Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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730 FXUS63 KFSD 101951 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 251 PM CDT Fri May 10 2024 .KEY MESSAGES... - Warm, dry, and breezy northwesterly winds will continue this afternoon, with any remaining cloud coverage clearing throughout the evening. - Mostly clear skies expected tonight for the potential geomagnetic storm, though some thin upper level cirrus can`t be ruled out. - Warmer and mainly dry conditions throughout the weekend will allow for the current minor river flooding across portions of NW Iowa to improve. - Scattered showers and thunderstorms likely on Sunday but severe weather will be very isolated at best. Another chance for showers and thunderstorms on Tuesday, but the severe weather threat looks to remain isolated. && .DISCUSSION... Issued at 250 PM CDT Fri May 10 2024 On the heels of a surface front that has just about finished moving through, afternoon satellite imagery shows a scattered cumulus field moving in from the north. At the surface, observations show temperatures climbing into the upper 60s to mid 70s, with an additional degree possible before temperatures start to cool off. Relative humidity values behind the front have dropped down into the mid 20s to mid 30s, though given the current conditions of the grasslands, will forgo any fire headlines. The over achieving breezy northwesterly winds will subside throughout the evening hours, with in general weak winds expected overnight. Overnight, we`ll be watching as a surface ridge axis slides across the area from northwest to southeast, swinging the winds around to the west- northwest by Saturday morning. Early morning lows in the mid to upper 40s expected. Saturday will see the 850mb ridge slide across the area throughout the day, keeping winds out of the west-southwest. As the surface heats up we will be able to mix up into the 750-700mb layer, and bring down 850mb temperatures in the +11 to +15 deg C range (roughly 5-9 deg C above normal). As a result, expect temperatures to rapidly warm after the mid-morning hours, likely peaking into the mid 70s to lower 80s across the region. Normally this is where we say "unfortunately this will require very breezy winds to mix down those warmer temperatures," but Saturday looks like winds will only be gusting into the teens and lower 20s! Thus, Saturday is poised to be a lovely spring day. Overnight lows will also be warmer than normal, with most staying in the lower to mid 50s. Low pressure moves through NE on Sunday with broad mid level warm advection moving through areas mostly south of I-90. Soundings indicate the potential for some weak to moderate instability, generally less than 1000 J/kg. The combination of the instability and incoming lift should allow for scattered showers and thunderstorms with a very small chance for isolated lower end severe weather. The better chances should be Sunday afternoon and Sunday night. Strong wind gusts appear to be the main concern with a fairly deep dry layer below about 6000 kft. Otherwise a very warm day with highs mostly in the upper 70s to mid 80s and seasonable winds. This system moves through Sunday night and there may be some lingering showery activity in mostly northwest IA Monday. Another weak system will move into central SD Monday afternoon but not much to work with so very isolated at best. While Monday will be a bit cooler as northeast flow settles into the area highs should still be in the 70s. A bit stronger system with fairly good model agreement should move through the area on Tuesday. The overall severe threat looks fairly low but with some weak shear and weak instability Tuesday afternoon and night will at least see a small chance for isolated severe storms. ANother day with highs in the 70s. Wednesday into Thursday model divergence increases so confidence on any solution is pretty low. Looks like a chance to remain in an active pattern with continued precipitation chances, just not real confident on any of the details. Some increasing confidence on a cold front coming through on Friday so maybe another threat for showers and thunderstorms and if enough instability some isolated severe storms. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 1221 PM CDT Fri May 10 2024 VFR throughout the period. Weak scattered showers are possible for another hour or two east of highway 71 in NW IA as a front pushes through, with a scattered cumulus field expected to develop throughout the rest of the afternoon hours. Cloud coverage clears during the evening hours, with breezy winds also decreasing into the evening. Winds become west-northwesterly overnight, remaining fairly light throughout the day with only marginally gusty winds expected. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...APT/08 AVIATION...APT