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849
FXAK67 PAJK 230022
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
322 PM AKST Wed Feb 22 2017

.SHORT TERM...A low pressure center over the N-NE gulf will weaken
as it progresses SE along the outside waters tonight. Clouds have
increased due to this system today along with very light snow
showers or flurries reported in Sitka, Yakutat, Gustavus and
Juneau. The radar has filled in, but looking at webcams majority
of what is seen on radar is not making it to the ground. Cordova
reported about 3 hours of snow before ending mid-day. Expect the
showers to increase somewhat across the central panhandle in the
early evening, but remain light with less than a half inch of
accumulation anywhere.

As the low moves SE the flurries will move into the southern
panhandle while the Yakutat area starts to clear out. By Thursday
morning majority of the precip will be out of the area with
decreasing clouds. The low will have weakened to an inverted
trough, causing N-NWLY winds to increase up to 15kt in the
afternoon.

Used a blend of the GFS and NAM for updates today. Models did not
handle where showers were already occurring today at all. Adjusted
POP based on current conditions and less so on models. Forecast
confidence is average on the overall pattern, but lower on any
accumulation actually occurring.

.LONG TERM...Ridging over the Gulf both at the surface and aloft
will dominate the weather over SE Alaska through late Friday. A
weak shortwave will track over the top of the ridge Friday night
into early Saturday. Models all seem to have a pretty good handle
on this feature. Think this will be a quick moving system with
only a 6 hour period of light precip Friday night and early
Saturday. This will be followed by rapid clearing as the ridge
rebuilds and the low level flow turns northerly behind it during
the day Saturday. Sped up the progression of this system based on
latest model consensus. Trimmed back the mention of snow along
our coastal areas and the southern panhandle as thicknesses look
too warm and there is not a tremendously cold airmass in place.
Left the mention of snow over the interior and northern inner
channels but even here, thicknesses become marginal Saturday
morning so could very well see only a rain/snow mix. Either way,
precipitation amounts should be light with only an inch of
accumulation at most.

Most of Saturday into early Monday should be dry and pleasant with
clearing skies and light winds over the inside waters. Early next
week there is fairly good agreement in both the ensembles and
operational models that a fairly robust and cold northern stream
trough will dig into the northern Gulf. This could potentially set
the stage for a significant snow event for parts of the panhandle.
Increased POP to likely for the Tuesday/Wednesday time frame and
decreased high temperatures slightly to reflect this trend. Of
course, the details of the evolution of this pattern are still to
be determined. Stay tuned.

Used primarily GFS/NAM for updates through Saturday, then latest
WPC guidance for early next week.


&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ051-052.
     Small Craft Advisory due to Seas for PKZ041>043.
&&

$$

Ferrin/DEL

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