Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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239 FXUS64 KJAN 161213 AAA AFDJAN Area Forecast Discussion...UPDATED National Weather Service Jackson MS 713 AM CDT Fri Aug 16 2024 ...New AVIATION... .DISCUSSION... Issued at 414 AM CDT Fri Aug 16 2024 Today and Tonight: A moist tropical air mass remains in place across the Lower Mississippi River Valley today, with analyzed PW values of 1.8-2.0 inches this morning representing the 50-75th percentile range for mid August. An upper-level low pressure system is spinning over the upper Midwest this morning, and a shortwave trough rounding its base is sustaining thunderstorms along a frontal boundary that extends from near the Great Lakes back towards Oklahoma. Warm advection is ongoing south of the front, helping to bring the heat from the Southwest ridge toward our forecast area. High temps again today should be in the 97-101 range for most of the area, especially if rain can hold off until the afternoon. The moist air mass in the region is capable of supporting shower and thunderstorm development with daytime heating again today, and it appears that convergence along an outflow boundary from storms in the Interstate 40 corridor this morning may serve to trigger additional convection by this afternoon as the disturbance continues south and east. Additionally, air mass thunderstorms are possible as convective temps are met during the day. Storms will have 2500-3500 J/kg of SBCAPE and 1000+ J/kg of DCAPE to work with, so localized damaging winds are possible with any strong to severe storms. Wind shear is expected to be a little stronger to the north and this should add a little more organization to storms especially if they can hold together along the outflow boundary as it approaches from the north. There is a Marginal Risk for severe thunderstorms tied specifically to this possibility this afternoon and evening, but again it is worth noting some isolated microburst potential exists elsewhere too. /NF/ Saturday through next Thursday... By Saturday, deep layer ridging will continue to prevail over the Southern Plains/Lower Miss Valley region as a strong midlevel high pressure spins over the Rockies into the Southern Plains. At the surface, anticyclonic flow will continue to promote westerly flow into the ArkLaMiss region, keeping dangerous heat in the headlines through the remainder of the weekend. High temperatures in the upper 90s to triple digits as well as heat indices ranging 105-115 degrees will be expected. The highest potential for "Significant" to "Extreme" heat stress are expected along and west of the I-55 corridor. Overnight lows on Saturday are expected to remain in the upper to middle 70s, which will continue the dangerous heat stress conditions. By Sunday, surface ridging is expected to maximize across the region ahead of a "cold" frontal boundary. Sunday looks to be our hottest day this week, with many areas along and west of I- 20 reaching triple digit highs and heat indices. Excessive Heat Warning/Heat Advisory products will be likely on Saturday and Sunday as dangerous heat stress dominates the beginning of the extended period. In addition to heat, conditions for a Marginal Chance of severe storms will be possible (5-15% chance) on Saturday and Sunday. Enhanced westerly flow along with increased instability will create the potential for damaging wind gusts with with more mature updrafts. The main threat for severe storms looks to exists mostly in the afternoon into the late evening. By Sunday afternoon into the evening, an upper trough is expected to bring a weak frontal boundary into the region, allowing for lower temperatures and drier air to infiltrate the ArkLaMiss region. By Monday into the remainder of the extended period, a much needed break from dangerous heat will take place. High temperatures will range in the upper 80s to lower 90s through Thursday, with lows in the low 60s to low 70s. Rain chances will remain fairly minimal with isolated (15-30%) chances in the far southeast on Thursday through beyond the extended period. /AJ/ && .AVIATION... (12Z TAFS) Issued at 712 AM CDT Fri Aug 16 2024 VFR conditions are expected to prevail through the TAF period, however the chance for SHRA or TSRA between around 20Z today to 01Z Saturday will bring possible brief periods of variable ceilings or visibility. /NF/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 98 76 99 77 / 30 20 40 20 Meridian 99 75 99 73 / 40 20 50 20 Vicksburg 99 77 99 78 / 20 20 20 10 Hattiesburg 98 76 98 76 / 40 20 40 10 Natchez 97 76 97 77 / 30 20 20 10 Greenville 100 78 99 76 / 20 20 10 10 Greenwood 101 77 99 75 / 20 20 20 20 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Excessive Heat Warning until 8 PM CDT this evening for MSZ018- 019-025>029-032-034>037-040>044-047>050-053>057-059>066- 072>074. Heat Advisory until 8 PM CDT this evening for MSZ030-031-033-038- 039-045-046-051-052-058. LA...Excessive Heat Warning until 8 PM CDT this evening for LAZ007>009-015-016-023>026. AR...Excessive Heat Warning until 8 PM CDT this evening for ARZ074- 075. && $$ NF/AJ