Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 120023 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 623 PM CST Wed Jan 11 2017 .SHORT TERM...(tonight through Saturday) Issued at 406 PM CST Wed Jan 11 2017 A relatively cold period the next few days with a couple chances for wintry precip. Cold air slammed into the region this morning behind another arctic cold front. Temperatures plunged from the 30s this morning into the teens and 20s on north winds gusting over 30 mph at times. The colder and dendritic temperatures and a little low level instability produced a few flurries this afternoon as well. A large and broad mid level low/trough sprawling across Canada and the northern tier of the CONUS was responsible for the cold air plunge. Flow over us was more zonal or slightly southwesterly this afternoon, with a ripple of energy noted entering northwest Nebraska. That ripple is forecast to slide across SD/NE border area tonight, triggering an area of snow across northern Nebraska into northern Iowa. Certainly cold enough for all snow with this system, but progressive movement and limited moisture suggest little more than a dusting of snow is expected in most of the area, with upwards of an inch or so in far northeast Nebraska. That system will be moving off to the east early Thursday, leaving cold temperatures in its wake, some 10 degrees below normal. Then a similar ripple is expected to ride along a similar path late Thursday night into Friday morning, with another dusting of snow possible in our north. Again cold temps will be reinforced on back side of this ripple for Friday afternoon when highs struggle into the 20s. Pattern begins to shift later Friday night into Saturday as upper low diving down the West Coast pumps up heights in the Southern Plains, and also spreads some moisture northward through OK/KS toward southeast Nebraska and southwest Iowa. Meanwhile cold air remains in place at the surface. The warmer and more moist air riding over the colder surface air suggests at least a small chance for freezing rain in our far southeast between midnight and sunrise Saturday. Most of this precipitation should remain to our south as model QPF is limited in southeast Nebraska and southwest Iowa, so for now am not painting any icing there. A rebound in temperatures toward 30 will follow for Saturday. .LONG TERM...(Saturday night through Wednesday) Issued at 406 PM CST Wed Jan 11 2017 The potential for a wintry mix of precipitation beginning Saturday night and continuing through Monday night is the main weather story for the longer term period. Upper low diving down the West Coast early in the weekend is expected to eject into the Plains Sunday and Monday. Plenty of Gulf moisture will spread north ahead of it, with precipitation potential beginning Saturday night in our south, and spreading across all of eastern Nebraska and southwest Iowa during the day Sunday and early Sunday evening. Temperature profiles show a warm layer aloft across the southern half of eastern Nebraska and western Iowa, with magnitude and depth of colder surface-based layer determining precip type here. And there is some discrepancy between longer-range output on what surface temps will be, as GFS is a little warmer than ECMWF. Still both are hinting that temps will be at or below freezing for a good part of Sunday and Sunday night when the bulk of the precipitation is forecast to fall. Liquid amounts of an inch or more are possible, so the potential exists for severe icing if temperature profiles hold as models show. However there are some indications above-freezing air will spread into southeast Nebrsaka and southwest Iowa. Farther north, say from I-80 and north, more of a mixed bag of precip seems more likely right now, with sleet/snow/freezing rain all possible. Deeper cold air that would change everything over to snow doesn`t arrive until most of the precipitation moves off Monday night into Tuesday. So for now, forecast package is based on a blend of GFS and ECMWF as far as temperature profiles are concerned, which lead to a plethora of precipitation types. Suffice it to say, we`ll have to wait a little longer for this system to show its hand as any slight wiggle in path or timing could lead to big differences in precipitation types and thus impacts Sunday and Monday. && .AVIATION...
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(For the 00Z TAFS through 00Z Thursday evening) Issued at 544 PM CST Wed Jan 11 2017 88d mosaic was showing area of -SN currently over wrn/cntrl Neb expanding NEWD...and beginning to spread into NE Neb. Given trajectory trends over the last several...expect only KOFK will any -SN activity/MVFR conditions during the evening hours. Otherwise...VFR conditions will prevail the rest of the fcst pd.
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&& .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE is the U.S. government's official web portal to all federal, state and local government web resources and services.