652 FXUS63 KFSD 042315 AFDFSD AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 515 PM CST Wed Mar 4 2020 .SHORT TERM...(This Evening through Thursday Night) Issued at 257 PM CST Wed Mar 4 2020 For tonight, the main story is the approaching cold front which will be passing through the area overnight. Cold air advection behind the front will create some gusty winds, and a few light rain showers are likely as well. Amounts will remain light, with a small chance for a brief rain/snow mixture as the precipitation comes to an end. Winds aloft will strengthen prior to sunrise, and will begin to mix down as the boundary layer destabilizes leading to strong sustained winds throughout the day Thursday. Sustained winds up to 35 mph are likely with gusts as high as 55 mph. As the cold front will have brought in cooler air, high temperatures will be limited to the 40's, which are still above normal for this time of the year. In areas with no snow, there is concern for fire danger due to the strong winds and low relative humidities expected on Thursday. Fire danger levels are currently reaching high to very high in areas with no snow, but current guidance for our area suggests relative humidity values will remain high enough for us not to issue a red flag warning. As mixing ceases with the sunset, the winds will decouple and be brought back down to reasonable levels as a surface high pressure slides in from the northwest. Temperatures will dip down into the 20s for most locations, while areas along Highway 14 could see upper teens Friday morning. .LONG TERM...(Friday through Wednesday) Issued at 257 PM CST Wed Mar 4 2020 Friday we begin to see the upper ridge build into the Plains, bringing well above normal temperatures to the region through the weekend. Friday is still a transition day, so a little uncertainty in exactly how much warm air will mix to the surface in the wake of departing surface ridge. However, given increasing south-southwest flow by midday, will favor the warmer side of guidance, which is dominated by bias-corrected solutions. For the upcoming weekend, broad blend already in the warmer half of guidance, so will not make significant temperatures changes, though will nudge our southern areas which have been free of snow for several days up a bit closer to bias-corrected guidance. Largest impact of this will be on Sunday, when some variances in frontal timing are resulting in cooler blended guidance than most of the latest models would suggest, again especially across our southern counties. In general, looking at a very mild weekend, with highs in the mid 50s-mid 70s Saturday, and a bit cooler Sunday. The primary difference from previous warm periods is overnight lows will remain well above freezing, especially Saturday night when lows in the 40s are expected for most of the forecast area. This will make a large dent in any remaining snow cover, and also lead to greater rises on area streams and rivers than we have seen thus far this late winter. Moisture initially somewhat lacking with the frontal passage on Sunday, so daytime hours expected to remain dry. However, do see some increase in moisture and some hint of weak instability as the front reaches our eastern counties in the evening, followed by a trailing wave through the Central Plains late Sunday night into Monday. Will keep chance pops across mainly the southeast half of the forecast area with these features, but does not look like any significant precip amounts in our area. In addition, instability not enough to introduce mention of thunder at this time, but may need to monitor this potential as we move through the upcoming days. Cooler temperatures settle back into the area early next week, below normal for early March, but with highs still above freezing in most areas. Another chance of light precipitation toward the end of the forecast period. Models showing little agreement on strength/timing the next wave, but some consensus pointing to Tuesday night as the better chance. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 511 PM CST Wed Mar 4 2020 A cold front will sweep through the area overnight, bringing a slight threat of a passing rain shower and gusty winds. In addition, as winds increase aloft, low level wind shear will occur at all TAF sites through Thursday morning. Northwesterly winds will continue to increase on Thursday, with gusts around 40 kts during the afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory from 9 AM to 6 PM CST Thursday for SDZ038>040-050- 052>071. MN...Wind Advisory from 9 AM to 6 PM CST Thursday for MNZ071-072-080- 081-089-090-097-098. IA...Wind Advisory from 9 AM to 6 PM CST Thursday for IAZ001>003- 012>014-020>022-031-032. NE...Wind Advisory from 9 AM to 6 PM CST Thursday for NEZ013-014. && $$ SHORT TERM...Trellinger LONG TERM...JH AVIATION...JM