Scientific Forecaster Discussion
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
609 am akdt Thursday Jul 31 2014
Short term...high pressure remains situated over the eastern Gulf
with a ridge axis that conforms to the outer coast and lies just
offshore. A low in the southwest Gulf continues to spin off clouds
that are visible on infrared satellite imagery. General motion is to the
northeast towards the coast, but individual cloud elements are
dissipating as they transit the surface ridge. What precipitation is
being generated by the low is confined to the far southwestern
portion of the offshore marine zone and will be no factor for
Southeast Alaska today or tonight.
Clearing skies overnight and high levels of surface moisture have
allowed fairly extensive radiational fog to form over the
Panhandle overnight. Have a dense fog advisory in place until 9 am
for portions of the central Panhandle, the southern outer coast
and the Yakutat area. Once the fog dissipates this morning, mostly
sunny skies will allow temperatures to rise to the upper 60s to
middle 70s today. Sea breezes will set up in the usual places by late
morning and last through the early evening. Overnight lows ranging
from the lower 40s to lower 50s tonight with decreasing temperatures
halting once fog re-develops. With a good drying day, am expecting
overnight fog to be a little less than Wednesday night, so have
not gone out with a dense fog advisory anywhere for Thursday
Stable pattern with no change in airmass. Previous forecast
remains on track, so little was changed overnight. Daytime highs
boosted by a degree or two for some locations. Likewise, overnight
lows lowered a degree or two in response to mostly clear skies
before the fog returns. Forecast confidence is average.
Long term...there weather for Southeast Alaska will remain dry
and warm through Sunday morning before rain moves back into the
area Sunday afternoon into early next week. The forecast models
have been stable with good run to run consistency for the past few
days. Minor changes were done to the Middle Range of the forecast and
used a blend of the 00z ec and 06z NAM. There is some timing issues
with the next significant front that will move out of the North
Pacific and over the Panhandle on Monday. So with that said there
was not many changes done to the forecast after Sunday.
At the start of the long range period a surface ridge will be over
the eastern Gulf with a stationary low pressure over the far
southwest Gulf. There will be a very weak pressure gradient over
the Inner Channels so the winds for the most part will be on the
light side but afternoon heating will produce some increased winds
in locations like, Cross Sound, Lynn Canal, and Clarence Strait.
Winds speeds in those areas will range from 15 to 25 knots. The
strongest winds in northern Lynn from the south Tom in small craft and
northwest winds 15 to 20 knots in Cross Sound and Clarence Strait. The area
will be sunny, dry and hot from Friday through Sunday with 850 mb
temperatures ranging from +10-14. This warm air and sunny skies will
produce high temperatures in the upper 60s to middle 70s. Night time lows
will not be that cold in some areas with mixing and lows will
remain in the middle to upper 50s while other places with light winds
temperatures getting down into the middle to upper 40s.
Overall there is high forecaster confidence for the weekend
forecast and about average going into next week.
Aviation...low ceilings and fog will impact aviation operations
through middle morning. Fog will return overnight and be an issue
again early Friday morning.
Marine...areas of fog over many of the Inner Channels this
morning and again late tonight will hamper marine navigation.
Afternoon small craft winds expected over Cross Sound under mostly
sunny skies. Elsewhere, no marine concerns.
public...dense fog advisory until 9 am akdt this morning for akz017-024-
Marine...Small Craft Advisory for pkz022.
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