251 
fxak67 pajk 191954 
afdajk 


Southeast Alaska forecast discussion 
National Weather Service Juneau Alaska 
1154 am akdt Sat Jul 19 2008 


Short term...main surface low deeper than previously forecasted 
yesterday. Track took center to Yakutat by 15z this morning. Pressure 
falling now in Yukon for The Jump inland and front has gone aloft 
into b.C. Satellite imagery shows pretty good looking bent back 
occlusion near Yakutat but no observation indications of strong winds 
associated with it but moderate showers. Main cold air aloft 
centered over Middleton isl with -26c @500 hpa on padq 12z radiosonde observation. 
Jet on track with 250 hpa core along 50n to an exit near 50n 140w 
around 130 knots. 


Still some Hydro problems this morning. Taiya river may have 
crested. Taku jokulhips some worry due to Falling Water temperatures but 
still may be diurnal. Creeks are booming but not flooding. 
Heaviest rain over. Flow aloft rapidly changing to SW as of this 
writing for less moisture surge up Lynn Canal. 


Expect a burst of southerly wind this morning maybe into this 
afternoon due to rising pressure from the S. By 12z sun all Ops models 
dig upper low centr to 55n 145w which is accepted over a surface low 
below 1000 mb as per 12z run AK-GFS-40. This should ease all surface 
pressure gradients over the Panhandle but south-southwest flow aloft especially over 
the southern zones will keep things real wet. By 00z Monday all 
models bring the upper low center 200 nm west of Craig which will 
lessen precipitation in the north. && 


Long term...some significant differences amongst the models in 
the upper levels this morning. GFS generally more amplified and 
faster to move short waves around the base of the long wave trough 
centered over the Gulf than European model (ecmwf). GFS is also dropping a 
significant low out of the Bering Sea and into the northwest Gulf 
next Friday. Believe GFS is diverting too much energy away from 
the parent upper low to develop this feature. Strong preference 
for the much more slowly evolving upper level low being depicted 
over the northern Gulf by European model (ecmwf). Better consensus between European model (ecmwf) 
and UKMET as well. Have opted to blend current grids to UKMET 
early on and then to both European model (ecmwf) and HPC. Included more European model (ecmwf) than 
HPC in order to capture a little more amplitude than HPC included 
in their ensemble blend today. 


Overall precipitation trend remains the same in the long range forecast 
as it has been for the past several days...a dominant wet pattern 
with a break for the southern Panhandle early to middle week. 
Agreement between GFS and European model (ecmwf) in this regard is very good in 
spite of differing surface pressure solutions. 


Low level temperatures already falling by the beginning of the 
long range forecast with a freezing level down to around 5000 feet 
over then northern Panhandle. A brief rebound during midweek as 
freezing levels climb up to around 6000 feet again but another cold 
shot of middle to upper level air will depress the freezing level 
down to around 4000 feet by next weekend...so the mountains will be 
getting some significant snow. 


Besides the typical diurnal small craft winds over the Inner 
Channels... will likely see small craft conditions over the 
northern coastal marine zones Wednesday afternoon/evening. Winds 
rise again Thursday night/Friday over Clarence Strait and the 
Dixon Entrance due to an approaching front. Right now am not 
expecting significant winds over the coastal marine zone with this 
front but potential exists especially over the southern coastal 
marine zones...so will have to watch this closely. 




&& 


Ajk watches/warnings/advisories... 
public...Wind Advisory until midnight akdt tonight for akz018. 
Marine...Gale Warning for pkz035-036. 
Small Craft Advisory for pkz011>013-021-022-031-032-034-041>043-051. 


&& 


$$ 


Jcc/fritsch 

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