Area Forecast Discussion
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
988 FXUS65 KPUB 202146 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 346 PM MDT Fri Sep 20 2024 .KEY MESSAGES... - Rain showers spread from south to north across the area on Saturday, with scattered thunderstorms possible, especially south of Highway 50. - Strong to potentially severe thunderstorms possible Saturday afternoon and evening for the San Luis Valley, southern mountains and portions of the Raton Mesa Region. - Snow levels may drop down to 8000-9000 feet, but with heavy wet snow accumulations up to around 10 inches for the higher peaks above 10-11kft north of Hwy 50. - Cold night time low temperatures are expected Sunday night into Monday morning, with a medium chance (40-50%) for low temperatures below 32 degrees especially across the San Luis Valley. && .SHORT TERM /THROUGH SATURDAY/... Issued at 341 PM MDT Fri Sep 20 2024 Currently, upper level low spinning over srn California at mid- afternoon, while initial push of deeper moisture/instability and weak short wave were producing a few showers/storms over the far sern plains. Temps have popped up into the 70s/80s at many locations, with deep mixing generating some pockets of breezy s-sw winds, especially along I-25. For the remainder of the afternoon into early evening, while most concentrated area of lift and showers has shifted into KS, did keep kept low pops along the NM and OK borders to account for potential storm reformation, as low moisture lingers and CAMs hint at one more wave of isolated convection possible. For late evening and overnight, expect a lull in precip activity, as upper low is still too far away to provide much vertical motion, and low level moisture return is rather meager. Most models have backed off precip chances overnight across the srn mts, and will remove pops from all areas through 12z. Saturday, upper low lifts across AZ toward the 4 Corners by late afternoon, while surface cold front drops south over the plains, ending up near the NM border by afternoon. Precip development Sat morning appears to be rather slow, with showers/light rain creeping northward from NM into srn zones through the morning, reaching roughly the Arkansas River by midday. By afternoon, upward motion begins to intensify, with widespread showers/embedded thunderstorms across much of the area by 00z. Limited surface instability will be the main negative factor for strong/severe storm potential Sat, though shear and dynamic lift will be very strong, and we could see at least some stronger storms over the San Luis Valley and near the NM border, where CAPE values reach perhaps 500 J/KG before storm formation. Some light snow possible toward 00z over the peaks of the central mountains, though colder air doesn`t arrive until later, so any daytime accums will be fairly light. For outdoor events Sat across the Pikes Peak and Pueblo region, rain will likely hold off until afternoon, though cold frontal passage early in the morning (7-9 am mdt) may produce some rather strong (gusts 30-40 mph) north winds into midday. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 341 PM MDT Fri Sep 20 2024 No real big changes in thinking or even with the forecast at the start of the period, as the anticipated large upper low continues to push overhead and bring widespread showers and thunderstorms to much of southern Colorado. The severe risk across the San Luis Valley and far southern I-25 corridor will continue to lower in the evening hours, though forecast soundings indicating some instability lingering into the evening in these locations. So, can`t completely rule out an isolated strong to severe storm in these locations during this time, but once again, the risk will further lower especially as the greatest ascent shifts east northeast. Further to the east, widespread showers with scattered thunderstorms are appearing likely over the plains. The risk of storms will be in place over most of the plains Saturday evening, however, highest risk will be east of the I-25 corridor and especially closer to the Colorado and Kansas border where the instability axis will be shunted. This looks to be more elevated instability and think the risk of severe storms will be low in the evening. However, can`t rule out at least a stronger storm capable of producing small hail, lightning, and brief heavy down pours. Over the higher elevations, expect precip development to continue though will continue to shift more northward in time. If any of the precip hadn`t changed to snow by then this will quickly change as the upper low pushes overhead and much colder air moves in. Once again, no big change in thinking with snow development from Saturday night into Sunday morning, with any snow remaining on the higher elevations of the higher terrain and at snow levels above 10 kft. With the arrival of the colder air Saturday night into Early Sunday morning, could easily see snow levels fall into the 8-9 kft range at least briefly. At this time though, think there is a low chance (20- 30%) for snow levels to drop to this range. If this were to occur, areas impacted would be lower elevations of Teller, Lake, and Chaffee counties. Will need to continue to monitor this potential, especially as this precip wraps around the slowly lifting upper low. Once again, no real big changes to snow totals with up to around 10 inches of snow expected over the higher elevations of the central mountains and Pikes peak by Sunday morning. Additionally, no changes made to the current Winter Weather Advisories in effect. The upper low will continue to slowly lift to the northeast on Sunday, with any lingering rain or snow diminishing and/or shifting to the east/northeast. Clouds will persist though and with a cooler air mass in place, cool and well below normal temperatures are expected area wide on Sunday. This will continue Sunday night into Monday morning, especially as clouds clear and winds further diminish. Only made small changes to Sunday nights low temps, with mid to upper 30s to low 40s expected over the lower elevations. With some uncertainty to some lingering cloud cover, did not go lower at this time. Do think there is a medium chance (40-50%) for low temps to fall below freezing across the San Luis Valley, and a low chance (20-30%) for low temps to fall below freezing across the plains. Additional trough swinging through early next week could bring additional showers and thunderstorms to the region late Monday into Tuesday. After this period, a drier period with more seasonal temperatures are expected for the remainder of the forecast period. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 1057 AM MDT Fri Sep 20 2024 VFR at all taf sites the next 24 hrs. S-SW winds will strengthen across the area this afternoon, with gusts 20-25 kts at all terminals 19z-02z, then winds diminish overnight. Cold front dropping south through the plains will bring strong north winds to KCOS and KPUB Sat morning, with gusts over 30 kts likely beginning around 13z at KCOS and by 15z at KPUB. Outlook for after 18z Sat, widespread showers and thunderstorms will develop across the area, with periods of MVFR and brief IFR conditions likely at all sites, especially Sat night into Sun morning. Mountains and passes will be obscured from midday Sat into least midday Sun. Slowly improving conditions Sun afternoon/evening. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from noon Saturday to noon MDT Sunday for COZ058-060-082. && $$ SHORT TERM...PETERSEN LONG TERM...RODRIGUEZ AVIATION...PETERSEN