Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14
FXAK67 PAJK 312331

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
331 PM AKDT TUE MAY 31 2016

.SHORT TERM...A weakening frontal band ahead of an upper level
trough over the eastern gulf will continue to lift north across
the panhandle tonight. Precipitation will have a tough time making
it into the northern panhandle with southeasterly flow aloft
dominating. Rain that does fall over the northern panhandle
tonight will be light. Across the southern and central panhandle
periods of rain will continue but still expect rainfall totals to
remain less than a quarter of an inch. Periods of rain will
increase across the central and northern panhandle Wednesday
morning and into the afternoon as the trailing trough lifts north
over the area. Once again, moisture is limited with this system
and expect rainfall totals to remain at a quarter inch or below
for Wednesday. With the front lifting north, expect light
northerly winds over the northern Inner Channels tonight with
15-20 kt southeasterlies over the central and southern Inner
Channels. As the trough passes on Wednesday, a ridge will quickly
build over the panhandle switching winds to southerly across the
entire area. Expect an increase to 15-20 kt across the central and
northern Inner Channels as this occurs.

Used the 12z NAM and Hi-Res ARW/NMM for updates to the inherited
forecast. Forecaster confidence is above average.

.LONG TERM...We have certainly been messaging the public about a
wetter week than last week. And while we currently spy moisture
plumes on water vapor imagery spraying eastward across the North
Pacific, NAEFS ensembles suggest nothing of the sort of earth-
shattering [read: stalled front funneling subtropical moisture]
event where we need to telegraph news to all living and playing
next to rivers. Consistent with yesterday, PW values fall between
1 and 2 standard deviations above normal for early June. Modeled
vorticity suggests a series of quick-moving systems brushing
across our region as prior forecasters have already noted.
Therefore, Southeast Alaska will experience light to moderate rain
in the days approaching the weekend, and even some bands of heavy
rain across our southern reaches. But these periods importantly
will be separated by short breaks in the precipitation. Fortunately
today, we are beginning to better identify when those breaks will
occur, especially over the north. For the south, more consistent
onshore flow will prevent us from completely separating periods of
rain within the public zone issued product. Instead, one need only
inspect rainfall amounts in our point-and-click forecasts to
better learn when rain will be heavier/steadier in one`s local
area of interest.

In conjunction with a lot of work on POP/QPF fields to take
advantage of clearer guidance, we also added a third wave for
Friday. This would be number three, should one begin count from
today`s wave currently curving northwest across the eastern Gulf
with the second the one arriving on Thursday. This work necessitated
bringing wind speeds up for the southern Panhandle both Thursday
and Thursday night.

Looking at the weekend, the third wave pushes onshore with
trailing showers likely behind it leading into Saturday and
possibly early Sunday. Afterwards, a ridge begins building behind
the system into early next week. This marks a beginning of a
drying trend with our forecasted temperatures conservatively
rising into next week and hinting at lower 60s and potentially

We used both NAM and ECMWF for guidance with minor tweaks to the
second wave on Thursday and more substantial edits for Thursday
night into Friday night. New WPC guidance arrived with stronger
confidence in ridging reflected in both pressure and pops.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ041>043-051-052.



Visit us at is the U.S. government's official web portal to all federal, state and local government web resources and services.