST AREA...
MAINLY OVER THE CASCADES. VISIBLE SATELLITE IS BEGINNING TO SHOW SOME
CLEARING OVER THE TUALATIN VALLEY AND WESTERN PORTIONS OF THE
WILLAMETTE AS WELL. THIS LIKELY DUE TO INCREASED ONSHORE FLOW AND
DOWNSLOPING ON THE EAST SIDE OF THE COAST RANGE. THIS OVERALL PATTERN
WILL CONTINUE THROUGH THE DAY...WITH HIGH PRESSURE BUILDING IN CLOUD
COVER WILL GRADUALLY DECREASE WITH THE WEST HALF OF THE WILLAMETTE
VALLEY AND THE HOOD RIVER VALLEY BEING THE SUNNIEST. WITH THE
INCREASE IN SUNSHINE TEMPS SHOULD COME CLOSER TO SEASONAL NORMS...
WITH MID TO UPPER 60S.
MAIN CHANGE TO THE MORNING FCST WAS TO HANG ON TO THE CLOUD COVER
OVER THE HIGHER TERRAIN A LITTLE LONGER...BUT OTHERWISE THE FORECAST
LOOKS TO BE IN GOOD SHAPE. REMAINDER OF SHORT/LONG TERM DISCUSSION IS
FROM THE PREVIOUS SHIFT AND STILL VALID... WEAGLE
MONDAY WILL BE THE SUNNIEST AND WARMEST DAY OF THE WORK WEEK WITH
HIGH PRESSURE REMAINING OVER THE AREA. MODELED 850MB TEMPERATURES
SUGGEST DAYTIME HIGHS WILL WARM A FEW DEGREES ABOVE NORMAL MONDAY.
A SIGNIFICANT CHANGE IN WEATHER IS EXPECTED TUESDAY AS AN
UNSEASONABLY DEEP AND COLD UPPER LOW WILL MOVE OVER THE REGION. THIS
LOW WILL RETURN RAIN ON TUESDAY...WITH SNOW LEVELS LOWERING TO THE
CASCADE PASSES TUESDAY NIGHT. WEDNESDAY WILL BE THE COOLEST DAY OF
THE WEEK WITH THE UPPER LOW CONTINUING RAIN AND MOUNTAIN SNOW
SHOWERS. INSTABILITY WILL RESULT IN ENHANCED SHOWERS IN THE
AFTERNOONS TUESDAY AND WEDNESDAY WITH SOME OF THE HEAVIER SHOWERS
CONTAINING SMALL HAIL. QPF AND CORRESPONDINGLY SNOW AMOUNTS ARE
DIFFICULT TO FORECAST FOR THESE TYPE OF LOANS.
CURRENTLY MODELS SUGGEST THAT SNOW AMOUNTS WILL REMAIN BELOW ADVISORY
CRITERIA...BUT CONVECTIVE SHOWERS TEND TO PRODUCE MORE THAN EXPECTED
PRECIPITATION. FORECASTING WHERE THE SHOWERS WILL BE THE MOST
CONSISTENT AND LIKELY HAVE THE HIGHER ACCUMULATIONS ADDS ANOTHER
CHALLENGE TO THE FORECAST. THE CURRENT FORECAST IS FOR NON-ADVISORY
SNOW...BUT WOULD NOT BE SURPRISED IF THIS CHANGES AS WE HAVE MORE
CONSISTENT MODEL DATA THE NEXT COUPLE OF DAYS.
.LONG TERM...WEDNESDAY EVENING THROUGH SATURDAY. CLOSED LOW PRESSURE
SYSTEM WILL LINGER OVER THE PAC NW THROUGH AT LEAST FRIDAY. EXPECT A
MORE DIURNAL TREND OF THE SHOWERS THURSDAY AND FRIDAY WITH LESS
SHOWERS AND POSSIBLE SUN BREAKS IN THE MORNINGS WITH SHOWER
ENHANCEMENT IN THE AFTERNOONS...ESPECIALLY FOR THE HIGHER TERRAIN.
TEMPERATURES WILL REMAIN BELOW THE SEASONAL NORMAL. MODELS ARE COMING
INTO BETTER AGREEMENT ON THE LOW MOVING EAST OF THE AREA FRIDAY
EVENING. DESPITE THE DEPARTURE OF THIS LOW...GENERAL LOW PRESSURE
WILL REMAIN OVER THE AREA AND CONTINUE SHOWERY AND
COOL CONDITIONS THROUGH MEMORIAL DAY WEEKEND.
&&
.AVIATION...MOIST AIR MASS MAINTAINS MVFR AND VFR CEILINGS THIS
MORNING. EXPECT CLOUDS TO GRADUALLY BREAK UP CLOSER TO 19Z...WITH
PREDOMINANTLY VFR CONDITIONS CONTINUING THROUGH THIS EVENING. HIGH
PRESSURE STRENGTHENS OVERNIGHT...WITH SOLID VFR EXPECTED THROUGH
MON.
KPDX AND APPROACHES...MVFR CEILINGS PERSISTS THROUGH 19Z/20Z THIS
MORNING...THEN EXPECT VFR CONDITIONS THROUGH TONIGHT AND MONDAY.
BKN CLOUD DECK AROUND 5K WILL LIKELY LINGER THROUGH THIS EVENING.
/27
&&
.MARINE...HIGH PRES OVER THE NE PAC WILL CONTINUE TO STRENGTHEN
TODAY AND TONIGHT...WITH N TO NW WINDS. THESE WINDS WILL INCREASE
AS PRES GRADIENTS TIGHTEN THROUGH MON...WITH WIND GUSTS TO 25 KT S
OF NEWPORT IN AFTERNOON/EVENINGS. WILL MAINTAIN SMALL CRAFT
ADVISORY FOR CENTRAL OREGON COASTAL WATERS FOR SUCH WINDS FROM
THIS AFTERNOON THROUGH MON EVENING. WINDS WEAKER TO THE N...BUT
COULD GET A BIT GUSTY ON MON.
SEAS HOLDING AT 4 TO 6 FT THROUGH TUE...THOUGH MAY GET BIT CHOPPY
WITH BRISK NW WINDS AT TIMES...MAINLY S OF CASCADE HEAD.
QUESTIONABLE WEATHER FOR MIDDLE OF NEXT WEEK. MODELS INDICATE
LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING BY WED AND THU. THIS IS
DUE TO MODELS SPINNING UP ANOTHER RATHER TIGHT LOW PRES OFF THE
OREGON COAST ON TUE AND WED. NOT CONVINCED THIS WILL PAN OUT AS
MODELS SUGGEST...SO WILL TREND CLOSER TO 10 FT AND WAIT FOR FURTHER
CONSISTENCY IN MODEL DATA BEFORE BITING.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO MIDNIGHT PDT
MONDAY NIGHT FOR COASTAL WATERS FROM CASCADE HEAD TO FLORENCE
OUT 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 191136
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
436 AM PDT Sun May 19 2013
.SYNOPSIS...
Another day of seasonably mild conditions are expected today with a
few mountain showers and possible thunderstorms. Monday will be a
dry and mild break period before a strong storm system enters the
region on Tuesday with a chance of showers and thunderstorms.
Showery and unseasonably cool conditions will envelop the region
from mid-week onward.
&&
.DISCUSSION...
Today and tonight...As longwave trof axis moves east ridging
moving in from the west will get within closer proximity to
Eastern Washington and Northern Idaho thus some decrease in
instability should result. Since the extreme western edge of the
trof is still close enough to influence the forecast area and
many short term model runs such as the HRRR depict some rotation
associated with the weak convection generated the idea is that
majority of the convection is of the elevated forced variety
rather than surface based type...especially when one considers
how much cloud cover is remaining in place which makes it much
much more difficult for surface based convection to initiate.
However since there is riding approaching from the west and getting
closer the drop in pops and precipitation amounts to near zero
after midnight remain a valid course of action. Forecast temps
given this trof remain just a sliver on the cool side of what
would be considered normal for this time of year. /Pelatti
Monday and Monday night...A relatively benign and quiet period
will prevail on Monday and Monday night as a weak upper level
ridge pops up over the region in advance of a deep upper level low
scheduled to arrive on or about Tuesday/Wednesday. thus...Monday
will probably be the last reasonably pleasant and dry day for the
region.
On Tuesday latest models are in good agreement and reasonably
consistent in digging a deep upper level low pressure out of the
Gulf of Alaska and placing it off the northwest coast by
afternoon. This will put the forecast area under a moist southerly
difluent flow on the east flank of this upper feature. This is a
showery and thundery pattern for the region...and while details
regarding actual frontal placement and deep instability are
uncertain at this time...confidence is growing that Tuesday will
be an increasingly active day of general deterioration from west
to east...with high temperatures over the east actually increasing
over Monday`s highs in a warm advective southerly flow
scenario...while over the west an onset of showers during the day
will moderate temperatures. The main thunder threat on Tuesday
will likely be over the east near the exiting thermal trough and
concentrated in the afternoon and evening hours.
From Tuesday night through Friday there is uncommonly good model
agreement...repeated over numerous run now and thus inspiring high
confidence...that the aforementioned deep closed low will take up
residence over or very near the forecast area. This will promote a
return to a cooler and showery pattern more like early April than
late May. Wednesday appears at this time to be the wettest
day...with the main tough baroclinic zone and surface cold front
efficiently enhancing available moisture into widespread showers
over most of the region. There is high confidecne that Thursday
and Friday will also be showery and cool...but the nature of the
showers will be more hit-and-miss with smaller areal extent than
Wednesday. Snow levels will likely drop down to the 4000 to 5000
foot range on average...4kft at night and 5kft during the day.
In summary...at this time there is high confidecne that Monday
will be dry and mild and Tuesday active and potentially
thundery. There is high confidence that Wednesday through Friday
will be cool and showery...with the best chance of very showery or
downright rainy conditions on Wednesday. /Fugazzi
Friday Night through Saturday Night: The unsettled weather pattern
looks to continue for the Inland NW. The low will remain almost
stationary given current model runs throughout the period which
will continue to pump Pacific moisture into the region. Given the
placement of the low and the increased cloud cover our daytime
high temperatures will not be able to reach potential maximums
keeping us a few degrees below normal and lows will follow the
same trend. Concerning the potential for rainfall in this pattern
I followed the same idea as the day shift with above climo POPs but
did increase a little for the NE Mtns of WA and the Mtns of the ID
Panhandle given the orientation of how the moisture will flow into
the region. Current models look to keep most of the heavier more
consistent rain north of the border in BC and lesser amounts in
the areas mentioned above. Given the location of the precip we
will have to continue to monitor the rivers and streams around the
region especially basins that receive contributions from the
areas of BC that will likely see more precip. Precip patterns and
amounts will continue to be refined as we push closer to this time
frame...but in general we can say the forecast will include below
normal temps with cloudy skies and an increased chance for precip.
/Fliehman
&&
.AVIATION...
12z TAFS: Weak low pressure gradualy moves east and allows for
an improvement as far as less clouds and drier conditions near
6Z Monday and beyond. Otherwise considerable mid level cloud cover
and some spotty shower activity remains but VFR conditions still
prevail. /Pelatti
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 66 46 72 52 76 42 / 20 10 0 0 20 50
Coeur d`Alene 65 44 71 47 77 42 / 30 20 0 0 20 60
Pullman 63 42 71 47 77 40 / 20 10 0 0 10 60
Lewiston 68 49 78 53 83 47 / 20 10 0 0 10 50
Colville 72 43 77 45 80 43 / 20 20 10 10 40 60
Sandpoint 65 42 72 44 77 41 / 50 30 10 0 30 70
Kellogg 60 46 70 50 76 41 / 40 30 10 0 20 60
Moses Lake 76 46 80 50 78 44 / 10 0 0 0 30 50
Wenatchee 73 49 78 53 72 44 / 0 0 0 0 40 50
Omak 74 43 78 46 76 44 / 10 10 0 0 50 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KPQR 190947
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
246 AM PDT SUN MAY 19 2013
.SYNOPSIS...SHOWERS WILL DECREASE THIS MORNING AS A WEAK
WEATHER SYSTEM MOVES EAST OF THE AREA AND HIGH PRESSURE BUILDS. MORE
SUNBREAKS SUNDAY AFTERNOON SHOULD LEAD TO MORE SEASONABLE
TEMPERATURES. HIGH PRESSURE WILL HOLD OVER THE AREA MONDAY WHICH WILL
BE SUNNY AND WARM. HIGH CLOUDS WILL BEGIN TO INCREASE FROM THE
NORTHWEST MONDAY EVENING IN ADVANCE OF THE NEXT SYSTEM...WHICH WILL
BRING A DRAMATIC CHANGE BACK TO CHILLY AND UNSETTLED WEATHER TUESDAY
THROUGH FRIDAY.
&&
.SHORT TERM...RADAR IMAGERY SHOWS SHOWERS ACROSS NW OREGON EARLY THIS
MORNING AS AN UPPER LEVEL SHORTWAVE TROUGH MOVES OVER THE REGION.
THIS WAVE WILL MOVE EAST OF THE CASCADES AROUND SUNRISE AND HIGH
PRESSURE WILL BUILD OVER THE AREA. THE SHOWERS WILL BE MOSTLY
CONFINED TO THE COAST RANGE AND THE CASCADES AFTER SUNRISE...THEN
DISSIPATE IN THE AFTERNOON. CLEARING THIS AFTERNOON WILL RESULT IN
MORE SUNSHINE AND INLAND TEMPERATURES SHOULD WARM TO THE MID AND
UPPER 60S.
MONDAY WILL BE THE SUNNIEST AND WARMEST DAY OF THE WORK WEEK WITH
HIGH PRESSURE REMAINING OVER THE AREA. MODELED 850MB TEMPERATURES
SUGGEST DAYTIME HIGHS WILL WARM A FEW DEGREES ABOVE NORMAL MONDAY.
A SIGNIFICANT CHANGE IN WEATHER IS EXPECTED TUESDAY AS AN
UNSEASONABLY DEEP AND COLD UPPER LOW WILL MOVE OVER THE REGION. THIS
LOW WILL RETURN RAIN ON TUESDAY...WITH SNOW LEVELS LOWERING TO THE
CASCADE PASSES TUESDAY NIGHT. WEDNESDAY WILL BE THE COOLEST DAY OF
THE WEEK WITH THE UPPER LOW CONTINUING RAIN AND MOUNTAIN SNOW
SHOWERS. INSTABILITY WILL RESULT IN ENHANCED SHOWERS IN THE
AFTERNOONS TUESDAY AND WEDNESDAY WITH SOME OF THE HEAVIER SHOWERS
CONTAINING SMALL HAIL. QPF AND CORRESPONDINGLY SNOW AMOUNTS ARE
DIFFICULT TO FORECAST FOR THESE TYPE OF LOANS.
CURRENTLY MODELS SUGGEST THAT SNOW AMOUNTS WILL REMAIN BELOW ADVISORY
CRITERIA...BUT CONVECTIVE SHOWERS TEND TO PRODUCE MORE THAN EXPECTED
PRECIPITATION. FORECASTING WHERE THE SHOWERS WILL BE THE MOST
CONSISTENT AND LIKELY HAVE THE HIGHER ACCUMULATIONS ADDS ANOTHER
CHALLENGE TO THE FORECAST. THE CURRENT FORECAST IS FOR NON-ADVISORY
SNOW...BUT WOULD NOT BE SURPRISED IF THIS CHANGES AS WE HAVE MORE
CONSISTENT MODEL DATA THE NEXT COUPLE OF DAYS.
.LONG TERM...WEDNESDAY EVENING THROUGH SATURDAY. CLOSED LOW PRESSURE
SYSTEM WILL LINGER OVER THE PAC NW THROUGH AT LEAST FRIDAY. EXPECT A
MORE DIURNAL TREND OF THE SHOWERS THURSDAY AND FRIDAY WITH LESS
SHOWERS AND POSSIBLE SUN BREAKS IN THE MORNINGS WITH SHOWER
ENHANCEMENT IN THE AFTERNOONS...ESPECIALLY FOR THE HIGHER TERRAIN.
TEMPERATURES WILL REMAIN BELOW THE SEASONAL NORMAL. MODELS ARE COMING
INTO BETTER AGREEMENT ON THE LOW MOVING EAST OF THE AREA FRIDAY
EVENING. DESPITE THE DEPARTURE OF THIS LOW...GENERAL LOW PRESSURE
WILL REMAIN OVER THE AREA AND CONTINUE SHOWERY AND
COOL CONDITIONS THROUGH MEMORIAL DAY WEEKEND.
&&
.AVIATION...RATHER MOIST AIR MASS ACROSS THE REGION THIS MORNING
WITH A MIX OF VFR AND MVFR CEILINGS. LITTLE CHANGE EXPECTED
THROUGH THE MORNING. WILL LIKELY SEE WIDESPREAD MVFR CEILINGS
BEFORE SUNRISE...THEN GRADUALLY BREAKUP OF CLOUDS AFTER 18Z AS
FLOW TURNS MORE N TO NWLY.
