372
FXUS66 KPQR 142216
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
316 PM PDT Fri Jun 14 2024

.SYNOPSIS...Cooler over the weekend as a weak cold front pushes
inland from the northeast Pacific. Will see rainfall and a
slight chance (20%) for thunderstorms along the northern
portions of the forecast area. Coolest temperatures will fall on
Sunday before a trend towards a warmer and drier pattern comes
mid next week.

&&

.SHORT TERM...Now through Sunday Night...Minimal change in the
forecast as the overall pattern remains on track. The low
pressure system and associated front spin just offshore with
rain falling along the north Oregon and south Washington coasts.
This rain will intensify through the evening, but will be more
showery in nature so there will be periods without rain. High
resolution models are quite "bubbly" with the simulated
reflectivity which can be connected to very sporadic yet
moderate rainfall at times. Chances for thunder have remained
the same (around 20%), but the overall areal coverage is
greater. The HREF is showing around a 20-30% chance of thunder,
especially in southern Washington. However, given the overall
strength of this system, even if chances are higher, the number
of strikes remains limited. Have decided to lower chances to
around 20% to account for this. Areas with the higher
probabilities are along the northern coast and northern Coast
Range.

Rain will be more widespread, as will temperature drops tonight
through Sunday. Rain accumulation does not appear impressive,
but, considering it will be showery, there may be periods of
heavier rain. Precipitable water amounts are not robust enough
for any kind of concerns...moreso washing your car level rain.

Models have come into better agreement on Sunday with a more
fine detailed forecast. There may be some lingering instability
which can be observed in the vorticity advection and the
alignment of the jet to the area. However, the trough is
flattening, and the jet is pushing further south inching us out
of the left exit region (more convective portion of the jet),
and into more "neutral" territory. Sunday will be dominated by
cooler air and a few lingering showers. -Muessle


.LONG TERM...Monday through Friday...The overall synoptic
pattern is comprised of a broad trough transitioning into a
ridge. Ensemble clusters are in very good agreement, especially
given the length of time into the future. Overall will see a
warmer and drier pattern starting Tuesday. Seasonable
temperatures in store with light winds, and no precipitation.
-Muessle


&&

.AVIATION...VFR conditions continue for most locations across the
airspace. However, a series of fronts are expected to impact the
region. The first front will be relatively weak and will slowly
move eastward across the airspace today. Expect MVFR conditions
for KAST starting around 22Z Friday and those MVFR conditions
slowly spreading southward and will likely reach KONP around 00Z
Saturday. There will also be a 15%-25% probability for IFR
conditions to develop starting between 22Z Friday and 00Z Saturday
along the coast. The coast is expected to maintain the MVFR/IFR
conditions through at least 18Z Saturday as the second stronger
front will start to move across the airspace around 06Z Saturday.
These fronts will bring showers with a slight chance of thunderstorms
(25% probability) being added for KAST starting around 06Z Saturday,
then spreading southward and reaching KONP around 12Z Saturday.

The first front reaches northern, inland locations around 00Z
Saturday and will result in a mixture of low-end VFR/high-end
MVFR conditions with cigs likely oscillating between FL030 and
FL040 for areas north of KMMV/KUAO along with light showers. Areas
south will likely maintain VFR conditions with FL040 or greater
with no precipitation expected. The second, stronger system will
impact inland locations starting around 09Z-12Z Saturday and will
likely maintain the low-end VFR/high-end MVFR mixture along with
widespread showers. This second front will also result in a slight
chance of thunderstorms (25% probability) for areas north of KCVO
starting around 12Z-15Z Saturday.

Any thunderstorms will have the potential to produce small hail
along with gusty and erratic winds.

Southerly winds across the airspace will become more westerly
after the first frontal passage.

PDX AND APPROACHES...VFR under clear skies will slowly transition
to a mixture of low-end VFR/high-end MVFR conditions, with cigs
likely oscillating between FL030 and FL040 as a series of fronts
move eastward through 18Z Saturday. Look for this transition to
start around 00Z Saturday as the first, weaker front crosses the
terminal. This first front will also bring light showers. Second,
stronger front will maintain oscillating flight levels and also
result in a slight chance of thunderstorms (25% probability)
starting around 12Z Saturday. -42

&&

.MARINE...Relatively benign conditions through the weekend and
into the start of the upcoming week. Seas around 5 to 7 ft at 9
to 11 seconds. A weak front will bring southerly winds through the
evening, before a stronger front will cause winds to become more
westerly tonight/early Saturday morning. Late Sunday/early Monday
strong northwesterly winds will return and will likely bring
marginal Small Craft Winds to all waters. There is still some
uncertainty in the timing and strength of the Monday system.
-42


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$

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