Gale Warning 130, NWS Juneau, AK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
520 AM AKDT Mon Apr 3 2017

.SHORT TERM.../ Monday and Monday night / A weak mid level
disturbance pushed inland overnight and produced rain and snow.
Highest amounts were observed over the central panhandle and
closest to the coast mountains. Precipitation rates tapered off
during the early morning hours. Look for precipitation to continue
on a downward trend through the day, lingering longest over the
northern zones. A storm force low near 50N and south of Kodiak
Island continues to track northeast and this will be the primary
weather maker for the next 48 hours. The associated front has
entered the central gulf and will move east through the day,
arriving along the outer coast this evening, where it will stall.
Snow level projected to be high enough that this will be a rain
event for all but the most eastern and northern locations.
However, with the front hung up on the outer coast, QPF values
farther inland are low, so overnight accumulations are expected to
be less than an inch.

/ Tuesday and Tuesday night / Currently churning well to the
southwest of the storm force low described above, tracks a potent
wave along the southerly storm track at 45 N in the North Pacific.
This wave will curl northeastward toward the southeast Gulf of
Alaska sometime late Tuesday. With a low level jet at 925 mb in
excess of 70 kt, there is moderate confidence for high winds
developing across the western portions of the Prince of Wales
Island Tuesday afternoon into Tuesday night. To account for
potential timing issues, we have issued a high wind watch for zone
27 from Tuesday morning into early Wednesday morning. The threat
may not end there, as there is lower confidence that areas just to
the east and to the northwest along the coast may also experience
impactful winds. The greatest threat for zones 28/23 including
Ketchikan/Sitka will be Tuesday night while for zones 22/17
Pelican/Yakutat on Wednesday. Rain will also spread northward with
this wave and will be potentially heavy at times across the south
and Baranof Island. Finally, temperatures were raised both for
Tuesday and Tuesday night to account for 850 mb temperatures
approaching 0 C or higher. Some areas in the northern Panhandle
could reach 50 degrees or higher with the possibility of rain at
White Pass.

.LONG TERM.../ Wednesday into Monday / Pronounced drying trend in
the works for the extended period as the strong upper level low
anchored over the western gulf for the first half of the week
weakens through the second half. Better model agreement on the
remaining trough lingering into Friday night with the Pacific
storm track forced well south, but model consistency compared to
yesterday for the weekend is lacking. GFS, Canadian, and even the
GFS ensemble mean are now introducing some strong upstream
ridging over the western gulf Saturday into Sunday with some of
it propagating over the panhandle by early next week. This should
preventing any weak short wave energy from producing rain over the
southern panhandle late weekend. At lower levels, Wednesday
continues to look windy and wet as a front moves north over the
panhandle Tuesday night. At least one strong post frontal wave
will enhance showers and allow them to persist into Thursday.
That same wave will also keep marine and land winds somewhat high
through Wednesday evening. The development of an inverted trough
over the panhandle Friday will bring and end to most of the
precipitation for the area as offshore flow takes over. Significant
breaks in the cloud cover should also develop allowing daytime
highs to warm up during that time. Still can not completely rule
out some precip for late weekend for the southern half of the
panhandle due to the abrupt change in pattern displayed by the GFS
and Canadian today while the ECMWF remained consistent with
yesterday. Thus, left a chance of precip for the late weekend
period until extended models come into better alignment.

&&

.AVIATION...Low level jet winds associated with the coming front
will increase to between 50 and 60 kts over Southeast Alaska
Monday night. LLWS primarily limited to the outer coast, but think
mod turbulence or worse will exist across most of the panhandle
with the far northern inner channels being least likely to see
these conditions. Isolated areas of IMC or low IMC limited to the
far northern inner channels early this morning but are expected to
improve late morning. Elsewhere, MVMC or better due to low CIGS.

&&

.MARINE...Main marine hazard will be high end gales over the
coastal marine zones with storm force winds forecast for offshore
zone 310 from mid day through the evening hours. Storm force winds
also forecast for offshore portions of marine zone 51 late this
afternoon and early evening. With the front stalling along the
outer coast and the parent low so far to the west, inner channel
response expected to max out at small craft intensity late
tonight.

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...High Wind Watch from Tuesday morning through late Tuesday night
     for AKZ027.
MARINE...Storm Warning for PKZ052.
     Gale Warning for PKZ041>043-051.
     Small Craft Advisory for PKZ021-022-033>036.
     Small Craft Advisory due to Seas for PKZ053.
&&

Fritsch/JWA

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