KPDX AND APPROACHES...MVFR CEILINGS WILL LIKELY FORM BY 12Z...AND
PERSIST THROUGH MUCH OF THE MORNING. LOCAL GUIDANCE SUGGESTS A
RETURN OF VFR CONDITIONS AROUND 19Z TO 20Z SUN. WILL MAINTAIN
THIS TREND IN THE 12Z TAFS.
&&
.MARINE...HIGH PRES OVER THE NE PAC WILL STRENGTHEN TONIGHT AND
SUN...WITH N TO NW WINDS. THESE WINDS WILL INCREASE AS PRES
GRADIENTS TIGHTEN SUN AND MON...WITH WIND GUSTS TO 25 KT S OF
NEWPORT IN AFTERNOON/EVENINGS. WILL MAINTAIN SMALL CRAFT ADVISORY
FOR CENTRAL OREGON COASTAL WATERS FOR SUCH WINDS FROM SUN
AFTERNOON THROUGH MON EVENING. WINDS WEAKER TO THE N...BUT COULD
GET A BIT GUSTY ON MON.
SEAS HOLDING AT 4 TO 6 FT THROUGH TUE...THOUGH MAY GET BIT CHOPPY
WITH BRISK NW WINDS AT TIMES...MAINLY S OF CASCADE HEAD.
QUESTIONABLE WEATHER FOR MIDDLE OF NEXT WEEK. MODELS INDICATE
LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING BY WED AND THU. THIS IS
DUE TO MODELS SPINNING UP ANOTHER RATHER TIGHT LOW PRES OFF THE
OREGON COAST ON TUE AND WED. NOT CONVINCED THIS WILL PAN OUT AS
MODELS SUGGEST...SO WILL TREND CLOSER TO 10 FT AND WAIT FOR FURTHER
CONSISTENCY IN MODEL DATA BEFORE BITING.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO MIDNIGHT PDT
MONDAY NIGHT FOR COASTAL WATERS FROM CASCADE HEAD TO
FLORENCE OR OUT 10 NM-WATERS FROM CASCADE HEAD TO FLORENCE
OR FROM 10 TO 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 190945
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
245 AM PDT SUN MAY 19 2013
.SYNOPSIS...AN UPPER RIDGE WILL BUILD INTO THE REGION TODAY...THEN
CROSS THE AREA ON MONDAY...FOR WARMER AND DRIER WEATHER. A LARGE
UPPER LOW WILL DROP INTO THE AREA ON TUESDAY AND REMAIN OVER THE
REGION THROUGH THE REMAINDER OF THE WEEK FOR SHOWERY WEATHER AND
BELOW NORMAL TEMPERATURES.
&&
.SHORT TERM...AN UPPER LEVEL TROUGH AXIS HAS SHIFTED EAST OF THE
CASCADES OVERNIGHT. THE FLOW ALOFT HAS TURNED NORTHWESTERLY AS UPPER
LEVEL RIDGING BEGINS TO BUILD INTO THE REGION TODAY. SURFACE OBS AND
RADAR SHOW THAT SHOWER ACTIVITY OVER THE LOWLANDS HAS PRETTY MUCH
ENDED. I HAVE REMOVED THE SHOWER CHANCE WORDING FOR EVERYWHERE BUT
THE MOUNTAINS THIS MORNING. WITH RISING HEIGHTS AND SOME MODEST
WARMING IN THE LOWER LEVELS...HIGH TEMPERATURES TODAY SHOULD BE
GENERALLY RIGHT AROUND NORMAL. A FEW DECKS OF STRATOCUMULUS AROUND
THE REGION THIS MORNING SHOULD BREAK UP AS SUBSIDENCE TAKES OVER FOR
A PARTLY SUNNY DAY AHEAD. THE UPPER LEVEL RIDGE AXIS WILL BE
OVERHEAD THIS EVENING...THEN SHIFT EAST OF CASCADES MONDAY MORNING.
SURFACE GRADIENTS BECOME WEAK NORTH OR NORTHEASTERLY TONIGHT AND
EARLY MONDAY. THIS ALONG WITH SOME ADDITIONAL WARMING IN LOWER
LEVELS...AROUND 3C OR SO AT 850 MILLIBARS...TRANSLATES TO WARMER
TEMPERATURES FOR MONDAY. SOME HIGH CLOUDINESS AHEAD OF THE NEXT
SYSTEM MAY BE ON THE INCREASE LATE IN THE DAY...BUT HIGH
TEMPERATURES SHOULD BE A LITTLE ABOVE NORMAL FOR A SINGLE DAY THIS
WEEK. SPOTS FROM SEATTLE SOUTHWARD IN THE INTERIOR SHOULD BE IN THE
LOWER 70S.
THE MODELS CONTINUE THE SLOWER TREND WITH THE ARRIVAL OF THE NEXT
SYSTEM. THE COAST WILL SEE A CHANCE OF RAIN MONDAY EVENING...BUT
INTERIOR AREAS SHOULD REMAIN DRY. CLOUDS WILL INCREASE MONDAY NIGHT
WITH RAIN SPREADING INLAND ACROSS WESTERN WASHINGTON EARLY TUESDAY
MORNING. THE COLD FRONT SHOULD BE MOVING THROUGH THE PUGET SOUND
AREA BY MIDDAY. THIS WILL USHER IN A MUCH COOLER AIR MASS...WITH
SNOW LEVELS FALLING THROUGH THE DAY FROM ABOVE 6000 FEET EARLY TO
NEAR 3000 FEET BY LATE TUESDAY NIGHT OR WEDNESDAY MORNING. THIS WILL
BEGIN AN EXTENDED PERIOD OF UNSETTLED CONDITIONS AS A BROAD UPPER
LEVEL TROUGH TAKES UP RESIDENCE OVER THE WEST COAST THROUGH THE
EXTENDED FORECAST PERIOD.
.LONG TERM...AS THE CASE HAS BEEN FOR SOME TIME NOW...THE MODELS
CONTINUE TO BE AT ODDS WITH THE EVOLUTION OF THE TROUGH FROM
THURSDAY ON THROUGH THE HOLIDAY WEEKEND. THERE ARE LIKELY TO BE SOME
DRY PERIODS AT TIMES...BUT A SERIES OF DISTURBANCES ROTATING THROUGH
THE TROUGH WILL BRINGS SHOWERS OR PERHAPS A STEADY LIGHT RAIN.
HEIGHTS DO RECOVER SOME...SO TEMPERATURES SHOULD MODERATE WITH TIME.
THE 00Z RUN OF THE GFS TAKES MUCH OF THE TROUGHS ENERGY AND PRECIP
INTO THE CANADIAN ROCKIES BY NEXT WEEKEND...WHILE THE 00Z EURO KEEPS
THE TROUGH CENTERED RIGHT OVER WASHINGTON STATE WITH AREAS OF PRECIP
SPREADING INTO THE REGION FROM THE EAST AT TIMES. DETAILS ARE NEARLY
IMPOSSIBLE TO PUT ANY REAL CONFIDENCE IN FOR THE HOLIDAY
WEEKEND...BUT THE TREND OF COOLER THAN NORMAL TEMPERATURES AND A
CHANCE OF SHOWERS AT TIMES LOOKS LIKE A GOOD FORECAST. 27
&&
.AVIATION...THE FLOW ALOFT WILL REMAIN NORTHWESTERLY TODAY WITH HIGH
PRES OFFSHORE. ACROSS WESTERN WA...A FEW LIGHT SHOWERS REMAIN OVER
THE CASCADES THIS MORNING. THE LOW LEVEL AIR MASS IS MOIST WITH A
MIXED BAG OF CEILINGS - FROM MVFR TO BASES AROUND 7000 FT. LOW
CLOUDS WILL LIFT AND SCATTER THIS AFTERNOON WITH VFR CONDITIONS
EXPECTED. 33
KSEA...VFR CONDITIONS WILL PREVAIL TODAY. LIGHT/VARIABLE WIND WILL
BECOME NORTHERLY THIS AFTERNOON. 33
&&
.MARINE...HIGH PRES OVER THE NE PACIFIC WILL MAINTAIN NORTHWESTERLY
FLOW ACROSS WESTERN WA TODAY AND MON. A SMALL CRAFT ADVISORY IS IN
EFFECT FOR THE CENTRAL AND EAST STRAIT OF JUAN DE FUCA THROUGH
TONIGHT. A FRONTAL SYSTEM WILL TRACK OVER THE OFFSHORE WATERS MON
NIGHT...THEN SHIFT SOUTH AND MOVE INLAND OVER OREGON OR NORTHERN CA
TUE MORNING. THE ECMWF...NAM AND CANADIAN SHOW SIMILAR TRACKS.
MODELS SHOW A SOUTHWEST PUSH TUE NIGHT AS THIS SYSTEM MOVES FARTHER
INLAND AND WEAKENS. THE FLOW WILL REMAIN ONSHORE THROUGH AT LEAST
MIDWEEK. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KOTX 190917
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
217 AM PDT Sun May 19 2013
.SYNOPSIS...
Another day of seasonably mild conditions are expected today with a
few mountain showers and possible thunderstorms. Monday will be a
dry and mild break period before a strong storm system enters the
region on Tuesday with a chance of showers and thunderstorms.
Showery and unseasonably cool conditions will envelop the region
from mid-week onward.
&&
.DISCUSSION...
Today and tonight...As longwave trof axis moves east ridging
moving in from the west will get within closer proximity to
Eastern Washington and Northern Idaho thus some decrease in
instability should result. Since the extreme western edge of the
trof is still close enough to influence the forecast area and
many short term model runs such as the HRRR depict some rotation
associated with the weak convection generated the idea is that
majority of the convection is of the elevated forced variety
rather than surface based type...especially when one considers
how much cloud cover is remaining in place which makes it much
much more difficult for surface based convection to initiate.
However since there is riding approaching from the west and getting
closer the drop in pops and precipitation amounts to near zero
after midnight remain a valid course of action. Forecast temps
given this trof remain just a sliver on the cool side of what
would be considered normal for this time of year. /Pelatti
Monday and Monday night...A relatively benign and quiet period
will prevail on Monday and Monday night as a weak upper level
ridge pops up over the region in advance of a deep upper level low
scheduled to arrive on or about Tuesday/Wednesday. thus...Monday
will probably be the last reasonably pleasant and dry day for the
region.
On Tuesday latest models are in good agreement and reasonably
consistent in digging a deep upper level low pressure out of the
Gulf of Alaska and placing it off the northwest coast by
afternoon. This will put the forecast area under a moist southerly
difluent flow on the east flank of this upper feature. This is a
showery and thundery pattern for the region...and while details
regarding actual frontal placement and deep instability are
uncertain at this time...confidence is growing that Tuesday will
be an increasingly active day of general deterioration from west
to east...with high temperatures over the east actually increasing
over Monday`s highs in a warm advective southerly flow
scenario...while over the west an onset of showers during the day
will moderate temperatures. The main thunder threat on Tuesday
will likely be over the east near the exiting thermal trough and
concentrated in the afternoon and evening hours.
From Tuesday night through Friday there is uncommonly good model
agreement...repeated over numerous run now and thus inspiring high
confidence...that the aforementioned deep closed low will take up
residence over or very near the forecast area. This will promote a
return to a cooler and showery pattern more like early April than
late May. Wednesday appears at this time to be the wettest
day...with the main tough baroclinic zone and surface cold front
efficiently enhancing available moisture into widespread showers
over most of the region. There is high confidecne that Thursday
and Friday will also be showery and cool...but the nature of the
showers will be more hit-and-miss with smaller areal extent than
Wednesday. Snow levels will likely drop down to the 4000 to 5000
foot range on average...4kft at night and 5kft during the day.
In summary...at this time there is high confidecne that Monday
will be dry and mild and Tuesday active and potentially
thundery. There is high confidence that Wednesday through Friday
will be cool and showery...with the best chance of very showery or
downright rainy conditions on Wednesday. /Fugazzi
Friday Night through Saturday Night: The unsettled weather pattern
looks to continue for the Inland NW. The low will remain almost
stationary given current model runs throughout the period which
will continue to pump Pacific moisture into the region. Given the
placement of the low and the increased cloud cover our daytime
high temperatures will not be able to reach potential maximums
keeping us a few degrees below normal and lows will follow the
same trend. Concerning the potential for rainfall in this pattern
I followed the same idea as the day shift with above climo POPs but
did increase a little for the NE Mtns of WA and the Mtns of the ID
Panhandle given the orientation of how the moisture will flow into
the region. Current models look to keep most of the heavier more
consistent rain north of the border in BC and lesser amounts in
the areas mentioned above. Given the location of the precip we
will have to continue to monitor the rivers and streams around the
region especially basins that receive contributions from the
areas of BC that will likely see more precip. Precip patterns and
amounts will continue to be refined as we push closer to this time
frame...but in general we can say the forecast will include below
normal temps with cloudy skies and an increased chance for precip.
/Fliehman
&&
.AVIATION...
06z TAFS: Mostly cloud skies are expected over the region through
tonight with showers remaining confined mainly across the northern
mountains. Some stratus may begin to develop in the Spokane/Coeur
d`Alene areas tonight as the boundary layer remains moist, but
confidence is low as thick mid level cloud cover may not result in
enough cooling tonight lower in the atmosphere for stratus
development. Mountain showers are expected to develop through
Sunday afternoon, which may push south off the northern mountains
into KGEG, KSFF and KCOE with -RA possible. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 66 46 72 52 76 42 / 20 10 0 0 20 50
Coeur d`Alene 65 44 71 47 77 42 / 30 20 0 0 20 60
Pullman 63 42 71 47 77 40 / 20 10 0 0 10 60
Lewiston 68 49 78 53 83 47 / 20 10 0 0 10 50
Colville 72 43 77 45 80 43 / 20 20 10 10 40 60
Sandpoint 65 42 72 44 77 41 / 50 30 10 0 30 70
Kellogg 60 46 70 50 76 41 / 40 30 10 0 20 60
Moses Lake 76 46 80 50 78 44 / 10 0 0 0 30 50
Wenatchee 73 49 78 53 72 44 / 0 0 0 0 40 50
Omak 74 43 78 46 76 44 / 10 10 0 0 50 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KOTX 190555
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1055 PM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
A quick update late this evening to add some patchy fog to the
forecast in the northern mountain valleys and down the Okanogan
Valley. Radar estimates indicate a quarter to a half an of
rainfall across some of these valley through this evening. Dew
point depressions are close to zero. Observations at Omak recorded
over three-tenths of an inch of rainfall this evening as a shower
persisted over this area through much of the evening. Thus, the
boundary layer will be moist enough and we should see enough
cooling through the night for some fog through early tomorrow
morning across these valley locations even with the mid level
cloud cover. /SVH
&&
.AVIATION...
06z TAFS: Mostly cloud skies are expected over the region through
tonight with showers remaining confined mainly across the northern
mountains. Some stratus may begin to develop in the Spokane/Coeur
d`Alene areas tonight as the boundary layer remains moist, but
confidence is low as thick mid level cloud cover may not result in
enough cooling tonight lower in the atmosphere for stratus
development. Mountain showers are expected to develop through
Sunday afternoon, which may push south off the northern mountains
into KGEG, KSFF and KCOE with -RA possible. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 66 46 72 52 76 / 10 20 10 0 0 20
Coeur d`Alene 45 65 44 71 47 77 / 10 30 20 0 0 30
Pullman 43 63 42 71 47 77 / 10 20 10 0 0 20
Lewiston 49 68 49 78 53 83 / 10 20 10 0 0 20
Colville 45 72 43 77 45 80 / 20 20 20 10 10 40
Sandpoint 46 65 42 72 44 77 / 10 50 30 10 0 30
Kellogg 44 60 46 70 50 76 / 10 40 30 10 0 20
Moses Lake 47 76 46 80 50 78 / 10 10 0 0 0 20
Wenatchee 49 73 49 78 53 72 / 10 0 0 0 0 20
Omak 48 74 43 78 46 76 / 30 10 10 0 0 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 190441
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
940 PM PDT SAT MAY 18 2013
.SYNOPSIS...AN UPPER TROUGH OVER THE CASCADES THIS EVENING WILL
CONTINUE TO MOVE EAST. AN UPPER RIDGE WILL START TO BUILD IN ON
SUNDAY...THEN CROSS THE AREA ON MONDAY...LEADING TO WARMER AND DRIER
WEATHER. A LARGE UPPER LOW WILL DROP INTO THE AREA ON
TUESDAY...CAUSING A STRONG COLD FRONT TO PUSH INLAND DURING THE DAY.
THE UPPER LOW WILL SIT IN PLACE THROUGH THE END OF THE
WEEK...MAINTAINING SHOWERY WEATHER AND BELOW NORMAL TEMPERATURES.
&&
.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL TROUGH AXIS OVER
THE CASCADES THIS EVENING. A FEW PRECIPITATION ECHOES LEFT ON THE
DOPPLER RADARS WITH THE SHOWERS MOVING NORTHWEST TO SOUTHEAST
INDICATING THAT NORTHWESTERLY FLOW ALOFT HAS DEVELOPED OVER THE
STATE. WITH THE CLOUD COVER AT 9 PM PRETTY NARROW TEMPERATURE RANGE
ACROSS THE AREA WITH MOST PLACES IN THE MID 50S.
