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Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska
331 PM akdt Monday Jul 6 2015

Short term...biggest issue over the next 24 hours is the extent
of the marine stratus tonight and Tuesday morning. This morning
the low clouds and fog made it as far east as Sisters Island in
Icy Strait. Expect a similar scenario tonight but concerned it
could make it a bit farther inland as the ridge begins to weaken
and tip over due to shortwave energy over the central Gulf. Did
bring it a little farther inland into Peril Strait and Tenakee
Inlet. Also included some drizzle along the outer coast. As the
ridge begins to weaken on Tuesday, this will allow more mainly
high cloud cover to spread over the Panhandle on Tuesday. A weak
area of low pressure associated with the energy mentioned above
will push a band of rain into the Yakutat area by midday Tuesday.
With weak forcing am expecting rain to be on the lighter side.

Very warm temperatures across Southeast Alaska this afternoon with
many locations across the southern Panhandle well into the 80s.
Some locations such as Hyder will likely reach 90 degrees this
afternoon. Slightly cooler conditions can be expected on Tuesday
but temperatures are still expected to get into the low 80s over
the southern Panhandle with 90 degrees possible again in Hyder.
Over the northern Panhandle cooler air aloft combined with
increasing cloud cover will lead to highs being 5 to 10 degrees
cooler than today. Winds will follow the same general diurnal
trends as the previous few days. Small craft winds near Cross
Sound and Cape Decision will weaken later this evening as solar
heating subsides. Lighter winds will be felt overnight with sea
breezes picking up again Tuesday morning. However with cooler
temperatures and increasing clouds, sea breezes will likely be a
bit weaker than today.

Mainly used the hi-res nmm for updates to the forecast through 24
hours. Changes were small and generally limited to local effect
changes. Forecaster confidence is average through Tuesday

Long term...while the Panhandle will will undergo a shift in
weather pattern at the start of the long range the upper level
features don't show as much change through the week. Not counting the
trough that moves across the northern Gulf Tuesday evening the 500
mb pattern keeps some form of a low over the Bering Sea, a high
pressure ridge over the Alaska Gulf and a second low located over
northern Canada. However each of these main features do move
enough to make some uncertainty in the extended forecast.

The Tuesday night trough crosses the Gulf and moves over the
Panhandle through the day on Wednesday with high pressure rebuilding
over the Alaska Gulf. With weak forcing along the wave believe precipitation
will hit the northern Panhandle coast but shear apart and not make
it much further inland, so have kept only chance probability of precipitation. Any rain
fall that does make it should be light. Temperatures will drop with the
increased cloud cover and diminishing 850 mb temperatures but as the
ridge rebuilds on Thursday seeing 850 mb temperatures increase again and
have some potential for clear breaks developing, especially over
the southern Panhandle. Warmed up temperatures there just a bit for
Thursday and Friday. What this late week pattern is lacking
compared to today's set up is the inverted trough extending over
the Panhandle, so high will only be in the 70s. Question as the
ridge rebuilds over the Gulf will be if marine layer forms and if
the onshore flow move that layer all the way inland.

With the exception of northern Lynn Canal which will remain at
small craft levels Tuesday night due to the tight pressure
gradient, winds will be less than 20 knots Tuesday and Wednesday
with overland winds becoming light. Wind direction for the central
Inner Channels was bit tricky Tuesday, as pressure gradient would keep
them more southerly, but flow around the ridge would be northerly.

By the weekend there are indications of another shortwave
crossing into the northern Gulf Friday night into Saturday with a
more substantial surface low potentially making it into the central
Gulf late Monday. Still bit early to put much confidence in this.

Models fell in line with the 12z runs and had good agreement for
the pressure pattern through day 6. Used a blend of the 12z
European model (ecmwf)/Gem for pressure as the NAM was bit off on short wave
location and the GFS had some issues over the Panhandle. Most
model pop fields seemed a bit high so kept with inherited fields.
Overall changes were minor with a few direction tweaks due to the
updated pressure field. Forecast confidence is average.


Hydrology...above normal temperatures will lead to a rise in the
taiya river during the afternoon and evening hours over the next
couple of days. The river will then follow the usual diurnal
cycle of falling during the early morning hours. At this time the
river is expected to crest around 16 feet both Tuesday and Wednesday
afternoon. This will continue to be monitored through middle week
before cooler temperatures move into the area.


Ajk watches/warnings/advisories...
Marine...Small Craft Advisory for pkz012-022-033-041-042.
Small Craft Advisory due to seas for pkz052.




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