Weather

276 
fxus66 kotx 281730 aaa 
afdotx 


Area forecast discussion...updated 
National Weather Service Spokane Washington 
1030 am PDT Thursday Aug 28 2008 


Synopsis... 
though not as windy as Wednesday afternoon...expect winds to be 
gusty once again this afternoon. Another weak disturbance will 
bring a chance of rain today mainly near the Canadian border. A 
slow warm up will occur through the remainder of the week with the 
warmest day on Friday before a cold front moves across the region 
Friday night and Ushers in cooler and windy weather Saturday. 


&& 


Update... 
quick update this morning to add sprinkles to Spokane/Kootenai 
counties as we have received reports of such this morning. Light 
rain to the north will continue through the morning hours. Quite a 
bit of cloud cover this morning across the County Warning Area. 
With the fairly strong moist westerly flow over the area would 
expect the middle and high level clouds to continue across the area 
through the afternoon. West to southwest winds about 10 to 15 miles per hour 
will occur this afternoon...but remain lower than what was 
experienced yesterday. /Nisbet 


&& 


Previous discussion... /issued 425 am PDT Thursday Aug 28 2008/ 


Satellite this morning reveals a very Flat Ridge over the region 
with the polar jet storm track just north of the Canadian border. 
There is a weak wave in this flow moving over Vancouver Isle this 
morning which will work it's way along the Canadian border today. 
There is also a deep and moist fetch of precipitable water 
streaming into the region on the zonal flow today. GFS and NAM 
models are quite similar and compare well to satellite 
extrapolation. This Pacific moisture feed and the weak disturbance 
aloft will bring a reasonable chance of very light rain to the 
northern tier zones late this morning and early afternoon...with 
moisture enhancing on a 300k isentropic surface over the 
northeastern zones. Given the speed of this system and rather weak 
lift...it is questionable whether measurable rain will occur in 
the valleys of the northern Panhandle and northeast 
mountains...but a widespread trace event and wetting of surfaces 
north of Deer Park and Sandpoint is a good bet from this system. 
Also...moist flow orographic showers on the west side of the 
Cascades will likely bleed over the crest for shower activity over 
the high Cascades today. Otherwise...zonal downslope middle level 
flow will likely keep the basin dry...however satellite is 
suggesting a mountain wave dense cirrus shield is forming in the 
Lee of the Cascades as the deeper moisture fetch infiltrates the 
region. This dense cirrus may stick around through much of the day 
filtering or even blocking sunshine over much of the basin. Once 
again today there is a potential for momentum mixing from aloft to 
the surface this afternoon for more gusty afternoon 
conditions...although middle level winds are not as strong as 
yesterday. Thus...other than the light precipitation over the 
northern zones...overall today will feature a dry forecast over 
most of the region...with variable high cloudiness and breezy 
afternoon conditions. High temperatures today will likely not rise 
much above yesterday's highs with no significant change to the low 
and middle level thermal field over yesterday in this general fast 
zonal flow. Tonight the digging Gulf of Alaska trough will force a 
slightly stronger ridge over the forecast area shunting the 
Pacific moisture fetch into Canada and likely bringing clearing 
skies. Winds will likely die off after sunset and become light and 
variable with a weak surface pressure gradient allowing the low 
level air mass to decouple. 


Friday through Saturday night...the region will transition to 
southwest flow aloft on Friday as an upper level trough approaches 
the Pacific northwest pushing a rather Flat Ridge to the east. 
Temperatures at 850mb will warm to around 18c over the inland 
northwest. This will translate to most valley temperatures peaking 
in the 80s. A cold front will move inland Friday night with a 
decent moisture tap that loses some of its punch once it reaches 
the Cascades. The best chance of showers with this system will be 
confined to the Cascade crest and the northern mountains. The 
upper trough starts to swing through the inland northwest on 
Saturday with a vorticity maximum rounding the base of the trough. This 
along with a jet maximum over the eastern half of the forecast area 
will provide lift in addition to upslope flow. Have kept probability of precipitation to a 
slight chance across our eastern zones as moisture is still 
marginal. After a very warm Friday temperatures will cool 8 to 10 
degrees on Saturday as the upper trough moves in and clouds 
increase. Sunday through Wednesday...as the upper trough deepens 
over the region models are trying to bring some moisture over the 
eastern portion of the forecast area up from the south. Compared 
to the 00z GFS...the latest European model (ecmwf) is now doing a better job of 
wrapping the moisture around to the northeast zones as a low 
closes off. The 12z run showed the GFS with the better moisture 
tap. Will not made changes to the extended forecast until models 
show a bit more consistency. Temperatures will continue cooler 
than seasonal normals through the extended period. /Kelch 


&& 
aviation... a weak weather disturbance will bring thick middle 
and high level clouds to the entire region today...with some very 
light precipitation over the mountains north of the Columbia 
Basin. Ceilings will remain above 10 to 12 kft at all taf sites 
today. Breezy conditions with gusts to near 25 kts are expected 
over the Columbia baisn this afternoon and early evening. Skies 
will clear after 03z tonight through 18z Friday. 


&& 


Preliminary point temps/pops... 
Spokane 74 53 82 55 73 47 / 10 10 0 0 10 10 
Coeur D'Alene 71 53 81 53 73 44 / 10 10 0 10 10 10 
Pullman 77 50 83 52 73 41 / 0 0 0 0 10 10 
Lewiston 84 61 91 61 81 52 / 0 0 0 0 0 10 
Colville 67 47 80 49 75 42 / 30 10 10 10 10 10 
Sandpoint 67 45 76 50 72 39 / 20 10 10 10 10 10 
Kellogg 69 56 80 55 69 44 / 10 10 0 10 10 10 
Moses Lake 84 54 86 56 79 46 / 0 0 0 0 0 10 
Wenatchee 80 61 85 58 76 51 / 0 0 0 0 10 0 
Omak 75 52 84 53 78 46 / 10 10 10 10 10 0 


&& 


Otx watches/warnings/advisories... 
Idaho...none. 
Washington...none. 
&& 


$$ 

National Weather Service Glossary of Abbreviations

Non-Expanded Version (with abbreviations)