898 FXUS63 KDMX 040212 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 812 PM CST Tue Mar 3 2020 ...Updated for Near Term Weather Trends... .UPDATE... Issued at 812 PM CST Tue Mar 3 2020 Trends this evening have pointed to the wintry precipitation being a bit farther south than previously thought by about a county or two. This shift can be seen in the arriving 00z NAM as well as recent runs of the HRRR and RAP. There is also some disparity in the amount of QPF and resulting snow. Generally, guidance is pointing towards around an inch or so of snow accumulations. However, the NAM and the 1z NBM v3.2 shows a narrow strip of higher totals from around Emmetsburg to Waverly. While the BUFKIT NAM data has not arrived yet, the NAM has had a very cold boundary layer this winter. Therefore, it is possible that it has a colder than reality surface temperature now and in the near future allowing for its higher snow totals. Further, Iowa DOT road temperatures are still above freezing in the low 40s across northern Iowa early this evening. If there were to be a narrow band of higher snowfall, it would likely be east of I-35 where the precipitation will fall with temperatures and road temperatures that would support more accumulation. Will continue to monitor environment and make adjustments as needed through the evening and overnight. && .SHORT TERM.../Tonight through Wednesday/ Issued at 312 PM CST Tue Mar 3 2020 Confidence: Medium Tonight and High Wednesday Main concern will be impacts from system tonight. Fast moving and compact PV anomaly dropping southeast into Iowa overnight. This will induce a weak surface low and associated H850 feature which are forecast to track across central Iowa, with the Euro placing the sfc low a bit farther south into southern Iowa. The low will track along a cool front dropping south as well. Most of the 12z synoptic models have backed off on qpf amounts with the hires models continuing to suggest a band of higher qpf just north of the low and mainly over northern Iowa. The better forcing arrives over our northwest forecast area around 03z and quickly tracks east and generally existing the east between 09-12z. Currently temperatures are in the lower to mid 40s over the north with mid 50s in the south. Road temperatures are in the mid 60s over much of the region this afternoon. Farther north, daytime temperatures remain in the mid 30s as far north as southern North Dakota. Tonight the area will first need to overcome the drier airmass and also today's warmth in the lower layers/roads prior to any real impacts tonight. With the potential for up to .20 inches of qpf, even with a changeover across the north, snowfall amounts continue to lean toward lighter amounts of around 1 inch with locally slightly higher totals. Generally it appears to be a battle between the arrival of the surface cooler air and the precipitation crossing the area though temperatures aloft will be cool enough to start off as snow. Tonight's lows will drop to the mid to upper 20s north while the south drops into the lower to mid 30s. The system will quickly depart Wednesday morning with a return of some sunshine as well as milder temperatures again over the south during the afternoon. High pressure will quickly slide east in the afternoon with a return of southwest flow by late day. .LONG TERM.../Wednesday night through Tuesday/ Issued at 312 PM CST Tue Mar 3 2020 Confidence: Medium to High Other than wind, the bulk of the forecast will be quiet for the next few days. Another storm will track along the US Canadian border late Wendesday night into Thursday with a trailing front and stronger mixing moving across our area. There remains a weak signal for some light precipitation over northern Iowa or southern Minnesota during from Thursday morning through Friday morning but confidence is currently low regarding occurrence. Winds Thursday afternoon will again be brisk with models suggesting that gusts may reach 40 to 45 mph during the late morning and afternoon hours. Will need to monitor for potential headlines. As well, colder temperatures should filter across the region by afternoon; especially north where highs are more likely to be near the 40 degree mark while the south will still see some lower to mid 50s. The drier airmass, stronger winds and mild temperatures over the southwest Thursday could result in an elevated grass fire situation, but will need to evaluate moving forward. The remainder of the extended will see a rapid warm up over the weekend with H850 temperatures reaching 8C by 00z Sunday and as warm as 9 to 10C by 00z Monday. This should propel highs into the 60s by afternoon. Both the GFS and Euro are in decent agreement for Monday into Tuesday with a well developed trough tracking east across the region late Sunday night/Monday followed by high pressure on Tuesday. Showers are likely into Monday then clearing later in the day. Highs will cool Monday into Tuesday back into the 50s then 40s. && .AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/ Issued at 542 PM CST Tue Mar 3 2020 Winds will decrease this afternoon as clouds spread over the area with a quick shot of wintry precipitation expected overnight, mainly over the northern half of Iowa. This wintry precipitation will arrive later this evening bringing MVFR and perhaps IFR at times to FOD/MCW/ALO. Farther south, there could be a brief shower at DSM. Conditions will have improved back into VFR by daybreak Wednesday with light winds from the northwest becoming from the southwest later in the day. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Ansorge SHORT TERM...REV LONG TERM...REV AVIATION...Ansorge