or discuss
Office: MFR
FXUS66 KMFR 182323
AFDMFR
Area Forecast Discussion
National Weather Service Medford OR
216 PM PDT Thu Apr 18 2024
...Updated AVIATION discussion...
.DISCUSSION...The steady dry and warming trend continues through
the rest of the work week, with high pressure overhead and a
thermal trough developing along the coast. This pattern is
producing a general east wind aloft, and this will then result in
downsloping winds, especially along the south coast near
Brookings, and will allow for strong overnight inversions for
inland valleys. This means that while daytime highs will be above
normal for this time of year, lows in the valleys will be cool. A
few pockets of frost and freeze are possible, but widespread
freezing conditions are not expected west of the Cascades.
A weak system will approach the area Saturday, with a mostly dry
cold front passing through by Saturday night. While precipitation
is possible along the coast, and perhaps into the Umpqua basin
and the Cascades, precipitation amounts will be very light.
Additionally, the main dynamics associated with this system are
very far north, so if the system shifts north at all we could miss
out entirely. Even a southward shift of the surface features
wouldn't help out too much, as all upper level support would still
remain well to the north. Behind the front, temperatures will
cool, with Sunday highs about 10 to 15 degrees cooler than Friday
or Saturday.
High pressure, with dry conditions and warm daytime temperatures
and cool nights (and another chance for frost/freeze conditions)
will return Monday into Tuesday, then the next system arrives by
late Tuesday or Tuesday night, with upper level troughing passing
overhead Wednesday into Thursday. Again, we do not expect this to
be much of a rainmaker. In fact, the frontal passage itself
appears almost completely dry, with more widespread precipitation
arriving behind the front as showers develop within the
instability under the upper level trough. Confidence is low in any
details at this time, given the wide spread in ensemble
solutions, so updates will likely be necessary over the coming
days.
&&
.AVIATION...19/00Z TAFs...Atmospheric stability will bring continued
VFR levels under clear skies for northern California and southern
Oregon through the TAF period. Gusty northerly winds over the Oregon
coast will continue into the evening but will calm overnight. Other
than that, no changes are expected. -TAD
&&
.MARINE...Updated 200 PM Thursday, April 18, 2024...A thermal
trough will continue to bring gusty north winds and steep seas to
all waters into tonight. The thermal trough weakens tomorrow and
conditions will improve. Relatively light winds and low seas
continue into Saturday, though a weak cold front will move through
with some rain. Gusty north winds and steep seas are expected to
return later in the weekend. -Spilde/Hermansen
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Friday
for PZZ350-356-370-376.
&&
$$
Office: PQR
FXUS66 KPQR 182131
AFDPQR
Area Forecast Discussion
National Weather Service Portland OR
231 PM PDT Thu Apr 18 2024
.SYNOPSIS...
High pressure over the region will remain through
Friday, maintaining mild sunny days and cool clear nights.
Offshore flow continues, with breezy easterly winds on the west
slopes of the Cascades and to some degree, the Coast Range.
Will return to cooler conditions this weekend, as a front pushes
across the region. Unsettled weather continues into early next
week.
&&
.SHORT TERM...TODAY THROUGH SATURDAY...High pressure continues
in the region, with sunny and warm conditions. Temperatures
today are on track to reach right about to 70 or just barely
into the low 70s throughout the Willamette Valley, while the
coast will be just a bit cooler, peaking in the upper 60s.
Offshore flow continues, with generally NE winds curling N in
the central and southern Willamette Valley. Generally pleasant
spring conditions expected today and tomorrow.
Breezy east winds through the Gorge are currently gusting to
around 25mph, but this is expected to continue increasing
through tonight and Friday as the thermal trough continues
building. High temperatures Friday will be just a degree or two
warmer, and east wind through the Gorge will increase late
Thursday night/early Friday morning. Exposed upper elevation
areas could see gusts potentially up to 35-50mph throughout most
of Friday, gradually weakening over Friday night. The rest of
the region should see NE or E breezy winds up to 10-20 mph. Will see
wind-reversal along the coast in the afternoon, with east to
northeast winds becoming southerly to south of Florence in the
afternoon, and as far north as Newport by sunset as the thermal
trough shifts inland over the Coast Range. This will allow for
cooler ocean air to spread back across the coastal zones at that
time. But, offshore flow persists on to the north overnight,
such as at Astoria. Likely be one of those afternoons where
Newport is 59 with light south wind and Astoria is around 70
with an east wind in the late afternoon.
