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FXAK67 PAJK 242340

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
340 PM AKDT SAT SEP 24 2016

.SHORT TERM...A large-scale thermal wave is currently in the
process of amplifying northward from the NERN PAC toward Haida
Gwaii. Resultant baroclinic zone extending SWWD from the SRN
panhandle will serve to focus modest surface cyclogenesis
Saturday night, and again late Sunday afternoon. However, both low
pressure systems are forecast to track primarily south of the SRN
panhandle, which will result in only minor impacts during the
short term period...mainly in the form of small craft east-
southeasterly winds over the southern marine zones.

Otherwise, a 30-40 kt LLJ will shift eastward across the CNTRL/SRN
panhandle during Saturday afternoon/evening. This jet combined
with a convective environment/passing showers will aid in locally
gusty winds. Winds are forecast to weaken significantly late
tonight, and when combined with increasing large-scale subsidence
and recent rainfall, will favor patchy fog for CNTRL/NRN areas.

Changes to the inherited forecast were generally cosmetic in
nature. NAM, GFS, and hi-res ARW/NMM model guidance were
utilized for grid modifications.

.LONG TERM...Models continue to show poor run to run consistency
regarding the low pressure tracking NE over the southern panhandle
Sun night into Mon. Majority of 12Z model guidance kept this
feature south of AOR with Canadian-NH a far northern outlier
tracking this low across the central panhandle. Given the poor
model consistency and decent spread in SREF/NAEFS and CMCE,
elected to maintain inherited pressure grids which gained better
support as 18Z Canadian-REG depicts a similar solution, however,
confidence in the exact track and resulting winds remains below
average. Little change to expected impacts from this storm with
moderate to heavy rain and gusty winds expected overnight Sun into
Mon. Biggest change was to increase winds slightly with gusts to
gale force expected over the southern inner channels and
potentially gusts to 40 MPH for AKZ027. This system will push
inland Mon and upper trough over the gulf begins to dig E-SE. Cold
pool aloft with this trough will be sufficient to maintain
generally chance PoPs in open cell cumulus. As the trough exits,
an upper ridge will build over the gulf with Nly flow resulting in
a drying and cooling trend for mid week. Mostly clear skies will
allow overnight temps to fall into the 30s in wind sheltered areas
and inland valleys with frost possible Wed-Thu mornings. Model
solutions diverge late next week with amplifying ridge over W/Ctl
gulf. Guidance in slightly better agreement with upper trough
deepening over SE AK heading into next weekend, but models differ
on timing and strength of this feature.


.AJK Watches/Warnings/Advisories...
MARINE...Small Craft Advisory for PKZ033>036-041-043-051-052.
     Small Craft Advisory due to Seas for PKZ022-042-053.



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