Marine Weather and Tide Forecast for Sergeant Bluff, IA
May 18, 2024 12:39 PM CDT (17:39 UTC) Change Location
 | Sunrise 5:58 AM Sunset 8:45 PM Moonrise 3:03 PM Moonset 2:44 AM |
Area Discussion for - Sioux Falls, SD
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FXUS63 KFSD 181705 AFDFSD
Area Forecast Discussion National Weather Service Sioux Falls SD 1205 PM CDT Sat May 18 2024
KEY MESSAGES
- Not as warm but still breezy today. Occasional gusts 30-40 mph this morning, but probability of reaching Wind Advisory criteria is low.
- Thunderstorm chances return Sunday into Monday. Level 1 of 5 risk for severe storms, mainly Sunday night and perhaps late Monday afternoon, though still some uncertainty in exact timing/location. Pockets of heavy rainfall also possible.
- Another round of thunderstorms arrives late Monday night- Tuesday bringing a risk of a few severe storms as well as potential for widespread 1-2+ inches of rainfall. This could bring renewed flooding along some area rivers.
- Cooler but still unsettled for the latter half of next week.
DISCUSSION
Issued at 433 AM CDT Sat May 18 2024
TODAY-TONIGHT: Breezy south winds continue early this morning, ahead of a cold front which has entered our western CWA, located east of Huron-Chamberlain as of 3 AM. Strongest winds appear to be downslope winds east of the Buffalo Ridge into Marshall at this time, though several areas gusting 25-30 mph near and east of US Highway 81.
Spotty light echoes on radar, but having a more difficult time getting rain to the surface with deeper sub-cloud dry layer. Despite that, will continue to carry a mention of sprinkles as the ACCAS slides east through mid-morning.
Focus for today will be on post-frontal winds, especially this morning as cold advection enables mixing into some stronger winds aloft. Forecast soundings show a brief period where winds atop the mixed layer reach 40kt, mainly in areas west of the James River within an hour or two of sunrise. Seeing isolated gusts in this range upstream in western SD as of 08Z, so cannot rule out some isolated advisory level winds in our far west early this morning.
However, does not look to be widespread or prolonged enough to warrant a Wind Advisory.
Aside from the wind, today should be a seasonally pleasant day with highs mainly in the 70s and plenty of sunshine. Winds actually will decrease through the afternoon in response to approaching surface high pressure which will provide light/variable winds through much of tonight, increasing late tonight along/west of the James River Valley.
SUNDAY-MONDAY: Rain chances on Sunday look to some in two waves.
First will spread northeast across the area through the morning to early afternoon, in response to broad warm advection and a mid-level wave sliding through the Tri-State Area. This wave may initially be fighting some dry air, especially in our east as the surface high is just departing, but eventually expect scattered-numerous showers and a few storms move across the area. Instability is rather limited at this time, so severe weather risk is low and rainfall amounts will likely be on the lighter side, largely less than a quarter inch.
CAMs are in fairly good agreement that this activity will wane by mid afternoon as the wave lifts off to the northeast.
Attention then turns to a trailing mid-upper level wave which will drag a cool front east into the area Sunday night-early Monday. This boundary should trigger scattered storms in southwest/central SD as it moves through that area during peak heating Sunday afternoon.
Question is whether storms will maintain organization and strength as they push east of the Missouri River, most likely after sunset.
CAMs would suggest a threat of at least isolated strong to severe storms, most likely a potential for hail with elevated storms in the late evening-overnight given moderately steep mid-level lapse rates.
However, deep layer shear appears lacking due to weak mid-level winds as storms move east, so may be difficult to remain organized.
SPC Day 2 Marginal Risk (Level 1 of 5) seems reasonable to cover the isolated threat, though confidence is on the low side given the weak shear profile.
This activity pushes east of the forecast area in the morning, then will watch for redevelopment across our southeast Monday afternoon, depending on the timing of the cold front which is currently progged to be east of the IA/MN Highway 60 corridor by 18Z. As is often seen with cold fronts, greater shear is displaced behind the boundary while greater instability is along/ahead, but could see some overlap along the boundary to support a few strong to severe storms in our far southeast later Monday afternoon-early evening.