FLAT UPPER LEVEL RIDGE ALREADY EVIDENT IN THE SATELLITE IMAGERY OUT
AROUND 130W WILL BUILD INTO WESTERN WASHINGTON ON SUNDAY. IN THE
MEANTIME WITH PLENTY OF LOW LEVEL MOISTURE AND A SLIGHTLY UNSTABLE
AIR MASS WILL KEEP THE CHANCE OF SHOWERS GOING INTO THE MORNING
HOURS ON SUNDAY. HAVE UPDATED THE ZONES AND TAKEN THE CHANCE OF
SHOWERS OUT OF THE LOWLANDS FOR THE AFTERNOON HOURS ON SUNDAY. IF
THE RIDGE BUILDS IN A LITTLE QUICKER LOOK FOR THE CHANCE OF SHOWERS
IN THE MORNING TO BE DROPPED IN THE MORNING FORECAST PACKAGE. WITH
THE LIGHT ONSHORE FLOW BECOMING MORE NORTHERLY IN THE AFTERNOON IT
WILL NOT BE A VERY WARM DAY WITH HIGH TEMPERATURES HOVERING NEAR
NORMAL FOR THIS TIME OF THE YEAR...MOSTLY IN THE 60S.
UPPER LEVEL RIDGE REMAINING OVER WESTERN WASHINGTON SUNDAY NIGHT
INTO MONDAY. TEMPERATURES ALOFT DO NOT WARM MUCH WITH THE 850 TEMPS
ONLY A COUPLE OF DEGREES C WARMER THAN SUNDAY BUT MODEL CROSS
SECTIONS SHOW THE WINDS IN THE 1000-850 LAYER BECOMING LIGHT
NORTHEASTERLY MONDAY MORNING. THIS PUFF OF OFFSHORE FLOW COMBINED
THE WARMER TEMPERATURES ALOFT SHOULD RESULT IN HIGHS ABOUT 5 DEGREES
WARMER ON MONDAY VERSUS SUNDAY WITH MANY PLACES FROM SEATTLE SOUTH
GETTING INTO THE LOWER 70S.
CONDITIONS DETERIORATE RAPIDLY ON TUESDAY AS A COLD UPPER LEVEL LOW
DROPS DOWN FROM THE NORTH BRINGING WITH IT WET AND UNSEASONABLY COOL
WEATHER FOR THE MIDDLE OF THE WEEK. THE RECORD LOW MAX FOR SEATTLE
ON TUESDAY IS 52 DEGREES WHICH DOES NOT LOOK TO BE THREATENED AT
THIS POINT BUT THE RECORD LOW MAX ON WEDNESDAY IS 54 DEGREES AND
THAT HAS THE POTENTIAL TO BE BROKEN. BY TUESDAY NIGHT 850 MB
TEMPERATURES WILL DROP BELOW 0C AND SNOW LEVELS COULD FALL AS LOW AS
3000 FEET FOR SNOW AT ALL OF THE PASSES. FELTON
.LONG TERM...PREVIOUS DISCUSSION FOLLOWS. ON WED...THE UPPER TROUGH
WILL MORPH INTO A CUTOFF LOW...DUE TO THE DEVELOPMENT OF AN UPPER
RIDGE OVER THE YUKON AND NRN B.C.. THIS WILL EFFECTIVELY BRING A
BLOCKING PATTERN AND CUT THE UPPER LOW OFF FROM ANY STEERING FLOW
WHICH COULD PUSH IT OUT. SO...WE WILL BE STUCK WITH THE UPPER LOW
FROM WED THROUGH THE REST OF THE NEW WEEK. SAFE TO SAY THAT A
SHOWERY WEATHER REGIME WILL BE IN PLACE WITH BELOW NORMAL
TEMPERATURES. THIS PATTERN COULD ALSO BRING A FEW INCHES OF SNOW TO
THE HIGHER PASSES...SUCH AS RAINY PASS AND CHINOOK PASS...WHICH HAVE
ALREADY RE-OPENED FOR THE SEASON. MODELS SHOW THE UPPER LOW BECOMING
MORE RAG-TAG NEXT FRI AND SAT AS IT SLOWLY FILLS AND THE LOW-LEVEL
AIR MASS EVER SO SLOWLY MODIFIES. TEMPS WILL SLOWLY RISE BACK TO
WITHIN A FEW DEGREES OF NORMAL BY DAY 7...AND SHOWER COVERAGE MAY
DECREASE. ONE CAVEAT FOR THU THROUGH SAT IS THAT IF THE UPPER LOW
CENTER MEANDERS FURTHER SOUTH INTO NW ORE...IT WILL OPEN UP THE DOOR
TO MORE WIDESPREAD DEFORMATION-STYLE RAINFALL SPREADING IN FROM THE
EAST. HAVE SEEN THIS IN PAST MAYS...AND IT IS ONE WAY OF BRINGING A
LIGHT ALL-DAY RAIN TO WRN WA THIS TIME OF YEAR. HOWEVER...DETAILS OF
INDIVIDUAL WAVES OR ROUNDS OF SHOWERS WITHIN THE UPPER LOW ARE
IMPOSSIBLE TO PIN DOWN 5-7 DAYS IN THE FUTURE. HANER
&&
.AVIATION...THE UPPER LEVEL TROUGH PUSHED EAST OF THE CASCADES THIS
EVENING WHILE HIGH PRES MOVES IN FROM THE WEST. THE AIR MASS ACROSS
WESTERN WA IS STABILIZING BUT REMAINS MOIST WITH LOW LEVEL ONSHORE
FLOW. ISOLATED LIGHT SHOWERS ACROSS THE REGION WILL DIMINISH AFTER
MIDNIGHT TONIGHT...MAINLY AFFECTING THE CASCADES. CIGS WILL HOVER
AROUND 3000-5000 FT TONIGHT. HIGH PRES WILL REMAIN OVER THE REGION
ON SUN FOR DRY/STABLE WEATHER. LOW CLOUDS WILL SCATTER BY THE
AFTERNOON FOR VFR CONDITIONS. 33
KSEA...LIGHT SHOWERS IN THE VICINITY WILL DIMINISH AFTER MIDNIGHT
TONIGHT. SURFACE FLOW IS LIGHT SOUTHERLY. CIGS 3000-5000 FT
TONIGHT. 33
&&
.MARINE...HIGH PRES OVER THE NE PACIFIC WILL MAINTAIN NORTHWESTERLY
FLOW ACROSS WESTERN WA TONIGHT THROUGH SUN. THE CENTRAL AND EAST
STRAIT OF JUAN DE FUCA MAY SEE SMALL CRAFT ADVISORY WINDS LATE SUN
AFTERNOON AND EVENING.
THE NEXT FRONTAL SYSTEM WILL FORM OFFSHORE ON MON...THEN MOVE INLAND
ON TUE. BUT MODELS DISAGREE ON THE EXACT TRACKING OF THE SURFACE LOW
AS IT MOVES ASHORE. THE GFS BRINGS A 1009 MB LOW INTO THE WA COAST
TUE MORNING...WHILE THE ECMWF AND NAM SOLUTIONS ARE BOTH WEAKER AND
FARTHER SOUTH /1017 MB LOW OVER NORTHERN CA/. THE CANADIAN IS CLOSER
TO THE ECMWF AND NAM...SO WILL LIKELY NUDGE THE FORECAST TOWARD
THESE SOLUTIONS. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KPQR 190319
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
819 PM PDT SAT MAY 18 2013
.SYNOPSIS...SHOWERS WILL SLOWLY DECREASE TONIGHT AND SUNDAY AS A WEAK
WEATHER SYSTEM MOVES OUT OF THE AREA INTO THE GREAT BASIN. MORE
SUNBREAKS SUNDAY SHOULD LEAD TO MORE SEASONABLE TEMPERATURES. MONDAY
WILL BE A PLEASANT...SUNNY AND WARM DAY UNDER HIGH PRESSURE WITH
TEMPS IN THE LOWER TO MID 70S. HIGH CLOUDS WILL BEGIN TO INCREASE
FROM THE NORTHWEST LATER IN THE DAY IN ADVANCE OF OUR NEXT
SYSTEM...WHICH WILL BRING A DRAMATIC CHANGE BACK TO CHILLY AND
UNSETTLED WEATHER TUESDAY THROUGH FRIDAY.
&&
.SHORT TERM...A WEAK FRONT WILL PUSH ASHORE THIS EVENING AND INTO THE
OVERNIGHT HOURS WITH DECREASING SHOWERS BEHIND THE FRONT. ON
SUNDAY...SHOWERS SHOULD MAINLY BE CONFINED TO THE FOOTHILLS AND
CASCADES AS THE FRONT EXITS THE REGION AND HIGH PRESSURE BUILDS IN.
MOST AREAS WILL SEE SOME SUNSHINE IN THE AFTERNOON HOURS AS WARM AIR
ALOFT MOVES AND STABILIZES THE ATMOSPHERE.
MONDAY LOOKS TO BE THE SUNNIEST AND WARMEST DAY NEXT WEEK WITH HIGH
PRESSURE REMAINING OVER THE AREA. TEMPS EXPECTED TO BE A FEW DEGREES
ABOVE NORMAL MONDAY.
A SIGNIFICANT PATTERN CHANGE BEGINS TO TAKE PLACE ON TUES THAT WILL
LAST THROUGH THE WEEK. AN UNSEASONABLY DEEP AND COLD UPPER LOW WILL
SINK SOUTHEAST INTO WA/OR SPREADING RAIN ACROSS THE REGION. RAIN
APPEARS LIKELY A GOOD PORTION OF THE DAY TUESDAY...WITH SNOW LEVELS
LOWERING TO THE CASCADE PASSES TUE NIGHT. THERE IS AN OUTSIDE CHANCE
WE MAY NEED TO CONSIDER SNOW ADVISORIES FOR THE CASCADES AS EARLY AS
TUE NIGHT. TW
.LONG TERM...TUESDAY EVENING THROUGH SATURDAY. CLOSED LOW PRESSURE
SYSTEM WILL LINGER OVER THE PAC NW THROUGH THE WEEK. WITH THE COLD
NATURE OF THE LOW...RECORD LOW MAXIMUM TEMPERATURES ARE POSSIBLE ON
WEDNESDAY...WITH SNOW DOWN TO PASS LEVEL LIKELY IN THE CASCADES.
THURSDAY AND BEYOND MODELS BEGIN TO DISAGREE ON WHERE THE LOW WILL
PROPAGATE...HOWEVER THE OVERALL TREND WILL REMAIN...WITH SHOWERY AND
COOL CONDITIONS PERSISTING THROUGH AT LEAST SATURDAY. BURGESS
&&
.AVIATION...RATHER MOIST AIR MASS ACROSS THE REGION THIS EVENING
WITH A MIX OF VFR AND MVFR CIGS. LITTLE CHANGE TONIGHT...THOUGH
SHOWERS WILL END OVERNIGHT. IF GET ANY CLEARING...WINDS ARE LIGHT
SO MAY SEE PATCHY FOG S OF KSLE AND ALONG COAST...BUT AT MOMENT
FEEL ONSHORE FLOW JUST ENOUGH THAT CLOUDS WILL REFORM ACROSS THE
REGION. LIKELY WILL SEE WIDESPREAD MVFR CIGS LATER TONIGHT INTO
SUN AM...THEN GRADUALLY BREAKUP OF CLOUDS AFTER 18Z AS FLOW TURNS
MORE N TO NWLY.
KPDX AND APPROACHES...EXPECT MOSTLY VFR CONDITIONS THIS EVENING.
HOWEVER...SUSPECT WITH MOIST LOW LEVELS...AREAS OF MVFR CIGS WILL
FORM AFTER 08Z...AND PERSIST INTO SUN AM. LOCAL GUIDANCE SUGGESTS
CIGS WOULD BREAK UP WITH SCATTERED CLOUDS AROUND 19Z TO 20Z SUN.
WILL MAINTAIN THIS TREND IN THE 06Z TAFS.ROCKEY.
&&
.MARINE...WEAKENING FRONT NOW JUST INLAND. HIGH PRES OVER THE NE
PAC WILL STRENGTHEN TONIGHT AND SUN...WITH N TO NW WINDS. THESE
WINDS WILL INCREASE AS PRES GRADIENT TIGHTENS ON SUN AND MON...
WITH WINDS GUSTY TO 25 KT S OF NEWPORT IN AFTERNOON/EVENINGS. WILL
HOIST SMALL CRAFT ADVISORY FOR CENTRAL OREGON COASTAL WATERS FOR
SUCH WINDS FROM SUN AFTERNOON THROUGH MON EVENING. WINDS WEAKER TO
THE N...BUT COULD GET BIT GUSTY ON MON.
SEAS HOLDING AT 4 TO 6 FT TONIGHT THROUGH TUE...THOUGH MAY GET BIT
CHOPPY WITH BRISK NW WINDS AT TIMES...MAINLY S OF CASCADE HEAD.
QUESTIONABLE WEATHER FOR MIDDLE OF NEXT WEEK. MODELS INDICATE
LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING BY WED AND THU. THIS IS
DUE TO MODELS SPINNING UP ANOTHER RATHER TIGHT LOW PRES OFF THE
OREGON COAST ON TUE AND WED. NOT CONVINCED THIS WILL PAN OUT AS
MODELS SUGGEST...SO WILL TREND CLOSER TO 10 AS WANT TO SEE FURTHER
CONSISTENCY IN MODEL DATA BEFORE BITING. ROCKEY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FOR SUN AFTERNOON THROUGH
MON EVENING ON THE CENTRAL OREGON COASTAL WATERS...OR FROM
CASCADE HEAD TO FLORENCE AND OUT 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 190018
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
518 PM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Late afternoon update to the forecast for this evening. Added some
isolated thunderstorms across mainly Okanogan County to Ferry
County. LAPS data shows CAPE values up to around 400 J/kg and we
have already seen a handful of lightning strikes this afternoon
across this area. The thunderstorm threat will mainly only go
through until sunset. Once we lose our surface heating across
these areas, we shouldn`t retain enough instability for
thunderstorms to continue. Also added some isolated showers across the
basin as the next wave crosses the Cascades. Radar imagery does show
some weak echoes developing across the Moses Lake Area into the
Upper Columbia Basin. These showers are not expected to produce
much in the way of rainfall, but we could see around a hundredth
or so through this evening underneath these showers. The HRRR
model has the possibility for these showers reaching the Spokane
Area around 8:00 PM; however, the best forcing with this wave across
the basin will remain more over our southern zones, so not
expecting much from these showers once they get this far east into
the Spokane Area. /SVH
&&
.AVIATION...
00z TAFS: An upper level trough and weak disturbances embedded
within will aid in generating showers especially over the
mountains. Isolated thunderstorms will also be possible mainly
over the mountains north of the Columbia Basin though 03z this
evening. Westerly flow in the mid levels will lead to downslope
flow off the Cascades with dry conditions persisting at KEAT/KMWH.
TAF sites that receive showers could see low stratus forming after
15Z but confidence is low that conditions will fall below VFR for
any TAF site. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 66 46 72 52 75 / 10 20 10 0 0 20
Coeur d`Alene 45 65 44 71 47 75 / 10 30 20 0 0 30
Pullman 43 63 42 71 47 76 / 10 20 10 0 0 20
Lewiston 49 68 49 77 53 83 / 10 20 10 0 0 20
Colville 45 72 43 78 45 79 / 30 20 20 10 10 40
Sandpoint 43 65 42 71 44 75 / 10 50 30 10 10 30
Kellogg 44 60 46 69 50 74 / 10 40 30 10 10 20
Moses Lake 47 76 46 80 50 79 / 10 10 0 0 0 20
Wenatchee 49 73 49 78 53 74 / 10 0 0 0 0 20
Omak 45 74 43 77 46 76 / 50 10 10 0 0 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KOTX 182318
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
418 PM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Tonight and Sunday...An upper level trough along the Washington
and Oregon coast this afternoon will move inland tonight. Energy
from this system will split with one piece crossing the East
Slopes of the Cascades and moving into the Okanogan Highlands this
evening and then stalling in this area overnight. A combination of
this wave passing through this evening combined with low level
instability with surface based CAPE values of 100-300 J/KG should
support scattered showers over the Okanogan Highlands. A stray
lightning strike is also possible. These showers should begin to
die down overnight with the loss of daytime heating but with the
aforementioned wave stalling isolated showers may persist
overnight. Meanwhile drier air along the East Slopes of the
Cascades will keep showers isolated this evening despite the wave
passage. The southern piece will move south of the area into
Oregon. With the splitting nature this is not expected to produce
too much nocturnal shower activity but isolated coverage is
possible. Elsewhere mainly isolated showers through early this
evening before falling apart with the loss of daytime heating. On
Sunday a short wave ridge will be moving towards the Cascades but
residual moisture and daytime heating will result in another round
of showers mainly over north Idaho and northeast Washington. Also
just enough instability may be present over the northern mountains
with CAPE values as high as 400 J/KG for isolated afternoon
thunderstorms. JW
Sunday evening through Wednesday evening...Looks like this period
will begin on a dry and warm note as an upper level ridge
temporarily builds over the Inland NW. Residual instability could
still trigger some showers or even a thunderstorm early over the
extreme northeast Washington and the northern Idaho but the odds
aren`t great as warmer air aloft begins to cap the depth of the
potential convection. Precipitation chances look like they will
diminish even further on Monday as the 500 mb ridge axis shifts
toward the WA/ID border...with plenty of dry air moving into the
850-500 mb layer. Although there still could be enough instability
for some cumulus clouds over the northern mountains...most
locations should see mostly sunny conditions and temperatures
returning to near normal or slightly warmer than normal levels.