Changes gradually arrive Fri night into early Sat, as a front well
offshore approaches. Will see offshore flow gradually weaken Fri
night, with increasing clouds later Fri night into Sat am. Timing
still suggest showers or pockets of light rain spreading to the coast
by midday Sat, and pushing inland during the afternoon. Again, not a
strong front, as rainfall expected on Sat being 0.10 to 0.25 inch
along the coast/coastal mountains, and 0.02 to 0.10 for
lowlands form Cowlitz Valley through the Willamette Valley. Will
be much cooler on Saturday, thanks to clouds and onshore flow.
Highs only in the 50s along the coast, and lower to middle 60s
inland. /Rockey/JLiu
.LONG TERM...SUNDAY THROUGH WEDNESDAY...Onshore flow begins
developing Saturday night into Sunday. Cooler conditions are
expected Sunday as a result, with coastal highs in the mid 50s,
and right around 60 inland. Ensemble guidance points towards a
brief shortwave ridge impacting the area on Monday and Tuesday
morning, allowing for warmer temperatures potentially back into
the 70s. Tuesday and Wednesday see potential for another front,
allowing for light showers and cooler temperatures again. /JLiu
&&
.AVIATION...VFR thresholds prevail through the entire TAF period
with easterly flow aloft. North to northeast surface winds through
06z with wind gusts 15-20 kt through around 06z Friday. Winds
turn more east to northeast and calm for most areas after 06z
Friday as high pressure settles east of the Cascades, though the
central and southern Willamette Valley will remain mostly
northerly. However, east winds through the Columbia River Gorge
begin increasing after 06z Friday with gusts up to 35 to 50 kt
possible through Friday.
PDX AND APPROACHES...VFR conditions expected through the entire
TAF period. Easterly winds 10-15 kt with gusts up to 25 kt,
settling after 03-05Z Friday to 10 kt or less. Once winds have
settled after 05Z Friday, surface winds could turn westerly due
to influence of the Columbia River. This could cause directional
LLWS due to enhanced easterly winds aloft from strong flow through
the Gorge, though there is not enough confidence in this scenario
or strength of LLWS to include in TAFS. Winds expected to
increase to 10-15 kts and turn easterly again by 15Z Friday, which
would eliminate any directional LLWS concerns. -HEC
&&
.MARINE...Surface high pressure has shifted onshore this afternoon
as a thermal trough remains over western Oregon. This has caused
a tightening of surface pressure gradients, which will bring
elevated wind gusts to 25-30 mph through this evening, resulting
in choppy waters. A Small Craft Advisory remains in effect through
this evening. Pressure gradients will weaken tonight, as the
thermal trough continues to build north along the Oregon Coast,
causing winds to weaken. This pattern will continue through Friday
until a Pacific front approaches the waters Friday night,
breaking down the thermal trough and turning winds southerly.
Southerly winds increase through the day Saturday as the front
moves through the waters, with Small Craft winds likely into
Sunday.
General seas through Saturday afternoon of 4 to 7 feet at 15 to
17 seconds, consisting of a long period southwest swell. Swell
becomes westerly Saturday evening into Sunday, increasing general
seas to 9 to 11 feet at 9 to 11 seconds. -HEC
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 8 PM PDT this evening for PZZ251-
271.
Small Craft Advisory until 11 PM PDT this evening for PZZ252-
253.
Small Craft Advisory until 11 PM PDT this evening for PZZ272-
273.
&&
$$
www.weather.gov/portland
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FXUS66 KPQR 182137 CCA
AFDPQR
Area Forecast Discussion
National Weather Service Portland OR
231 PM PDT Thu Apr 18 2024
Corrected marine discussion.
.SYNOPSIS...
High pressure over the region will remain through
Friday, maintaining mild sunny days and cool clear nights.
Offshore flow continues, with breezy easterly winds on the west
slopes of the Cascades and to some degree, the Coast Range.
Will return to cooler conditions this weekend, as a front pushes
across the region. Unsettled weather continues into early next
week.
&&
.SHORT TERM...TODAY THROUGH SATURDAY...High pressure continues
in the region, with sunny and warm conditions. Temperatures
today are on track to reach right about to 70 or just barely
into the low 70s throughout the Willamette Valley, while the
coast will be just a bit cooler, peaking in the upper 60s.
Offshore flow continues, with generally NE winds curling N in
the central and southern Willamette Valley. Generally pleasant
spring conditions expected today and tomorrow.
