Area forecast discussion National Weather Service Pueblo Colorado 854 PM MDT Wednesday may 22 2013 Update... issued at 853 PM MDT Wednesday may 22 2013 Updated forecast to reflect current observational trends in probability of precipitation and sky cover. Update issued at 559 PM MDT Wednesday may 22 2013 Made some minor changes to overnight sky cover and evening probability of precipitation. && Short term...(this evening through thursday) issued at 256 PM MDT Wednesday may 22 2013 ..cool front backs up to the mountains overnight... Upper high pressure centered over southern Colorado this afternoon with a little bit of high based convection under the ridge occurring over the mountains and ridges. Surface dew points remain in the 20s and 30s for the most part across the forecast area...although some 40s are found in the lower Arkansas River valley east of La Junta. Expect isolated convection to continue into the evening hours mainly over and near the mountains. With the dry surface air mass in place...primary storm threats this evening will continue to be lightning and wind gusts to around 45 miles per hour. Tonight...the upper low pressure system over the upper Midwest will send a surge of cool...moist air into eastern Colorado at the lower levels. Easterly winds will back this air mass up to the mountains overnight...and hold it there for Thursday. A deck of low stratus clouds should develop across the plains overnight...become widespread by morning and remain in place through Thursday. Doesn't look like much...if any...precipitation develops with this air mass over the plains tonight...although there could possibly be a few patches of fog and or drizzle. On Thursday...no precipitation initially but as the day wears on...could see some spotty precipitation develop in a few locations. The best chance for showers or thunderstorms looks to be along and near the southern mountains...especially near the New Mexico border...late in the day. This area will be at the fringe of the stable air mass over the plains and have the forcing of the mountains to help initiate convection. There is also a small chance for some isolated light rain showers or drizzle out east across the plains as the afternoon GOES on. Models have been hinting at this. Although...the setup for any kind of meaningful precipitation is not very convincing...there could be some spotty light amounts if the stratus deck comes in thick enough on Thursday. For everyplace west of the southern Front Range...not much moisture available...mainly just warm and dry southwest flow...so an isolated late day storm possible...but certainly not likely. The other noticeable change in the weather for Thursday will be the temperatures over the plains. Under cloudy or mostly cloudy skies and cool upslope flow...afternoon highs will be about 10 or so degrees cooler than today over the east...and just about 10 degrees below average as well. Little change in temperatures west of the southern front ranges. On a final note...the Fire Weather Watch for the San Luis valley for Thursday has been discontinued due to a change in fuels status as of this morning. The latest status report indicates there is enough green up occurring to reduce the fire threat for the time being. It will still be windy and dry across the valley Thursday afternoon... however...so caution to avoid fire starts is still a good idea. Lw Long term...(thursday night through wednesday) issued at 256 PM MDT Wednesday may 22 2013 The pattern will remain stagnant across the Continental U.S. With an area of low pressure centered over the Pacific northwest and high pressure over the Central Plains. Thursday night...moist southeasterly upslope flow will spread northward Thursday evening with widespread low stratus...areas of drizzle and some fog expected through the overnight. Not anticipating any accumulating precipitation at this time. Overnight lows will fall into the 50s across the plains. Expect low level flow to begin transitions more southwesterly by early Friday morning as stronger southwesterly flow aloft shifts east into The Rockies. This should allow low stratus...fog and any drizzle to dissipate from south to north through Friday morning. Friday...models still point to possible strong to severe thunderstorms by Friday afternoon and evening over the far eastern plains. Much depends on where the dryline sets up with models varying in exact position. The NAM sets up the dryline from Eads down to west of Springfield which would put the eastern half of the plains under the threat. The GFS has the dryline set up along the Kansas border...which would put the extreme far eastern areas under the threat. Moisture looks good ahead of the dryline with dew points in the 50s...and shear is modest at 30-40 kts. This area will continue to be monitored for model consensus with future runs. In addition to the thunderstorm threat...strong mixing will allow gusty southwesterly winds and low humidity values to spread into the San Luis valley and I-25 corridor Friday afternoon. Extreme caution is advised for any outdoor burning activities. The pattern remains consistent Saturday through Monday before the area of low pressure breaks down into an open trough Tuesday and Wednesday. Any convection Saturday through Monday will depend heavily on where the dryline sets up. Most solutions have it along the Kansas border...or east into Kansas each afternoon and evening heading into early next week. For now have low probability of precipitation along the border to account for this possible thunderstorm activity. Elsewhere expect dry conditions. Continued southwesterly flow and mixing will lead to widespread critical fire weather conditions across much of southern Colorado. Any fire weather highlights will be dependent on fuel status. Extreme caution is advised with all outdoor burning activities...including grilling on Memorial Day. Temperatures will remain warm with upper 80s to middle 90s across the region. Chunks of energy will break off the opening trough over the western Continental U.S. Tuesday and Wednesday leading to increased chances for shower and thunderstorm activity over the central mountains and Palmer Divide. Temperatures will be slightly cooler behind a cool front with 80s for highs. Mozley && Aviation...(for the 00z tafs through 00z Thursday evening) issued at 256 PM MDT Wednesday may 22 2013 Generally VFR across flight area until around 06z...including all 3 taf sites. However...isolated thunderstorms will be possible over and near the mountains until then...with local MVFR to LIFR conditions associated with that activity. Also...erratic wind gusts to around 45 miles per hour possible with that activity. Starting around 06z...a shallow cold front will push in from the east and bank up against the southern Front Range. This front will bring widespread MVFR stratus and patchy fog to the eastern plains and the possibility of some scattered light precipitation through the rest of the night and into Thursday. Could even be some IFR conditions across the plains associated with the stratus layer. MVFR to IFR conditions associated with stratus layer later tonight and Thursday will affect kcos and kpub but not kals. The chances for thunderstorms Thursday will mainly be limited to areas along and near the southern mountains...and mainly late in the day. Lw && Pub watches/warnings/advisories... none. && $$ Update...28 short term...lw long term...mozley aviation...lw