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fxus65 kgjt 192059 
afdgjt 


Area forecast discussion 
National Weather Service Grand Junction Colorado 
259 PM MDT Sat Jul 19 2008 


Short term...tonight through Monday... 
drier air is in place across the forecast area today especially 
across the central and north where dew points are down 10 to 20 
degrees from 24 hours ago in some places. Temperatures are 
considerably warmer for most of the area as well due to the upper 
high becoming positioned over western Colorado. A few thunderstorms 
have managed to pop early this afternoon and this will continue until 
about sunset. The drier air and subsidence will limit areal coverage 
to isolated and keep them short lived. 


No significant change in the forecast thinking as the upper high is 
still prognosticated to shift east tonight and Sunday and allow for 
increasing moisture. This looks like it will begin tonight across 
the far south with thunderstorm outflows over New Mexico pushing some 
moisture into southeast Utah and southwest Colorado. Satellite also 
indicates a northward push of moisture taking place across Arizona. 
Models forecast a surge of precipitable water near one inch along the 
Utah and Colorado border by late Sunday afternoon and broaden the 
moisture across the area through Monday. The forecast was geared in 
this direction so only minor adjustments were made to the forecast 
grids with increasing probability of precipitation Sunday and Monday. 


The moistening airmass will respond slower to heating on Sunday 
and with more clouds around expect afternoon highs to trend down a 
few degrees across the south. Slightly cooler or persistence for 
highs Sunday across the central and northern valleys. Not as warm 
across the board for Monday. 


Long term...Monday night through Saturday... 
the upper ridge axis remains along and just east of The Divide Monday 
night. Winds aloft generally in a southwesterly direction. 
Subtropical moisture tap is indicated to continue. The GFS shows an 
upper low tracking under the ridge and over the southern portion of 
the County Warning Area. This feature could help with storm development. Kept the 
current trend with a few slight increases in probability of precipitation over the south. 
Upper trough tracks over the northern rockies and flattens and 
elongates the ridge slightly by middle week. Flow aloft turns more 
westerly overhead cutting down the moisture influx. Low level 
moisture will linger. The ridge shifts west and amplifies again later 
next week. 


&& 


Aviation... 
a few isolated thunderstorms will occur over the mountains until 
sunset this evening. Localized MVFR ceilings and/or visibilities possible with 
the storms with potential for gusty outflow winds near 45 miles per hour. 
Otherwise...VFR conditions to prevail through tonight. Increase 
coverage of thunderstorms on Sunday especially across the high 
terrain of eastern Utah and southwest Colorado. Isolated 
thunderstorms are expected over the lower valleys middle to late 
afternoon Sunday. 


&& 


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


$$ 


Short term.....Tal 
long term......as 
aviation.......tal