194 FXUS63 KOAX 072111 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 311 PM CST Thu Nov 7 2019 ...Updated Forecast Discussion for Tonight through Thursday... .DISCUSSION... Issued at 310 PM CST Thu Nov 7 2019 Forecast Summary: Not much of a change to the going forecast through next week. Northwest mid level flow will dominate the weather, ushering in reinforcing surges of cold air. Will see some modest warming ahead of these cold surges, but will be short-lived. Also, there will be at least a small precipitation chance on Sunday, but the main weather story will be the colder temperatures through the period. This afternoon through Saturday: Surface high pressure had settled over eastern Nebraska and southwest Iowa this afternoon, bringing mainly clear skies and relatively light winds. This scenario allowed temperatures to really bottom out this morning, with lows in the single digits in northeast Nebraska and teens elsewhere. We were already seeing return flow setting up across central and northeast Nebraska with southwest winds there. Southerly winds will increase later tonight and Friday before becoming west and northwest on Saturday after surface trough tied to shortwave diving into the northern Great Lakes slides through the region. 850 temps in the 6 to 10C below range this morning are forecast increase to 2 to 7C Friday afternoon, then closer to 12 to 14C on Saturday. Mainly clear skies along with favorable warm advection pattern will nudge temperatures toward 50 on Friday, then into the 60s on Saturday when favorable westerly wind component enhances warming. Saturday night through Tuesday: Strong cold front is still forecast to plunge through the Plains Saturday night and Sunday, ushering in an airmass that is even colder than the one currently overhead. 850 temps drop 25 to 30C from Saturday afternoon through Monday afternoon, bottoming out in the 15 to 20C below range then. Surface temperatures may gain a few degrees into the upper 30s to middle 40s on Sunday before cold advection kicks in with earnest later in the day. ECMWF is the most aggressive of the synoptic scale models in developing precipitation with this surge of cold air, indicating accumulating snows are possible across all of our area, with several inches indicated in northeast Nebraska from Sunday afternoon through Sunday night. The GFS is less aggressive with precipitation amounts and was favored as the atmosphere remains relatively dry. However a deep dendritic temperature regime will favor efficient snow-making atmosphere even in low moisture. So will at least maintain small snow chances all areas, and paint some minor accumulations across our northern CWA. Surface high pressure settles into the region on Monday before retreating east on Tuesday afternoon. Given magnitude of cold atmosphere, temperatures will struggle to climb out of the middle 20s on Monday despite sunny skies. Monday night lows will be the coldest of the season so far as all areas should see single digits. We could slip below zero in our north if accumulating snow occurs. Return flow sets up Tuesday afternoon, but with the cold start to the day, we'll likely see another day in the 20s. Wednesday and Thursday: Some slight moderation in temperatures is forecast Wednesday as 850 temps again swing back to the positive side of 0C, but another reinforcing shot of colder air will quickly follow Wednesday night and Thursday. This system is not nearly as cold and Monday's, but will keep temperatures well below normal through Thursday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1114 AM CST Thu Nov 7 2019 VFR conditions are expected across the TAF sites through the TAF cycle as an area of surface high pressure moves overhead. Some mid-clouds in northeast Nebraska will co continue to drift east and diminish this afternoon leaving clear skies across the area into Friday. As surface high pressure slides east, increasing southerly flow will push winds into the 10-20kt range with gusts up to 25kts by 18z Friday. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Dergan AVIATION...Kern