646 
FXAK67 PAJK 281421
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
621 AM AKDT Wed Mar 28 2018

.SHORT TERM...Overnight remnants of the NE Gulf low pressure 
system tracked into the panhandle with shower activity continuing
over the panhandle early this morning. Some locally moderate to 
heavy showers have been reported, but these are very short lived. 
As the wave weakens due to loss of upper level support and 
continues moving east shower activity will diminish with only 
isolated showers this evening. Arctic boundary remained over the 
far northern panhandle keeping snow showers for the Skagway area 
until finally seeing winds shift to the south and temperatures 
increasing. Brief increase in winds this morning as gradient 
creates southerly push, then diminishing trend through the day. 

By Wednesday evening low pressure system developing under mid
level trough over the N Pacific will track toward Haida Gwaii.
Better model agreement with the location of the low center over
Haida Gwaii by thursday morning but still some spread in depth of
the low center with ECMWF deepest. Precip around this low expected
to reach the far southern portions of the panhandle with only the
NAM keeping precip south of the region. Main weather impact from 
the advancing low will be a shift in pressure gradient and a 
return to northerly winds.As of now only expecting northern inner 
channel winds to reach small craft levels by Thursday. Westerly 
winds over the AK Gulf will last through the day the shift more 
to the northwest was the souther gulf low moves in.

Weak surface feature develops over the gulf Friday under next mid
level trough dropping in from the north. As of now only getting
low pops over the gulf. Not expecting any phasing so this 
northerly feature likely to keep any further waves from the N 
Pacific south of the region. 

Highs across the panhandle in the low to mid 40s today. Warmed 
overnight temps over the southern areas to mid/upper 30s as the 
Haida Gwaii low moves in with low temps in the 20s for the
remained of the area due to radiational cooling and shift to
northerly flow keeping 850 mb temps in the -6 to -10 C range. 

Used a blend of 00z GFS/ECMWF due to better agreement on position
of the southern low. Forecast confidence is average.


.LONG TERM.../Saturday through Wednesday as of 10 PM Tuesday/...
Potentially two different systems heading into Friday/Saturday and
Sunday/Monday. Models are still having trouble defining whether or
not a shortwave interacting with a building ridge will have enough
energy to overcome it for the Friday/Saturday period. A secondary
low may track northeastward through the Gulf Sunday into Monday.
Depending on if or how this low evolves through the eastern Gulf,
it could give strong outflow winds and potentially enough of a 
cold air intrusion to lead to a late season snowfall. 

Pressure changes were made using mostly WPC, as well as some ECMWF 
to start to give definition to the feature Sunday into Monday. 
Temperatures were adjusted downward using MOS Guidance. Maximum 
temperatures will remain relatively stable throughout the week. 
However, minimum temperatures could be tricky into the latter part
of the weekend, as showers or clear skies could change these 
values. This could also lead to p-type issues- warm enough for 
rain during the day and cold enough for snow at night. Models have
a somewhat better handle on precip patterns into the weekend. 
POP's were adjusted using some SREF early on, then blending to 
WPC. This decreased any POP's we had and kept most of the 
precipitation farther south. Confidence still remains low to 
medium after Day 4, depending on timing and tracks of these next 
two systems. 

&&

.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory due to Seas for PKZ022-041>043-051>053. 

&&

$$

PRB/RWT/SS

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