Area Forecast Discussion
Issued by NWS Oklahoma City, OK
Issued by NWS Oklahoma City, OK
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936 FXUS64 KOUN 250903 AFDOUN Area Forecast Discussion National Weather Service Norman OK 403 AM CDT Sat May 25 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today and tonight) Issued at 403 AM CDT Sat May 25 2024 Significant severe weather is possible late this afternoon and this evening, but there are also potential complications. A shortwave in southern California is progged to move toward the southern Plains this afternoon, although it is also progged by most models to weaken as it approaches. In the broad sense, very high instability and strong deep layer wind shear are forecast across the area today. With these parameters, thunderstorms that do develop today will be capable of producing large hail, strong winds, and tornadoes (and potentially strong tornadoes) if storms can take full advantage of these parameters. But there are also some questions and things we will be watching through the day. First, low-level moisture will be a relatively late arrival, and there will likely be a limit on how far north the best moisture advects. The front that moved through the area yesterday has allowed dry low-level air into the area. The current dewpoint at KCSM and KWWR is 44 with KSPS down to 58 with a north component to the wind. Dewpoints have also mixed out across portions of northeast Texas behind yesterday`s convection and some of the models do not recognize this yet. There are isolated dewpoints in the 70s in north central Texas, but the more widespread 70s dewpoints are currently south of the metroplex and winds in that area are currently light. Southerly winds will increase today and start allowing higher dewpoints to start advecting north, but some of the models are beginning to recognize that (a) it may not advect too far north, and (b) it likely will not advect all the way west to the dryline progged to set up in the eastern Texas panhandle or far western Oklahoma. With the latter, any storms that develop near the dryline would likely be high-based initially, and the question would be if they could prevent becoming outflow dominant before moving into better moisture. But even these storms would have the potential of producing large hail and strong winds. So another question is will storms be able to develop in the warm sector, perhaps with confluence near the moisture gradient east of the primary dryline. The best pressure falls will be in northwestern Oklahoma associated with the deepening low in eastern Colorado/western Kansas, and we may not see significant backing of the low-level winds apart from northwest Oklahoma, but low-level moisture likely more limited there. And even if portions of western Oklahoma mix out more with the shallow low-level moisture, the progged 850 mb flow is still strongly southerly, so we may not see much veering of the flow west of the moisture gradient to get decent confluence except on the dryline itself. But we have seen cases where even subtle confluence is enough to get at least isolated storm development, and some of the CAMs do suggest some backing so we definitely can not write off the potential. Classic jet dynamics suggest that most of Oklahoma would not be in the most favorable area of lift with the best upper-level diffluence and associated rising motion that looks to be mostly across Kansas and perhaps far northern Oklahoma. But could this be offset by any sub-synoptic features? As far as tornado potential, the 0-1 km shear is not terribly strong until after 00Z when the low-level jet increases and therefore increases the low-level shear vector. But surface-based CIN will be increasing then as well so will there be any surface-based storms to utilize this low-level shear? Although there are these uncertainties and factors that complicate the forecast and we will be watching these closely today, the instability/shear parameter space that will exist over the area will keep the potential for significant severe thunderstorms including large hail and strong tornadoes if things come together right, so we encourage our partners and residents to prepare for this potential and keep updated with weather situation today and tonight. Most models develop at least widely scattered thunderstorms late this afternoon or early this evening. The 06Z NAM and 00Z GFS both look to be suffering from convective feedback so may be a bit too aggressive with storm coverage. Whatever storms do develop should move east out of the area late tonight or very early Sunday morning. /26 && .LONG TERM... (Sunday through Friday) Issued at 403 AM CDT Sat May 25 2024 The weather should be quiet Sunday and Monday behind this system and behind a Pacific front that brings a drier (but not significantly cooler) airmass into the area. Some thunderstorms will be possible Monday night into Tuesday with isentropic lift as moisture begins returning north. But it also looks like easterly to southeasterly low-level flow persists into the middle and later part of the week allowing for daytime thunderstorm development over the high plains and into the area as mesoscale convective systems in the evening and overnight hours each night. /26 && .AVIATION... (00Z TAFS) Issued at 956 PM CDT Fri May 24 2024 Some stratus will be possible early Saturday with MVFR ceilings. Otherwise, VFR ceilings are expected with mid and high clouds. Winds will gradually shift towards the E and then the SE or S this TAF period. Some storms will be possible late Saturday afternoon/evening. Chances are currently too low at some places for mention in TAF. Strong, variable winds and large hail will be possible with the storms Saturday. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 89 70 91 61 / 20 30 0 0 Hobart OK 94 65 94 61 / 20 20 0 0 Wichita Falls TX 95 71 96 64 / 20 30 0 0 Gage OK 92 60 89 55 / 20 10 0 0 Ponca City OK 87 68 88 58 / 20 30 0 0 Durant OK 88 72 94 66 / 20 20 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ SHORT TERM...26 LONG TERM....26 AVIATION...25