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FXAK67 PAJK 252312
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
312 PM AKDT WED MAY 25 2016

.SHORT TERM...An upper level low and weak surface reflection can
be seen on satellite west of Cross Sound this afternoon. This is
causing westerly flow over the central/southern panhandle and the
help of orographic lift is squeezing out a few showers today.
The weak surface reflection will cause winds to be somewhat variable
then become NWLY behind it but remaining on the light side.

The low will progress SE along the panhandle through the evening and
take majority of the showers with it. A strong N-NWLY jet has
been consistently forecasted by the models to drop into the gulf
behind the low then remain over the eastern gulf through
Thursday. This flow pattern tends to be a dry one for us, however
there are some high clouds on satellite and models are trying to
bring in some showers from the Yukon. For this reason have
included a slight chance of a shower for Skagway this afternoon
and tomorrow afternoon and left in more clouds than this flow
pattern would normally provide. Largest sunny breaks tomorrow will
likely be over the inside waters and should allow temperatures to
be several degrees warmer than today, closer to 60 degrees.

Overall models are in good agreement, used an ensemble approach
today with an emphasis on the NAM12 and CanadianReg. Forecast
confidence on the benign/low impact/zero hazard weather is above
average...but slight lower for timing of showers and clouds.

.LONG TERM...Long range period remains relatively quiet as an
upper level ridge over the gulf dominates the weather for the
first half of the forecast. It does not last, as the upper ridge
gets pinched off over the weekend into an isolated upper high
over western Alaska by a digging trough over the panhandle and a
low over the Aleutian Islands. The isolated high eventually gets
pushed into NE Russia by mid next week while the Aleutian Islands
low moves into the SW gulf.

At the surface, there is not much change from the previous
forecast through the mid range. The digging upper trough over the
panhandle will bring some showers to the northern panhandle on fri
before stalling over the southern panhandle for the weekend. The
result is drier offshore flow for the north (slight chance or less
for showers as there is still some upper level energy trying to
bring some showers over the mountains) and wetter onshore flow
for the south (chance of showers) for sat and sun. Winds remain
low with highest winds possible with any sea breezes that develop
during the afternoons. Lingering upper level energy over the
northern panhandle keeps a chance of showers at most over the
panhandle into early next week.

For the extended, the Aleutian Islands low will have moved far
enough east to at least threaten to send fronts into the
panhandle. The 12z gfs suggested just that for mid next week with
the 12z ecmwf following suit though this is a large change from
previous runs. Did not jump on it as the remaining surface ridge
over the panhandle may help keep the fronts offshore through next
week. This was supported by the 18z run of the gfs which has
backed off on sending the front into the panhandle. Needless to
say the extended forecast remains low confidence with
disagreements on where the Aleutian Islands low will go and large
model spread in that time period. Generally stayed with WPC for
extended guidance with their used of more stable ensemble means.


&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...None.
&&

$$

Ferrin/EAL

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