Area Forecast Discussion
Issued by NWS Aberdeen, SD
Issued by NWS Aberdeen, SD
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366 FXUS63 KABR 202342 AAA AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 642 PM CDT Mon May 20 2024 .KEY MESSAGES... - Mainly rain showers possible through late this evening (20-40%). - A strong system will spread a swath of precipitation (40-100%) across the forecast area late tonight into early Wednesday. Total rainfall amounts could range from a few hundredths of an inch across north central SD up to 1 to 2 inches over far northeastern SD into west central MN. - Another shot at moisture is possible during the Thursday - Friday timeframe. - Except for a brief potential warm up on Thursday, generally at or below normal temperatures are expected for the next several days. && .UPDATE... Issued at 636 PM CDT Mon May 20 2024 Aviation discussion updated below for the 00Z TAFs. && .SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/... Issued at 205 PM CDT Mon May 20 2024 At 2 PM CDT, skies were partly to mostly cloudy, and a band of southwest to northeast-oriented rain showers were extending from south central South Dakota up into northeast South Dakota. The whole line was slowly translating east across the region. North-northwest winds of 10 to 20 mph with gusts up to 30 mph have been advecting cooler air into the CWA today. That and the clouds and rain have kept the lid on temperatures, with most of the CWA registering readings in the 50s and 60s. Until the deformation zone associated with the low pressure system out over the Rockies begins to set up late tonight/early Tuesday morning, the mid-level baroclinic zone (the cause of the current banded rain showers) in place over the region is expected to remain active through late this evening, with one or more bands of rain (perhaps some embedded thunder) forecast to set up across the region and gradually work east-northeast. But, once the deformation zone sets up, periods of moderate to heavy rainfall will be possible from late tonight through late Tuesday night. It still looks like there will be a notable gradient in the amount of precipitation the CWA receives with this next low pressure system. SuperEnsemble plumes indicate less than a half inch of qpf is appropriate at KMBG. But, from KPIR eastward to KETH, the plumes trend considerably up, with the mean at KABR just over an inch and close to two-and-a-half inches at KETH by Tuesday night. Not sure why the qpf guidance for the forecast continues to remain on the conservative side, but at least the amounts have been increased some over what the mid-shift was given to use as a starting point. Plenty of clouds and rain around on Tuesday, with cloudiness expected to stick around Tuesday night. Should yield high temperatures only in the 50s across much of the CWA. But, the cloudiness Tuesday night should help "hold in the heat" and keep temperatures from falling below 40F degrees. Wind speed/gusts are also a concern on Tuesday. Soundings and ensemble guidance indicate there is a strong signal for wind advisory strength conditions across the eastern third of the CWA (Prairie Coteau eastward into Minnesota) by the time late Tuesday morning rolls around, persisting into Tuesday evening before the pressure gradient relaxes and winds begin to diminish. Issued a Wind Advisory, as such, for far northeast South Dakota and west central Minnesota. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 205 PM CDT Mon May 20 2024 The forecast period begins on Wednesday with a surface low pressure system departing the region to the northwest, with perhaps light showers over the far NE corner of the CWA. Most of Wednesday and through the first half of Thursday appears to be mostly dry, with perhaps some WAA pcpn Thursday morning. The WAA should produce seasonal temperatures with highs in the 70s on Thursday. An area of low pressure and associated frontal boundary should cross the region Thursday afternoon through Friday morning, bringing the potential for widespread showers and thunderstorms. Models and ensembles vary some, with a mix of a drier or wetter storm passage. It does appear as though North Dakota may see the heaviest pcpn. The storm system should depart the region sometime of Friday, leaving behind a period of dry conditions until perhaps Saturday night, or moreso Sunday afternoon. This is when another storm system should cross the region, bringing more showers and storms. Timing and placement of the late weekend storm is still a little unclear, causing more of a broad brush approach to pops Sunday through Monday. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 636 PM CDT Mon May 20 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast to start the TAF period, even as areas of -RA/-SHRA move through the region. Conditions will gradually deteriorate into Tuesday morning as CIGs lower to MVFR/IFR and precipitation expands and intensifies. VSBY may be reduced to MVFR, or even IFR in areas of heavier rainfall. Strong northerly surface winds gusting to around, or over 40 knots are possible in KATY towards the end of the TAF period. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory from 11 AM to 11 PM CDT Tuesday for SDZ007-008-011- 019>023. MN...Wind Advisory from 11 AM to 11 PM CDT Tuesday for MNZ039-046. && $$ UPDATE...TMT SHORT TERM...Dorn LONG TERM...SD AVIATION...TMT