MONDAY NIGHT-TUESDAY: Should see increasing broad-scale lift across the area as Monday night progresses, as a deepening trough slides east into the Plains. Will see increasing shear as this system moves across the forecast area Tuesday, with potential for destabilization across our far southeast as mid-level dry slot works into northwest Iowa. Some uncertainty in the details regarding exactly where a developing surface low/associated boundaries may track, but current thinking brings the surface low northeast across northwest Iowa during peak heating, with differential heating adding to the thermal gradient across the boundary. Given proximity of the surface low and boundaries, along with strong shear/moderate instability (1000-1500 J/kg), all severe weather hazards appear possible Tuesday afternoon.
Northwest of the surface low track, widespread/persistent rain and embedded storms could produce areas of moderate to heavy rainfall.
Ensemble mean rainfall tops 1" across portions of southeast SD and southwest MN Tuesday into Tuesday evening, with the 90th percentile greater than 2" across this same area. Given the lack of instability in these areas, would not expect excessive rainfall rates, though localized urban flooding or ponding in low-lying areas is possible.
Additional rainfall into already swollen rivers across northwest IA may also bring a renewed threat of river flooding in these areas.
WEDNESDAY-FRIDAY: Details for this period are low confidence as there is little agreement among the longer range models. However, moderate consensus in some cooler air settling into the northern Plains mid to late week with periodic rain chances.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1202 PM CDT Sat May 18 2024
VFR conditions and gusty northwest winds will continue through the daytime hours of Saturday. Overnight, winds may weaken, but high clouds gradually spread northward. However a mid-lvl cloud deck will approach from the southwest towards daybreak as some rain tries to moves through Nebraska. This rain may struggle to reach northward as dry air continues to be an issue. What is likely at this point would be a thickening mid-lvl cloud field with a PROB30 group for SHRA developing by mid-morning.
One thing to watch will be winds Sunday morning, as some stronger gusts may start to mix downward quickly in the morning.
Additionally the edges of any stratiform rain may provide some focus for evaporative cooling enhanced winds that could push 35 to 40 knots.
FSD WATCHES/WARNINGS/ADVISORIES
SD...None.
MN...None.
IA...None.
NE...None.
Area Forecast Discussion National Weather Service Sioux Falls SD 1205 PM CDT Sat May 18 2024
KEY MESSAGES
- Not as warm but still breezy today. Occasional gusts 30-40 mph this morning, but probability of reaching Wind Advisory criteria is low.
- Thunderstorm chances return Sunday into Monday. Level 1 of 5 risk for severe storms, mainly Sunday night and perhaps late Monday afternoon, though still some uncertainty in exact timing/location. Pockets of heavy rainfall also possible.
- Another round of thunderstorms arrives late Monday night- Tuesday bringing a risk of a few severe storms as well as potential for widespread 1-2+ inches of rainfall. This could bring renewed flooding along some area rivers.
- Cooler but still unsettled for the latter half of next week.
DISCUSSION
Issued at 433 AM CDT Sat May 18 2024
TODAY-TONIGHT: Breezy south winds continue early this morning, ahead of a cold front which has entered our western CWA, located east of Huron-Chamberlain as of 3 AM. Strongest winds appear to be downslope winds east of the Buffalo Ridge into Marshall at this time, though several areas gusting 25-30 mph near and east of US Highway 81.
Spotty light echoes on radar, but having a more difficult time getting rain to the surface with deeper sub-cloud dry layer. Despite that, will continue to carry a mention of sprinkles as the ACCAS slides east through mid-morning.
Focus for today will be on post-frontal winds, especially this morning as cold advection enables mixing into some stronger winds aloft. Forecast soundings show a brief period where winds atop the mixed layer reach 40kt, mainly in areas west of the James River within an hour or two of sunrise. Seeing isolated gusts in this range upstream in western SD as of 08Z, so cannot rule out some isolated advisory level winds in our far west early this morning.
However, does not look to be widespread or prolonged enough to warrant a Wind Advisory.
Aside from the wind, today should be a seasonally pleasant day with highs mainly in the 70s and plenty of sunshine. Winds actually will decrease through the afternoon in response to approaching surface high pressure which will provide light/variable winds through much of tonight, increasing late tonight along/west of the James River Valley.
SUNDAY-MONDAY: Rain chances on Sunday look to some in two waves.
