Scientific Forecaster Discussion
fxak67 pajk 222244
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
244 PM akdt Thu Jun 22 2017
Synopsis...ridge of high pressure extends across the northern
and eastern Gulf. The next weather front moving up from the
southwest into the central Gulf on Friday morning will push the
ridge into the Panhandle.
Short term...models continue to be in good agreement with the
general weather pattern and timing. The GFS and NAM were used to
do minor changes to the forecast, with more GFS than NAM used.
The biggest issues with todays forecast package was the timing of
the erosion of the clouds and the showers ending. Sunny breaks
have increased this afternoon and should continue overnight making
for sunny to mostly sunny day across the Panhandle for Friday.
That said, late tonight into early Friday morning we are expecting
a low cloud layer to form and possible patchy fog in the areas
that saw showers today. This should be a short lived event and
dissipate quickly after sunrise.
The convective characteristics we have had over the past few days
is ending with the advance of the weather front. Ahead of the
front is stable air that will slowly move into the southcentral
Gulf early Friday morning, finally reaching the outer coastal
areas late Saturday night.
Another tricky aspect to the forecast today was temperatures.
Decreasing clouds should make for adequate radiational cooling
bringing our overnight lows down by 5 to 10 degrees than we have
been having. Along with low temperatures, tomorrows high is also
strongly dependent on cloud coverage. If the clouds get tripped up
and do not dissolve than expect to see warmer lows and cooler
Wind changes leaned on the GFS with a trickiness with the
direction as the different patterns move through. Variable wind
directions will be the solution to describing the change from the
current northerly flow to a southerly flow Friday evening. Wind
speed remain 15 kt or less, with the exception of Cross Sound and
northern Lynn Canal.
Long term...Sunday through Thursday...models in decent agreement
with the low moving towards the central Panhandle Sat night into
sun before moving slowly inland Mon. Surface ridge is progged to
develop over the Gulf early next week and push eastward through
mid next week. Model solutions diverge by mid next week with high
pressure pushing east as low pressure moves into the Gulf.
This will result in increased pops Sat into early next week before
a drying and warming trend through mid next week. Inherited
forecast represents this well, but did increase east winds in Cross
Sound to advisory levels for about 6 hours as high pressure moving
east interacts with the low moving into the Gulf.
Marine...Small Craft Advisory for pkz012.