Area Forecast Discussion
Issued by NWS Oklahoma City, OK
Issued by NWS Oklahoma City, OK
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
590 FXUS64 KOUN 240352 AFDOUN Area Forecast Discussion National Weather Service Norman OK 1052 PM CDT Thu May 23 2024 ...New AVIATION... .UPDATE... Issued at 1209 PM CDT Thu May 23 2024 Watching a complex severe weather forecast this afternoon and evening. Boundary layer moisture return has been extremely robust this morning following the overnight round of convection. The outflow boundary from those previous storms could be seen in surface observations as a sharp warm front across central Oklahoma; surface wind fields on the Oklahoma Mesonet have shown a distinct diffusion of this front over the last 2 hours. With that said, dewpoints in northwest Oklahoma are in the mid-60s with a distinct gradient to dewpoints in the low-to-mid 70s across western north Texas and southern Oklahoma. A stratus deck is also shown on satellite across most of the area, particularly near the 100th meridian. Given the moisture advection ongoing, there are some questions about how long this takes to mix out. If stratus does linger into the afternoon, the severe risk would likely be reduced. Over the past hour, however, GOES satellite has shown some thinning of the stratus across the 100th meridian and corresponding eastern portions of the Texas panhandle, which coincides with an easterly push of the dryline off of the Caprock. The expectation is that the western fringe of the cloud cover will continue to downscale into cumulus over the next several hours, which will allow for partial insolation. The number of storms we receive is similarly in question and in part dependent on how much insolation we receive. Most members of the HREF/MPAS do try to cue up at least one or a few storms by late this afternoon in western Oklahoma, with a particular focus on the triple point between the effective warm front and the dryline. Meanwhile, another area will be watched in southern and central Oklahoma where some models have shown a signal for convection initiation within a warm advection regime. There appears to be a negative correlation between storm coverage in the two regimes; in other words, more WAA storms to the east could reduce or even remove storm coverage along the dryline later. The early storms, should they develop, will have access to 3,000- 4,000 J/kg of MLCAPE and sufficient bulk shear for the development of supercells. Low-level shear will be weak, so the main concern would be for severe hail and damaging winds, but a very low tornado risk would accompany these storms. Off to the west, any storms that develop along the dryline will initially be favored to become supercellular and produce large to very large hail. There is a noticeable uptick in the LLJ on model guidance beginning about 8:00 pm, so there will be a window for any established supercells to produce tornadoes this evening as they move eastward. Meister && .SHORT TERM... (This evening through Friday) Issued at 144 PM CDT Thu May 23 2024 Any severe weather that is ongoing from the near-term will linger into the evening and overnight period. The threat for supercells with tornadoes, very large hail, and damaging wind gusts will persist with aid from a strengthening LLJ in the 7:00 pm to 10:00 pm timeframe. At some point during the early overnight period, stabilization of the surface layer should bring an end to this round of storms. Mercifully, CAM guidance doesn`t show any indication of an overnight/early morning round of storms tomorrow morning. The night will be very humid with lows only dropping into the upper 60s to near 70 across much of the area. The exception will be in northern Oklahoma, where a cold front will come sweeping in just before daybreak. Marginally cooler and drier air will filter in behind this cold front. That cold front will continue to push south through late morning, by which point it will be roughly along the I-44 corridor. Here, most guidance indicates a significant slowing of the frontal boundary as it encounters the rougher terrain south of I-44. With MLCAPE in excess of 4,000 J/kg on the warm side of the front and considerable convergence, convection initiation is likely by midafternoon southeast of a line from Seminole to Ardmore. Shear profiles should favor initial supercellular mode with large to potentially very large hail and a very low tornado risk. The undercutting nature of the front will likely limit the discrete supercellular window, with storms either becoming elevated or potentially growing upscale into clusters. The risk would then transition to hail and damaging winds. These storms should exit our area by mid-evening. For those of you who are behind the front, make sure to get outside and enjoy the afternoon. Highs will remain in the low 80s with humidity decreasing throughout the day. This may be one of your last chances to enjoy dewpoints under 45 with temperatures under 100 before September, so enjoy it! Meister && .LONG TERM... (Friday night through next Wednesday) Issued at 144 PM CDT Thu May 23 2024 Next verse, same as the first: Saturday`s storms might be a little bit louder and they might be a whole lot worse. A 60-knot west-southwesterly mid-level jet ejecting directly into our area isn`t terribly common in May, but that`s what pretty much every model is showing. Equally concerning is the degree with which models show this jet streak overspreading a tight dryline with 3,000- 5,000 J/kg of MLCAPE in the afternoon. And to add another layer to the concern, the GFS/FV3/NAM all show that region immediately to the east of the dryline to be characterized by classic sickle-shaped hodographs with 0-3 km SRH approaching 300 J/kg. This environment would be very favorable for the development of multiple supercells in the afternoon across western Oklahoma and western north Texas. Those supercells would be capable of tornadoes (some of which may be strong), large to giant hail, and damaging wind gusts. Uncertainty continues to lower as we pull within 60 hours of Saturday evening, and with it the higher-end outcomes appear to be increasing in probability with no "failure modes" immediately obvious that may mitigate the risk. This spring has taught and retaught the lesson that we still have so much left to learn when it comes to severe weather; there is still plenty of opportunity for some sort of synoptic, mesoscale, or storm-scale detail to show up that may prevent us from experiencing a high-end severe weather event. With that said, at a minimum we urge people to continue to follow updates with the forecast as Saturday approaches. The dryline will mix further to the east on Saturday. This will focus the severe risk in or east of our eastern counties. For the rest of us, downsloping winds will lead to a hot afternoon across much of the area. Another cold front should intrude through much of the area Sunday night through Monday afternoon. Monday does look like the best bet to be our first no-storms day in a while, with cooler temperatures and drier air look to be filtering in. The early part of next week looks to be a game of sloshing moisture with northwest flow aloft. Right now, the best guess is that highs will be warm but not hot, and precipitation chances will exist but can`t be pinpointed yet. Meister && .AVIATION... (06Z TAFS) Issued at 1050 PM CDT Thu May 23 2024 VFR/MVFR ceilings expected this TAF period. Southerly winds will shift towards the north as a cold front moves across the area late tonight into Friday. Storms will continue to affect parts of central and southern OK overnight. Additional storms will be possible Friday, mainly in eastern parts of the fa. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 68 84 61 90 / 30 10 0 40 Hobart OK 66 84 59 95 / 40 10 0 20 Wichita Falls TX 69 89 64 95 / 30 0 0 30 Gage OK 58 81 53 93 / 20 0 0 10 Ponca City OK 67 81 56 88 / 20 20 0 40 Durant OK 69 90 68 89 / 20 20 10 40 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Flood Watch until 1 AM CDT Friday for OKZ032-041>043-046>048- 050>052. TX...None. && $$ SHORT TERM...04 LONG TERM....04 AVIATION...25