Area Forecast Discussion
Issued by NWS Shreveport, LA
Issued by NWS Shreveport, LA
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266 FXUS64 KSHV 121728 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 1228 PM CDT Sun May 12 2024 ...New AVIATION... .UPDATE... Issued at 1021 AM CDT Sun May 12 2024 Quick zone update issued to account for the issuance of SVR Watch #232 for Cherokee, Angelina, and Nacogdoches Counties until 20Z. Watching clusters of elevated convection ongoing across portions of Cntrl/ECntrl TX in advance of a shortwave perturbation over Cntrl TX. The steepest mid level lapse rates remain over Cntrl TX into the Hill Country, although the latest mesoanalysis depicts a plume of steep 2-6km lapse rates that do extend E into the Sam Rayburn and Toledo Bend Country of Deep E TX/WCntrl LA, with effective bulk shear of 55-60 kts maintaining this convection as it shifts east atop the stable sfc hail. Thus, large hail will remain the greatest threat in the more organized convection, although this threat may become more marginal especially as areas of convection development continues to expand E across the region through the afternoon. Did not adjust temps at all in the update, but did tweak pops late this morning based on the latest radar trends, while also adding svr wording to the Svr Watch area. Also delayed mention of heavy rain for much of the Flood Watch area until this afternoon with the progged increase in H850 convergence along an inverted trough that is expected to develop from N TX SE into Deep E TX to the Lower Sabine Valley. 15 && .SHORT TERM... (Sunday through Monday) Issued at 156 AM CDT Sun May 12 2024 The active pattern will finally get underway today, as heavy rain chances begin to increase by this morning, and the severe weather threat increases into the afternoon. All of this weather is associated with a rather potent shortwave trough moving through the Plains, with a weak low pressure and surface boundary extending across the Slight risk area. This boundary will move north today as a warm front, which will help set the stage for more widespread severe weather tomorrow, when the boundary reverses course as a cold front. The main weather story in all of this today into tonight will be the heavy rain, as the Moderate ERO has been expanded into NW LA to account for this heaviest activity. Widespread 2-4 inches of rainfall are possible through Monday night, with pockets of 6+ inches certainly not out of the question. In turn, the day shift flood watch has been expanded in size, and extended in time as well to account for additional rainfall through Tuesday morning. The first round of rainfall will exit the region by tonight, before PoP coverage increases again by Monday afternoon. This round of heavy rain will be associated with the cold front moving SE, which will also coincide with the severe weather chances on Monday. Very little has changed in the thinking with this severe weather, as large hail and damaging winds remain the main threats. A very narrow window exists during first initiation in which an isolated tornado will be possible as well. However, that threat is almost tertiary in nature given the heavy rainfall. /44/ && .LONG TERM... (Monday Night through Sunday) Issued at 156 AM CDT Sun May 12 2024 Rain chances will begin to fade by Tuesday morning, with a very short "dry period" anticipated through Wednesday night. However, the next trough will begin moving into the Midwest by Thursday morning. This will be our next round of heavy rain and potential severe weather, with another 2-4 inches of rainfall possible in our southern zones. With that being said, this heavy rainfall axis may shift south (or north) over the next few days, which would greatly change the need for another flood watch based on rainfall here in the short-term. The severe weather threat continues to look uncertain based on airmass recovery between heavy rainfall, but there is still plenty of time for that to change into the weekend as well. /44/ && .AVIATION... (18Z TAFS) Issued at 1216 PM CDT Sun May 12 2024 For the 12/18Z TAF update, active weather will continue through most of the period with VCTS/-TSRA likely to keep MVFR/IFR vis/cigs through 13/06Z. A lull from precipitation at 13/06Z-14Z will allow cigs to build in at IFR airspace-wide before the next batch of VCTS/-TSRA arrives right before the end of the period. /16/ && .PRELIMINARY POINT TEMPS/POPS... SHV 67 84 66 84 / 80 40 20 10 MLU 65 85 66 84 / 90 60 40 10 DEQ 62 80 60 80 / 60 50 10 10 TXK 65 82 64 82 / 80 50 10 10 ELD 62 79 63 82 / 90 50 20 10 TYR 67 85 64 84 / 70 20 10 0 GGG 66 85 64 84 / 80 30 10 0 LFK 68 86 64 87 / 70 40 20 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...Flood Watch through Tuesday morning for LAZ001-002-010-011-017- 018. OK...None. TX...Flood Watch through Tuesday morning for TXZ124>126-136>138- 149>153-165>167. && $$ SHORT TERM...15 LONG TERM....15 AVIATION...16