Area Forecast Discussion
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
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972 FXUS65 KPUB 152034 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 234 PM MDT Sun Sep 15 2024 .KEY MESSAGES... - Showers and thunderstorms will be possible into the evening, with an isolated severe threat across far southeastern Colorado. - The chance for showers and thunderstorms will increase on Monday for the San Juans and San Luis Valley. - Strong to severe storms possible Tuesday afternoon, mostly across the eastern plains. && .SHORT TERM /THROUGH MONDAY/... Issued at 232 PM MDT Sun Sep 15 2024 The latest mid-level analysis indicates that a trough axis is centered along the Pacific NW coast with the local area in a moist, southwesterly flow ahead of this feature. East of the area, weak ridging is in place over the central and southern Plains. The latest relative humidity time-height cross section for Pueblo indicates a dry layer from the surface up to around 500mb. A RAP sounding for KPUB shows this well with an inverted V signature from 525mb down to the surface. The latest satellite imagery and radar show convection developing from the San Luis Valley eastward to SE Plains with partly cloudy skies across much of the area. This evening and tonight, the trough and its associated closed low will slide southward into northern California and the mid-level ridge keeps its strong hold across the southern and central Plains. This will leave the local area in a southwesterly flow between the two features. Instability will be relatively weak for thunderstorms this evening (in the 500-1000 J/kg), but enough to provide instability for the possibility of isolated thunderstorms. A strong to severe wind threat cannot be ruled out given the inverted V signature indicated by RAP model soundings. Showers and storms will mostly diminish overnight everywhere except the San Juan Mountains. For the San Juans, deeper moisture will advect into the area from the southwest, allowing for the chance (30-50%) of showers and thunderstorms to continue overnight and trend upward to be more likely (60% probability) near dawn on Monday. The snow level will drop to around 13,500 ft, so not out of the question some of our highest peaks will see some snow mixing in late Sunday night into Monday morning. On Monday, mid-level moisture will stream into the area from the southwest, increasing cloud coverage and showers and thunderstorm chances with fuel from day-time heating. Instability, for the majority, appears weak (<500 J/kg SBCAPE) and shear is marginal (25- 30kts 0-6km bulk shear). Thus, showers and thunderstorms should be most likely over the San Luis Valley and San Juan Mountains with the best access to monsoonal moisture, with lesser chances eastward to a nearly dry forecast for the extreme southeastern Colorado. For temperatures, the forecast is closest to the National Blend of Models. Lows tonight will range from the lower 60s in SE Colorado to the lower to mid 50s along the I-25 corridor to the mid 40s in the San Luis Valley to the 30s in the highest terrain. On Monday, areas across the Plains of far southeastern Colorado will see the warmest temperatures closer to the ridge with some locations warming into the lower 90s. Temperatures will be progressively cooler westward, in the 80s along the I-25 corridor, in the upper 60s to lower 70s in the San Luis Valley to the 40s and 50s across higher terrain. /04- Woodrum/ && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 232 PM MDT Sun Sep 15 2024 Monday Night: Monday evening and night will bring some active weather to portions of south central and southeastern Colorado. An amorphous wave will be exiting the region, with moist southwest flow persisting behind the wave. While broader forcing will lessen, orographic forcing will continue given the rising southwest flow. With broader forcing decreasing, most showers and storms across the region are expected dissipate during the evening hours and much of the area will remain dry. The exception to this will be along the mountains, particularly the San Juan Mountains, where orographic forcing will persist given the increasing southwest flow and increasing moisture. While only mostly showers are expected, occasional rumbles of thunder and thundershowers are possible given minor instability remaining overnight. Otherwise, mild temperatures, relatively light winds, and partly cloudy skies are anticipated. Looking at temperatures, much of the region will remain mild and above seasonal values overnight given downsloping winds and cloud cover. Tuesday: Tuesday brings an uptick in active weather for much of south central and southeastern Colorado. A closed low to the northwest of the region will quickly eject to the northeast throughout the day. While the core of this feature will remain to the northwest and north of the area, strong synoptic and orographic forcing is still expected as the southern fringes of the low passes over. Along with that, a moisture plume will advect northward ahead of the primary larger wave. With the surge in forcing and moisture, there is high to very high (70-90%) confidence in scattered showers and storms throughout the day. Showers and storms will initially blossom along the Continental Divide area during the morning hours, and then push eastward, following the strongest forcing throughout the day. A few strong, to possibly severe, thunderstorms are possible, especially across the eastern plains, during the afternoon hours when moisture, instability, and shear will be maximized. The most likely hazard with any stronger storms will be strong outflow winds given DCAPE values around 1000-1200 J/kg, but also due to mature thunderstorm downdrafts mixing stronger winds aloft to the surface. With that all said, as the low/wave continues to rapidly eject to the northeast and exit the region, forcing will quickly lessen, and any showers or storms present across the area are anticipated to dissipate during the evening hours. Otherwise during the day, warm temperatures, windy conditions, and partly cloudy skies are expected. As for temperatures, areas generally along and east of the I-25 corridor will hover around and slightly above seasonal values given less clouds, while areas generally west of there will hover around and slightly below seasonal values given early daytime cloud cover. Wednesday - Thursday: For part of the midweek period, a period of quieter weather is anticipated. Southwest flow will reestablish over south central and southeastern Colorado, though drier air will be in place behind the Tuesday storm system. So while orographic forcing will continue, the drier air will limit precipitation development, and given that, dry conditions are expected for much of the region. The exception to this may be a highly isolated shower or two along the mountains, though mostly on Thursday. The greatest concern for Wednesday and Thursday will be returning critical fire weather conditions. Given the drier conditions and breezy winds persisting, critical fire weather conditions may materialize for portions of the lower elevations, though confidence is low (20-30%) in timing and areas of greatest concern at this time. Outside of that though, warm temperatures continue, with breezy winds, and scattered afternoon clouds. Focusing on temperatures, the warmth does continue. Most of the region will remain above seasonal values for mid September. Friday - Saturday: For the end of the week and start of the weekend, active weather makes a return to south central and southeastern Colorado. Synoptically the broad trough that brought the Tuesday system will finally push eastward, bringing another wave during this timeframe. Ensemble model guidance are in relatively good agreement about this, leading to at least medium to high (50-70%) confidence in this pattern evolution. With the uptick in forcing, and despite moisture remaining limited, showers and thunderstorms are expected to increase in coverage, especially along the mountains where forcing will be greatest. Besides that though, cooler temperatures, relatively lighter winds, and periods of cloudy skies are anticipated. Looking at temperatures, yep a cool down is expected. Friday will hover around seasonal temperatures, with temperatures dropping below seasonal values Saturday as the system pushes overhead and shoves a cold front southward during this period. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1139 AM MDT Sun Sep 15 2024 VFR conditions will mostly prevail across the terminals throughout the TAF period as the lower levels remain dry. Some high-based showers and thunderstorms will develop this afternoon nearby the terminals, however confidence is not high enough in coverage/restrictions to mention as a TEMPO group. Thus, prevailing VCSH is mentioned starting at 19Z at Alamosa and at 21Z at Pueblo and Colorado Springs. Showers and storms will diminish by around 02Z as VFR conditions continue overnight into early on Monday. Winds will mostly be southerly through the period at 10-15 kts with gusts to 20-25 kts through 01Z and then decreasing to less than 10 kts overnight. && .PUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...WOODRUM LONG TERM...SIMCOE AVIATION...WOODRUM