Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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531 FXUS65 KBOU 081119 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 519 AM MDT Wed May 8 2024 .KEY MESSAGES... - Freeze warning for the Palmer Divide...and a Frost Advisory most of the plains and I-25 corridor early this morning. - Continued light snowfall in the mountains with some blowing snow over the higher passes. - Cool and unsettled weather Thursday through Friday. - Warming Saturday through Tuesday with late day showers and limited thunderstorms. && .SHORT TERM /Through tonight/... Issued at 346 AM MDT Wed May 8 2024 The upper level low will be over the central High Plains today with a continuation of WNW flow aloft. Overall, the flow will gradually decrease thru the day so wind speeds won`t be as high as the last few days. However, for this morning, there will be at least a minor mtn wave which will combine with cross-barrier flow in the 35-40 kt range to produce of period of gusty winds in and near the foothills. At this point, gusts should stay below 60 mph. By midday, winds should gradually decrease as mtn wave breaks down and cross- barrier flow decreases. In the mtns, cross-sections still show enough moisture combined with favorable orographics to produce periods of light snow mainly north of I-70. Across the plains, it will be dry, although with improving lapse rates by aftn can`t rule out a slight chc of showers near the WY-NE border area. As far as highs, readings this aftn will be in the upper 50s to lower 60s over nern CO. For tonight, the upper level low will gradually elongate and split apart as one piece of energy moves WSW into wrn CO by 12z Thu. Meanwhile, a cold front will move across nern CO overnight with upslope flow developing. May see a gradual increase in shower development in the nrn foothills and nrn portions of the I-25 Corridor after midnight which will spread southward into the srn foothills and the rest of the I-25 Corridor by 12z Thu. In the mtns, best chc of additional snow will be on east facing slopes overnight. Finally, as far as frost/freeze winds have been stg enough to keep temps well above freezing in most areas. However, near sunrise may still see an hour or two where readings may drop to near freezing, so will keep highlights in place. && .LONG TERM /Thursday through Tuesday/... Issued at 306 AM MDT Wed May 8 2024 Models have an east-west oriented upper trough across the CWA on Thursday. By late Thursday night, an upper closed low is over the Great Basin and Utah with weak troughing over us. This pattern stays that way all day Friday into the evening, then the upper circulation moves a bit east and is over southern Utah by 12Z Saturday morning. There is weak downward vertical velocity over much of the CWA concerning the synoptic scale energy Thursday and Thursday night. Weak upward vertical velocity is progged Friday afternoon through Friday night. The low level pressure and wind fields have upslope in place for the plains Thursday and Thursday evening. Normal diurnal wind patterns should be in place Friday and Friday night. Looking at moisture, it is pretty deep on Thursday, especially over the western half of the forecast area. Moisture stays pretty deep over the western half of the CWA Thursday night well into Friday night. The eastern CWA is fairly moist Thursday into Friday mid day. The QPF fields show limited measurable precipitation for much of the CWA Thursday, with just the far east to stay mostly dry. Precipitation is progged over the alpine areas through Thursday night, Friday and most of Friday night. There could be some snow mixed in over the plains above 5,500 feet with the heavier precipitation areas Thursday. Expected snowfall amounts in the high country do not look significant through Friday night. Looking at temperatures, Thursday still looks to be the coolest day, with highs up to 20 F below seasonal normals over the plains. Friday warms up 3-6 C with most of the plains to make it into the lower 60s F. For the later days, Saturday through Tuesday, models continue to show the pinched off upper closed low to move across Utah and get into Colorado Saturday night. Upper ridging gets into our state by Sunday night. There is weak northwesterly flow aloft on Monday and weak to moderate zonal flow aloft on Tuesday. Most of the models point to late day convection each day with the best chance of precipitation to be over the mountains and foothills. The insatiability is not great, so the thunderstorm coverage will be minor. Temperatures warm slowly each day with readings to be a bit above seasonal normals Sunday. Monday and Tuesday. && .AVIATION /12Z TAFS through 12Z Thursday/... Issued at 514 AM MDT Wed May 8 2024 Once again winds have remained gusty overnight from the west. However, they have become more WSW in the last hour. By 15z, they should go back to more WNW with gusts up to 25 mph thru 20z. After 20Z, they will go more NW but decrease in speed. By 01z, expect a north direction which will switch more to the NE by 03z. Overnight they will become SE by 07z. VFR conditions for today but will see ceilings drop to around 9000 ft early this evening. Late tonight, will likely see MVFR ceilings by 12z Thu. && .BOU WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 8 AM MDT this morning for COZ038>040- 042>047-049. Freeze Warning until 8 AM MDT this morning for COZ041. && $$ SHORT TERM...RPK LONG TERM....RJK AVIATION...RPK