Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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722 FXUS63 KOAX 221957 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 257 PM CDT Sun Oct 22 2017 .SHORT TERM...(Tonight through Wednesday) Issued at 255 PM CDT Sun Oct 22 2017 Quiet weather today across the area. Subjective 12Z upper-air analysis indicates an upper-level trough extending through the Plains from near the Dakotas-MN border to eastern NE/central KS/central OK. A shortwave was noted in southern BC/AB. A 150kt upper-level jet extended into northern WA. A low at 850mb was centered in northern MB, with front extending through WI/IL-IA border through MO and into AR. Moisture was shunted ahead of that front, with a ribbon of 8C+ dewpoints from TX/LA through MI, and a cool pocket behind the front had brought single digit 850mb temperatures into the central/northern Plains to upper Midwest. Surface high at 19Z was located in western OK to southwest TX, with ridge axis through eastern KS to western IA to central MN. A surface low was noted upstream in southern SK. Main forecast concern in the short term is wind potential on Monday. As the upper-level shortwave in western Canada moves across the northern Plains to upper Midwest. it will draw a cold front through the central US, along with a tightening pressure gradient. Strong winds from the mid-levels downward are indicated from morning through around sunset. Core of the troposphere fold is progged to descend from the Dakotas through northeast NE/western IA during peak heating and mixing, which should optimize the wind gusts. Have high confidence in reaching wind advisory criteria for at least areas north of I-80, with moderate confidence south of there. In coordination with neighboring offices (and keeping in mind that offices to our west do not issue wind advisories), will include the entire CWA in an advisory on Monday. Latest information indicates grassland fuels are still rather green, with wet surface conditions; only the dried fields are really brown right now. Fire risk is higher tomorrow because of the wind and the 25-35% RH, but because it is limited to farm fields with harvest activity that could spark fires, will mention the risk as a part of the wind advisory information and opt to not issue fire weather headlines. Winds will remain somewhat gusty out of the north to northwest on Tuesday as tight mid-level to surface gradient persists, though it should weaken through the afternoon. 850mb temperatures take a dip to the low single digits on Tuesday, and thus have kept highs in the 50s despite quality mixing. Winds turn more westerly on Wednesday, allowing some warm-air advection and a bump in surface temperatures as dry northwesterly upper-level flow continues. .LONG TERM...(Wednesday night through Sunday) Issued at 255 PM CDT Sun Oct 22 2017 An upper-level trough, deepening to a low, will descend into the central US on Thursday-Friday. With this low, a significant cold push will plow into the central US, bringing sub-0C 850mb temperatures to a wide swath of the central US. Frontal passage on Thursday actually looks dry for our area, with more coherent precip signature closer to the mid-level low in the northern Plains and also closer to better moisture in the southern Plains. Have bumped up winds on Thursday behind the front, given strong cold air advection. If precipitation did brush the area on Thursday night/Friday morning (which is no longer in our forecast, per coordination with neighboring offices), there is a good chance that it could at least mix with something frozen. For now, those chances are very low and mainly on the fringes of the forecast area, with even lower chance of anything that accumulates or sticks - so don`t hit the panic buttons just yet. That said, temperatures on Friday morning are likely to be near or below freezing, though winds should keep temperatures from bottoming out. Highs on Friday will reluctantly recover only into the 40s as coldest air is overhead. With clearing skies and lighter winds on Friday night, temperatures may plunge pretty far on Saturday morning, with current lows forecast in the 20s everywhere and even in the lower 20s in northeast NE. That would be a killing freeze for sure and would finish off whatever is left of the growing season. Temperature recovery may only be a little better on Saturday as the tail end of cold air lingers, with highs maybe approaching the 50s. Subfreezing temperatures are possible again on Sunday morning as the cool airmass lingers, though some moderation should begin around Sunday as the upper low moves eastward and 500mb heights rise, with surface to mid-level winds returning to the west/southwest and providing warm air advection. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) Issued at 1221 PM CDT Sun Oct 22 2017 VFR conditions are expected through the TAF cycle, with clear skies and unrestricted visibility. Winds may get a bit gusty this afternoon but should relax to around 5-10kt tonight. As strong mid-level winds reach the area, all sites are at risk of low-level wind shear later tonight into Monday morning. After some heating in the morning, those stronger winds will mix down to the surface, with wind speeds ramping up quickly into the 20-30kt range with 30-40kt gusts through late morning into early afternoon. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Wind Advisory from 10 AM to 7 PM CDT Monday for NEZ011-012- 015>018-030>034-042>045-050>053-065>068-078-088>093. IA...Wind Advisory from 10 AM to 7 PM CDT Monday for IAZ043-055-056- 069-079-080-090-091. && $$ SHORT TERM...Mayes LONG TERM...Mayes AVIATION...Mayes

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