256 
fxak67 pajk 231424 
afdajk 


Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska 
524 am akst Monday Nov 23 2009 


Short term...a strong low just east of Kodiak will move to just S of 
the Kenai Peninsula this afternoon...then continue north but dissipate 
over south-central Alaska by late tonight. A strong occluded front 
over the eastern Gulf will move through Southeast Alaska today. 


Main forecast concerns will be winds and snow amounts. As for 
winds...have advisory level gusts over the southern area early this 
morning. Expect those to continue until the front moves through there 
by mid-morning...when winds will diminish. Expect gale to storm 
force winds ahead of the front over the eastern Gulf...and gales over 
the southern and western Inner Channels...with Small Craft Advisory level winds over the northern 
and eastern Inner Channels...until the front moves through when winds 
should drop to Small Craft Advisory levels or less. After front moves past the pagy 
area late this afternoon...winds will pick up and advisory level south-southwest 
winds are likely there tonight. 


As for snowfall...lift is strong and well located in the dendrite 
growth zone. Limiting factor is the Ely flow surface-5000 feet...but 
this will weaken as the strongest pre-frontal upward vertical velocities arrive this 
morning. Deepest cold air to overrun will be around Haines...where a 
Winter Storm Warning was issued for 4 to 8 inches of snow today. 
Further S...for pags/paoh/pajn...expect 3 to 5 inches of snow 
before it mixes with then changes to rain in the afternoon. Have 
kept the winter weather advisories going there. Elsewhere...should see about 
2 to 4 inches of snow around paya and 3 to 6 inches around Hyder 
before changing to rain this afternoon. Also...pagy will likely 
get 1 to 3 inches of snow...which is below advisory levels so 
cancelled their Winter Weather Advisory. Other areas should be mainly rain 
with any snow at the onset quickly changing to rain. 


Once the front moves through...should see showers move in this 
afternoon over the S and this evening over the north. Post-frontal 
mild maritime airmass will keep snow levels well above sea level 
so all rain showers mentioned in the zones tonight. There may be 
some thunderstorms over the southeast Gulf and adjacent coastal area this 
afternoon as coldest air aloft moves in with cape values near 300 
j/kg...but lack of any strong upper vorticity maxima or surface trough will 
keep them isolated at most. 




&& 


Long term...a double low feature moving into the central Gulf 
Tuesday and Wednesday. The first of the lows will move north over 
Easter Gulf spreading is frontal band alon and onshore Southeast 
Alaska for Tuesday afternoon. The orientation and strength of the 
front looks like it could be storm force for the coastal marine 
zones south of Cross Sound. There is also the possibility of 
another round of wind advisories for the southwest coastal zones 
as well. The rain will spread in through Tuesday and the front 
should be through by late Tuesday night. The second low will 
continue to move northeast and should spread across Wednesday a 
the upper level trough will be being lifted northeast and out of 
the Gulf by ridge moving into western Gulf. Expect one more quick 
trough under an upper trough to move through the Panhandle 
Wednesday night. At the moment there looks to be ridge moving 
across the eastern Gulf and Southeast Alaska for the Thanksgiving 
Holiday but another strong windy front moving into the the central 
Gulf Coast Thursday night and the remainder of the area Friday. 


Models through the middle week in fair agreement and the grid 
adjustments were with the GFS and European model (ecmwf) blend through early 
Thursday. Longer range portions of the forecast periods were 
minimally adjusted as the discrepancies at that time frame so 
decided to continue with the current forecast package. Forecast 
for the next weekend could be seeing a change if they continue to 
show a new large low moving in to the Gulf from the northern 
Pacific Ocean. 






Ajk watches/warnings/advisories... 
public...Wind Advisory until 9 am akst this morning for akz023-027>029. 
Winter Weather Advisory until 3 PM akst this afternoon for 
akz020-021-025. 
Winter Storm Warning until 6 PM akst this evening for akz019. 
Wind Advisory from 6 PM this evening to 3 am akst Tuesday for 
akz018. 
Marine...Storm Warning for pkz043-051-052. 
Gale Warning for pkz021-022-032>036-041-042. 
Small Craft Advisory for pkz011>013-031. 


&& 


$$ 


Rwt/bezenek 

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