591 
fxus65 kgjt 211033 
afdgjt 


Area forecast discussion 
National Weather Service Grand Junction Colorado 
333 am MST Friday Nov 21 2008 


Short term...today through Saturday night... 
models are in good synoptic agreement...with the NAM favored with 
its more conservative moisture and temperature advection fields but its 
guidance continues to produce overly strong surface winds. 


Today: open Pacific trough works through the northern rockies with 
the jet and dynamics staying north of the forecast area. Some weak 
cold advection occurs north of I-70 today. Some non-accumulating 
flurries are possible in the northern Park Range today. Northern 
clouds will diminish this afternoon and allow some mixing northwest 
gradient winds. 


Tonight-Saturday night: broad ridging builds in from the west 
allowing for strong inversion to form again. The next weaker 
Pacific disturbance passes through the northern rockies with little 
effect this far south...perhaps some northern clouds and mountain 
breezes. Afternoon temperatures remain above normal. 


Long term...Sunday through Friday... 
model consistency continues to be fairly good through about Tuesday 
..and has improved for the rest of the week as the European model (ecmwf) moved much 
closer to the GFS solution in the 00z run. 


On Sunday a shortwave trough will pass over the northern rockies and 
drop down the Front Range. There should be little affect west of the 
Continental Divide from this system...except for increasing clouds 
and winds over the northern and central Colorado mountains...and a few 
degrees of cooling. 


Monday and Tuesday...strong ridging is expected with a warming 
trend and dry conditions. 


Tuesday night through Friday should see a shift a trough-dominated 
pattern over the western U.S. Midrange models provide a better 
consensus this morning by producing a phased split trough along the 
West Coast Tuesday night. The southern portion appears to be strongest 
and closed at 500 mb. It quickly fills as it moves into the western 
Great Basin and by Wednesday the European model (ecmwf) and GFS carry the northern and 
southern portions of the split in phase through the northern rockies 
and eastern Great Basin. Clouds and precipitation will increase from 
west to east and move across the forecast area Tuesday night and Wednesday. 


The main 500 mb trough is expected to pass over the area Thursday... 
with northwest flow over the forecast area by Thursday afternoon. Friday 
should bring a brief transition to ridging before a stronger low 
developing along the West Coast begins to affect the area. 


&& 


Aviation... 
VFR conditions will predominate into next week. Some MVFR 
or even locally IFR conditions possible over the northern mountains 
today. Cold frontal passage this morning across NE Utah and midday 
in northwest Colorado could produce locally moderate to strong turbulence in 
those areas. 


&& 


Gjt watches/warnings/advisories... 
Colorado...none. 
Utah...none. 


$$ 


Short term.....Joe 
long term......cjc 
aviation.......tgjt