Just how long the ridge will retain its grip on the region is the
tough question to answer. All model solutions gradually replace
the ridge with a very deep and unusually cool upper level low
sometime on Tuesday as it dives into the region from the
northwest. The ECMWF takes the center of the the central
Washington coast by late Tuesday afternoon and subsequently shoves
a strong cold front through the Cascades and into the central
Columbia Basin. Meanwhile the GFS and GEM models are at least 6-12
hrs slower. The latest ECMWF is a fast outlier...however it has
some support from its ensemble. The timing of the front will have
a big impact on high temperatures for Tuesday. Suffice it to
say...the eastern third of the forecast area looks like it will
see significant warming compared to Monday with readings surging
into the mid 70s to lower 80s...whereas the western areas will
have a tougher time reaching values that warm as clouds and the
threat of precipitation moves in ahead of the cold front. Another
issue will be threat of deep convection and possibly some strong
thunderstorms as the heat and significant moisture advection
coincides with moderate upper level divergence ahead of the upper
level jet. The situation is somewhat similar to what we saw last
Monday...however the upper level forcing looks weaker with the
core of the 500 mb energy diving south of our forecast area. Of
all solutions...the NAM looks most favorable for big thunderstorms
with SBCapes reaching 500-800 j/kg with little if any CIN over NE
WA and N ID. The GFS meanwhile is much less impressive. Hopefully
there will be more resolution as the event nears.
Once the front passes and the core of the low shifts into the
region...we will be faced with much cooler and wetter
weather...and this pattern will persist for quite some time as the
low takes up residence over the area. In all cases...it appears
the front will move quite slowly and bring widespread
precipitation...including locally heavy precipitation with the
greatest threat over the northern third of Washington and into the
Idaho Panhandle. How much impact this will have on area rivers
remains questionable as the snow levels will fall precipitously
minimizing much of the snow melt contribution. The rivers most
susceptible to the significant rises will be those over north
Idaho....especially considering some model solutions are placing
the heaviest precipitation to our east and north. fx
Wednesday night through Saturday...Models remain in agreement with
the large scale pattern depicting an upper level low centered
somewhere over the Pacific Northwest during the extended forecast
period. The finer detains of the exact track of the vorticity lobes
have yet to come into sharper focus. Confidence is high that we will
see lots of clouds and cooler than normal daytime temperatures, but
exactly where, when and how much precipitation will fall across the
Inland Northwest will have to wait until the event nears. PoPs
continue the above climo trend while temps will remain below
seasonal normals. /Kelch
&&
.AVIATION...
00z TAFS: An upper level trough and weak disturbances embedded
within will aid in generating showers especially over the
mountains. Isolated thunderstorms will also be possible mainly
over the mountains north of the Columbia Basin though 03z this
evening. Westerly flow in the mid levels will lead to downslope
flow off the Cascades with dry conditions persisting at KEAT/KMWH.
TAF sites that receive showers could see low stratus forming after
15Z but confidence is low that conditions will fall below VFR for
any TAF site. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 66 46 72 52 75 / 20 20 10 0 0 20
Coeur d`Alene 45 65 44 71 47 75 / 20 30 20 0 0 30
Pullman 43 63 42 71 47 76 / 20 20 10 0 0 20
Lewiston 49 68 49 77 53 83 / 10 20 10 0 0 20
Colville 45 72 43 78 45 79 / 30 20 20 10 10 40
Sandpoint 43 65 42 71 44 75 / 30 50 30 10 10 30
Kellogg 44 60 46 69 50 74 / 20 40 30 10 10 20
Moses Lake 47 76 46 80 50 79 / 10 10 0 0 0 20
Wenatchee 49 73 49 78 53 74 / 10 0 0 0 0 20
Omak 45 74 43 77 46 76 / 20 10 10 0 0 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 182249
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
348 PM PDT SAT MAY 18 2013
.SYNOPSIS...AN UPPER TROUGH WILL PASS ACROSS WESTERN WASHINGTON THIS
EVENING...ACCOMPANIED BY A FEW SHOWERS. AN UPPER RIDGE WILL START TO
BUILD IN ON SUNDAY...THEN CROSS THE AREA ON MONDAY...LEADING TO
WARMER AND DRIER WEATHER. A LARGE UPPER LOW WILL DROP INTO THE AREA
ON TUESDAY...CAUSING A STRONG COLD FRONT TO PUSH INLAND DURING THE
DAY. THE UPPER LOW WILL SIT IN PLACE THROUGH THE END OF THE
WEEK...MAINTAINING SHOWERY WEATHER AND BELOW NORMAL TEMPERATURES.
&&
.SHORT TERM...A WEAK UPPER TROUGH AXIS IS MOVING ONSHORE...WITH
SCATTERED SHOWERS AND CLOUDS PRECEDING THE TROUGH AXIS. ONCE THE
TROUGH AXIS MOVES EAST OF THE CASCADES LATE TONIGHT...UPPER HEIGHTS
WILL RISE QUICKLY AND SHOWER ACTIVITY WILL DIMINISH GREATLY. IN
FACT...VISIBLE SATELLITE SHOWS RAPIDLY CLEARING SKIES OFFSHORE
BEHIND THE TROUGH AXIS. ON SUNDAY OVER THE INTERIOR
LOWLANDS...LOOKING FOR A LARGELY DRY SUNDAY. A SUBSIDENCE INVERSION
WILL DEVELOP AROUND 8000 FT MSL...SO ANY SHOWER ACTIVITY WILL BE
LIGHT AND SPOTTY AT MOST. IN FACT...WOULD EXPECT SHOWERS ON SUNDAY
AFTN TO BECOME CONFINED TO THE CASCADES...FOOTHILLS AND THE
PERIMETER OF THE OLYMPICS. A NORTH WIND WILL KICK IN THROUGH THE
PUGET SOUND LOWLANDS IN THE AFTN...A FAIR WEATHER DIRECTION FOR THE
LOWLANDS.
THE UPPER HEIGHT RISES WILL SET THE STAGE FOR AN UPPER RIDGE AXIS TO
PASS ACROSS WRN WA ON MON...MAKING MONDAY THE WARMEST AND DRIEST OF
THE NEXT 7 DAYS FOR WRN WA. AFTER A COOL START OWING TO MOSTLY CLEAR
SKIES AT SUNRISE...INTERIOR LOWLANDS WILL RISE INTO 70S ON MON AFTN.
ON TUE...A BIG CHANGE TOWARD COOL AND SHOWERY WEATHER WILL TAKE
PLACE. A HIGH AMPLITUDE UPPER TROUGH WILL SETUP NEAR 130W...BRINGING
A STRONG MARINE PUSH AND COLD FRONT THROUGH WRN WA DURING THE DAY.
AFTER A MILD START TO THE DAY...AFTN TEMPS WILL FALL IN MOST
PLACES...AND SHOWERS WILL QUICKLY BECOME WIDESPREAD. AN UNSEASONABLY
COOL AIR MASS WILL OVERSPREAD WRN WA. BY TUE NIGHT...850 MB TEMPS OF
-1C TO +1C WILL BE COMMON...AND SNOW LEVELS COULD FALL AS LOW AS
3000 FT. HANER
.LONG TERM...ON WED...THE UPPER TROUGH WILL MORPH INTO A CUTOFF
LOW...DUE TO THE DEVELOPMENT OF AN UPPER RIDGE OVER THE YUKON AND
NRN B.C.. THIS WILL EFFECTIVELY BRING A BLOCKING PATTERN AND CUT THE
UPPER LOW OFF FROM ANY STEERING FLOW WHICH COULD PUSH IT OUT.
SO...WE WILL BE STUCK WITH THE UPPER LOW FROM WED THROUGH THE REST
OF THE NEW WEEK. SAFE TO SAY THAT A SHOWERY WEATHER REGIME WILL BE
IN PLACE WITH BELOW NORMAL TEMPERATURES. THIS PATTERN COULD ALSO
BRING A FEW INCHES OF SNOW TO THE HIGHER PASSES...SUCH AS RAINY PASS
AND CHINOOK PASS...WHICH HAVE ALREADY RE-OPENED FOR THE SEASON.
MODELS SHOW THE UPPER LOW BECOMING MORE RAG-TAG NEXT FRI AND SAT AS
IT SLOWLY FILLS AND THE LOW-LEVEL AIR MASS EVER SO SLOWLY MODIFIES.
TEMPS WILL SLOWLY RISE BACK TO WITHIN A FEW DEGREES OF NORMAL BY DAY
7...AND SHOWER COVERAGE MAY DECREASE. ONE CAVEAT FOR THU THROUGH SAT
IS THAT IF THE UPPER LOW CENTER MEANDERS FURTHER SOUTH INTO NW
ORE...IT WILL OPEN UP THE DOOR TO MORE WIDESPREAD DEFORMATION-STYLE
RAINFALL SPREADING IN FROM THE EAST. HAVE SEEN THIS IN PAST
MAYS...AND IT IS ONE WAY OF BRINGING A LIGHT ALL-DAY RAIN TO WRN WA
THIS TIME OF YEAR. HOWEVER...DETAILS OF INDIVIDUAL WAVES OR ROUNDS
OF SHOWERS WITHIN THE UPPER LOW ARE IMPOSSIBLE TO PIN DOWN 5-7 DAYS
IN THE FUTURE. HANER
&&
.AVIATION...SCATTERED SHOWERS ARE OVER THE AREA AS A WEAK FRONT
BREAKS UP OVER THE REGION. THE AIR MASS IS MOIST AND SOMEWHAT
UNSTABLE WITH FAIRLY LIGHT SW FLOW ALOFT BECOMING NW TONIGHT. THE
MOUNTAINS AND FOOTHILLS ARE MOSTLY OBSCURED. MORNING CLOUDS WILL
GIVE WA TO AFTERNOON SUNSHINE SUNDAY.
KSEA...SCATTERED SHOWERS WILL CONTINUE THROUGH THE EVENING AS A
FRONT BREAKS UP OVER THE AREA. THE SHOWER ACTIVITY WILL END
OVERNIGHT AS THE WEAK UPPER TROUGH IS REPLACED BY A RIDGE THROUGH
SUNDAY. LIGHT PRESSURE GRADIENTS...A LIGHT AND VARIABLE WIND.
&&
.MARINE...A COLD FRONT IS BREAKING UP OVER THE COASTAL WATERS THIS
AFTERNOON. NW FLOW WILL EVENTUALLY INCREASE BEHIND THE FRONT...BUT
IT DOES NOT LOOK LIKELY THAT THE CENTRAL AND EASTERN STRAIT OF JUAN
DE FUCA WILL SEE MORE THAN ABOUT 20KT WLY WINDS LATER THIS EVENING.
HIGH PRES OVER THE NE PAC WILL MAINTAIN NW FLOW SUN AND MON. ANOTHER
FRONT WILL ARRIVE FOR TUE AND WED.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KOTX 182158
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
258 PM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Tonight and Sunday...An upper level trough along the Washington
and Oregon coast this afternoon will move inland tonight. Energy
from this system will split with one piece crossing the East
Slopes of the Cascades and moving into the Okanogan Highlands this
evening and then stalling in this area overnight. A combination of
this wave passing through this evening combined with low level
instability with surface based CAPE values of 100-300 J/KG should
support scattered showers over the Okanogan Highlands. A stray
lightning strike is also possible. These showers should begin to
die down overnight with the loss of daytime heating but with the
aforementioned wave stalling isolated showers may persist
overnight. Meanwhile drier air along the East Slopes of the
Cascades will keep showers isolated this evening despite the wave
passage. The southern piece will move south of the area into
Oregon. With the splitting nature this is not expected to produce
too much nocturnal shower activity but isolated coverage is
possible. Elsewhere mainly isolated showers through early this
evening before falling apart with the loss of daytime heating. On
Sunday a short wave ridge will be moving towards the Cascades but
residual moisture and daytime heating will result in another round
of showers mainly over north Idaho and northeast Washington. Also
just enough instability may be present over the northern mountains
with CAPE values as high as 400 J/KG for isolated afternoon
thunderstorms. JW
Sunday evening through Wednesday evening...Looks like this period
will begin on a dry and warm note as an upper level ridge
temporarily builds over the Inland NW. Residual instability could
still trigger some showers or even a thunderstorm early over the
extreme northeast Washington and the northern Idaho but the odds
aren`t great as warmer air aloft begins to cap the depth of the
potential convection. Precipitation chances look like they will
diminish even further on Monday as the 500 mb ridge axis shifts
toward the WA/ID border...with plenty of dry air moving into the
850-500 mb layer. Although there still could be enough instability
for some cumulus clouds over the northern mountains...most
locations should see mostly sunny conditions and temperatures
returning to near normal or slightly warmer than normal levels.
Just how long the ridge will retain its grip on the region is the
tough question to answer. All model solutions gradually replace
the ridge with a very deep and unusually cool upper level low
sometime on Tuesday as it dives into the region from the
northwest. The ECMWF takes the center of the the central
Washington coast by late Tuesday afternoon and subsequently shoves
a strong cold front through the Cascades and into the central
Columbia Basin. Meanwhile the GFS and GEM models are at least 6-12
hrs slower. The latest ECMWF is a fast outlier...however it has
some support from its ensemble. The timing of the front will have
a big impact on high temperatures for Tuesday. Suffice it to
say...the eastern third of the forecast area looks like it will
see significant warming compared to Monday with readings surging
into the mid 70s to lower 80s...whereas the western areas will
have a tougher time reaching values that warm as clouds and the
threat of precipitation moves in ahead of the cold front. Another
issue will be threat of deep convection and possibly some strong
thunderstorms as the heat and significant moisture advection
coincides with moderate upper level divergence ahead of the upper
level jet. The situation is somewhat similar to what we saw last
Monday...however the upper level forcing looks weaker with the
core of the 500 mb energy diving south of our forecast area. Of
all solutions...the NAM looks most favorable for big thunderstorms
with SBCapes reaching 500-800 j/kg with little if any CIN over NE
WA and N ID. The GFS meanwhile is much less impressive. Hopefully
there will be more resolution as the event nears.
Once the front passes and the core of the low shifts into the
region...we will be faced with much cooler and wetter
weather...and this pattern will persist for quite some time as the
low takes up residence over the area. In all cases...it appears
the front will move quite slowly and bring widespread
precipitation...including locally heavy precipitation with the
greatest threat over the northern third of Washington and into the
Idaho Panhandle. How much impact this will have on area rivers
remains questionable as the snow levels will fall precipitously
minimizing much of the snow melt contribution. The rivers most
susceptible to the significant rises will be those over north
Idaho....especially considering some model solutions are placing
the heaviest precipitation to our east and north. fx
Wednesday night through Saturday...Models remain in agreement with
the large scale pattern depicting an upper level low centered
somewhere over the Pacific Northwest during the extended forecast
period. The finer detains of the exact track of the vorticity lobes
have yet to come into sharper focus. Confidence is high that we will
see lots of clouds and cooler than normal daytime temperatures, but
exactly where, when and how much precipitation will fall across the
Inland Northwest will have to wait until the event nears. PoPs
continue the above climo trend while temps will remain below
seasonal normals. /Kelch
&&
.AVIATION...
18z TAFS: An upper level trough and weak disturbances embedded
within will aid in generating showers especially over the
mountains. Isolated thunderstorms will also be possible mainly over
the mountains north of the Columbia Basin from 20z today through 03z
this evening. Westerly flow in the mid levels will lead to downslope
flow off the Cascades with dry conditions persisting at KEAT/KMWH.
CIGS are expected to be primarily VFR...with brief MVFR conditions
possible around KSFF/KCOE through 20z. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 66 46 72 52 75 / 20 20 10 0 0 20
Coeur d`Alene 45 65 44 71 47 75 / 20 30 20 0 0 30
Pullman 43 63 42 71 47 76 / 20 20 10 0 0 20
Lewiston 49 68 49 77 53 83 / 10 20 10 0 0 20
Colville 45 72 43 78 45 79 / 30 20 20 10 10 40
Sandpoint 43 65 42 71 44 75 / 30 50 30 10 10 30
Kellogg 44 60 46 69 50 74 / 20 40 30 10 10 20
Moses Lake 47 76 46 80 50 79 / 10 10 0 0 0 20
Wenatchee 49 73 49 78 53 74 / 10 0 0 0 0 20
Omak 45 74 43 77 46 76 / 20 10 10 0 0 30
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KPQR 182135
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
234 PM PDT SAT MAY 18 2013
.SYNOPSIS...PLENTY OF CLOUDS AND OCCASIONAL RAIN TODAY AS A WEAK LOW
PRESSURE SYSTEM SLOWLY MOVES INTO OREGON AND WASHINGTON. SHOWERS WILL
SLOWLY DECREASE TONIGHT AND SUNDAY AS THE SYSTEM MOVES INTO THE
GREAT BASIN AND FALLS APART. MORE SUNBREAKS SUNDAY SHOULD LEAD TO
MORE SEASONABLE TEMPERATURES. MONDAY IS SHAPING UP TO BE A PLEASANT
SUNNY AND WARM DAY UNDER HIGH PRESSURE WITH TEMPS IN THE LOWER TO MID
70S. HIGH CLOUDS WILL BEGIN TO INCREASE FROM THE NORTHWEST LATER IN
THE DAY IN ADVANCE OF OUR NEXT SYSTEM...WHICH WILL BRING A DRAMATIC
CHANGE BACK TO CHILLY AND UNSETTLED WEATHER TUESDAY THROUGH FRIDAY.
