Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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268 FXUS63 KABR 130910 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 410 AM CDT Sat Jul 13 2024 .KEY MESSAGES... - There is a 20-30% chance of showers and thunderstorms across northeastern SD into west central MN this afternoon and evening. Additional thunderstorms are possible (20-40%) over the forecast area late tonight into Sunday morning. A few of these storms could become strong to severe during this time. - High temperatures will be in the 90s through Sunday, with some areas potentially reaching the century mark this afternoon. - There is a 30-60% chance of showers and thunderstorms across north central and northeast South Dakota into west central Minnesota by early Sunday evening. A few of these storms could become strong to severe. - Temperatures will moderate with lower humidity for the first half of next week before readings warm back up toward the end of the week. && .SHORT TERM /TODAY THROUGH SUNDAY AFTERNOON/... Issued at 408 AM CDT Sat Jul 13 2024 Ensembles continue to indicate the large mid level high settled over the Rockies and Southwestern US with more of a quasi zonal flow to the north of this high. Even warmer temperatures aloft to the surface are expected through the weekend, thanks to this high. 700mb temps by this afternoon will range between 12-14C and Sunday, up to 15C, highest over south central SD as winds will be from the west/southwest. 850mb temps will range between 23-27C with similar temps expected for Sunday and winds from the west to the south. With daytime mixing, highs for today will range in the 90s, with some areas across central SD reaching close or around 100 degrees. However, HRRR Vertically Integrated Smoke Model does show another round of elevated smoke moving in across the CWA from the west/northwest. It does not look to get too thick so hard to tell if it will impact temps at all. Highs for Sunday will be similar or a couple degrees cooler (mainly over northeastern SD), but still ranging in the 90s. It is moist out there with dewpoints ranging in the upper 60s to lower 70s and continuing through Sunday. The combination of heat and higher dew points will lead to heat indices in the upper 90s to the lower 100s across central SD into areas of northeastern SD. A heat advisory is in place for today over much of the CWA, excluding our northwestern CWA. Similar heat indices for Sunday with more of the upper 90s to around 100 across central to south central SD. Collab with other offices decided to wait on issuing a headline for Sunday at this point since there is one out today. Through the day, the shortwave that was overhead will continue to push east/northeast and over MN/eastern Dakotas border this evening. With moderate quasi zonal flow north of the high and south of a low in Canada, models indicate ongoing shortwave energy moving in from the west/northwest and over the Northern Plains. At the surface, a trough will be centered over over central SD with a low over ND and cold front extending westward. By this evening, this front will extend over SD/ND border and northwestward into MT, stalling out, as another surface trough sets up over central to western SD. Overnight, this frontal boundary dips a bit south over central SD. The heat and very moist air mass is leading to higher instability as CAPE values will be increasing to over 2000 j/kg, east of the Mo River, this afternoon and evening with shear around 30kts. EFI indicates CAPE 0.5-0.8 with a shift of tails of 0 in this area. If this instability can break the cap (according to HREF it should?), the best area for convection will be across northeastern SD into MN this afternoon/evening as HREF 2-5KM UH>75 shows this, indicating organized convection. UH>150 does show a few paintballs over northeastern SD indicating discrete cells. Several of the CAMs show thunderstorms firing up over this area into MN as a linear system/MCS forms over ~central MN and pushes south/southeast. CAMs struggled with this morning`s convection and are struggling with placement and timing of afternoon convection so confidence remains lower on this and if it will occur. HRRR/HREF also shows clusters turning into a line of elevated convection coming in from the northwest and into our CWA late tonight. Confidence is higher on this happening as there is stronger winds aloft with this next shortwave. With ongoing sufficient instability and shear increasing to 40kts over north central SD, the main threat would be large hail with any discrete storms/clusters then becoming more of a wind threat as the convection becomes linear. There is still a difference in some of the CAMs on timing of this and intensity. There is a slight risk (2/5) for severe weather for most of our CWA for this afternoon into the overnight with a 15% hatched area for wind over north central SD with the linear system. && .LONG TERM /SUNDAY EVENING THROUGH FRIDAY/... Issued at 408 AM CDT Sat Jul 13 2024 The flow pattern Sunday night is very zonal in appearance (subdued/flattened upper level ridge over the western CONUS). Tuesday through Thursday models/clusters have pumped the western CONUS upper ridge back up and introduced an eastern CONUS/eastern Canada long wave trof/upper level closed low. But by the end of the period, the upper ridge may just be the dominant flow pattern feature over the lower 48. The main shortwave of interest continues to be progged to push through the region Sunday night/Monday, dragging a notable airmass- changing cold frontal boundary through the CWA. Much cooler/drier air for Tuesday through Thursday. Then, potentially, a many days long period of return flow southerly warm up/humidity return. The airmass over this CWA Sunday night may be starting off rather warm and humid. But by the middle of Monday, low level dry air advection and cold air advection should be making a dent in all the heat and humidity. But, prior to all that, it still appears as though adequate deep-layer shear and instability is progged for the Sunday night frontal passage. Tough to anticipate what type of potential severe weather could be developing over the region Sunday afternoon into Sunday night (including over this CWA), but a significant wind-producing severe weather system could be in the running. Beyond that, with the flow pattern becoming increasingly northwesterly and the boundary layer drying out/stabilizing for a couple of days, it looks like pretty limited PoPs (generally less than 25% chances) in the 7-day forecast until you get out toward Friday and beyond. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1228 AM CDT Sat Jul 13 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions through the end of the TAF period. Rain showers (and a few thunderstorms) continue to push east/southeast over central SD this morning. Chance of thunderstorms tonight that could impact KMBG/KPIR. Low confidence on precipitation forecast so left any mention out of the TAFs at this time. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Heat Advisory from 1 PM CDT /noon MDT/ this afternoon to 8 PM CDT /7 PM MDT/ this evening for SDZ006>008-010-011-017>023- 033>037-045-048-051. MN...Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for MNZ039-046. && $$ SHORT TERM...MMM LONG TERM...Dorn AVIATION...MMM