Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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128 FXUS63 KOAX 121742 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1242 PM CDT Wed Jun 12 2024 .KEY MESSAGES... - Staying warm into next week. Heat index values could approach or exceed 100 in at least parts of the area this afternoon, Thursday, Sunday, and Monday. - Our next chances for stronger to severe storms arrive this afternoon/evening (northeast Nebraska) and Thursday afternoon/evening (southeast Nebraska and southwest Iowa). - Details remain unclear, but we`ll have daily storm chances Friday into next week with potential for strong to severe storms at times. && .DISCUSSION... Issued at 335 AM CDT Wed Jun 12 2024 Today and Tomorrow: Water vapor imagery this morning features zonal flow aloft, with a cutoff low continuing to spin off the California/Baja coast, small shortwave impulses departing the far northern High Plains, and a broad shortwave lingering in the TX/LA/MS/AR region. Looking at a recent surface analysis of the local area, there is a wide variance in surface moisture across eastern Nebraska with a 51 degree dewpoint in Norfolk while Lincoln and Millard read 60 degrees, in addition to another dry pocket to the south in central Kansas. This dryness could negatively influence storm potential this afternoon/evening, which is the primary focus of the short-term forecast. Looking at regional radar, elevated convection is beginning to initiate in central South Dakota where warm air advection and low-level jet nosing provide just enough lift. Those storms should waft east-southeast through the morning and could potentially clip northeast Nebraska with some light rain and rumbles of thunder but will largely remain north. For the afternoon hours, windy conditions and some of the warmest temperatures of the year are expected to develop across with the hot spot being far northeast Nebraska in Knox and Cedar Counties (topping out in the upper 90s to near 100 degrees). Alongside the heat, storm chances redevelop this afternoon as strong warm air advection tries to overpower dry air -- a problem that is exacerbated by such warm temperatures. Latest runs of the CAMs have a split decision on storm initiation, with the RAP/HRRR (which currently have the best F00 hold on the direr surface dewpoints) showing little to no activity aside from a stray elevated storm after 7 PM, while the ARWs and NAMNest showing a southward moving cluster of storms beginning 4 PM. These storms regardless should remain largely elevated and have threats of damaging wind and hail based on the abundance of instability and shear. Timing for storms will generally be from 4 PM to 10 PM, with a 30% chance of occurring (meaning most stay dry). For Thursday, a weak front that will have dove in from the northwest will have found itself in the southeast Nebraska/northeast Kansas area, extending east-northeast. In the vicinity of this front, the oppressive temperatures will have shifted to from the high point in northeast Nebraska to Falls City and areas along the NE/KS border. Fortunately, lower relative humidity values will mean that heat indices don`t reach too far above forecasted temperatures. As far as storm chances go, it continues to look like the main axis of instability will reside south of the area, and that while convection could initiate in eastern Nebraska and Iowa, it will be a short affair before it quickly shifts to Kansas and Missouri. Overall storm chances currently max out at around 30% in far southeast Nebraska, making it a second day in a row where most stay dry despite the storm potential. Storms that do form would have the primary hazards of hail and wind once again. Friday and Saturday: Going into the weekend, we`ll keep the trend of storm chances going with thankfully lower temperatures set for Friday ranging generally in the mid-to-upper 80s. An approaching shortwave trough will have made it to the central High Plains to kick off an organized MCS in the northeast CO/northwest KS/western NE area. This cluster of storms is expected to travel eastward bringing better chances for showers and storms to the forecast area late in the evening into the overnight hours. Severe potential will be limited locally by limited instability as the MCS moves eastward, but some stronger wind gusts may make it to eastern Nebraska. By Saturday, the main forcing that kicked of the Friday MCS will have wafted eastward, bringing a warm front northeast through the forecast area. Widespread shower and storm chances are expected, lingering through much of the day with what could be potential for a severe storm or two (especially in far northeast Nebraska where afternoon peak instability best lines up with the lifting warm front). Sunday and Beyond: Rounding out the weekend into early next week, our mid/upper pattern will shift from zonal to southwesterly flow. Some kind of front will be perpetually in the vicinity of eastern Nebraska into Iowa, serving as a focus for additional shower and storm activity (though Monday currently looks mostly dry). Highs are expected to range from the upper 80s to low 90s, making for typical summertime temperatures. If there is something to look for during the extended forecast, it`ll be the increasing potential for a deeper shortwave/full-on trough to pivot eastward from the southwesterly flow, providing a more dynamic system to the area compared to the weaker forced setups that we`ve been seeing lately. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1237 PM CDT Wed Jun 12 2024 There are a couple of VCSH to OMA through 18Z, but likely precipitation free after 18Z other than a very small chance for a storm in the 01-04Z time frame. Do expect LLWS at LNK and OMA for several hours with a sharp speed chance and some directional change from surface into the 1500-2000 ft AGL level. Otherwise, expect VFR conditions with wind changes through the TAF period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...Barjenbruch