&&
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...VISIBLE SATELLITE IMAGERY
SHOWS SOLID CLOUD COVER ACROSS THE DISTRICT THIS AFTERNOON. KRTX
RADAR SHOWS AN AREA OF LIGHT RAIN SPREADING ACROSS WASHINGTON COUNTY
AND ENTERING THE GREATER PORTLAND AND EVENTUALLY VANCOUVER METRO
AREA. ADDITIONALLY AREAS OF LIGHT RAIN PERSIST ALONG THE COAST AND
MUCH OF THE REST OF OUR FORECAST AREA. SNOW LEVELS REMAIN RATHER
HIGH...ODOT PASS CAMS SHOW OCCASIONAL RAIN AND IT APPEARS TO BE
RAINING AT TIMBERLINE AS WELL.
WEAK AND POORLY DEFINED LOW PRESSURE CIRCULATION JUST OFFSHORE FROM
ASTORIA WILL DRAG A WEAK COLD FRONT ONSHORE OVER THE NEXT FEW HOURS
WITH DECREASING SHOWERS THEREAFTER. WHAT IS LEFT OF THE FRONT WILL
FINALLY LUMBER EAST ACROSS THE CASCADES TONIGHT WITH DECREASING
SHOWERS BEHIND THE FRONT. BY SUNDAY MORNING SHOWERS WILL BE MAINLY
CONFINED TO THE HIGHER TERRAIN...THOUGH A STRAY SHOWER IS STILL
POSSIBLE ELSEWHERE DUE TO WEAK SHALLOW INSTABILITY.
MADE VERY FEW CHANGES FOR MONDAY AND TUESDAY. THE MOVE THE MIDNIGHT
SHIFT MADE TO BUMP UP MONDAY TEMPS INTO THE 70S APPEARS TO BE A GOOD
ONE. THE AIR MASS LOOKS RATHER DRY THROUGHOUT MONDAY ON NAM BUFR
SOUNDINGS...FROM EUGENE ALL THE WAY UP TO PORTLAND. WITH 850 MB TEMPS
PUSHING +10 DEG C IN THE WILLAMETTE VALLEY...HIGHS COULD GET WELL
INTO THE 70S SOME AREAS WITH PLENTY OF SUNSHINE. ONSHORE GRADIENTS
WILL KEEP THE COAST FROM WARMING UP TOO MUCH.
MODELS SHOWING GOOD AGREEMENT ON RAIN FROM OUR NEXT SYSTEM HOLDING
OFF UNTIL TUESDAY MORNING. AS TUESDAY PROGRESSES IT APPEARS AN
UNSEASONABLY DEEP AND COLD UPPER LOW WILL SINK SOUTHEAST INTO WA/OR
SPREADING RAIN ACROSS THE REGION. RAIN APPEARS LIKELY A GOOD PORTION
OF THE DAY TUESDAY...WITH SNOW LEVELS LOWERING TO THE CASCADE PASSES
TUE NIGHT. THERE IS AN OUTSIDE CHANCE WE MAY NEED TO EVENTUALLY
CONSIDER SNOW ADVISORIES FOR THE CASCADES AS EARLY AS TUE NIGHT.
WEAGLE
.LONG TERM...TUESDAY EVENING THROUGH SATURDAY...FEW CHANGES. CLOSED
LOW PRESSURE SYSTEM WILL LINGER OVER THE PAC NW THROUGH THE WEEK.
WITH THE COLD NATURE OF THE LOW...RECORD LOW MAXIMUM TEMPERATURES
ARE POSSIBLE ON WEDNESDAY...WITH SNOW DOWN TO PASS LEVEL LIKELY IN
THE CASCADES. THURSDAY AND BEYOND MODELS BEGIN TO DISAGREE ON WHERE
THE LOW WILL PROPAGATE...HOWEVER THE OVERALL TREND WILL
REMAIN...WITH SHOWERY AND COOL CONDITIONS PERSISTING THROUGH AT
LEAST SATURDAY. BURGESS
&&
.AVIATION...MIX OF VFR AND MVFR CIGS ACROSS THE REGION. A
WEAKENING FRONT IS PUSHING ACROSS THE REGION...BUT BACK EDGE OF
THE FRONT IS STILL OFFSHORE AND NOT LIKELY TO CLEAR THE CASCADES
UNTIL THIS EVENING. NOT MUCH CHANGE...WITH SCATTERED SHOWERS AND
MOSTLY LOW VFR AND POCKETS OF MVFR THROUGH TONIGHT. CASCADES AND
PASSES WILL FREQUENTLY BE OBSCURED IN CLOUDS. SHOWERS SHOULD
DIMINISH OVERNIGHT BEHIND THE FRONT...WITH MVFR CIGS AT THE COAST
AND MOSTLY VFR INLAND. SOME PATCHY FOG POSSIBLE TOMORROW MORNING
IN THE SOUTHERN WILLAMETTE VALLEY IF ANY CLEARING
OCCURS...POSSIBLY AFFECTING KEUG.
KPDX AND APPROACHES...EXPECT A MIX OF VFR AND MVFR IN SCATTERED
SHOWERS THROUGH THIS AFTERNOON AS A COLD WORKS ITS WAY THROUGH.
SHOWER ACTIVITY SHOULD DECREASE LATER THIS EVENING BEHIND THE
FRONTAL PASSAGE. MOSTLY VFR CONDITIONS OVERNIGHT. PYLE
EXPECT LIGHT RAIN OR SHOWERS OFF AND ON THROUGH THE DAY.
PREDOMINANTLY VFR CONDITIONS MAY DROP TO MVFR AT TIMES DURING HEAVIER
SHOWERS. SHOWER ACTIVITY SHOULD TAPER OFF SOMEWHAT THIS EVENING...
WITH MAINLY VFR CONDITIONS DURING THE EVENING AND OVERNIGHT HOURS.
PYLE
&&
.MARINE...A COLD FRONT IS PUSHING THROUGH THE COASTAL WATERS THIS
AFTERNOON. THE FRONT HAS BEEN SLOWER THAN EXPECTED...SO DECIDED
TO EXTEND THE SMALL CRAFT ADVISORY FOR WINDS INTO THE EARLY
EVENING HRS. EXPECT WINDS TO DECREASE AND TURN NW LATER THIS
EVENING BEHIND THE FRONT. HIGH PRES WILL BUILD OVER THE NE PAC
SUN INTO EARLY NEXT WEEK. IT APPEARS THAT THERE WILL BE A FEW
CHANCES FOR SMALL CRAFT ADVISORIES FOR WINDS OVER THE NEXT FEW
DAYS. SUNDAY AND MONDAY MAY SEE WIND GUSTS INTO THE 20 TO 25 KT
RANGE DURING THE LATE AFTERNOON AND EARLY EVENING HRS.
SEAS REMAIN AT 5 TO 6 FT THROUGH THE WEEKEND. SEAS MAY BUMP UP A
BIT DURING THE PERIODS OF GUSTY WINDS ON SUN AND MON. A LARGE
LOW PRESSURE SYSTEM MAY BRING ANOTHER SMALL CRAFT FOR WINDS ON
WED...ALONG WITH SEAS ABOVE 10 FT. PYLE
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 PM PDT THIS EVENING FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 181754
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1054 AM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Water vapor satellite imagery shows a mid level wave tracking
across Eastern Washington and North Idaho this morning. This
combined with mid level instability will continue to generate
showers this morning over the Okanogan Valley and Highlands,
Northeast Washington Mountains, and over North Idaho mainly north
of Lewiston. For this afternoon into the evening hours another
wave will track across the region which combined with afternoon
heating will generate more showers especially over the northern
mountains where high dew points in the upper 40s and lower 50s
exist due to the shower activity this morning. The forecast for
this morning has been updated to increase shower wording in the
valleys north of Highway 2 in Washington...and over North Idaho.
Also made some sky cover adjustments to show more cloud cover this
morning...and to increase clouds over Central Washington this
afternoon as the next wave crosses the Cascades. These clouds will
keep high temperatures down more then previously expected and highs
were adjusted downward mainly areas north of a line from Omak to
Spokane to Kellogg. JW
&&
.AVIATION...
18z TAFS: An upper level trough and weak disturbances embedded
within will aid in generating showers especially over the
mountains. Isolated thunderstorms will also be possible mainly over
the mountains north of the Columbia Basin from 20z today through 03z
this evening. Westerly flow in the mid levels will lead to downslope
flow off the Cascades with dry conditions persisting at KEAT/KMWH.
CIGS are expected to be primarily VFR...with brief MVFR conditions
possible around KSFF/KCOE through 20z. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 63 45 66 46 70 49 / 40 20 20 10 0 10
Coeur d`Alene 62 44 64 43 69 45 / 60 30 30 20 0 10
Pullman 62 43 63 41 69 45 / 20 20 20 10 0 10
Lewiston 69 49 70 48 76 51 / 20 20 20 10 0 10
Colville 66 44 73 43 76 44 / 70 40 30 20 10 10
Sandpoint 60 43 64 42 69 43 / 70 40 40 30 10 10
Kellogg 58 44 60 45 67 46 / 60 30 40 40 10 10
Moses Lake 72 47 76 45 79 48 / 10 10 10 0 0 10
Wenatchee 69 48 72 49 76 51 / 10 10 10 0 0 10
Omak 69 43 74 42 77 46 / 50 20 10 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 181635
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
935 AM PDT SAT MAY 18 2013
.SYNOPSIS...A WEAK COLD FRONT AND AN UPPER TROUGH WILL MOVE INLAND
TODAY GIVING A COOL SHOWERY DAY. AN UPPER RIDGE WILL BUILD
OFFSHORE SUNDAY AND MOVE INLAND MONDAY FOR WARMER AND MOSTLY DRY
WEATHER. A DEEP UPPER LOW WILL REACH THE AREA TUESDAY AND LINGER
THROUGH THE REST OF NEXT WEEK FOR SHOWERY AND UNSEASONABLY COOL
WEATHER.
&&
.SHORT TERM...A WEAK UPPER TROUGH AXIS WILL MOVE ONSHORE AND ACROSS
WRN WA FOR THE REST OF TODAY. HEIGHT RISES BEHIND THE TROUGH ARE
STRONGER THAN THE HEIGHT FALLS PRECEDING THE TROUGH...INDICATING
THAT THE TROUGH WILL BE WEAKENING AND FILLING AS IT MOVES OVERHEAD.
FOR NOW...KLGX RADAR SHOWS A LARGE AREA OF SHOWERS AND RAIN OFF THE
COAST...JUST IN ADVANCE OF THE TROUGH AXIS. THIS WILL MOVE ONTO THE
COAST LATER THIS MORNING...THEN INTO THE PUGET SOUND LOWLANDS LATE
THIS AFTN. WITH THE WEAKENING TREND OF THE TROUGH...RAINFALL FURTHER
INLAND SHOULD BE FAIRLY LIGHT THIS AFTN...WITH JUST A FEW HUNDREDTHS
OF AN INCH OF RAIN EXPECTED ALONG THE I-5 CORRIDOR NORTH OF OLYMPIA.
A LITTLE MORE RAIN SOUTH OF OLYMPIA...BUT REMAINING BELOW 1/4 INCH.
ONCE THE DISSIPATING TROUGH AXIS MOVES EAST OF THE CASCADES THIS
EVNG...UPPER HEIGHTS WILL RISE QUICKLY. THE AIR MASS WILL DRY
QUICKLY ON SUNDAY...ESPECIALLY ABOVE ABOUT 8000 FT MSL. A NORTH WIND
WILL KICK IN THROUGH THE PUGET SOUND LOWLANDS...A FAIR WEATHER
DIRECTION FOR THE LOWLANDS. WITH FAIRLY SHALLOW MOISTURE AND
NORTHERLY ONSHORE FLOW...WOULD EXPECT SHOWERS ON SUNDAY TO BE LIGHT
AND CONFINED TO THE CASCADES...FOOTHILLS AND THE PERIMETER OF THE
OLYMPICS.
THE UPPER HEIGHT RISES WILL SET THE STAGE FOR AN UPPER RIDGE AXIS TO
PASS ACROSS WRN WA ON MON...MAKING MONDAY THE WARMEST AND DRIEST OF
THE NEXT 7 DAYS FOR WRN WA. INTERIOR LOWLANDS WILL RISE INTO 70S ON
MON AFTN. HANER
.LONG TERM...FROM PREVIOUS DISCUSSION...THE EXTENDED MODELS ARE IN
GENERALLY GOOD AGREEMENT WITH THE ARRIVAL OF A RATHER DEEP UPPER
LEVEL TROUGH ON TUESDAY THAT SETTLES OVER THE PACIFIC NORTHWEST ON
WEDNESDAY. AS PREVIOUSLY DISCUSSED...THIS WILL LEAD TO SHOWERY AND
COOL WEATHER WITH RATHER LOW SNOW LEVELS FOR LATE MAY. THE MODELS
QUICKLY DIVERGE WITH THE EVOLUTION OF THE TROUGH AS WE GET INTO THE
LATER HALF OF NEXT WEEK. THE CANADIAN TAKES A CLOSED LOW CENTER INTO
NORTHERN CALIFORNIA BY LATE THURSDAY. THE EURO TAKES THE BASE OF THE
TROUGH INTO THE NORTHERN GREAT BASIN DURING THE SAME PERIOD WHILE
GFS KEEPS THE LOW CENTER RIGHT OVER WESTERN WASHINGTON. ALL OF THE
MODELS KEEP A BROAD TROUGH OVER THE WEST COAST INTO LATE NEXT
WEEK...BUT HAVE SIGNIFICANTLY DIFFERENT IDEAS WITH THE TRACKS OF
DISTURBANCES ROTATING THROUGH IT. CONFIDENCE IN ANY LEVEL OF DETAIL
FOR THE BEGINNING OF THE HOLIDAY WEEKEND FORECAST IS VERY LOW AT
THIS TIME. NO SIGNIFICANT CHANGES WERE MADE TO THE EXTENDED FORECAST
OVERNIGHT. 27
&&
.AVIATION...ANOTHER ROUND OF SHOWERS FOR WESTERN WA TODAY AS A COLD
FRONT MOVES OVER THE REGION. THE AIR MASS IS MOIST AND SOMEWHAT
UNSTABLE WITH FAIRLY LIGHT SW FLOW ALOFT BECOMING NW TONIGHT. THE
MOUNTAINS AND FOOTHILLS WILL BE OBSCURED. MORNING CLOUDS WILL GIVE
WA TO AFTERNOON SUN SUNDAY.
KSEA...SHOWERS WILL INCREASE THIS MORNING AS A COLD FRONT APPROACHES
AND MOVES INLAND. SHOWER ACTIVITY WILL DECREASE TONIGHT AS THE UPPER
LEVEL TROUGH EXITS. THE SURFACE FLOW WILL REMAIN SOUTHERLY.
&&
.MARINE...A COLD FRONT WILL CROSS THE REGION TODAY...WITH ONSHORE
FLOW INCREASING TONIGHT. THE CENTRAL AND EASTERN STRAIT OF JUAN DE
FUCA MAY SEE SMALL CRAFT ADVISORY WINDS THIS EVENING. HIGH PRES OVER
THE NE PAC WILL MAINTAIN NNW FLOW SUN AND MON. ANOTHER FRONT WILL
ARRIVE ON TUE.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KPQR 181609
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
908 AM PDT SAT MAY 18 2013
.SYNOPSIS...A WEAK FRONTAL SYSTEM IS SPREADING LIGHT RAIN ACROSS
FORECAST AREA THIS MORNING. OCCASIONAL RAIN WILL CONTINUE THROUGH THE
DAY WITH CLOUDY SKIES AND TEMPS STUCK AROUND 60 DEGREES FOR THE
LOWLANDS. SNOW LEVELS WILL REMAIN WELL ABOVE THE PASSES. SHOWERS WILL
GRADUALLY DECREASE TONIGHT AND SUNDAY AS THE SYSTEM MOVES INTO THE
GREAT BASIN AND HIGH PRESSURE BEGINS TO BUILD. THIS HIGH PRESSURE
SHOULD RESULT IN DRIER AND WARMER CONDITIONS SUN NIGHT INTO MON.