Breezy east winds through the Gorge are currently gusting to
around 25mph, but this is expected to continue increasing
through tonight and Friday as the thermal trough continues
building. High temperatures Friday will be just a degree or two
warmer, and east wind through the Gorge will increase late
Thursday night/early Friday morning. Exposed upper elevation
areas could see gusts potentially up to 35-50mph throughout most
of Friday, gradually weakening over Friday night. The rest of
the region should see NE or E breezy winds up to 10-20 mph. Will see
wind-reversal along the coast in the afternoon, with east to
northeast winds becoming southerly to south of Florence in the
afternoon, and as far north as Newport by sunset as the thermal
trough shifts inland over the Coast Range. This will allow for
cooler ocean air to spread back across the coastal zones at that
time. But, offshore flow persists on to the north overnight,
such as at Astoria. Likely be one of those afternoons where
Newport is 59 with light south wind and Astoria is around 70
with an east wind in the late afternoon.
Changes gradually arrive Fri night into early Sat, as a front well
offshore approaches. Will see offshore flow gradually weaken Fri
night, with increasing clouds later Fri night into Sat am. Timing
still suggest showers or pockets of light rain spreading to the coast
by midday Sat, and pushing inland during the afternoon. Again, not a
strong front, as rainfall expected on Sat being 0.10 to 0.25 inch
along the coast/coastal mountains, and 0.02 to 0.10 for
lowlands form Cowlitz Valley through the Willamette Valley. Will
be much cooler on Saturday, thanks to clouds and onshore flow.
Highs only in the 50s along the coast, and lower to middle 60s
inland. /Rockey/JLiu
.LONG TERM...SUNDAY THROUGH WEDNESDAY...Onshore flow begins
developing Saturday night into Sunday. Cooler conditions are
expected Sunday as a result, with coastal highs in the mid 50s,
and right around 60 inland. Ensemble guidance points towards a
brief shortwave ridge impacting the area on Monday and Tuesday
morning, allowing for warmer temperatures potentially back into
the 70s. Tuesday and Wednesday see potential for another front,
allowing for light showers and cooler temperatures again. /JLiu
&&
.AVIATION...VFR thresholds prevail through the entire TAF period
with easterly flow aloft. North to northeast surface winds through
06z with wind gusts 15-20 kt through around 06z Friday. Winds
turn more east to northeast and calm for most areas after 06z
Friday as high pressure settles east of the Cascades, though the
central and southern Willamette Valley will remain mostly
northerly. However, east winds through the Columbia River Gorge
begin increasing after 06z Friday with gusts up to 35 to 50 kt
possible through Friday.
PDX AND APPROACHES...VFR conditions expected through the entire
TAF period. Easterly winds 10-15 kt with gusts up to 25 kt,
settling after 03-05Z Friday to 10 kt or less. Once winds have
settled after 05Z Friday, surface winds could turn westerly due
to influence of the Columbia River. This could cause directional
LLWS due to enhanced easterly winds aloft from strong flow through
the Gorge, though there is not enough confidence in this scenario
or strength of LLWS to include in TAFS. Winds expected to
increase to 10-15 kts and turn easterly again by 15Z Friday, which
would eliminate any directional LLWS concerns. -HEC
&&
.MARINE...A thermal trough continues to build over the western
Oregon coast this afternoon with surface high pressure off the
WA/B.C. coast. This has caused a tightening of surface pressure
gradients, which will bring elevated wind gusts to 25-30 mph through
this evening, resulting in choppy waters. A Small Craft Advisory
remains in effect through this evening. Pressure gradients will
weaken tonight as the thermal trough continues to build north along
the Oregon Coast, causing winds to weaken. This pattern will
continue through Friday until a Pacific front approaches the waters
Friday night, breaking down the thermal trough and turning winds
southerly. Southerly winds increase through the day Saturday as the
front moves through the waters, with Small Craft winds likely into
Sunday.
General seas through Saturday afternoon of 4 to 7 feet at 15 to 17
seconds, consisting of a long period southwest swell. Swell becomes
westerly Saturday evening into Sunday, increasing general seas to 9
to 11 feet at 9 to 11 seconds. -HEC
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 8 PM PDT this evening for PZZ251-
271.
Small Craft Advisory until 11 PM PDT this evening for PZZ252-
253.
Small Craft Advisory until 11 PM PDT this evening for PZZ272-
273.