First will spread northeast across the area through the morning to early afternoon, in response to broad warm advection and a mid-level wave sliding through the Tri-State Area. This wave may initially be fighting some dry air, especially in our east as the surface high is just departing, but eventually expect scattered-numerous showers and a few storms move across the area. Instability is rather limited at this time, so severe weather risk is low and rainfall amounts will likely be on the lighter side, largely less than a quarter inch.
CAMs are in fairly good agreement that this activity will wane by mid afternoon as the wave lifts off to the northeast.
Attention then turns to a trailing mid-upper level wave which will drag a cool front east into the area Sunday night-early Monday. This boundary should trigger scattered storms in southwest/central SD as it moves through that area during peak heating Sunday afternoon.
Question is whether storms will maintain organization and strength as they push east of the Missouri River, most likely after sunset.
CAMs would suggest a threat of at least isolated strong to severe storms, most likely a potential for hail with elevated storms in the late evening-overnight given moderately steep mid-level lapse rates.
However, deep layer shear appears lacking due to weak mid-level winds as storms move east, so may be difficult to remain organized.
SPC Day 2 Marginal Risk (Level 1 of 5) seems reasonable to cover the isolated threat, though confidence is on the low side given the weak shear profile.
This activity pushes east of the forecast area in the morning, then will watch for redevelopment across our southeast Monday afternoon, depending on the timing of the cold front which is currently progged to be east of the IA/MN Highway 60 corridor by 18Z. As is often seen with cold fronts, greater shear is displaced behind the boundary while greater instability is along/ahead, but could see some overlap along the boundary to support a few strong to severe storms in our far southeast later Monday afternoon-early evening.
MONDAY NIGHT-TUESDAY: Should see increasing broad-scale lift across the area as Monday night progresses, as a deepening trough slides east into the Plains. Will see increasing shear as this system moves across the forecast area Tuesday, with potential for destabilization across our far southeast as mid-level dry slot works into northwest Iowa. Some uncertainty in the details regarding exactly where a developing surface low/associated boundaries may track, but current thinking brings the surface low northeast across northwest Iowa during peak heating, with differential heating adding to the thermal gradient across the boundary. Given proximity of the surface low and boundaries, along with strong shear/moderate instability (1000-1500 J/kg), all severe weather hazards appear possible Tuesday afternoon.
Northwest of the surface low track, widespread/persistent rain and embedded storms could produce areas of moderate to heavy rainfall.
Ensemble mean rainfall tops 1" across portions of southeast SD and southwest MN Tuesday into Tuesday evening, with the 90th percentile greater than 2" across this same area. Given the lack of instability in these areas, would not expect excessive rainfall rates, though localized urban flooding or ponding in low-lying areas is possible.
Additional rainfall into already swollen rivers across northwest IA may also bring a renewed threat of river flooding in these areas.
WEDNESDAY-FRIDAY: Details for this period are low confidence as there is little agreement among the longer range models. However, moderate consensus in some cooler air settling into the northern Plains mid to late week with periodic rain chances.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1202 PM CDT Sat May 18 2024
VFR conditions and gusty northwest winds will continue through the daytime hours of Saturday. Overnight, winds may weaken, but high clouds gradually spread northward. However a mid-lvl cloud deck will approach from the southwest towards daybreak as some rain tries to moves through Nebraska. This rain may struggle to reach northward as dry air continues to be an issue. What is likely at this point would be a thickening mid-lvl cloud field with a PROB30 group for SHRA developing by mid-morning.
One thing to watch will be winds Sunday morning, as some stronger gusts may start to mix downward quickly in the morning.
Additionally the edges of any stratiform rain may provide some focus for evaporative cooling enhanced winds that could push 35 to 40 knots.
FSD WATCHES/WARNINGS/ADVISORIES
SD...None.
MN...None.
IA...None.
NE...None.
| Airport | Dist | Age | Wind kt | Vis | Sky | Weather | Temp | DewPt | RH | inHg |
| KSUX SIOUX GATEWAY/BRIG GEN BUD DAY FIELD,IA | 2 sm | 47 min | NW 21G30 | 10 sm | Clear | 72°F | 52°F | 50% | 29.81 |
Omaha, NE,
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