Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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010 FXUS63 KFSD 060315 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 1015 PM CDT Sun May 5 2024 .KEY MESSAGES... - A Wind Advisory has been issued for most of our area Monday, excluding northwest Iowa. Additional expansion may still be needed. - A few strong to severe storms will be possible Monday afternoon and evening, with the greatest severe threat currently focused along and south of the Missouri River and Highway 18 corridor. - Periodic rain chances continue for much of the upcoming week, with highs in the 60s to lower 70s. && .DISCUSSION... Issued at 251 PM CDT Sun May 5 2024 CURRENT/TONIGHT: Quiet conditions continue to prevail across the region, with latest observations showing sunny skies and temperatures in the 60s. S/SE winds have picked up a bit during this time, with gusts between 20 to 30 mph being noted thanks to a deepening sfc trough over eastern MT/WY. As alluded to in the previous discussion, will see this sfc trough continue to deepen and shift eastward as an upper level low near the Rockies ejects northeastward towards the Northern Plains. This will result increasing cloud cover and continued breezy winds for much of our area during the overnight period. Given the tightening SPG in place, have gusts ranging between 20 to 40 MPH by daybreak Monday. Lastly, with broad WAA overhead, should see lows remain on the milder side as temperatures only fall into the upper 40s to lower 50s. MONDAY: Expect the aforementioned upper level low to edge closer to the western Dakotas Monday morning as a sfc warm front simultaneously lifts northeastward across our area. As noted in days past, will see a fairly robust S/SE LLJ develop overhead, which coupled with a tightening SPG will result in windy conditions through the afternoon. Currently have gusts ranging between 30 to 50 MPH, thus, after collaboration with neighbors have issued a Wind Advisory for most of our area, excluding northwest Iowa. Additional expansion may still be needed, so continue to monitor the forecast for the latest updates. With the aid of WAA, should see afternoon highs rise into the upper 60s to lower 70s, with dewpoints largely in the 50s. In terms of precipitation, could see some light showers begin near/shortly after daybreak west of the James River. Precipitation should become more widespread through the late morning and afternoon ahead of an advancing cold front. Latest SPC Day 2 Outlook still maintains a Slight Risk (Level 2 of 5) across the lower MO River Valley/northeast Nebraska/and parts of northwest Iowa, with a Marginal Risk (Level 1 of 5) encompassing those areas north up to the I-90 corridor. Regarding dynamics, most guidance still shows CAPE values around 500-1000 J/kg in addition to ample bulk shear (40+ kts). That being said, ensembles continue with low probabilities of CAPE greater than 1000 J/KG - at only 10-20% over our area. Soundings have also have maintained their tall and skinny profile - so think the primary threats with any storm that does become strong to severe will be damaging gusts up to 70 MPH and heavy rainfall, with hail to the size of half dollars being a secondary threat. Confidence remains high that this event will produce yet another round of meaningful rainfall for most of our area, as PWATs exceed an inch. In terms of accumulations, the current forecast has QPF ranging between a quarter of an inch to an inch, with the highest amounts generally along and east of I-29. Thus, given the recent rains and saturated soils in place, can`t rule out the possibility of seeing isolated to scattered flash flooding occur in urban and low lying areas. Ponding would be expected in areas elsewhere. So, in summary - Monday poses the risk of seeing a few strong to severe storms, with the greatest threat currently focused along and south of the MO River Valley and Highway 18 corridor. As with any event, we strongly encourage you to have a way to receive warnings. Otherwise, expect showers and storms to continue eastward overnight, allowing largely quiet conditions to return by daybreak Tuesday. TUESDAY THROUGH FRIDAY: Upper level low continues to spin and wobble over the Northern Plains through late-week, resulting in persistent PoPs (20-50%) through Friday. Winds also look to remain fairly breezy during this period, with gusts as high as 25 to 35 MPH possible each afternoon. In regard to temperatures, look for highs to rise into the 60s and lows to fall into the 40s. SATURDAY THROUGH SUNDAY: Dry conditions are forecast to largely prevail over the weekend as the aforementioned upper level low pushes eastward, causing northwesterly flow to set up overhead. Afternoon highs in the 60s to lower 70s will become common during this time, with lows remaining in the 40s. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1013 PM CDT Sun May 5 2024 VFR conditions are expected into the overnight hours as we continue to see a very scattered mid-lvl cloud field develop. However more impactful will be a stream of stratus that develops and spreads across the area from the Southwest. Initially at MVFR levels, stratus may fall into the IFR category by mid-late morning. Scattered showers may then develop by mid-afternoon ahead of an approaching frontal boundary that will sweep east later this in the afternoon and early evening. The progression of thunder may be quite limited, only within a few hours of the frontal passage. Throughout the daytime hours, expect period wind gusts to 40 mph at most locations. These strong winds will begin to weaken after the front passes east Monday evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory from 10 AM to 7 PM CDT Monday for SDZ039-040- 054>056-060>062-065>071. Wind Advisory from 7 AM to 7 PM CDT Monday for SDZ038-050-052- 053-057>059-063-064. MN...Wind Advisory from 11 AM to 7 PM CDT Monday for MNZ071-072-080- 081-089-090-097-098. IA...Wind Advisory from 11 AM to 7 PM CDT Monday for IAZ001>003-012- 013-020. NE...Wind Advisory from 10 AM to 7 PM CDT Monday for NEZ013-014. && $$ DISCUSSION...SST AVIATION...Dux