Area Forecast Discussion
Issued by NWS Shreveport, LA
Issued by NWS Shreveport, LA
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119 FXUS64 KSHV 180239 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 939 PM CDT Tue Sep 17 2024 ...New UPDATE... .UPDATE... Issued at 936 PM CDT Tue Sep 17 2024 Clear skies overhead tonight as mid-level ridging slides east into the Four State Region. Overnight will trend quiet, but humidity will remain as area dew points will sit in the upper 60`s and low 70`s. Areawide patchy fog expected once again this evening as the winds will generally sit below 5 mph. Aside from adjusting hourlies to meet latest trends, no changes were needed with the evening update. KNAPP && .SHORT TERM... (This evening through Wednesday Night) Issued at 209 PM CDT Tue Sep 17 2024 Around 18z this afternoon, the mid and upper levels of the atmosphere feature a Rex Block over the Eastern US, with a ridge of high pressure noted over the Great Lakes and low pressure centered over the southern Appalachians. To the west of this lies on elongated ridge from SW to NE across the Southern Plains into the Northern MS Valley downstream of a strong longwave trough over the Western US, with a closed low around the Great Basin. In the lower levels, an expansive area of high pressure stretches across the NE into Great Lakes and Midwest, while a sfc low sits over the Carolinas and a stationary front sits near the northern Gulf Coast. Focusing closer to home, water vapor imagery shows a very subtle shortwave trough/shear axis near the S LA and S MS border, with showers developing in its vicinity. This disturbance is the remnants of Francine, of which will continue to move SE through tonight. Lift/deformation within the disturbance`s vicinity, along with plentiful low level moisture characterized by dewpoints in the low 70s will allow for the development of isolated showers through the afternoon and early evening hours. The highest chance (roughly 30%) for showers will be across eastern and southern zones, with about a 15-20% chance of an isolated shower elsewhere. Thunder chances will remain low but nonzero as MLCAPE values hang around 250J/kg despite meager low level and mid level lapse rates of less than 6 C/km. Shower activity will then wind down after sunset with the loss of daytime heating and the continued E/SE progress of the mid level disturbance. On Wednesday, the longwave trough over the Western US will remain active, with an area of closed low pressure deepening over the Northern Rockies and another digging shortwave along the Central CA Coast. The progression and deepening of this longwave trough will then shift the elongated ridge axis eastward across the ArkLaTex. This will make for rising temperatures back towards 90 for the region as subsidence aloft increases. Before the heat returns, patchy fog will greet the area early Wednesday morning as moisture remains plentiful near the surface underneath the ridge. Fog will likely redevelop again overnight Wednesday into Thursday as low level moisture remains trapped underneath the ridge under clear skies and light winds. Kovacik && .LONG TERM... (Thursday through next Monday) Issued at 209 PM CDT Tue Sep 17 2024 At the start of the long term forecast period, the digging trough over Central CA will continue to dig slowly S/SE towards S CA. This will further amplify the ridge downstream across the Four State Region and Southern Plains, allowing temperatures to continue to rise back into low to mid 90s. Similar conditions can be expected for Friday as the S CA closed low moves slowly E into the desert SW. For the weekend, WPC cluster solutions and most ensemble means support the idea of the desert SW closed low beginning to lift towards the Southern Rockies. This will begin to dampen the ridge on its NW periphery, likely allowing for the advection of high level clouds into northern zones. High pressure both aloft and at the sfc will hold strong enough for the remainder of the area to remain hot and dry, with highs again in the low to mid 90s with dewpoints near 70. Currently seeing decent agreement in the ensemble guidance Sunday into next week with the low lifting into the Central Plains and dampening the northern periphery of the ridge further. Based on the current projected track of this system, would expect sfc cyclogenesis in the lee of the Rockies to commence across the OK panhandle or western KS, which will keep the brunt of the dynamics and associated frontal boundary development to the north of the Four State Region. That being said, there will remain some discrepancy with this and it still appears possible a cold frontal boundary could approach far northern zones at the end of the forecast period, supporting at least low end rain chances. With increasing cloud cover likely across most of the forecast area from this system, high temperatures will likely cool a few degrees into early next week. Kovacik && .AVIATION... (00Z TAFS) Issued at 604 PM CDT Tue Sep 17 2024 For the 18/00z TAF update...Satellite imagery is showing some low to mid level clouds moving across much of the region this evening. Radar imagery on the other hand remains quiet this evening. As has been the story with the past couple of nights, we should once again widespread MVFR to IFR flight conditions with BR and lower visibility expected towards daybreak. Aside from this, winds should remain fairly light throughout this TAF period for all terminals. /33/ && .PRELIMINARY POINT TEMPS/POPS... SHV 72 90 72 93 / 0 0 0 0 MLU 68 89 67 91 / 10 10 0 0 DEQ 66 89 66 92 / 0 0 0 0 TXK 69 90 70 94 / 0 0 0 0 ELD 65 88 65 92 / 10 0 0 0 TYR 71 93 73 95 / 0 0 0 0 GGG 70 91 71 94 / 0 0 0 0 LFK 72 92 72 94 / 0 10 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...23 LONG TERM....23 AVIATION...33