Weather

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fxus66 kpqr 060433 
afdpqr 


Area forecast discussion 
National Weather Service Portland or 
830 PM PST Monday Jan 5 2009 


Synopsis...the next major weather event will begin later tonight 
as a strong Pacific warm front spreads rain across the area. Warm 
rains will increase Tuesday night and continue through Thursday 
morning with the highest rainfall totals expected across the north 
Oregon Coast Range and southwest Washington. It will also be 
quite windy along the coast during this time. This heavy rain 
combined with very high snow levels will produce a significant flood 
risk across much of the area. A ridge of high pressure is forecast to 
develop late in the week to finally give US a reprieve in the weather 
for a few days. 


&& 


Short term...radar and satellite imagery shows clouds and light 
sprinkle type precipitation spreading into the Pacific northwest 
ahead of a broad Pacific warm front this evening. Infrared satellite 
imagery shows cooling tops offshore and expect precipitation 
increasing as the warm frontal zone intensifies over night. A strong 
jet stream axis north of the forecast area will drop south Wednesday 
night and Thursday. The warm front will intensify more Tuesday night 
through Wednesday with increasing rain especially over southwest Washington 
and the north Oregon coast and the north Oregon Coast Range. The 
latest model runs show the heaviest rains in our forecast area during 
this time period focused across southwest Washington. The final 
heaviest rain is expected as the jet stream axis to the north drops 
south and the baroclinic zone becomes a cold front that will move 
from north to south across the area Wednesday night and Thursday morning. Snow 
levels will rise above the passes tonight and remain very high until 
the cold front moves through Wednesday night and Thursday. Heavy rains combined 
with snow melting due to high freezing levels will produce the risk 
of flooding. A Flood Watch was issued on the previous shift for this. 
It will also be quite windy along the coast Tuesday afternoon through Thursday 
morning. As disturbances moves across the Pacific and energize the 
baroclinic zone winds will increase and may reach high wind criteria 
at times. The strongest winds will likely occur Wednesday night through Thursday 
as the final cold front moves through. A high wind watch was also 
issued by the previous shift for this. Willson 


Long term...no changes. Previous discussion follows... 
guidance in good agreement showing an upper ridge 
centered off of northern California and dominating the eastern Pacific during 
the extended 4 to 7 day period. However the ridge may be a bit too 
far S to guarantee completely dry weather...with the potential of a 
weak system moving through the north part of the ridge at times and 
brushing the northern zones. At this time probability of precipitation below climatology 
look appropriate. Night and morning fog looks likely especially 
sheltered southern inland valleys...while east gorge winds appear to be 
fairly weak. Rain shower 




&& 


Hydro...just one Flood Warning left for the pudding river. The 
pudding river typically takes days to recede and rainfall over the 
next few days will slow the current recession. A very wet and warm 
period will begin tonight and continue through Thursday. As a result...a 
Flood Watch has been issued for Tuesday night through Friday for all of 
northwest Oregon and southwest Washington. 


&& 


Aviation...developing warm front offshore will move into the area 
late tonight. Warm front will move over the area Tuesday morning 
north of area Tuesday afternoon. Mainly VFR conditions over the area 
this evening with areas of MVFR along the coast. MVFR will become 
widespread along the coast late tonight with areas of IFR developing 
by morning. These conditions will continue Tuesday morning with 
main MVFR Tuesday afternoon. VFR conditions will continue inland 
most of tonight with areas of MVFR developing by morning. MVFR will 
become widespread Tuesday morning with conditions improving to VFR 
south Tuesday afternoon. 


Kpdx and approaches...VFR conditions in the kpdx area this evening 
will continue most of tonight. Areas of MVFR will develop late 
tonight and become widespread Tuesday morning. 
&& 


Marine...warm front approaching waters will move into waters later 
tonight. Warm front pushes ashore and north of waters by early 
Tuesday afternoon. Low pressure and cold front in Gulf of Alaska 
Tuesday afternoon with high pressure well south of waters will give 
increasing southerly flow to waters. Small craft winds will develop 
in the waters later tonight. Gale force winds will develop in the 
northern waters Tuesday afternoon and continue through Wednesday. 
Gale force winds will develop in the southern waters Tuesday 
evening. Seas will remain above 10 feet reaching the upper teens 
Tuesday night and Wednesday. 


&& 


Pqr watches/warnings/advisories... 
or/WA...Small Craft Advisory for winds Cape Shoalwater to Cascade 
Head late tonight into Tuesday afternoon. 
Small Craft Advisory with hazardous seas Cape Shoalwater 
to Cascade Head tonight into Tuesday afternoon. 
Small Craft Advisory for winds Cascade Head to Florence 
late tonight through Tuesday evening. 
Small Craft Advisory for hazardous seas Cascade Head to 
Florence tonight through Tuesday evening. 
Gale Warning Cape Shoalwater to Cascade Head later Tuesday 
afternoon through Wednesday. 
Gale Warning Cascade Head to Florence Tuesday evening 
through Wednesday evening. 
Small Craft Advisory for rough Columbia bar through Tuesday 
night. 
Flood Watch for all of northwest Oregon and southwest 
Washington Tuesday night through Friday. 
High wind watch for the South Washington and the north and 
central Oregon coast Tuesday afternoon through Thursday morning. 
&& 


$$ 


More weather information online at... 
http://weather.Gov/Portland 


This discussion is for northwest Oregon and southwest Washington from 
the Cascade crest to 60 nautical miles offshore. The area is commonly 
referred to as the forecast area.