Area Forecast Discussion
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FXAK67 PAJK 241322
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
522 AM AKDT Tue Apr 24 2018

.SHORT TERM.../As of 4 AM Tuesday/ Wet weather continues this
morning across the Panhandle as widespread shower activity
persists. As the upper level trough supporting these showers
propagates east through the morning shower activity will diminish
especially over the far southern Panhandle. The northern Panhandle
stays relatively wet even as shower activity diminishes due to a
weather front currently over the central gulf tracking east
through the day. The bulk of the moisture and precipitation
associated with the front is expected to impact the northeast gulf
coast, which will experience periods of heavy rain late this
afternoon and during the evening hours. Dependent upon how much
clearing occurs this afternoon over the southern Panhandle fog
could become a concern with the very moist surface that will be
present this evening and overnight.

This front looks to shear apart rather quickly, which will limit
its impacts on the rest of the Panhandle. Wednesday will follow a
drying trend as the remnants of the front dissipate and a surface
ridge of high pressure begins to build over the gulf of Alaska.

Little change was made to the existing forecast. Primary
adjustments were made to the first 12 hours of the forecast ahead
of the approaching front. Cloud cover and shower activity was
increased during the morning hours today. Forecast confidence is
above average in the short term.

.LONG TERM.../Thursday through Tuesday as of 10 pm Monday/
Slowed the eastward movement of the occluded front early in the
period (daytime Thu), but it should dissipate by Thu evening. Used
18z GFS to handle the 12z Thu-06z Fri time frame. Still some
questions about potential systems moving into the area over the
weekend, with GFS most bullish with precip threat and GEM/EC both
fairly dry over the area. Decided to stay the course for the Fri
to Sun period to allow the models a chance to sort out the
details better. Did bring in latest WPC for 12z Mon onward, which
pushed the sfc ridge further S over the gulf than previous
forecast had it.

For Thu into Thu night, kept in the higher POPs over the N half of
the area, but the precip should diminish from the NW through the
daytime hours. Am expecting Thu night to be mainly dry with high
pressure building across the area from the SW.

For Fri-Sun, sticking with low POP forecast for now, but later
shifts will need to monitor this time frame for potential precip
threats, especially Sat-Sun. Even Mon-Tue seem to be tricky as the
model differences persist during early next week. Forecast
confidence for the Sat-Tue time frame is low at this point.

&&

.AVIATION...Marginal vfr conditions will persist through the
morning hours as shower activity remains ongoing over the
Panhandle. As the shower activity diminishes this afternoon expect
flight conditions to improve. The biggest concern today is along
the northeast gulf coast including Yakutat where a very moist
weather front will bring periods of heavy rain into the area. Some
possibility of fog exists over the southern panhandle late this
evening as a very moist surface will be in place under clearing
skies. As the afternoon progresses the clearing should be easier
to judge and fog prediction will become more certain.

&&

.MARINE...Late season gales will build in Lynn Canal today and
persist into Wednesday morning associated with a favorable
pressure gradient due to high pressure building over the Panhandle
with low pressure north of the Panhandle. Additionally, a small
period of gale force winds is expected in between Cape Saint
Elias and Yakutat as the front progresses eastward tonight.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...Strong Wind from 10 AM AKDT this morning through late tonight
     for AKZ018.
     Strong Wind late tonight for AKZ017.
MARINE...Gale Warning for PKZ012-051-052.
     Small Craft Advisory for PKZ013-021-022-031-042-043-053.
     Small Craft Advisory due to Seas for PKZ041.

&&

$$

JB/RWT

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