Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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102 FXUS63 KABR 231513 AAB AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 1013 AM CDT Thu May 23 2024 .KEY MESSAGES... - A slight risk for severe storms (2 out of 5) this afternoon. Threats include damaging wind (~60-70 mph), large hail (up around the size of golfballs) as well as a low tornado probability. - Showers and weak storms continue into Friday (30-70%) with rain chances diminishing southwest to northeast through Friday evening. The unsettled weather pattern continues with additional chances of moisture Saturday into Monday (30-50%). - Temperature will be around or slightly below average Saturday-Monday, in the upper 60s to lower 70s. && .UPDATE... Issued at 1012 AM CDT Thu May 23 2024 The forecast remains on track this morning. No major changes are planned. && .SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/... Issued at 412 AM CDT Thu May 23 2024 Main focus is severe weather potential this afternoon/evening. Right now we are seeing widespread light returns associated with mid level warm advection/elevated convection. As the day progresses, low pressure develops in central South Dakota, with a dry line extending to the south, and a warm front along the ND state line. The focus area for CAPE is between the Missouri and James valleys where CAMS generate a line of convection around the Pierre area and north associated with that dry line, with more isolated cells scattered across the forecast area near the warm front. NAM MLCAPE peaks around 1500-3000j/kg along this axis where 0-6kt shear is between 30 and 50kts with the 0-6km shear gradient running from south to north respectively. This ribbon of higher uncapped instability depicted within the NAM is fairly close to those in the CAMS...which generally wiggle between the James and Mo valleys. BUFKIT profiles show a nice looping hodograph with strong unidirectional shear above the mixed layer and 60-70kts of flow at 300mb. NAM DCAPE also runs about 1000j/kg. So looking at storms with occasional supercell characteristics and wind and large hail threats. Everything pushes east in the evening though weak convection continues under the low through the late evening with wrap around showers into Friday morning across the northern tier of the CWA. On the backside of the system, 1/2km winds increase to 40kts with a 8-10mb pressure bubble coming in from the west. Mixed winds for Philip top out at 40kts, however for Pierre its only in the 30s so some question how well these winds mix down and whether we will see advisory criteria. CAM ensembles only show around a 10-15% probability of exceeding 45mph so for now will hold off on any wind related headlines late in the short term. && .LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/... Issued at 412 AM CDT Thu May 23 2024 Clusters agree on a troughing pattern continuing over the western CONUS (which has moved slightly east since Friday) as the shortwave departs the area and tracks northeast, with the axis over northern MN/southwestern Ontario (along with the 850mb/surface low) around 12Z Saturday. An active pattern continues as another shortwave swings down from western Canada and over the Pacific Northwest during this time as well. Little bit of a difference in the strength of the trough between the Clusters. Through the day into Sunday this wave pushes east/southeast with the southern trough pushing east. Ensembles indicate these system merge together over the Rockies ~Sunday morning. Sunday evening into Monday this wave will push east but quite a bit of variability between the Clusters on the location of the axis and strength. Clusters do agree on an amplifying ridge over the western CONUS, creating a +PNA pattern, early next week. This ridge moves east and over much of the central parts of the country midweek or so. Again, timing and intensity vary between the ensembles. Behind this departing low, models do show some lingering moisture with EC showing this only over extreme northeastern SD/western MN. Latest NBM indicates this well with 15-20% pops in this area between 00Z-06Z Saturday. With this next wave over the Rockies Saturday morning, the ensembles indicate we could see light moisture from this across central to south central SD (NBM pops 20-30%) then spreading northeast across the CWA through the afternoon and evening as a Colorado low forms on the lee side of the Rockies from 850mb to the surface. NBM pops of 20-40%, highest over south central SD, are forecasted Saturday afternoon and evening. Sunday this low will track east then northeast. It appears this low will track further away from our CWA than the previous two but still could bring moisture to the area. Another system will form over the northern Rockies at this time as well which could bring additional across parts of the central and western CWA. NBM pops Sunday will range 30-50% with chances decreasing west to east through Monday. Dry weather then expected Tuesday though midweek as the low departs and ridge moves in, along with a surface high. Possible moisture could return for the end of the week with another low/shortwave. Cool temps forecasted Friday night into Saturday morning as the high moves in with temps dipping into the upper 30s to the lower 40s. Highs for the weekend will be at or below average ranging in the upper 60s to the lower 70s. Temps warm back into the 70s/80s midweek with the ridge overhead. && .AVIATION /12Z TAFS THROUGH 12Z FRIDAY/... Issued at 612 AM CDT Thu May 23 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions initially, however all terminals have the opportunity to see convection this afternoon and evening. On the backside of the system we will also see MVFR CIGS move into KMBG and then KPIR late in the TAF period. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Wise SHORT TERM...Connelly LONG TERM...MMM AVIATION...Connelly