&&
$$
www.weather.gov/portland
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Office: PDT
FXUS66 KPDT 190000
AFDPDT
Area Forecast Discussion
National Weather Service Pendleton OR
500 PM PDT Thu Apr 18 2024
Updated Aviation Discussion
.AVIATION...00Z TAFs...VFR conditions over the next 24 hours. SCT
high clouds possible BDN/RDM, clear skies all other sites. Winds
occasionally breezy this afternoon all sites, but dominant winds
should be around 5-15 knots becoming less than 10 knots overnight,
with gusts 15-20 knots tomorrow expected primarily at YKM.
Goatley/87
&&
.PREV DISCUSSION... /issued 158 PM PDT Thu Apr 18 2024/
SHORT TERM...
Tonight through Saturday night... Dry northwesterly flow will be in
place tonight through Friday. A ridge will move over the Pacific
Northwest Friday night and early Saturday before moving eastward
later Saturday into Saturday night.
An upper level low will move to the north, generally over British
Columbia and Northern Washington by Sunday morning. The flow will
become more zonal or even slight troughing as a result, and the
pressure gradient will tighten.
There will be some breezy conditions tomorrow mainly over the
western sections of the Oregon Basin and then the Simcoe Highlands.
the NBM probabilities of winds gusting >=39 mph on Friday are 50
to 60% across the Simcoe Highlands and 30-50% across the western
Columbia Basin of Oregon. Winds will increase again Saturday
evening and continue into Saturday night, with wind gusts 30 to 40
mph mainly during this time across the Simcoe Highlands, Yakima
Valley, Columbia Basin, and Foothills of the Blue Mountains. NBM
wind gusts probabilities >=39 mph are 50-80% in the Simcoe
Highlands, Yakima Valley and and 40 to 60% in the Columbia Basin
and Blue Mountain Foothills. NBM wind gust probabilities >=47 mph
drop to 40 to 50 % across the Simcoe Highlands and Yakima Valley
and less than 20% most elsewhere.
Dry conditions are expected everywhere through later Saturday.
Then, some precipitation will impact the Cascades. Snow levels
will initially be over 7000 feet in the Oregon Cascades and over
5000 feet in the Washington Cascades, so any precipitation will
be all rain, except at the highest peaks of the Washington
Cascades. However, snow levels will fall through Sunday morning
and will be around 3000 feet, so there could be some very light
accumulations (less than 1 inch) accumulations at pass level and
perhaps a couple of inches at the higher elevations.
Elsewhere by Sunday morning, precip chances increase by Sunday
morning. However, QPF values are fairly light generally only a few
hundredths. It is also interesting that most of the deterministic
NAM is quite dry, with the GFS and ECMWF wetter.
Temperatures will be cold again tonight but look warmer than last
night. With that said, will hold off on any freeze warnings at
this time as widespread freezing conditions do not appear likely
at this time, except for the Kittitas Valley. There could be some
spotty areas that reach below freezing and this will continue to
be watched. The NBM probabilities for low temperatures <=32
degrees at Hermiston is about 25%, about 10% at Pendleton, about
30% at Yakima and upwards of 90% at Ellensburg.
Highs will be close to normal on Friday, then a few degrees above
normal on Saturday. Overnight lows should begin to warm up a bit
as well.
LONG TERM...
Sunday through Thursday...A shortwave passing along the Canadian
border on Sunday will provide a few showers to the mountains but
otherwise cool and dry with some breezy to windy westerly winds.
This will be followed by the rebuilding of an upper level ridge
over the region providing dry seasonal conditions Monday and
Tuesday. The ridge moves off to the east Tuesday night as an
approaching upper level trough comes onshore. This trough will be
splitting with some energy dropping south towards California. The
northern portion will move inland along the Canadian border on
Wednesday followed by a deepening upper level trough over the
region on Thursday. This will increase the possibility of
precipitation on these days but with snow levels remaining 5000
feet or higher.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 32 63 35 66 / 0 0 0 0
ALW 34 67 37 70 / 0 0 0 0
PSC 37 69 40 71 / 0 0 0 0
YKM 33 64 35 67 / 0 0 0 0
HRI 34 68 37 70 / 0 0 0 0
ELN 32 61 34 64 / 0 0 0 0
RDM 28 62 34 69 / 0 0 0 10
LGD 30 61 34 69 / 0 0 0 0
GCD 30 64 36 73 / 0 0 0 10
DLS 39 67 42 68 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Freeze Warning from 2 AM to 9 AM PDT Friday for WAZ026.
&&
$$
SHORT TERM...77
LONG TERM....91
AVIATION...87