HOWEVER IT APPEARS LIKELY AN UNSEASONABLY COLD UPPER LOW WILL BRING
COOL AND UNSETTLED WEATHER TUESDAY THROUGH FRIDAY.
&&
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...LATEST RADAR IMAGERY AND
SURFACE OBSERVATIONS SHOW LIGHT RAIN SPREADING ACROSS THE PORTLAND
AND VANCOUVER METRO THIS MORNING...MOVING EAST INTO THE CASCADES. A
WEAK FRONTAL SYSTEM MOVING ONSHORE IS RESPONSIBLE FOR THIS...WITH THE
FIRST BAND OF RAIN ASSOCIATED WITH WEAK ISENTROPIC LIFT.
LATEST MSAS SFC PRESSURE ANALYSIS SHOWS AN ELONGATED LOW PRESSURE
TROUGH JUST OFFSHORE...WHICH SEEMS TO MATCH VISIBLE IMAGERY FAIRLY
WELL. LOOPING THIS IMAGERY SEEMS TO SHOW A VERY FAINT CIRCULATION IN
THE LOW CLOUDS CENTERED NEAR 46N/126W...MOVING NORTHEAST. THIS WEAK
LOW WILL LIKELY DRAG A WEAK COLD FRONT ACROSS THE DISTRICT THIS
AFTERNOON...SPREADING ANOTHER BATCH OF RAIN ACROSS THE FORECAST AREA.
OVERALL RAINFALL AMOUNTS TODAY THROUGH THIS EVENING WILL PROBABLY BE
0.10-0.20 INCH IN THE VALLEYS...UP TO 0.50-0.75 INCH IN THE HIGHER
TERRAIN. EXPECT LITTLE TO NO BREAKS IN THE CLOUDS TODAY WITH THE VERY
MOIST AIR MASS...TEMPS WILL STRUGGLE TO REACH 60 DEGREES AND MOS
GUIDANCE APPEARS TO BE CATCHING ON TO THIS CONCEPT.
THERE WILL BE MORE BREAKS IN THE CLOUDS SUNDAY AS HIGH PRESSURE
BEGINS TO BUILD INTO THE REGION. SOME WEAK AND SHALLOW INSTABILITY
LEFT BEHIND BY ALLOW AN ISOLATED SHOWER OR TWO...WITH THE BEST CHANCE
OVER THE HIGHER TERRAIN. THE AIR MASS WILL BE RAPIDLY WARMING
ALOFT...CAPPING THE INSTABILITY AND KEEPING IT TOO SHALLOW FOR TSTMS
SUNDAY DESPITE THE WARMER SFC TEMPS IN THE MID TO UPPER 60S. WEAGLE
REMAINDER OF FCST DISCUSSION UNCHANGED FROM PREVIOUS SHIFT...HIGH
PRESSURE MAINTAIN DRY WEATHER FOR MONDAY WHICH WILL LIKELY BE
THE WARMEST DAY OF THE WEEK. INCREASED SUNSHINE SHOULD WARM INTERIOR
TEMPERATURES TO SLIGHTLY ABOVE NORMAL...LOW 70S AND COASTAL AREAS TO
NEAR NORMAL...LOWER 60S. AN UPPER LEVEL LOW WILL APPROACH MONDAY
NIGHT AND BRING A RETURN OF SHOWERS AND MUCH COOLER WEATHER TO THE
REGION. MODELS HAVE BACKED OFF THE TIMING OF THE ONSET OF RAIN AROUND
12 HOURS. THE COLDEST AIR ASSOCIATED WITH THE LOW WILL BEGIN MOVING
OVER THE AREA TUESDAY NIGHT AND SNOW LEVELS SHOULD LOWER TO AROUND
3500 TO 4000 FEET.
.LONG TERM...WEDNESDAY THROUGH FRIDAY...A COLD CLOSED LOW WILL
CONTINUE UNSETTLED WEATHER WITH UNSEASONAL COLD TEMPERATURES
WEDNESDAY...WITH RECORD LOW MAXIMUM TEMPERATURES POSSIBLE. WEDNESDAY
WILL BE THE COLDEST DAY OF THE WORK WEEK. TEMPERATURES WILL REMAIN
BELOW THE SEASONAL NORMALS THURSDAY AND FRIDAY AS A COUPLE OF
SHORTWAVE TROUGHS WILL CONTINUE SHOWERY AND COOL CONDITIONS.
&&
.AVIATION...A FRONTAL BOUNDARY MOVING THROUGH THE REGION WILL
BRING PERIODS OF LIGHT RAIN OR SHOWERS THROUGH MUCH OF THE DAY.
EXPECT A MIX OF VFR AND MVFR CONDITIONS...WITH THE PERIODS OF MVFR
COINCIDING WITH THE HEAVIER SHOWERS. EXPECT SHOWER ACTIVITY TO
CONTINUE BUT BECOME MORE SCATTERED THIS EVENING BEHIND THE FRONTAL
PASSAGE. EXPECT MAINLY VFR CONDITIONS THIS EVENING...WITH MVFR
CIGS PUSHING INTO THE COAST OVERNIGHT.
KPDX AND APPROACHES...EXPECT LIGHT RAIN OR SHOWERS OFF AND ON
THROUGH THE DAY. PREDOMINANTLY VFR CONDITIONS MAY DROP TO MVFR AT
TIMES DURING HEAVIER SHOWERS. SHOWER ACTIVITY SHOULD TAPER OFF
SOMEWHAT THIS EVENING...WITH MAINLY VFR CONDITIONS DURING THE
EVENING AND OVERNIGHT HOURS. PYLE
&&
.MARINE...A FRONT WILL PUSH ACROSS THE COASTAL WATERS THIS
MORNING...THEN INLAND EARLY THIS AFTERNOON. NOT A LOT OF WIND
CURRENTLY BEING OBSERVED...BUT EXPECT THAT WINDS WILL PICK UP A
BIT LATER THIS MORNING AS THE COLD FRONT COMES THROUGH. THERE
SEEMS SO BE ENOUGH GRADIENT TO POP GUSTS 20 TO 25 KT RIGHT AHEAD
OF THE FRONT. SO WILL MAINTAIN CURRENT SMALL CRAFT ADVISORY.
OTHERWISE...WINDS TURN W TO NW BEHIND THE FRONT IN THE AFTERNOON
AND BEGIN TO EASE.
HIGH PRES WILL BUILD OVER THE NE PAC SUN INTO EARLY NEXT WEEK.
THIS WILL KEEP NW WINDS 10 TO 15 KT THROUGH MUCH OF THE COMING
WEEK...THOUGH MAY BRIEFLY GET 20 TO 25 KT GUSTS MON AFTERNOON INTO
THE EVENING.
SEAS REMAIN AT 5 TO 6 FT FOR INTO EARLY NEXT WEEK. MAY SEE SEAS
BUILD UP AND BECOME CHOPPY AT TIMES WITH THE BRISK NW WINDS ON THE
CENTRAL OREGON COASTAL WATERS NEXT WEEK.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 PM PDT THIS AFTERNOON FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 181531
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
831 AM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Water vapor satellite imagery shows a mid level wave tracking
across Eastern Washington and North Idaho this morning. This
combined with mid level instability will continue to generate
showers this morning over the Okanogan Valley and Highlands,
Northeast Washington Mountains, and over North Idaho mainly north
of Lewiston. For this afternoon into the evening hours another
wave will track across the region which combined with afternoon
heating will generate more showers especially over the northern
mountains where high dew points in the upper 40s and lower 50s
exist due to the shower activity this morning. The forecast for
this morning has been updated to increase shower wording in the
valleys north of Highway 2 in Washington...and over North Idaho.
Also made some sky cover adjustments to show more cloud cover this
morning...and to increase clouds over Central Washington this
afternoon as the next wave crosses the Cascades. Current forecast
high temperatures may be slightly on the high side over Northeast
Washington and North Idaho based on latest guidance and may update
later to lower highs. JW
&&
.AVIATION...
12Z TAFS: Disturbances moving through the somewhat unstable
atmosphere over the aviation area will allow for elevated forced
showers during the overnight and early morning hours along with
surface based convection coupled with peak heating in the near
afternoon and evening hours...but all in all VFR conditions
are expected to prevail.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 65 45 66 46 70 49 / 40 20 20 10 0 10
Coeur d`Alene 64 44 64 43 69 45 / 60 30 30 20 0 10
Pullman 63 43 63 41 69 45 / 20 20 20 10 0 10
Lewiston 70 49 70 48 76 51 / 20 20 20 10 0 10
Colville 70 44 73 43 76 44 / 70 40 30 20 10 10
Sandpoint 64 43 64 42 69 43 / 70 40 40 30 10 10
Kellogg 60 44 60 45 67 46 / 60 30 40 40 10 10
Moses Lake 73 47 76 45 79 48 / 10 10 10 0 0 10
Wenatchee 68 48 72 49 76 51 / 10 10 10 0 0 10
Omak 71 43 74 42 77 46 / 50 20 10 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 181518
AFDSEW
.AVIATION...ANOTHER ROUND OF SHOWERS FOR WESTERN WA TODAY AS A COLD
FRONT MOVES OVER THE REGION. THE AIR MASS IS MOIST AND SOMEWHAT
UNSTABLE WITH FAIRLY LIGHT SW FLOW ALOFT BECOMING NW TONIGHT. THE
MOUNTAINS AND FOOTHILLS WILL BE OBSCURED. MORNING CLOUDS WILL GIVE
WA TO AFTERNOON SUN SUNDAY.
KSEA...SHOWERS WILL INCREASE THIS MORNING AS A COLD FRONT APPROACHES
AND MOVES INLAND. SHOWER ACTIVITY WILL DECREASE TONIGHT AS THE UPPER
LEVEL TROUGH EXITS. THE SURFACE FLOW WILL REMAIN SOUTHERLY.
&&
.MARINE...A COLD FRONT WILL CROSS THE REGION TODAY...WITH ONSHORE
FLOW INCREASING TONIGHT. THE CENTRAL AND EASTERN STRAIT OF JUAN DE
FUCA MAY SEE SMALL CRAFT ADVISORY WINDS THIS EVENING. HIGH PRES OVER
THE NE PAC WILL MAINTAIN NNW FLOW SUN AND MON. ANOTHER FRONT WILL
ARRIVE ON TUE.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KOTX 181129
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
426 AM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Today through Sunday...Low pressure trof containing typical spring
somewhat unstable air-mass along with nuisance mesoscale shortwaves
rotating through and around it remains. The subtle change is that
the axis of the trof moves east and as a result higher pressure
approaches from the west and gets in closer proximity with time.
The result of such a scenario described above is continued clutter
of moderate to low pops the show a decreasing but not disappearing
trend into Sunday to account for not only surface based convection
in the afternoon and evening but also some minor elevated
convection during the overnight and early morning hours associated
with these nuisance small scale shortwaves. Precipitation amounts
can be best conveyed by describing this convection as hit and miss
showers and even more remote weak thunderstorms. With the eastward
migration of the trof axis height rises moving in from the west
suggest an ever so slight and not entirely homogeneous warming
trend in max temperature going into Sunday. /Pelatti
Sunday night through Monday night: Evening showers will taper off
over north Idaho within the vicinity of the upper trough axis.
Meanwhile a high pressure ridge will nose in over eastern
Washington. A few more instability showers or thunderstorms are
possible Monday afternoon and evening over the higher mountains of
the Idaho Panhandle as the weaken trough axis slowly exits the
region. Temperatures will be close to seasonal normals.
Tuesday through Thursday morning: The weather will be focused on the
presence of a deep upper level low. This Pacific low will swing
toward the WA coast Tuesday morning with light showers spread east
of the Cascades by Tuesday afternoon. This is slightly slower than
previous forecast and have indicated this in the forecast and kept
seasonal temperatures through Tuesday. Then as the upper low
center slowly moves inland, the impact will be in the form of a
deformation band of steady moderate precipitation which will shift
across eastern Washington and into north Idaho Tuesday night into
Wednesday. There are a few model differences on the track and
placement of this low center, which will effect the type and
intensity of the precipitation, but for the part did show the
low center meandering on either side of the Cascades. Areas
closer to the low center will encounter more convective
precipitation and lower snow levels down to near 4k ft. The
majority of the medium range models show the best chance of the
steady moderate precipitation from the deformation band will be
across southern BC and into the Canadian Rockies from Wednesday
night through Thursday morning. This will impact runoff and
mountain snow melt from the headwaters of several Inland Northwest
rivers, including the Okanogan, Kootenai, Kettle and Moyie.
Overall, anticipate cooler temperatures by Thursday with a threat
of near freezing conditions by early Thursday morning. /rfox
Thursday Afternoon through Friday Night: This time frame will be the
continuation of the previous period as the stubborn low pressure
system will continue to influence our weather pattern. With the
low in control we will see our temperatures fall to below normal
and slowly creep back towards normal by the end of the period.
Models are in decent agreement given the time frame in keeping the
low pivoting around the Pacific NW region...but the precise
location still remains uncertain given model discrepancies. Longer
range models have the center of the low scattered throughout the
region so above normal climo POPs was the trend in the extended
with the unsettled weather pattern in place. As we progress models
should align better giving a better idea as to where precip will
be more likely. As temps do start to reach more normal values
towards the weekend snow levels will be on the rise...which will
allow for greater runoff contribution to streams. Overall given
current model runs it appears that the brunt of the precip will
have already past but we will need to continue to watch rivers and
streams for any flooding concerns. Even given the far
extended...models are still reluctant to move this system out of
the region so it looks like we will remain in this unsettled pattern
for quite some time. /Fliehman
&&
.AVIATION...
12Z TAFS: Disturbances moving through the somewhat unstable
atmosphere over the aviation area will allow for elevated forced
showers during the overnight and early morning hours along with
surface based convection coupled with peak heating in the near
afternoon and evening hours...but all in all VFR conditions
are expected to prevail.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 65 45 66 46 70 49 / 40 20 20 10 0 10
Coeur d`Alene 64 44 64 43 69 45 / 40 30 30 20 0 10
Pullman 63 43 63 41 69 45 / 20 20 20 10 0 10
Lewiston 70 49 70 48 76 51 / 20 20 20 10 0 10
Colville 70 44 73 43 76 44 / 50 40 30 20 10 10
Sandpoint 64 43 64 42 69 43 / 40 40 40 30 10 10
Kellogg 60 44 60 45 67 46 / 40 30 40 40 10 10
Moses Lake 73 47 76 45 79 48 / 10 10 10 0 0 10
Wenatchee 68 48 72 49 76 51 / 10 10 10 0 0 10
Omak 71 43 74 42 77 46 / 40 20 10 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KPQR 180946
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
246 AM PDT SAT MAY 18 2013
.SYNOPSIS...A COLD FRONT WILL SPREAD LIGHT RAIN ACROSS THE REGION
TODAY. SHOWERS WILL DECREASE TONIGHT BUT CONTINUE OVER THE MOUNTAINS
THROUGH SUNDAY MORNING. HIGH PRESSURE WILL RESULT IN DRIER AND
GRADUALLY WARMER TEMPERATURES SUNDAY AND MONDAY. AN UPPER LEVEL LOW
WILL BRING A RETURN OF RAIN AND MUCH COLDER WEATHER TUESDAY WITH
LIGHT SNOW ACCUMULATIONS POSSIBLE BELOW THE CASCADE PASSES BY
WEDNESDAY MORNING. COOL AND SHOWERY WEATHER WILL CONTINUE THROUGH
FRIDAY.
&&
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...THE NEXT FRONT IS
APPROACHING THE COAST. ASCAT SATELLITE DERIVED WINDS SHOWED THE COLD
FRONT AROUND 300 MILES OFFSHORE AT 11 PM LAST NIGHT. RADAR IMAGERY
SHOWS RAIN AHEAD OF THE FRONT JUST REACHING THE NORTHERN OREGON COAST
AT 2 AM THIS MORNING. AMSU SHOWS TROPICAL PRECIPITABLE WATER AROUND
AN INCH WITH THE FRONT. AN UPPER LEVEL JET POINTED TOWARDS SOUTHERN
OREGON WILL PROVIDE ENOUGH LIFT TO TAP INTO THIS MOISTURE...RESULTING
IN LIGHT RAIN OVER MUCH OF THE REGION TODAY. THE FRONT SHOULD MOVE
ACROSS NW OREGON THIS AFTERNOON WITH ISOLATED TO SCATTERED
POST-FRONTAL SHOWERS TONIGHT.
SHOWERS OVER THE HIGHER TERRAIN WILL LIKELY PERSIST THROUGH SUNDAY
MORNING...BUT OTHERWISE DRY WEATHER CAN BE EXPECTED SUNDAY AS HIGH
PRESSURE BUILDS OVER THE AREA. SUNDAY MORNING WILL LIKELY BE CLOUDY
WITH PARTIAL CLEARING IN THE AFTERNOON...LEADING TO INLAND DAYTIME
HIGHS IN THE MID TO UPPER 60S AND COASTAL HIGHS IN THE UPPER
50S...SLIGHTLY BELOW THE SEASONAL NORMAL.
