Area Forecast Discussion
Issued by NWS
FXAK67 PAJK 291405
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
605 AM AKDT Sat Apr 29 2017
.SYNOPSIS...Major upper low center 80 miles W of Shemya which
seems very far away yet an upper trough all the way from this
center is negatively tilted to SW of Haida Gwaii. The cold air for
this trough is all the way back near Kodiak, but there is enough
to support a 1000 MB gale center near 52N 138W which will affect
the Southern Panhandle today. Jet stream axis remains below 50N.
Light offshore winds and clear skies in the north have caused
areas of radiation fog after significant rains. Offshore flow will
increase in the north today as the surface gale center moves onto
Haida Gwaii by 9 PM tonight.
.SHORT TERM...Fog is at least patchy but fairly thick where you
have it this morning. As the offshore flow develops in the north
think that the fog will dissipate rapidly plus solar heating
fairly early. The next challenge is how to spread the rain north
from the low to the south. We kept the high POPs south today then
have the major upper low advance eastward to give us SW flow aloft
later on Sunday for rain. Confidence high in this scenario. Had
to adjust to cooler temps this morning but made highs in the 50s
today with sunshine.
.LONG TERM /Monday through Saturday/...As of 1030 pm Friday night
the models are diverging on their solutions, nudged the inherited
grids with NAM/GFS in the mid range and with a strong nudge to
WPC for next Friday and Saturday.
Monday keeps the ridge of high pressure over the panhandle and
slowly drifts into Canada as it weakens. This will not be enough
to keep the precipitation from returning across the area. With
poor model agreement the actual intensity is in question. A low
will traverse into the central gulf mid week with potential for
strong winds over the outside waters. This system will be
monitored over the next few days to see if models continue
trending up. Wet weather is solidly in place through the forecast
Update: 30/00Z models came in in good agreement with a storm force
low moving into the central Gulf Later Tuesday into Wed.
Development appears to be along 150W. Updated marine wind and seas
outside to reflect this. Anchorage concurs along with WPC.
.AVIATION...LIFR in fog as of this writing for PAJN and PAPG and
in/out LIFR at Yakutat. Breakout 17 to 18Z or so. MVFR this
evening south TAFs with the rain.
.MARINE...Gale Warning still looks on track for PKZ-041 off Prince
of Wales due to the Low center with some outflow wind north of
there along the outer coast. A slight barrier jet around Cape
Suckling early this morning which will reverse pretty quick today.
Updated the outside and offshore for the strong low Tue and Wed
which the models predict some really big seas. Kept them below 20
FT but we will have some time to dial in on these to see if an
increase is in order. High combined sea heights for this time of
MARINE...Gale Warning for PKZ041.
Small Craft Advisory for PKZ042-052.
Small Craft Advisory due to Seas for PKZ043.
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