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Area Forecast Discussion
Issued by NWS Shreveport, LA
Issued by NWS Shreveport, LA
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938 FXUS64 KSHV 260550 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 1250 AM CDT Wed Jun 26 2024 ...New AVIATION... .UPDATE... Issued at 1002 PM CDT Tue Jun 25 2024 Diurnally-driven convection had dissipated for tonight across the forecast area. Our attention turns to the north to the storms ongoing across Central Oklahoma. Most of the model guidance keeps these storms just to our west before dissipating during the early morning hours. However, I did maintain slight chance PoPs in Southeast Oklahoma during the hours before sunrise. The bigger question surrounds any convection and its affects on temperatures and heat index values for tomorrow. Much of the guidance suggests the storms will hold off until late in the afternoon, but the HRRR bring a weakening complex southward across the area during peak daytime heating to near the Interstate 20 corridor by mid afternoon. If the convection does not arrive until late afternoon or early evening, peak heat index values should easily rise above advisory criteria areawide. If the storms arrive earlier in the day, it may be more uncertain. If the HRRR verifies, heat indices should warm to at least 105 degrees F for areas south of a line from Mineola TX to Farmerville LA. Farther north, there could be just enough time for temperatures and humidity levels to recover to advisory criteria. Given our current conditions and past trends, warming typically occurs very quickly. Given the factors above, and after collaboration with neighboring WFOs, a Heat Advisory has been issued for Wednesday from 15z-00z (10 AM to 7 PM CDT). CN && .SHORT TERM... (This evening through Thursday) Issued at 311 PM CDT Tue Jun 25 2024 Heat Advisory criteria (heat indices of 105-110 degrees) has been met as of mid-afternoon over all but the Wrn sections of E TX, but this too should verify over the next couple of hours once temps top out in the mid to upper 90s. As expected, limited mixing though over Srn AR/NCntrl LA has maintained mid 70s dewpoints over these areas, as low level moisture pooling continues farther to the E across the Lower MS Valley along the W side of a stationary front that persists from the Mid-South region into NCntrl MS/SW and Srn Al. This has resulted in heat indices near 110 degrees over these areas, and may briefly reach Warning criteria before daytime heating diminishes late this afternoon. Will allow the Heat Advisory to ride as is for the entire region through 00Z Wednesday. All remains quiet too as the afternoon visible satellite has maintained a relatively flat cu field over the region. The exception has been over ECntrl LA/SCntrl AR where the cu is a bit more agitated, with isolated convection possible over these areas through 00Z before diminishing with the setting sun. Much if not all of the overnight hours should remain quiet across the region tonight, although the transition to NW flow aloft may yield some unsettled weather courtesy of shortwave energy progged to drop SE into the region late, along the Ern periphery of the upper ridge centered from the Desert SW into W TX. In fact, various short term progs suggest that convection will initiate by early evening over NW OK along the lead shortwave trough axis, but should gradually weaken through late evening with reduced forcing. However, the GFS is a lone outlier dropping a potential MCS SE into the region by and after daybreak Wednesday, maintaining the convection through much of the day. Not quite buying this solution yet given the lack of other model support, with the potentially more feasible compromise in solutions suggesting that convection will be later to develop over Nrn AR Wednesday morning along a weak sfc front and attendant shortwave trough that will drop SE through the Mid-South and Lower MS Valley. Again, considerable timing variabilities exist with convection eventually building S into the region by afternoon, which could impede heating and potential Heat Advisory criteria being met again. After collaborating with adjacent WFO`s, have opted to defer the issuance of a Heat Advisory to the mid shift, as hopefully better model agreement will come into play with regards to the convection timing. Do believe that one will be needed for at least portions of E TX/N LA, but would rather avoid potentially flip flopping the forecast with the potential heat headlines. Did maintain chance pops though for Srn AR/N LA, which could linger during the evening before diminishing. This convection could reinforce the sfc bndry SSW into the area by Thursday, which would only result in additional moisture pooling over the region just as the upper ridge begins to expand back S into AR/LA by afternoon. Thus, heat products will likely be needed again areawide Thursday, with some consolation that isolated to scattered convection will remain possible near the stationary front. 15 && .LONG TERM... (Thursday night through next Monday) Issued at 311 PM CDT Tue Jun 25 2024 The ridge aloft will continue expanding E across the Lower MS Valley Thursday night, but remain relatively flat before amplifying further this weekend into much of next week. Thus, the extreme heat is on as more expansive areas of triple digit temps are expected through the remainder of the long term period. Heat Headlines will be needed through the remainder of the period, with very limited relief expected at night as temps struggle to fall to/just below 80 degrees. Still can`t rule out the potential for isolated diurnal convection over portions of the area, but believe that wetting rains will be hard to come by and will do very little to the continued drying conditions in place. 15 && .AVIATION... (06Z TAFS) Issued at 1235 AM CDT Wed Jun 26 2024 Clouds will begin to increase overnight, with most terminals remaining in VFR category. However, enough clouds could form at KLFK to briefly drop them to MVFR past 26/10z. Elsewhere, shower and thunderstorms will begin to increase into the morning hours, but confidence was only high enough to carry any precipitation at KELD and KMLU at this time. /44/ && .PRELIMINARY POINT TEMPS/POPS... SHV 97 77 96 78 / 20 20 20 10 MLU 96 73 93 74 / 40 30 40 10 DEQ 95 73 93 73 / 40 20 10 0 TXK 98 75 96 76 / 30 20 10 0 ELD 94 71 91 72 / 40 30 20 0 TYR 97 77 98 78 / 20 20 10 0 GGG 96 77 96 76 / 20 20 20 10 LFK 96 77 97 75 / 20 20 20 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for ARZ050-051-059>061-070>073. LA...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for LAZ001>006-010>014-017>022. OK...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for OKZ077. TX...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for TXZ096-097-108>112-124>126-136>138-149>153-165>167. && $$ SHORT TERM...09 LONG TERM....15 AVIATION...44