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afdotx 


Area forecast discussion...updated 
National Weather Service Spokane Washington 
446 am PDT Sat Jul 5 2008 




..updated aviation... 


Synopsis...expect near normal temperatures and a dry forecast 
through the rest of the Holiday weekend for the lower elevations. 
Temperatures will begin a warming trend Monday...peaking by Thursday. 
It not until Thursday night and Friday that a cold front will move 
off the Pacific and usher in a cooler air mass for the weekend. 


&& 


Discussion... 
today and tonight...the forecast focus will be on the short-wave trough 
currently around 135w that is forecast to weaken and move into the 
region by Sunday morning. Guidance is similar with the timing of 
this feature...with the only significant difference being the 
wetter NAM. Lg-scale forcing for ascent is overall fairly weak 
with the passage of this wave...likely partly a result of stable 
middle-level lapse rates. With the developing split flow along the 
Pacific northwest coast...further weakening/shearing of the wave looks likely 
into tonight. That said...we're left with surface based instability or 
shallow layer instability aloft to help generate any showery precipitation. 
The usually most unstable and wettest NAM drops small amnts of 
precipitation over north Idaho...seemingly tied more to orographic- based forcing 
and instability. Per coordination with surrounding offices...we 
are favoring a dry forecast overall...with the exception of an 
isolated shower over the hi mountains of north Idaho and close to the Cascade 
crest under moist westerly onshore flow. Thunder threat is very 
marginal...so we left it out for now. A mild night is still 
anticipated under middle cloud ceilings Sunday morning. Temperatures today 
at or a bit cooler than Friday. Bz 


Sunday through Tuesday...there are few...if any...significant 
model differences during this portion of the forecast on the 00z 
model cycle. All models start out dry...and get increasingly dry 
into the beginning of the work week. As a weak wave from Sunday 
pushes East...Heights begin to rise...and warm advection starts on 
all of the models. By Monday...500 mb heights rise to near 580 
dam. By Tuesday...they rise again to near 585 dam. While these 
levels are not as high as our most recent heat wave...warm air is 
again undoubtedly on the way. Although the models are still 
warming things up substantially...the lack of high amplitude 
ridging and a rather progressive pattern through the week will 
likely keep temperatures from soaring for a substantial period of 
time...likely limited to just the midweek period. 


Midweek and beyond...temperatures at 850 mb peak out around 23c on 
the European model (ecmwf)...GFS...dgex...and even the gefs mean is about 23c by 
Wednesday afternoon. The models indicate some slight cooling from 
those levels by Thursday...before a more precipitous decline by 
the end of the week. All major models have finally come into 
agreement in bringing a decent trough over the area in the 
Friday/Saturday time frame. As a result...high temperatures fall 
off around a dozen degrees from midweek...however with very weak 
moisture profiles below 500 mb...any chances of precipitation are 
largely negligible. /Fries 


&& 


Aviation... 
VFR conditions expected at all taf sites through 12z Sunday. Scattered 
middle cloud ceilings this morning ranging from 11000-15000ft above ground level 
will move rapidly NE across the region with precipitation not expected to 
fall from these clouds. The best chance of precipitation will only be 
isolated and should be limited to the high mountains of north Idaho and NE Washington. 
Occasional wind gusts to 20 knots is expected for most terminals under a 
nearly uniform SW flow from the surface to 750mb. Bz 




&& 


Preliminary point temps/pops... 
Spokane 80 58 80 52 84 57 / 0 0 0 0 0 0 
Coeur D'Alene 80 56 80 52 83 54 / 0 0 0 0 0 0 
Pullman 78 54 79 49 82 52 / 0 0 0 0 0 0 
Lewiston 86 64 86 58 90 57 / 0 0 0 0 0 0 
Colville 84 52 83 51 86 51 / 10 10 0 0 0 0 
Sandpoint 78 52 78 48 81 48 / 10 10 0 0 0 0 
Kellogg 78 56 77 53 80 51 / 10 10 0 0 0 0 
Moses Lake 82 59 86 57 90 58 / 0 0 0 0 0 0 
Wenatchee 82 61 84 59 89 61 / 0 10 0 0 0 0 
Omak 85 56 85 52 89 55 / 10 10 0 0 0 0 


&& 


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


$$