000 FXUS65 KPUB 232027 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 227 PM MDT Fri Jul 23 2021 .SHORT TERM...(This evening through Saturday) Issued at 225 PM MDT Fri Jul 23 2021 Tonight... Starting the short term period, an active period of weather is expected. Synoptically, an upper level low pressure system will begin trekking westward just to the south of the Pueblo CWA. As the low pressure system moves closer to southern Colorado, pockets of positive vorticity advection (PVA), will begin influencing the area and will aid in increased synoptic level ascent. Also, winds aloft will begin to shift more easterly in response to this low pressure system just to the south of the area. This upper level low will also begin advecting low and mid level moisture around the eastern periphery into the region. With orographic forcing increasing overnight, the support of the PVA, increasing moisture, and mixed-layer CAPE (ML CAPE) values around 200-500 j/kg, rain showers and thunderstorms will persist into the overnight hours, particularly over the mountains and mountain valleys. With CAPE values beginning to decrease by late overnight and into early morning, rain showers and thunderstorms will begin to dissipate in coverage. Elsewhere over the Pueblo CWA, isolated thunderstorms will be possible over the I25 corridor this evening, but will dissipate by around 12 am, and otherwise expect dry conditions overnight east of the I25 corridor. Lows will hover just above normal, with the plains falling into the low/mid 60s, the valleys dropping into the mid 40 and low 50s, and the mountains cooling to the low/mid 40s. Saturday... Continuing into the short term period, the aforementioned upper level low will continue to influence the region. Winds throughout the column will maintain a easterly component, and will maintain a steady state throughout the day. Low and mid level moisture will continue to be advected around the eastern side of the low pressure system and into the area. With persistent easterly winds aloft, inducing orographic lift, decent mid level moisture, and ML CAPE values 500+ j/kg over the region, rain showers and thunderstorms will initiate over the mountains throughout the afternoon. Given moisture pooling along the eastern mountains, especially within the upper Arkansas River Valley, which will increase CAPE values, the most vigorous thunderstorms will likely be along the northern parts of the I25 corridor. Despite having decent moisture streaming into the region, large temperature and dewpoint spreads will increase DCAPE values over the region. With bulk shear values only around 10-15 kts over the Pueblo CWA, minimal organization of convection is expected. The main hazards with these thunderstorms will then be heavy rain and gusty outflow winds to around 50 mph. Over the eastern plains, unless a parcel reaches the convective temperature, which will be possible, expect no thunderstorms as a weak CAP and the lack of a lifting mechanism inhibit any sustained updraft development. High temperatures tomorrow will hover at or just below normal highs. The plains will warm into the mid 80s and mid 90s, the valleys rising into the low 70s and low 80s, and the mountains reaching into the low 50s and upper 60s. .LONG TERM...(Saturday night through Friday) Issued at 225 PM MDT Fri Jul 23 2021 ...Better chance for convection on the plains Sunday and Monday... ...Drying trend next week... .Sunday...As the main ridge axis temporarily builds over the Great Basin, the jet stream may dip far enough south to get some northwest flow aloft over the region. A weak disturbance will move across Wyoming and into the high plains during the day. GFS and NAM12 suggest an MCS may develop to our north and east during the afternoon and into the evening. The weak northwest flow would allow for the potential for storms to move off of the mountains during the afternoon and into the evening. The best chances for storms over the plains will be northeast Colorado. Precipitable waters decrease over the mountains, but they still are modestly above average. The threat for flash flooding will be reduced, but slow storm motions can still result in some flash flooding. .Monday...The MCS from Sunday may push a boundary across the eastern plains. In addition, a weak disturbance will move westward across New mexico. This pattern could result in an increase in convection on the plains Monday. The models suggest the best chances for storms on the plains will be south of US 50. The NBM PoPs continue to show higher PoPs along the Raton Mesa. Will have to wait and see how the specifics develop with the amount of moisture on the plains, but there could be an enhanced risk for stronger storms with locally heavy rain along the southern border. .Tuesday through Thursday...Upper high gradually builds to the north and wanders to the east. Amount of convection will depend on minor details, but the overall trend is for a warming and drying. The best chances for storms will be over the Continental Divide region with PoPs decreasing towards the east. Near the Kansas border, only have silent PoPs .Friday...The ensemble means indicate a stronger trough will move into the midwest. This could send a cold front through the region at the end of the week. The potential increase in low level moisture along with northwest flow aloft increases the chances for convection to move onto the plains. --PGW-- && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 225 PM MDT Fri Jul 23 2021 KCOS: VFR conditions are expected over the next 24 hours. Widely scattered rain showers and thunderstorms are expected this afternoon and evening. The main impacts from the precipitation will be brief heavy downpours and erratic outflow winds. While precipitation should stay scattered in nature, the TAF site could still experience gusty outflow winds away from any precipitation. Precipitation will dissipate late this evening. Rain showers and thunderstorms will also be likely tomorrow afternoon and be scattered in nature. Tonight, winds will become light and clouds will begin to thin. KALS: VFR conditions are expected over the next 24 hours. Isolated to widely scattered rain showers and thunderstorms are expected this afternoon and into overnight. The main impacts from the precipitation will be brief heavy downpours and erratic outflow winds. Rain will be the primary concern overnight, but thunder can not be ruled out. Precipitation will begin to dissipate by early morning hours. Isolated thunderstorms will again be possible tomorrow afternoon. KPUB: VFR conditions are expected over the next 24 hours. Isolated to widely scattered rain showers and thunderstorms are expected this afternoon and early evening. The main impacts from the precipitation will be brief heavy downpours and erratic outflow winds. While precipitation should stay scattered and to the northwest of the TAF site, KPUB could still experience gusty outflow winds away from any precipitation. Precipitation will dissipate late this evening, but isolated thunderstorms will again be possible tomorrow afternoon. && .PUB WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until midnight MDT tonight for COZ058-060-061- 064>068-072-073. && $$ SHORT TERM...SIMCOE LONG TERM...PGW AVIATION...SIMCOE