HIGH PRESSURE MAINTAIN DRY WEATHER FOR MONDAY WHICH WILL LIKELY BE
THE WARMEST DAY OF THE WEEK. INCREASED SUNSHINE SHOULD WARM INTERIOR
TEMPERATURES TO SLIGHTLY ABOVE NORMAL...LOW 70S AND COASTAL AREAS TO
NEAR NORMAL...LOWER 60S.
AN UPPER LEVEL LOW WILL APPROACH MONDAY NIGHT AND BRING A RETURN OF
SHOWERS AND MUCH COOLER WEATHER TO THE REGION. MODELS HAVE BACKED OFF
THE TIMING OF THE ONSET OF RAIN AROUND 12 HOURS. THE COLDEST AIR
ASSOCIATED WITH THE LOW WILL BEGIN MOVING OVER THE AREA TUESDAY NIGHT
AND SNOW LEVELS SHOULD LOWER TO AROUND 3500 TO 4000 FEET.
.LONG TERM...WEDNESDAY THROUGH FRIDAY...A COLD CLOSED LOW WILL
CONTINUE UNSETTLED WEATHER WITH UNSEASONAL COLD TEMPERATURES
WEDNESDAY...WITH RECORD LOW MAXIMUM TEMPERATURES POSSIBLE. WEDNESDAY
WILL BE THE COLDEST DAY OF THE WORK WEEK. TEMPERATURES WILL REMAIN
BELOW THE SEASONAL NORMALS THURSDAY AND FRIDAY AS A COUPLE OF
SHORTWAVE TROUGHS WILL CONTINUE SHOWERY AND COOL CONDITIONS.
&&
.AVIATION...A FRONT WILL APPROACH THE AREA THIS MORNING WITH CIGS
GRADUALLY LOWERING...WITH MVFR AND OCCASIONAL RAIN INCREASING BETWEEN
10Z AND 14Z. FRONT IS FAST MOVING...SO RETURN TO VFR LIKELY
BETWEEN 19Z AND 22Z...FIRST ON COAST AND LATER INLAND AS THE FRONT
SWEEPS EAST OF THE CASCADES BY MID AFTERNOON.
KPDX AND APPROACHES...VFR CONDITIONS FOR THE NEXT COUPLE OF HOURS.
AREAS OF MVFR CIGS DOWN NEAR 2500 FT INCREASE BETWEEN 12Z AND 15Z.
FRONT WILL PUSH ACROSS KPDX OPS AREA BETWEEN 20Z AND 22Z...WITH
RETURN TO VFR WITH SCATTERED SHOWERS.
&&
.MARINE...A FRONT WILL PUSH ACROSS THE COASTAL WATERS THIS
MORNING...THEN INLAND IN THE AFTERNOON. WINDS NOT ALL THAT
IMPRESSIVE BUT THERE SEEMS SO BE ENOUGH GRADIENT TO POP GUSTS 20
TO 25 KT THIS MORNING. SO WILL MAINTAIN CURRENT SMALL CRAFT
ADVISORY. OTHERWISE...WINDS TURN W TO NW BEHIND THE FRONT IN THE
AFTERNOON AND BEGIN TO EASE.
HIGH PRES WILL BUILD OVER THE NE PAC SUN INTO EARLY NEXT WEEK.
THIS WILL KEEP NW WINDS 10 TO 15 KT THROUGH MUCH OF THE COMING
WEEK...THOUGH MAY BRIEFLY GET 20 TO 25 KT GUSTS MON AFTERNOON INTO
THE EVENING.
SEAS REMAIN AT 5 TO 6 FT FOR INTO EARLY NEXT WEEK. MAY SEE SEAS
BUILD UP AND BECOME CHOPPY AT TIMES WITH THE BRISK NW WINDS ON THE
CENTRAL OREGON COASTAL WATERS NEXT WEEK.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 6 AM TO NOON
PDT TODAY FOR ALL COASTAL WATERS.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 180931
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PDT SAT MAY 18 2013
.SYNOPSIS...A WEAK COLD FRONT AND AN UPPER TROUGH WILL MOVE INLAND
TODAY GIVING A COOL SHOWERY DAY. AN UPPER RIDGE WILL BUILD
OFFSHORE SUNDAY AND MOVE INLAND MONDAY FOR WARMER AND MOSTLY DRY
WEATHER. A DEEP UPPER LOW WILL REACH THE AREA TUESDAY AND LINGER
THROUGH MIDWEEK FOR SHOWERY AND UNSEASONABLY COOL WEATHER.
&&
.SHORT TERM...A WEAK COLD FRONT CONTINUES TO HOLD TOGETHER AS IT
APPROACHES THE COAST EARLY THIS MORNING. MODEL QPF IS QUITE LIGHT
WITH THIS SYSTEM AND IT IS EXPECTED TO WEAKEN AS IT MOVES ACROSS
WESTERN WASHINGTON TODAY. DESPITE THE LIKELY WORDING IN THE
FORECAST...INTERIOR AREAS WILL PROBABLY ONLY SEE A FEW HUNDREDTHS OF
PRECIP AT BEST. THE FRONT WILL BE EAST OF THE CASCADES BY THIS
AFTERNOON WITH THE TRAILING UPPER LEVEL TROUGH MOVING OVER WESTERN
WASHINGTON EARLY THIS EVENING. HIGH TEMPERATURES WILL BE ON THE COOL
SIDE WITH THE CLOUDS AND SHOWERS AROUND...3 TO 5 DEGREES BELOW
NORMAL. UPPER LEVEL RIDGING WILL BE REBUILDING OVER THE REGION BY
SUNDAY MORNING. I HELD ON TO THE LOW CHANCE OF SHOWERS FOR SUNDAY
MORNING...BUT IT SHOULD BE A DRY DAY WITH PARTLY SUNNY SKIES AND
TEMPERATURES REBOUNDING TO NEAR SEASONAL NORMALS. I NUDGED THE
EXPECTED HIGHS FOR SUNDAY UP A FEW DEGREES FROM THE PREVIOUS
FORECAST.
THE UPPER RIDGE AXIS WILL BE OVER THE AREA SUNDAY NIGHT WITH 500 MB
HEIGHTS AT OR ABOVE 570 DAM. THE RIDGE AXIS SHIFTS EAST OF THE
CASCADES ON MONDAY...BUT HEIGHTS ONLY FALL SLOWLY. DESPITE ONSHORE
FLOW...INTERIOR AREAS FROM SEATTLE SOUTHWARD HAVE A GOOD SHOT AT
REACHING 70 DEGREES OR BETTER MONDAY AFTERNOON. THE MODELS HAVE
PUSHED THE ARRIVAL OF THE NEXT SYSTEM BACK BY 6 TO 12 HOURS. I
SCALED BACK POPS MONDAY AFTERNOON AND EVENING. MOST INTERIOR AREAS
SHOULD BE DRY MONDAY EVENING...WITH RAIN CHANCES INCREASING LATE
MONDAY NIGHT AS AN UPPER LEVEL TROUGH AND ASSOCIATED FRONT PUSH
SOUTHEASTWARD INTO THE AREA. THIS WILL BEGIN WHAT COULD BE AN
EXTENDED PERIOD OF UNSEASONABLY COOL TEMPERATURES AND OCCASIONALLY
SHOWERY WEATHER MUCH OF NEXT WEEK.
.LONG TERM...THE EXTENDED MODELS ARE IN GENERALLY GOOD AGREEMENT
WITH THE ARRIVAL OF A RATHER DEEP UPPER LEVEL TROUGH ON TUESDAY THAT
SETTLES OVER THE PACIFIC NORTHWEST ON WEDNESDAY. AS PREVIOUSLY
DISCUSSED...THIS WILL LEAD TO SHOWERY AND COOL WEATHER WITH RATHER
LOW SNOW LEVELS FOR LATE MAY. THE MODELS QUICKLY DIVERGE WITH THE
EVOLUTION OF THE TROUGH AS WE GET INTO THE LATER HALF OF NEXT WEEK.
THE CANADIAN TAKES A CLOSED LOW CENTER INTO NORTHERN CALIFORNIA BY
LATE THURSDAY. THE EURO TAKES THE BASE OF THE TROUGH INTO THE
NORTHERN GREAT BASIN DURING THE SAME PERIOD WHILE GFS KEEPS THE LOW
CENTER RIGHT OVER WESTERN WASHINGTON. ALL OF THE MODELS KEEP A BROAD
TROUGH OVER THE WEST COAST INTO LATE NEXT WEEK...BUT HAVE
SIGNIFICANTLY DIFFERENT IDEAS WITH THE TRACKS OF DISTURBANCES
ROTATING THROUGH IT. CONFIDENCE IN ANY LEVEL OF DETAIL FOR THE
BEGINNING OF THE HOLIDAY WEEKEND FORECAST IS VERY LOW AT THIS TIME.
NO SIGNIFICANT CHANGES WERE MADE TO THE EXTENDED FORECAST OVERNIGHT.
27
&&
.AVIATION...A COLD FRONT WILL CROSS THE REGION TODAY FOR ADDITIONAL
SHOWERS. THE AIR MASS IS MOIST AND UNSTABLE WITH WESTERLY FLOW
ALOFT. MVFR CIGS ARE POSSIBLE WITH HEAVIER SHOWERS. SHOWERS WILL
MAINLY AFFECT THE CASCADES TONIGHT AS THE UPPER LEVEL TROUGH SHIFTS
EAST OF THE CASCADES. 33
KSEA...SHOWERS WILL INCREASE THIS MORNING AS A COLD FRONT APPROACHES
AND MOVES INLAND. SHOWER ACTIVITY WILL DECREASE TONIGHT AS THE UPPER
LEVEL TROUGH EXITS. THE SURFACE FLOW WILL REMAIN SOUTHERLY. 33
&&
.MARINE...A COLD FRONT WILL CROSS THE REGION TODAY...WITH ONSHORE
FLOW INCREASING TONIGHT. THE CENTRAL AND EASTERN STRAIT OF JUAN DE
FUCA MAY SEE SMALL CRAFT ADVISORY WINDS. HIGH PRES OVER THE NE PAC
WILL MAINTAIN NORTH/NORTHWESTERLY FLOW SUN AND MON. ANOTHER FRONT
WILL ARRIVE ON TUE. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KOTX 180930
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
230 AM PDT Sat May 18 2013
.SYNOPSIS...
Scattered showers and isolated thunderstorms will develop again
this afternoon and evening. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday afternoon and into Wednesday as a
a very cool and wet upper level low parks itself over the Inland
Northwest. Steady, moderate precipitation will be possible
especially over northeast Washington and the northern Panhandle.
&&
.DISCUSSION...
Today through Sunday...Low pressure trof containing typical spring
somewhat unstable air-mass along with nuisance mesoscale shortwaves
rotating through and around it remains. The subtle change is that
the axis of the trof moves east and as a result higher pressure
approaches from the west and gets in closer proximity with time.
The result of such a scenario described above is continued clutter
of moderate to low pops the show a decreasing but not disappearing
trend into Sunday to account for not only surface based convection
in the afternoon and evening but also some minor elevated
convection during the overnight and early morning hours associated
with these nuisance small scale shortwaves. Precipitation amounts
can be best conveyed by describing this convection as hit and miss
showers and even more remote weak thunderstorms. With the eastward
migration of the trof axis height rises moving in from the west
suggest an ever so slight and not entirely homogeneous warming
trend in max temperature going into Sunday. /Pelatti
Sunday night through Monday night: Evening showers will taper off
over north Idaho within the vicinity of the upper trough axis.
Meanwhile a high pressure ridge will nose in over eastern
Washington. A few more instability showers or thunderstorms are
possible Monday afternoon and evening over the higher mountains of
the Idaho Panhandle as the weaken trough axis slowly exits the
region. Temperatures will be close to seasonal normals.
Tuesday through Thursday morning: The weather will be focused on the
presence of a deep upper level low. This Pacific low will swing
toward the WA coast Tuesday morning with light showers spread east
of the Cascades by Tuesday afternoon. This is slightly slower than
previous forecast and have indicated this in the forecast and kept
seasonal temperatures through Tuesday. Then as the upper low
center slowly moves inland, the impact will be in the form of a
deformation band of steady moderate precipitation which will shift
across eastern Washington and into north Idaho Tuesday night into
Wednesday. There are a few model differences on the track and
placement of this low center, which will effect the type and
intensity of the precipitation, but for the part did show the
low center meandering on either side of the Cascades. Areas
closer to the low center will encounter more convective
precipitation and lower snow levels down to near 4k ft. The
majority of the medium range models show the best chance of the
steady moderate precipitation from the deformation band will be
across southern BC and into the Canadian Rockies from Wednesday
night through Thursday morning. This will impact runoff and
mountain snow melt from the headwaters of several Inland Northwest
rivers, including the Okanogan, Kootenai, Kettle and Moyie.
Overall, anticipate cooler temperatures by Thursday with a threat
of near freezing conditions by early Thursday morning. /rfox
Thursday Afternoon through Friday Night: This time frame will be the
continuation of the previous period as the stubborn low pressure
system will continue to influence our weather pattern. With the
low in control we will see our temperatures fall to below normal
and slowly creep back towards normal by the end of the period.
Models are in decent agreement given the time frame in keeping the
low pivoting around the Pacific NW region...but the precise
location still remains uncertain given model discrepancies. Longer
range models have the center of the low scattered throughout the
region so above normal climo POPs was the trend in the extended
with the unsettled weather pattern in place. As we progress models
should align better giving a better idea as to where precip will
be more likely. As temps do start to reach more normal values
towards the weekend snow levels will be on the rise...which will
allow for greater runoff contribution to streams. Overall given
current model runs it appears that the brunt of the precip will
have already past but we will need to continue to watch rivers and
streams for any flooding concerns. Even given the far
extended...models are still reluctant to move this system out of
the region so it looks like we will remain in this unsettled pattern
for quite some time. /Fliehman
&&
.AVIATION...
06Z TAFS: A slow moving system beginning to push into southern WA
late this evening will continue to produce isolated to scattered
rain showers across the region tonight into tomorrow afternoon. Cigs
are expected to remain above 4 kft agl with vfr conditions through
Saturday afternoon. Winds are expected to pick up a bit out of the
west late Saturday afternoon at KEAT with gusts up to 30 mph
possible. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 65 45 66 46 70 49 / 40 20 20 10 0 10
Coeur d`Alene 64 44 64 43 69 45 / 40 30 30 20 0 10
Pullman 63 43 63 41 69 45 / 20 20 20 10 0 10
Lewiston 70 49 70 48 76 51 / 20 20 20 10 0 10
Colville 70 44 73 43 76 44 / 50 40 30 20 10 10
Sandpoint 64 43 64 42 69 43 / 40 40 40 30 10 10
Kellogg 60 44 60 45 67 46 / 40 30 40 40 10 10
Moses Lake 73 47 76 45 79 48 / 10 10 10 0 0 10
Wenatchee 68 48 72 49 76 51 / 10 10 10 0 0 10
Omak 71 43 74 42 77 46 / 40 20 10 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KOTX 180547
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1047 PM PDT Fri May 17 2013
.SYNOPSIS...
A series of weak weather disturbances coupled with an unstable air
mass will result in occasional showers and isolated thunderstorms
through most of the weekend. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday and into the middle of next week
as a very cool and wet upper level low parks over the Inland
Northwest. Moderate to locally heavy precipitation will be
possible especially over northeast Washington and the northern
Panhandle.
&&
.DISCUSSION...
Forecast from the afternoon package is largely on track. The upper
level shortwave trough of lower pressure responsible for the
showers across the region is pivoting into northeast Oregon up
into southwestern WA this evening. Scattered showers are expected
to continue across much of the region through the late evening
hours and then slowly push across northern portions of eastern WA
and over the ID Panhandle for the overnight hours. I did keep a
mention of some isolated thunderstorms across the Central
Panhandle Mountains and Northern Panhandle through the late
evening hours as we continue to get a few lightning strikes from
some of the stronger cells across these areas. We may see a strike
or two after about 1100 PM tonight, but instability aloft is
fairly weak for much in the way of thunderstorms to continue
through the nighttime hours. /SVH
&&
.AVIATION...
06Z TAFS: A slow moving system beginning to push into southern WA
late this evening will continue to produce isolated to scattered
rain showers across the region tonight into tomorrow afternoon. Cigs
are expected to remain above 4 kft agl with vfr conditions through
Saturday afternoon. Winds are expected to pick up a bit out of the
west late Saturday afternoon at KEAT with gusts up to 30 mph
possible. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 47 65 45 66 45 69 / 50 40 20 20 10 10
Coeur d`Alene 47 64 44 64 44 68 / 50 40 30 30 20 10
Pullman 47 63 43 63 42 68 / 20 20 20 20 10 0
Lewiston 51 70 49 70 48 75 / 20 20 20 20 10 0
Colville 47 70 44 73 43 75 / 40 50 40 30 20 10
Sandpoint 46 64 43 64 42 68 / 60 40 40 40 30 10
Kellogg 47 60 44 59 45 66 / 70 40 30 40 40 10
Moses Lake 50 73 47 76 46 77 / 30 10 10 10 0 0
Wenatchee 50 68 48 72 48 75 / 20 10 10 10 0 0
Omak 48 71 43 74 42 75 / 30 40 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KSEW 180455
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
955 PM PDT FRI MAY 17 2013
.SYNOPSIS...A WEAK COLD FRONT AND AN UPPER TROUGH WILL MOVE INLAND
SATURDAY GIVING A COOL SHOWERY DAY. AN UPPER RIDGE WILL BUILD
OFFSHORE SUNDAY AND MOVE INLAND MONDAY FOR WARMER AND MOSTLY DRY
WEATHER. A DEEP UPPER LOW WILL REACH THE AREA TUESDAY AND LINGER
THROUGH MIDWEEK FOR SHOWERY AND UNSEASONABLY COOL WEATHER. SOME
IMPROVEMENT IS POSSIBLE BY MEMORIAL DAY WEEKEND.
