Area Forecast Discussion
Issued by NWS Tulsa, OK
Issued by NWS Tulsa, OK
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844 FXUS64 KTSA 201718 AFDTSA Area Forecast Discussion National Weather Service Tulsa OK 1218 PM CDT Fri Sep 20 2024 ...New AVIATION... .SHORT TERM... (The rest of today) Issued at 1020 AM CDT Fri Sep 20 2024 Showers and thunderstorms have developed across the northwestern fringes of the forecast area this morning, with GLM and NLDN data indicating the bulk of the lightning threat isolated to portions of Osage County so far. An earlier update added slight chance POPs for this activity, isolated to portions of northeast Oklahoma west of Highway 75. This mention has been extended through 18Z, with the mention of thunderstorms limited to areas near the Kansas border given recent radar and lightning observations. The expectation remains that this activity should diminish toward midday. Additional isolated to possibly, scattered showers and thunderstorms remain expected across the northern fringes of the area, including into far northwest Arkansas, with the bulk of the afternoon/evening development still expected to be just outside the forecast area. On the heat and humidity front, minor adjustments were made to both temperatures today and to the dew point trends, using influence from the HRRR for temperatures and the HREF for dew points. This did not change the expectations of afternoon heat index values right around/just above 105 for a good chunk of eastern Oklahoma and in the Arkansas River Valley areas. The Heat Advisory appears good area/impact wise for now, with the only concern being areas where the mid cloud and precipitation may keep the higher temperatures from being realized. The only other notable adjustment to the previous forecast has been to the Sky cover, as the NBM continues to underforecast cloud cover even in the near term. Have adjusted the Sky cover upward with the NBM 90th percentile to more closely match current satellite observations/trends. Updated forecast already out. && .LONG TERM... (Tonight through Thursday) Issued at 210 AM CDT Fri Sep 20 2024 Over the next several days the strong ridge of high pressure that has been centered over and south of the area will begin to weaken and shift south in response to an approaching upper level trough from the west. In spite of upper level cooling, the lower levels will remain quite hot, with high temperatures once again in the mid 90s to near 100 F. As the previously mentioned trough approaches, a few late afternoon or evening storms may develop Saturday, with the best chance in northwest AR. Some cooling will likely begin Sunday with more extensive cloud cover. Additionally, an upper level jet streak will increase mid level flow, wind shear, and upper level divergence. These factors, along with sufficient instability, will likely result in a round of showers and thunderstorms along a frontal boundary. There is a marginal risk (5% chance) that a few of the storms could be severe. This will be the best and most widespread chance of precipitation for most areas during the forecast period, with Pops of 40-60% most areas. A few areas of locally heavy rainfall could result in minor flash flooding, but recent dry conditions will mostly limit that threat. Model guidance remains in good agreement for Monday, with much cooler temperatures moving into the area. Most areas will remain in the 70s with relatively dry conditions developing from northwest to southeast during the day. The forecast becomes much more uncertain for the middle to end of next week. Ensemble guidance does agree that behind the previously mentioned trough, a secondary upper level trough will dive south. However, model guidance is very inconsistent with this feature. Some guidance merges the two upper lows and they stay over the area with very cool and showery conditions, while other guidance moves the new upper low to the east leaving us cool but mostly dry. Still other guidance takes the initial low east while the follow on low goes west and a ridge builds over the area. Suffice it to say, the spread of possible outcomes is very high for next week. Guidance is roughly evenly split between these generalized outcomes, so no particular solution is favored at this time. && .AVIATION... (18Z TAFS) Issued at 1218 PM CDT Fri Sep 20 2024 VFR conditions are forecast to persist through the period. Thunderstorm redevelopment remains expected later this afternoon and into the evening that could impact mainly the NE OK and far NW AR terminals, but coverage is expected to be small enough to leave any impacts out of the TAFs at this point. Gusty winds ongoing at the NW AR sites should diminish by early evening. && .PRELIMINARY POINT TEMPS/POPS... TUL 77 98 75 90 / 20 20 20 40 FSM 76 97 75 93 / 10 20 10 10 MLC 74 98 73 94 / 0 0 10 10 BVO 73 99 70 88 / 20 20 30 60 FYV 73 92 70 89 / 20 30 20 30 BYV 73 92 71 90 / 20 40 20 30 MKO 76 96 74 92 / 10 20 10 20 MIO 74 96 71 89 / 20 20 30 50 F10 74 98 73 92 / 10 20 10 30 HHW 73 96 72 93 / 0 0 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Heat Advisory until 8 PM CDT this evening for OKZ054>057-059>062- 064>068-070>076. AR...Heat Advisory until 8 PM CDT this evening for ARZ019-020-029. && $$ SHORT TERM...22 LONG TERM....06 AVIATION...22