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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 73 °
• Low: 43 °
• Partly Cloudy

• Thursday
• 
• High: 64 °
• Low: 39 °
• Partly Cloudy

• Friday
• 
• High: 75 °
• Low: 48 °
• Mostly Cloudy

• Saturday
• 
• High: 68 °
• Low: 43 °
• Partly Cloudy

• Sunday
• 
• High: 66 °
• Low: 37 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Grand Junction Colorado 
839 am MDT Wednesday may 23 2012 


Update... 
issued at 839 am MDT Wednesday may 23 2012 


Radar mosaic and surface observation indicating front is slowly sagging 
southward across the park/Gore Range back toward the western 
Book Cliffs. Some light rainfall/sprinkles making it to the lower 
elevations with some cooling behind the front with the 
precipitation so made some tweaks to the temperature trends...probability of precipitation 
and sky cover this morning. Will continue to watch progress of 
front and how active it gets over the next few hours for later 
updates this morning. There will be a favorable upper jet location 
to help with ascent by late morning so some blossoming of the 
precipitation with some lightning is expected through the 
afternoon hours. Will also continue to monitor the stronger winds 
along the southern border...but the advisory level winds may wait 
until around peak heating to show up as mixing hits the higher 
winds aloft...though a tightening gradient by the front sagging 
south could also get things going as well. 


&& 


Short term...(today through Thursday night) 
issued at 343 am MDT Wednesday may 23 2012 


Latest satellite and water vapor imagery clearly shows cold front 
approaching from the northwest though it is shearing out over northestern Utah. 06z 
nam12 cuts back on precipitation assod with this system until noon 
onwards so followed suit with forecast for showers/storms kicking 
off. What has not changed is the fact that winds over southern areas 
will remain breezy today and humidities will remain low. Red flag 
warning continues for southern areas as described below. Some concern 
about Wind Advisory at this time with MOS guidance showing sub- advisory 
wind speeds while forecast skew-T shows good mixing all the way up 
to near 500mb where winds upwards of 40 kts are expected to mix 
down. Will keep advisory as is and will alert day shift to 
dichotomy in solutions. So for remainder of today...more clouds than 
sun up north with isolated showers and storms while areas south will 
see sunshine and breezy conditions. 


Tonight...the surface front stalls just south of The Four Corners so 
gusty winds may continue over the SW San Juan Mountains perhaps even 
mixing into the southern valleys at times. Across the north the jet 
is oriented west-east along the Roan-Tavaputs-Flattops and -23c cold core 
lingers near the Wyoming border. 700mb specific humidity is around 5 
g/kg for the park-Gore-Elk Mountains where at least scattered showers 
will continue into Thursday morning. 


Thursday a deep low approaches the Oregon coast. The jet lifts to 
the NE and weak warm advection begins as the flow backs to SW. The 
front lifts back through the southern zones as a weak warm front. 
Daytime winds will gust to 20-25mph or so...just a light breeze 
compared to the upcoming weekend. 


Thursday night-Friday...SW gradient sharpens as the upper low digs into 
central California. 700-600mb layer winds indicated 40-50 miles per hour 
winds developing ahead of the California low. This will produce 
mild overnight lows and afternoon highs back up above normal. 
Moisture is quite limited raising fire weather concerns yet again. 


Long term...(friday night through Tuesday night) 
issued at 343 am MDT Wednesday may 23 2012 


Minimal change to long-term forecast as impressive closed low 
continues to tighten pressure gradient over County Warning Area as strong southwesterly 
flow continues. The low does start filling Friday night as upper 
level support nudges low pressure newrd. Moisture remains limited 
over County Warning Area as warm front sets up over eastern Idaho...northern Wyoming and southern Montana. So 
much so in fact that almost no precipitation is expected over eastern Utah and 
Colorado except for extreme northern areas. What makes this low impressive is 
the winds. 700 mb winds reaching 60kts have been advertised for last 
several model runs so confidence is high that these winds will be 
realized. Mixing remains good so surface winds of 40 to 50 kts with 
higher gusts will not be uncommon. At this point...a Wind 
Advisory would not be surprising with some areas possibly seeing a High 
Wind Warning. 


By Sunday...winds will start to die down as gradient relaxes due 
to low pressure moving to central Montana. Wraparound flow will keep 
the chance for some precipitation in the picture for northern areas but they 
will be very isolated in nature. By early Monday morning...zonal 
flow sets up and will remain so through Tuesday night with calm 
conditions and pleasant temperatures. 


&& 


Aviation...(for the 12z tafs through 12z Thursday morning) 
issued at 343 am MDT Wednesday may 23 2012 


Mainly VFR expected to continue today though some broken clouds 
north of Interstate 70 are expected as a reinforcing shot of cold 
air moves down from the northwest. Ceilings around 10k are expected this 
afternoon. Areas south should see plenty of sunshine though gusty 
surface winds are expected. Only taf sites that may see some 
issues will be kege and kase with afternoon convection. 




&& 


Fire weather... 
issued at 930 PM MDT Tuesday may 22 2012 


The shallow cold front will remain stretched across the central 
portion of the forecast area overnight. South of the front...dry 
and windy conditions are again expected to develop over southwest 
Colorado by Wednesday afternoon. Conditions will remain critical 
into Wednesday evening as the front pushes to the south. 


Conditions may temporarily improve on Thursday...but strengthening 
winds on Friday and the weekend will keep fire weather concerns 
elevated. 


&& 


Gjt watches/warnings/advisories... 
Colorado...red flag warning from noon today to 9 PM MDT this evening for 
coz207-290-292. 


Fire Weather Watch from Friday afternoon through Friday evening 
for coz200>203-207-290-292-293. 


Wind Advisory from noon today to 9 PM MDT this evening for 
coz018-019-021>023. 


Utah...Wind Advisory from noon today to 9 PM MDT this evening for 
utz022. 


&& 


$$ 


Update...15 
short term...tgr/Joe 
long term...tgr 
aviation...tgr 
fire weather...eh+joe