Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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969 FXUS63 KABR 020840 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 340 AM CDT Thu May 2 2024 .KEY MESSAGES... - Light rain showers lingering through the day with some clearing from west to east. Clearing will result in destabilization, enough to generate scattered weak thunderstorms (30% coverage). Only hazard would be lightning and small hail. - Next shot at moisture comes mid-day Friday. Probability of 1/4" moisture is only 20-40% along and south of a line from Pierre to Watertown. - Much larger system looks to affect the region on Monday, with widespread moderate rainfall. Threat for severe weather still appears low at this time (higher across NE/KS/OK), but will continue to monitor trends. && .SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/... Issued at 340 AM CDT Thu May 2 2024 Weak low pressure over North Dakota and a second system to the south is responsible for shower activity and cloud cover across the state along with stable easterly low level flow. As we move through the day, there is only a slow progression of POPs and low clouds eastwards. BUFKIT profiles and CAMS suggest that once we see clearing as low level winds become westerly, the atmosphere will destabilize enough for shower/weak thunderstorm development. NBM 25th/75th percentiles range from 100-600j/kg. BUFKIT profiles depict skinny CAPE with westerly unidirectional flow and nearly all the convection falling below 0C. That translates into potential for thunder and small hail given how cold it is aloft, but otherwise not a severe weather risk. Another period of dry weather develops during the overnight hours before the next southwest flow wave brings moisture back to the CWA for Friday. Again, just another round of mid level warm advection to support these showers, with a cold front already having undercut this band of moisture as the low develops to the south. Probability of 1/4" moisture is only 20-40% along and south of a line from Pierre to Watertown. && .LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/... Issued at 340 AM CDT Thu May 2 2024 Period starts off Friday night with yet another shortwave crossing the Northern Plains, along with a 100 kt upper level jet max shown on the 00Z EC deterministic run. Models continue to bring the northern fringe of precipitation from south central SD up though northeast SD into western MN. It appears north central SD may miss out entirely on this Friday night wave of precipitation. Models continue to suggest this will be a fairly light precip event, with GEFS/GEPS/ENS QPF means all below 0.50in. It`s not until we get into the higher end model scenarios (90th percentile) where potential QPF exceeds 0.50in on the Grand Ensemble across the southeast CWA. No real instability to speak of either, so just looking at a general light rainfall Friday night, with the highest chances (40-60%) stretching from the southwest CWA into the southeast CWA. Models then show surface high pressure building into the region on Saturday, with clearing skies and light winds. Aloft, upper ridging begins moving in by Sunday. So, actually looking at a pretty nice weekend (albeit breezy/windy on Sunday) with highs rising into the upper 60s to low 70s by Sunday. Focus then shifts to the potentially larger and stronger low pressure system moving in on Monday. All four clusters off the cluster analysis feature an upper trough across the northern Rockies into the High Plains/Northern Plains Day 5 into Day 6. As expected, there are some differences noted in the amplitude of the 500mb wave, but all basically feature a negatively tilted trough moving into the region. This gives fairly high confidence in precipitation affecting a somewhat large coverage of the Northern Plains. We start to get some instability working northward as well during the day Monday, although GEFS/GEPS/ENS mean CAPE values are all still below 1000 J/KG. As for any severe weather threat with this large system coming out, joint probabilities for CAPE>500 J/KG, CIN>-25 J/KG, and 0- 500mb bulk shear>30 kts are still only about 5-15% (Grand Ensemble) across the CWA, with much higher values well south into the Central Plains. This seems to line up with the recently released Day 5 severe weather outlook, highlighting an area from Nebraska southward into Kansas/Oklahoma. CIPS analogs for Day 5 (Monday) 24-hr probs for severe does bring the 10% contour up into southeast SD, but not into the ABR CWA. Will be watching these trends over the coming days to see if any of these features nudge northward at all. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1226 AM CDT Thu May 2 2024 Terminals KABR,KATY,KPIR,KMBG While initially TAFS will be VFR, CIGS will lower through the course of the overnight hours and persist into the day Thursday. Showers are expected to linger through most of the TAF period for all terminals with just a short break around mid day. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ SHORT TERM...Connelly LONG TERM...TMT AVIATION...Connelly