Scientific Forecaster Discussion
Southeast Alaska forecast discussion...corrected
National Weather Service Juneau Alaska
900 am akdt Friday Aug 1 2014
Short term...a low continues to spin in the southwest Gulf.
A middle level disturbance did produce some high cloud that tracked
north over the central Panhandle, but they have dissipated as of
early this morning. Remnants of this disturbance may produce some
clouds over Yakutat this morning, but overall, sunny skies will
prevail today with daytime highs as warm or a few degrees warmer
Some areas of fog developed overnight along the outer
coast west of Icy Bay, between Cross Sound and Kruzof Island, and
along the coast of Prince of Wales down into the Dixon Entrance.
With a good day of drying yesterday, the situation is much better
than last night in terms of the areal extent of the fog. Another
dense fog advisory was, however, necessary for zone 27. Am
expecting this fog to dissipate by 9 am today.
Fairly weak surface pressure gradient remains over Southeast
Alaska with some local enhancement to onshore winds in
Disenchantment Bay and Lynn Canal. Sea breezes will set up once
again today in the usual places by middle to late morning. Did not
see the pressure gradient to support small craft winds in northern
Lynn Canal, so decreased southerly winds there to 20 kts for this
afternoon. Suspect clear skies and a weak onshore gradient will
produce small craft north westerlies in Cross Sound late this
afternoon and early evening. Farther south, steady northwest winds
10 to 15 kts over Clarence Strait.
Very stable pattern and previous forecast remained on track, so no
changes other than those mentioned above. Forecast confidence is
Long term...the forecast models continue to tell the same story
for the weekend and into next week. The ridge of high pressure
over the eastern Gulf will slowly drift to the east through
Saturday night and be over the Panhandle on Sunday. The low
pressure over the western Gulf will send a weakening weather front
into the eastern Gulf on Sunday with chance precipitation along the
coastal areas on Sunday. A more substantial weather front from the
same low over the western Gulf will try to develop a wave and lift
over the forecast area on Monday. The 00z ec is indicating a
stronger wave and more precipitation over the area while the 06z GFS is
showing the wave much weaker. So with that said there is lower
forecast confidence in that portion of the forecast and into middle
next week. There is too much uncertainty at this time that far
out. There is above forecaster confidence for the weekend and used
a mix of NAM/Gem/ec where changes were made.
Overall there were small changes done to the forecast. It will be a
wonderful dry and warm Saturday with clouds moving in slowly on
Sunday with them on the coast in the morning with the approaching
weak front and then over the Inner Channels by the afternoon. High
temperatures on Saturday will be in the 70s with upper 60s for places
near the water from afternoon sea breezes. Winds over the Inner
Channels on Saturday will be relatively light. There will be
increased northwest winds near Cross Sound to 20 knots and min small craft in
northern Lynn in the afternoon but they will relax in the evening.
For Sunday there will be some thick clouds over the coastal area
but for the Inner Channels it will be partly sunny and a nice day.
High temperatures over the Inner Channels again will be near 70 but the
coastal areas will see temperatures closer to the middle 60s. The front will
fall apart as it gets to the coast but there will be a chance of
rain through Sunday evening. Winds will switch on Sunday as the
ridge moves over the area with southeast winds increasing through
the day. The winds will not be that strong and will range from 10
to 15 knots.
Aviation...a few pockets of very low imc will persist through middle
morning near the outer coast. Otherwise, no impacts anticipated
today or tonight.
Marine...seas to 4 feet in Lynn Canal this afternoon and up to 5 feet
in 25 kts winds over Cross Sound this afternoon and early evening.
Seas to 3 feet in Clarence Strait. Elsewhere, no impacts.
public...dense fog advisory until 9 am akdt this morning for akz027.
Marine...Small Craft Advisory for pkz022.
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