Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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978 FXUS63 KFSD 072023 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 323 PM CDT Tue May 7 2024 .KEY MESSAGES... - A Wind Advisory is in effect for for Gregory, Jerauld, Brule, Aurora, Charles Mix, and Douglas counties until 7 pm this evening. Gusts up to 45 mph are expected in the Advisory. - Shower and storm chances return on Wednesday. Some storms could be strong to severe and bring another round of meaningful rainfall. Locations along and east of I-29 have the highest probability (30- 50% chance) for exceeding a half an inch of rain. - Warmer and mainly dry conditions move in for the weekend and into early next week. && .DISCUSSION... Issued at 313 PM CDT Tue May 7 2024 Vertically stacked low pressure systems continues to spin over the North Dakota and South Dakota border this afternoon. This has resulted in west/southwest winds across the area with gusts between 30 to 45 mph, strongest along and west of the James River. A Wind Advisory remains in effect through 7 pm this evening for this area. Sprinkles to light showers remain possible under the diurnally driven strato-cumulus field. Winds along with any chance for rain will wane this evening and the boundary layer stabilizes. Low temperatures will fall to the 40s overnight. The upper level low wobbles over part of the forecast area tomorrow, brining another chance for showers and storms. An occluded front looks to set up east of I-29 tomorrow afternoon. Destabilization looks to briefly occur early tomorrow afternoon where CAPE values may max out around 1,000 J/kg. However, dry air in the low levels will allow for stronger mixing to occur which could mix out the instability to some degree. The strong mixing will allow for high temperatures to warm up to the 60s tomorrow afternoon. With a deep mixed layer and some instability along the front, thunderstorms look to develop. Where storms develop remains a bit uncertain at this time as hi-res guidance varies on how far north or south the boundary sets up. Given the vorticity along the boundary along with dry low levels, think cold air funnels along with damaging winds up to 60 mph are the primary hazards with the storms that do develop. Sufficient shear is present as well but will be on a decreasing trend as the upper low moves overhead. This will present an isolated hail risk to hail up to the size of half dollars but this will be the secondary risk. The other aspect to tomorrows storms is another round of meaningful rainfall. Difficult to say how much rain will fall in any one particular location or area as hi-res guidance varies significantly in where convection develops. However, latest HREF probabilities show a 30-50% chance for locations east of I-29 receiving a half an inch of rain. The additional rainfall may lead to ponding on roadways and minor flooding in rivers and streams. Low temperatures will fall to 40s overnight. Broad upper level troughing persists across the Northern Plains for the rest of the work week and weekend. With a northwest flow regime in place due to the troughing, dry conditions are expected to prevail. High temperatures will warm to the 60s, 70s, and potentially reaching up to about 80 degrees F on Sunday. The GFS and Canadian ensembles support this possibility as they show a 30-50+% chance for exceeding 80 degrees F. The Euro ensemble is the outlier as it shows a near zero probability for exceeding 80 degree F temperatures. Another trough looks to push into the Northern Plains early next week as ensembles are consistent with this potential. This trough may also bring renewed rain potential but details remain uncertain at this time. Aside from rain potential, highs look to remain in the 70s with lows in the 50s. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1230 PM CDT Tue May 7 2024 VFR conditions are expected for the TAF period. Surface low pressure continues to spin over the North Dakota and South Dakota border this afternoon. Gusty west/southwest flow will persist through the afternoon hours with gusts up to 30-40 knots, strongest along and west of the James River. A CU field has developed this afternoon, based around 5,000 ft but should lift to around 8,000 ft as mixing further increases. Sprinkles to very light showers are possible beneath the CU but confidence is only high enough to include in KHON`s TAF at this time. The diurnally driven CU field will dissipate as mixing ceases this evening. Winds will also wane to light and variable during the overnight hours. Variable winds will finish out the TAF period as another surface low pressure system pushes into northwest Iowa. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory until 7 PM CDT this evening for SDZ050-052-057- 058-063-064. MN...None. IA...None. NE...None. && $$ DISCUSSION...Meyers AVIATION...Meyers