&&
.SHORT TERM...SATELLITE IMAGERY SHOWS CLOUDY SKIES OVER MOST OF
WESTERN WASHINGTON THIS EVENING. WEAK UPPER LEVEL TROUGH MOVED INTO
THE AREA IN THE AFTERNOON HOURS TRIGGERING SOME SHOWERS BY LATE IN
THE AFTERNOON. MOST OF THE SHOWER ACTIVITY HAS COME TO AN END OVER
THE AREA OR WILL COME TO AN END BEFORE MIDNIGHT. THE EXCEPTION IS
OVER ISLAND...SAN JUAN AND WESTERN SKAGIT AND WHATCOM COUNTY WHERE
WEAK CONVERGENCE WILL KEEP THE SHOWERS GOING PAST MIDNIGHT.
TEMPERATURES AT 9 PM WERE IN THE 50S.
SATELLITE IMAGERY ALSO SHOWS WEAK COLD FRONT OFFSHORE NEAR 130W AT
04Z. CLOUD TOP TEMPERATURES ARE NOT WARMING AS THE FRONT APPROACHES
THE COAST INDICATING THAT THE SYSTEM IS NOT WEAKENING. THE UPPER
LEVEL TROUGH BEHIND THE FRONT WILL DIG SOUTH A BIT ON SATURDAY WITH
THE JET AIMED AT SOUTHERN OREGON/NORTHERN CALIFORNIA. THIS WILL SLOW
DOWN THE EASTWARD MOVEMENT OF THE SYSTEM AND WEAKEN IT AS IT MOVES
INLAND ON SATURDAY. EVEN WITH THE FRONT WEAKENING EXPECT LIGHT
PRECIPITATION ALONG THE COAST FOR MOST OF THE DAY WITH MORE SPOTTY
PRECIPITATION OVER THE INTERIOR. HIGHEST POPS OVER THE INTERIOR IN
THE AFTERNOON VERSUS THE MORNING HOURS STILL LOOK GOOD. FRONT
DISSIPATES OVER THE AREA LATE IN THE DAY WITH THE UPPER LEVEL TROUGH
EAST OF THE CASCADES BY 06Z. THIS WILL BRING ABOUT AN END TO MOST OF
THE SHOWER ACTIVITY.
UPPER LEVEL RIDGE OFFSHORE BUILDING INLAND ON SUNDAY. SURFACE
GRADIENTS REMAINING ONSHORE BUT 00Z MODEL RUNS HAVE 500 MB HEIGHTS
570 DM PLUS BY THE AFTERNOON HOURS. STILL A CHANCE OF AN ISOLATED
SHOWER EARLY SUNDAY MORNING. DAYTIME HIGHS SHOULD RECOVER BACK TO
NEAR NORMAL.
RIDGE SHIFTING TO THE EAST ON SUNDAY WITH SOUTHWESTERLY FLOW ALOFT
OVER THE AREA. WEAK ONSHORE PRESSURE GRADIENTS CONTINUE BUT THE
PRECIPITATION ASSOCIATED WITH A COOL UPPER LEVEL LOW APPROACHING THE
AREA STILL WELL OFFSHORE AT 00Z TUESDAY. WARMEST LOCATIONS ON MONDAY
SHOULD CREEP BACK INTO THE LOWER 70S. CURRENT FORECAST LOOKS A
LITTLE ON THE COOL SIDE FOR SUNDAY AND MONDAY. WILL LET THE MIDSHIFT
MAKE THE FINAL DECISION ON BUMPING THE MAX TEMPS UP A COUPLE OF
DEGREES BOTH DAYS. NO UPDATE THIS EVENING. FELTON
.LONG TERM...PREVIOUS DISCUSSION FOLLOWS. THE UPEPR LOW DEEPENS AND
MOVES TO JUST OFF THE COAST ON TUESDAY. THE GFS AND EURO AGREE ON
THIS. THEN BOTH MODELS MOVE THE UPPER LOW INLAND AND KEEP IT MORE OR
LESS OVER THE AREA WEDNESDAY AND THURSDAY...ALTHOUGH BY THURSDAY THE
TRACKS ARE DIVERGING SIGNIFICANTLY. THE GFS MOVES THE LOW NORTH AND
THE EURO MOVES IT SOUTH...THEREBY MAKING FRIDAY A DRIER AND WARMER
DAY COMPLETELY BY COINCIDENCE.
IF THE MODELS ARE RIGHT...TUESDAY THROUGH THURSDAY ARE GOING TO BE
COOL AND SHOWERY DAYS. HIGHS MAY NOT GET OUT OF THE 50S. THERE COULD
BE SNOW SHOWERS IN THE MOUNTAINS WITH THE SNOW LEVEL DIPPING TO 3000
FEET OR SO. CONFIDENCE IS NOT PARTICULARLY HIGH IN ANY DETAILS. FOR
INSTANCE...THE ENSEMBLE GFS SOLUTIONS SHOW KSEA HIGHS ON TUESDAY
RANGING FROM 55 TO 68. HOWEVER IT SEEMS LIKELY THERE WILL BE SOME
VERY COOL DAYS WITH SHOWERS...PROBABLY MIXED IN WITH SOME PARTLY
SUNNY DAYS. BURKE
&&
.AVIATION...AN UPPER LEVEL TROUGH OVER THE PAC NW WILL MAINTAIN
ISOLATED TO SCATTERED SHOWERS ACROSS WESTERN WA TONIGHT. THE FLOW
ALOFT IS LIGHT WESTERLY. SHOWERS WILL INCREASE IN COVERAGE SAT
MORNING AS A COLD FRONT MOVES INLAND. ONSHORE FLOW WILL INCREASE
BEHIND THIS FRONT SAT NIGHT. 33
KSEA...ISOLATED LIGHT SHOWERS WILL REMAIN IN THE VICINITY
TONIGHT...WITH SOUTHERLY FLOW AT THE SURFACE. SHOWERS WILL INCREASE
ON SAT AS A COLD FRONT MOVES INLAND. 33
&&
.MARINE...ONSHORE FLOW WILL CONTINUE ACROSS WESTERN WA TONIGHT. A
COLD FRONT WILL CROSS THE REGION ON SAT FOR INCREASING WINDS.
HIGHEST WINDS WILL BE FOUND THROUGH THE STRAIT OF JUAN DE FUCA -
SMALL CRAFT ADVISORY WINDS ARE LIKELY. HIGH PRES OVER THE NE PAC
WILL MAINTAIN ONSHORE FLOW SUN AND MON. ANOTHER FRONT WILL ARRIVE ON
TUE. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML
000
FXUS66 KOTX 180330
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
830 PM PDT Fri May 17 2013
.SYNOPSIS...
A series of weak weather disturbances coupled with an unstable air
mass will result in occasional showers and isolated thunderstorms
through most of the weekend. The greatest threat of thunder will
occur over the northeast corner of Washington and much of the
Idaho Panhandle. Precipitation chances will diminish a bit on
Sunday and by Monday most locations will be dry. This drying will
come to an abrupt end by Tuesday and into the middle of next week
as a very cool and wet upper level low parks over the Inland
Northwest. Moderate to locally heavy precipitation will be
possible especially over northeast Washington and the northern
Panhandle.
&&
.DISCUSSION...
Forecast from the afternoon package is largely on track. The upper
level shortwave trough of lower pressure responsible for the
showers across the region is pivoting into northeast Oregon up
into southwestern WA this evening. Scattered showers are expected
to continue across much of the region through the late evening
hours and then slowly push across northern portions of eastern WA
and over the ID Panhandle for the overnight hours. I did keep a
mention of some isolated thunderstorms across the Central
Panhandle Mountains and Northern Panhandle through the late
evening hours as we continue to get a few lightning strikes from
some of the stronger cells across these areas. We may see a strike
or two after about 1100 PM tonight, but instability aloft is
fairly weak for much in the way of thunderstorms to continue
through the nighttime hours. /SVH
&&
.AVIATION...
00Z TAFS: Widely scattered showers will affect most TAF sites
through 03Z. Isold -tsra will be possible but the threat is too
low to include in TAF forecast. Surface based convection will
dissipate after 03z but a weak midlevel wave lifting through the
region will bring the potential for nocturnal showers mainly east
of Moses Lake through the overnight period. Afternoon convection
will develop again after 18Z, but coverage will be spotty. /Kelch
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 47 65 45 66 45 69 / 50 40 20 20 10 10
Coeur d`Alene 47 64 44 64 44 68 / 50 40 30 30 20 10
Pullman 47 63 43 63 42 68 / 20 20 20 20 10 0
Lewiston 51 70 49 70 48 75 / 20 20 20 20 10 0
Colville 47 70 44 73 43 75 / 40 50 40 30 20 10
Sandpoint 46 64 43 64 42 68 / 60 40 40 40 30 10
Kellogg 47 60 44 59 45 66 / 70 40 30 40 40 10
Moses Lake 50 73 47 76 46 77 / 30 10 10 10 0 0
Wenatchee 50 68 48 72 48 75 / 20 10 10 10 0 0
Omak 48 71 43 74 42 75 / 30 40 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
000
FXUS66 KPQR 180305
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
800 PM PDT FRI MAY 17 2013
.SYNOPSIS...SCATTERED SHOWERS WILL SHIFT INTO THE CASCADES THIS
EVENING AS WEAK SURFACE HIGH PRESSURE BUILDS INTO OREGON AND SW
WASHINGTON. THE NEXT PACIFIC SYSTEM WILL MOVE IN FOR SATURDAY...
BRINGING A PERIOD OF STEADY LIGHT RAIN SATURDAY FOLLOWED BY
DECREASING SHOWERS SATURDAY NIGHT AND SUNDAY. DRIER WEATHER IS
EXPECTED SUN NIGHT/MON... BUT IT IS LOOKING MORE LIKELY THAT A COOL
AND UNSETTLED PATTERN WILL SET UP OVER THE PACIFIC NORTHWEST FOR THE
MIDDLE OF NEXT WEEK.
&&
.SHORT TERM...TONIGHT THROUGH MONDAY...THE BACK EDGE OF SLOW MOVING
SHOWER ACTIVITY HAS SHIFTED INTO THE FOOTHILLS AND CASCADES AS HIGH
PRESSURE NOSES INTO NW OREGON AND SW WASHINGTON. HIGH PRESSURE WILL
REMAIN IN PLACE FOR THE REMAINDER OF THE EVENING AND INTO THE EARLY
OVERNIGHT HOURS...THUS EXPECT MOST AREAS OUTSIDE OF THE CASCADES AND
EVENTUALLY THE COAST TO REMAIN DRY UNTIL LATE TONIGHT.
A GRADUAL END TO SHOWER ACTIVITY HAS OCCURRED BUT MANY AREAS WILL
REMAIN MOSTLY CLOUDY DUE TO THE MOIST LOW LEVEL AIR MASS. THE
EXCEPTION WILL BE IN LEE OF THE COAST RANGE FOR THE REMAINDER OF THE
EVENING. NAM CROSS SECTIONS THROUGH THE WILLAMETTE VALLEY SEEM TO
SUPPORT THIS THINKING. EITHER WAY...IT WILL NOT BE LONG BEFORE HIGHER
CLOUDS BEGIN TO MOVE IN AHEAD OF OUR NEXT SYSTEM NOW SHOWN INSIDE
130W ON IR/WV SATELLITE IMAGERY. KMD
REST OF THE SHORT TERM FORECAST DISCUSSION UNCHANGED...STILL LOOKS
LIKE A DECENT CHANCE FOR RAIN THROUGHOUT THE DISTRICT SATURDAY AS
THAT MODEST FRONTAL SYSTEM MOVES ONSHORE. THERE WILL BE SOME WEAK
ISENTROPIC LIFT AHEAD OF THIS SYSTEM...SO JUST ABOUT EVERYONE SHOULD
GET SOME LIGHT RAIN. ONLY MODEST OROGRAPHIC ENHANCEMENT WITH 15-25
KT SW 850 MB WINDS...SO EXPECT RAIN TOTALS TO RANGE FROM 0.10-0.25
INCH IN THE VALLEYS AND 0.50 TO LOCALLY 1 INCH IN THE HIGHER
TERRAIN. RAIN WILL TAPER TO SHOWERS SATURDAY NIGHT WITH A FEW
LINGERING INTO SUNDAY...MAINLY OVER THE HIGHER TERRAIN.
TEMPERATURES WILL HOVER NEAR OR A LITTLE BELOW NORMAL THROUGH THE
WEEKEND. SNOW LEVELS SHOULD REMAIN ABOVE THE PASSES THROUGHOUT THE
WEEKEND...BUT MAY GET AS LOW AS 4500-5000 FT AT TIMES. MONDAY APPEARS
TO BE A DRIER DAY WITH MILD TEMPS AS A SHORTWAVE RIDGE MOVES ACROSS
THE PACIFIC NORTHWEST...BUT THIS WILL BE BRIEF AS THE NEXT SYSTEM
LOOMS FOR TUESDAY AND MIDWEEK. WEAGLE
.LONG TERM...MONDAY EVENING THROUGH FRIDAY...COLD CLOSED LOW
PRESSURE SYSTEM WILL PUSH ONSHORE MONDAY NIGHT...BRINGING RAIN AND
MUCH COOLER TEMPERATURES TO THE AREA. THIS LOW WILL LINGER OVER THE
PAC NW TUESDAY AND MUCH OF THE DAY WEDNESDAY...WITH RECORD LOW
MAXIMUM TEMPERATURES POSSIBLE ON WEDNESDAY. BY THURSDAY MODELS
DISAGREE ON WHERE THE LOW WILL PROPAGATE...BUT THE OVERALL TREND IS
FOR SHOWERY AND COOL CONDITIONS TO PERSIST THROUGH THE END OF THE
WEEK. BURGESS
&&
.AVIATION...AIR MASS STABILIZING THIS EVENING...AS MORE STABLE AIR
MASS SPREADS INTO THE REGION. SKIES REMAIN VFR THIS EVENING...WITH
WORST CONDITIONS AGAINST THE CASCADES. AS FRONT APPROACHES...CIGS
GRADUALLY LOWER LATE TONIGHT...WITH MVFR AND OCCASIONAL RAIN
INCREASING BETWEEN 10Z AND 14Z SAT. FRONT IS FAST MOVING...SO
RETURN TO VFR LIKELY BETWEEN 19Z AND 22Z...FIRST ON COAST AND
LATER INLAND AS THE FRONT SWEEPS EAST OF THE CASCADES BY MID
AFTERNOON.
KPDX AND APPROACHES...VFR TONIGHT. AREAS OF MVFR CIGS DOWN NEAR
2500 FT INCREASE BETWEEN 12Z AND 15Z. MVFR WITH RAIN DOMINATES
SAT AM. FRONT WILL PUSH ACROSS KPDX OPS AREA BETWEEN 20Z AND
22Z...WITH RETURN TO VFR WITH SCATTERED SHOWERS.ROCKEY.
&&
.MARINE...WINDS WILL GRADUALLY TURN MORE SOUTHERLY TONIGHT AS
ANOTHER FRONT APPROACHES. THIS FRONT WILL PUSH ACROSS THE COASTAL
WATERS SAT AM...THEN INLAND IN THE AFTERNOON. WINDS NOT ALL THAT
IMPRESSIVE BUT SEEMS THAT BE ENOUGH GRADIENT TO POP GUSTS 20 TO 25
KT SAT AM. SO WILL PUT UP SMALL CRAFT ADVISORY FOR THAT TIME
FRAME. OTHERWISE...WINDS TURN W TO NW BEHIND THE FRONT IN THE
AFTERNOON AND BEGIN TO EASE.
HIGH PRES WILL BUILD OVER THE NE PAC FOR SUN INTO EARLY NEXT WEEK.
THIS WILL KEEP NW WINDS 10 TO 15 KT THROUGH MUCH OF THE COMING
WEEK...THOUGH MAY BRIEFLY GET 20 TO 25 KT GUSTS MON AFTERNOON INTO
THE EVENING.
SEAS REMAIN AT 5 TO 6 FT FOR INTO EARLY NEXT WEEK. MAY SEE SEAS
BUILD UP AND BECOME CHOPPY AT TIMES WITH THE BRISK NW WINDS ON THE
CENTRAL OREGON COASTAL WATERS NEXT WEEK. ROCKEY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS SAT AM ON ALL COASTAL WATERS.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
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