Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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511 FXUS63 KOAX 191724 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1224 PM CDT Sat May 19 2018 .UPDATE... Issued at 1214 PM CDT Sat May 19 2018 Cold front early this afternoon remains in the region, with most of the area on the northern, cooler of the frontal boundary. This is going to limit the severe threat later today. A band of showers has lifted northward through the region, but there hasn`t been any thunder this morning. There is a definitive southern edge, extending from about Albion, NE east southeast toward Red Oak, IA. Showers continue north of this line, but dry conditions persist south. Latest GoesEast Satellite does show some thinning of the clouds in southeast NE, with some cumulus developing along the KS/NE border. This is the area we`ll continue to monitor for severe weather later this afternoon. High resolution CAMs suggest convective initiation by 4-5 pm, with storms moving east northeast along the boundary. Thus, there is still a severe threat for extreme southeast NE and extreme southwest IA later today into this evening, but areas along/north of I80 have a pretty low overall severe weather threat. Due to the fact that our office remains on the northern side of the front, we opted to not do an 18z upper air sounding since it may not have contributed to any overall value to the severe threat setting up to our south. Also, our KOAX 88D radar has been out of service since about 745 am this morning. Electronics technicians are on site performing repairs. We do not currently have an estimated repair completion time. Thus, please use surrounding 88D radars from other NWS offices until the KOAX radar comes back online. && .SHORT TERM...(Today through Monday) Issued at 320 AM CDT Sat May 19 2018 Main concerns again are thunderstorm coverage and intensity today into tonight and potential for severe storms. SPC Day 1 Outlook seems on track. Mid level pattern had one shortwave off to our east and several ripples moving out of trough to the west. Main low appeared to be back over southern CO according to water vapor satellite imagery early this morning. MCS that formed to our west and southwest last evening continued to lift northeast, with a couple of MCVs noted in the regional radar loop. Some showers and isolated thunder have also been over parts of northeast NE early this morning. Much of the short range high resolution model guidance lifts the remnants of the MCS across our area this morning, which seems reasonable. Have used recent runs of the experimental HRRR and SPC HRRR to time the precipitation this morning. High pressure building southeast across the Northern Plains will bring colder air south over the area. Have adjusted highs down a bit especially for northeast NE, to a few degrees either side of 60. The far southeast corner of NE could still reach near 80. Coverage of showers/storms should start to increase again in the 3 to 5 pm window. Storms should then linger into the evening. Initially, storms may be somewhat discrete with potential for large hail and possibly a few tornadoes. Convective mode then should turn more linear with time. Details on just how warm it gets at the surface in southeast NE and southwest IA will depend on the frontal location. Those things will be important in regards to how much severe weather occurs. Shear should be adequate for rotating updrafts and current 0-1 km ML CAPE values could reach 2000-3000 J/kg. Generally felt the 00Z GFS solution seemed reasonable in regards to precipitation potential for later tonight into Sunday and Sunday night. Sunday will be cool with highs mainly in the 60s for our area. Monday looks mainly dry at this time, and warmer with highs in the 70s. .LONG TERM...(Monday night through Friday) Issued at 320 AM CDT Sat May 19 2018 At the start of this period, will will be in fairly zonal flow locally, but a closed low will be back across the southern parts of CA and NV. That low should slowly open up and lift out toward MT and WY by Thursday. Several shortwave troughs are expected to affect the nations mid section next week with chances for showers and storms. Although the operational GFS and ECMWF are in fair agreement with the pattern, then differ on timing and details. Expect highs to average in the lower and mid 80s with lows in the 60s. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1214 PM CDT Sat May 19 2018 Messy and complicated TAF set today, with ongoing showers at KOFK/KOMA for another hour or two. Then convective trends later in the period with additional development expected. Also dealing with MVFR conditions, eventually becoming IFR through time. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ UPDATE...DeWald SHORT TERM...Miller LONG TERM...Miller AVIATION...DeWald

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