Scientific Forecaster Discussion
Southeast Alaska forecast discussion
National Weather Service Juneau Alaska
341 PM akst Friday Mar 7 2014
Short term...European model (ecmwf) was model of choice as it initialized really
well over the Gulf. European model (ecmwf) was also the model with the most
definition of two distinct fronts or troughs to pass through the
Panhandle...one this afternoon and late this evening lifting
north across the Panhandle and even passing Yakutat later
tonight. Another front to move into the Panhandle tomorrow
morning. Temporal resolution difficult with only 6 hour
time-steps. Chose not to discern strong winds along the
coast...but think highest gusts will be this afternoon and early
evening...then diminishing. Another peak of gusts will occur with
second front late tonight into tomorrow morning. Another quandary
was how far north to push these southerlies. European model (ecmwf) now in line
with other models in keeping cold air in place over Lynn Canal.
And MOS guidance numbers colder than last couple of days with
temperatures over north/central Panhandle for Saturday morning.
Hence went ahead and extended Winter Weather Advisory through
9 am tomorrow. Winter Storm Warning remains good for Haines.
Skagway Winter Weather Advisory extended to 4 PM Saturday. Winter
Weather Advisory for Hyder on track with 4 inches registered this
morning. Snow has intensified according to visibility at Steward
today. Snow flurries in Juneau will increase this
evening...although somewhat worrisome that Juneau downtown has
gone southeast. Dewpoint still good. And five finger blowing
solidly at 30 knots from the north.
Finally using the 850 winds, did try to strengthen southerlies
for tomorrow...especially for north-south passages...but more
hesitant for northern Chatham...Glacier Bay...southern Lynn, and
Stephens Passage. Concerned that gradients not as strong as
previously indicated even with strong 850 mb winds. Also
lightened Lynn Canal as gradients will gradually come down
Forecast confidence in forecast average.
.Long term...The Panhandle continues with an active pattern next
week as deep layer SW flow continues. Several storms are riding
along the SW flow and will be impacting the Panhandle throughout
the week. Storm number one is a carry over from the short range
that will slowly be on the downward trend. By Sat night wind in
most places will have switched around to a southerly direction
and any place that has not started to mix with or change over to
rain will do so. The only places that will not are Haines,
Skagway, and the associated highways. There northerly winds will
still be blowing Sat evening but will be threatening to switch
overnight Sat night. As such temperatures will remain below
freezing through Sun afternoon with snow falling. By this point
quantitative precipitation forecast amounts are on the downward trend so snow accumulations are
expected to remain just below advisory through Sun afternoon.
Conditions quiet down a bit through Monday as SW flow continues to
bring in showers for the area but with temperatures in most
places at or above freezing most of those will be rain showers.
Monday night into Tuesday night starts getting interesting again as a
new strong front takes aim at the Panhandle. This one is looking
to be another warm one as strong southeast flow ahead of the front blows
up the Panhandle. As such winds have been raised in the Gulf and
along the Panhandle Monday night into Tuesday in anticipation of the
oncoming front. The outer coastal waters may see min gale force
winds Monday night which will move into the Inner Channels Tuesday with
small craft advisories and strong wind headlines for the outer
coast and southern Panhandle. As for precipitation most places will be
rain as there was hardly any cool down behind the previous
system. Hydro issues may need to be monitored for the southern
and central Panhandle Tuesday into Tuesday night as this front will tap
into some sub tropical air and will stayed aimed at the Panhandle
for around 24 hours before it gets pushed off to the east by the
next front on Thursday. The Haines and Klondike highways may need to
be watched as they may still be cold enough for snow.
Past this point long range models start to diverge significantly
with the GFS quickly bringing in two more fronts before the week
is out. The European model (ecmwf) only brings in one front in the same time
period. The wpc guidance leaned more on the ensemble means today
which displayed more consistency than the operational models
today so went in that direction for extended updates.
public...Winter Weather Advisory until 6 PM akst this evening for akz026.
Strong wind through Saturday morning for akz023-027.
Winter Weather Advisory until 9 am akst Saturday for akz020>022-
Strong wind until 9 PM akst this evening for akz028.
Winter Weather Advisory until 5 am akst Saturday for akz029.
Winter Storm Warning from 9 PM this evening to 4 PM akst
Saturday for akz019.
Winter Weather Advisory from midnight tonight to 4 PM akst
Saturday for akz018.
Marine...Gale Warning for pkz012-021-022-033-036-041>043.
Small Craft Advisory for pkz011-013-031-032-034-035-051-052.
Small Craft Advisory due to seas for pkz053.