059 FXUS63 KOAX 271119 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 519 AM CST Sat Feb 27 2021 ...Updated Aviation Forecast Discussion... .DISCUSSION... Issued at 300 AM CST Sat Feb 27 2021 The main forecast issues are the chance for rain showers and snow the next 24 hours. Two areas of height falls were noted on the 00Z upper air plot at 500 mb last evening. One was centered over MN, moving away from our area and another was back over OR/UT/NV. There was a 145 knot jetstreak at 300 mb moving southward from the Pacific Northwest on the backside of that shortwave trough. This will help bring some precipitation to at least parts of our area later today and into tonight. Water vapor loop showed clouds thickening to our west as the system moves closer. There is still a fairly large spread of model solutions as to exactly what will happen, but tended to use a blend of the GFS/ECMWF and some of the short range CAMs. Increased POPs across much of the area for today, but especially for northeast NE. Forecast soundings show that lapse rates will steepen later today and this evening, especially in southeast NE, east central NE and southwest IA where RAP model shows some positive CAPE with parcels lifted from around 825 mb. Slantwise instability is noted farther north, mainly from MN back into parts of eastern SD. Heaviest snow amounts should be up in that area where parameters are more favorable and lift is stronger in the dendritic growth zone aloft. As for snow locally in our area, did increase snow amounts a bit across our northern counties, especially Knox and Cedar counties where 1 to 2 inches of snow could accumulate. Low pressure initially over eastern CO will track toward north central KS by late afternoon and strengthen. This should bring gusty south winds to parts of southeast NE and southwest IA, where gusts could reach around 35 mph today. It appears the surface low will track to near Omaha mid evening, and then to just north of the MN/IA/WI border area by 12Z Sunday. Brisk northwest winds are expected for our area on the backside of the low later tonight and Sunday. Highs Sunday should reach the upper 30s to mid 40s with lows Sunday night dropping to the lower and mid 20s. Monday through Friday... This period looks mainly dry. Some model guidance brings a push of colder air in from the north for Monday and this seems reasonable. A weak system does track to our south Tuesday, but not get close enough to give us any rain. We we will have to watch for some potential light precipitation Thursday into Friday. The 00Z GFS is still wetter than the ECMWF in that period, but much shows much lighter QPF compared to 24 hours ago. Here is what we expect for high temperatures next week. Monday - mostly in the mid 30s to mid 40s. Tuesday - in the 50s. Wednesday and Thursday - mid 50s to lower 60s. Friday - in the 50s. Saturday - in the 50s to lower 60s. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 451 AM CST Sat Feb 27 2021 Deteriorating conditions are expected toward late afternoon in respond to a passing upper level disturbance. At that time an areal increase of RA is expected across eastern NE with the heaviest precip occurring over northeast NE. Given relatively high confidence have prevailing RA at all terminals through mid evening at all terminals. It appears that KOFK will be right on the line separating RA/SN. At this point confidence is low any SN will be seen at KOFK. Thus will opt for RA as dominate precip type. && .HYDROLOGY... Issued at 300 AM CST Sat Feb 27 2021 A flood watch remains in effect until Noon Monday for areas near the Platte, Elkhorn, and Loup Rivers. Warm weather the past week has caused enough snow melt to flush ice out of the Loup Basin. Ice jams will be possible the next few days, with the highest chances of that in the Platte River. See specific warnings for details. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch through Monday morning for NEZ016-031>033-042>045- 050>053-067. IA...None. && $$ DISCUSSION...Miller AVIATION...DEE