Scientific Forecaster Discussion
fxak67 pajk 161502
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
602 am akst Tue Jan 16 2018
Short term...no substantial changes were made for the short-term
period- it is a tale of two lows. The first low will track across
the central Gulf and its associated front will pass over the
Panhandle late tonight. The second low will track northeastward
by Wednesday. Most of the short- term will remain warm and wet,
before transitioning to a drier period.
Minor changes were made to winds along the border and due to local
effects. A strong wind headline is in effect for Sitka for this
afternoon, as winds are expected to pick up with the frontal
passage. Wind shear could play a factor in air travel today.
Winds along the outer coast will reach gale force and several
inland locations will be gusty throughout the day. A GFS/NAM blend
was used for pressure.
Most temperatures were within guidance, only needing to lower
maximum temperatures by a degree and minimum temperatures
decreased for tomorrow night. Maximum temperatures have increased
throughout the night, but will decrease with the cold front
coming in. Both Sitka and Annette airports had record high
temperatures in the 60s yesterday, surpassing records set in 1981.
Looking forward into the week, there will be a downward trend in
temperatures to near average values. 500 mb temperatures seem to
be about normal (-20c range) for the remainder of the short-term
A blend of GFS, namdng, and sref seemed to move the pop pattern
along faster and new quantitative precipitation forecast runs lowering the storm total quantitative precipitation forecast for the
today and tonight period. Snow does not seem to be a concern for
lower elevations this week.
Forecast confidence remains moderate at best for the timing and
location of these next two systems.
Long term.../Thursday through Tuesday as of 10 PM Monday/
complicated flow pattern looks to be developing in the long range.
Higher latitudes will be transitioning to a blocky pattern with a
ridge over the Bering Sea, a trof over Mainland AK, and another
weak ridge over northwest Canada by late week. Mid latitudes will be
somewhat progressive with many shortwaves passing east across the Pacific
toward the Pacific northwest states. The interaction between the northern and
southern streams will be the tricky part of the forecast. Some
models suggest phasing of streams over the epac/Gulf of Alaska area
for late weekend and early next week, with other models keeping
Main adjustment for Thu-Fri was to shift a low that moves toward
the haida gwaii area in short range further S and to decrease
pops. Also, a cooling trend looks likely for much of the long term
period, but there are some model differences on how cold it will
get. Temps were tweaked down some based on trends. Did make some
wind tweaks through 00z sun to show more low level ridging over
the Gulf. Overall, due to the complicated flow pattern developing,
forecast confidence is well below average.
public...strong wind until 3 PM akst this afternoon for akz023.
Marine...Gale Warning for pkz041>043-051-052.
Small Craft Advisory for pkz021-022-032>036.
Small Craft Advisory due to seas for pkz053.