Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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638 FXUS64 KJAN 041941 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 241 PM CDT Thu Jul 4 2024 ...New DISCUSSION... .DISCUSSION... Issued at 240 PM CDT Thu Jul 4 2024 Tonight through Friday... Ridge is expected to flatten through Friday. Longwave trough analyzed this morning over the northern Plains is progged to swing eastward across the Great Lakes. This will help drive a frontal boundary southeastward into the Mid-South to Gulf Coast states tonight & into Friday. Ongoing rain & storm chances should wind down into the evening, which could alleviate concerns for any upcoming outdoor activities. With clouds & deep tropical moisture persisting, expect seasonably warm lows, some 5-7 deg F above normal, in the mid-upper 70s. Another night of record warm lows are possible at most climate sites along & north of the I-20 corridor. Rain chances will begin to encroach into the Hwy 82 corridor before daybreak Friday, into the I-20 corridor by mid- morning Friday & areawide into Friday afternoon. With anomalously high tropical moisture, near climatological maximum around 2.25 inches, there remains continued support that some of these downpours could be heavy (i.e. HREF prob match mean (PMM) of 3" & localized PMM of >3-4" maxima). For now, there isn`t enough confidence to narrow down an area for HWO graphics but localized flash flooding can`t be ruled out. Also with some northerly mean bulk shear >10kts in the 0-2 to 0-3km layers, some strong to isolated severe storms can`t be fully ruled out but not enough confidence to add to the HWO. There are low probs in CSU machine learning probs for marginally severe convection Friday. Main concerns will be dangerous heat but that is much more uncertain than previous days. With the boundary moving into the Gulf Coast region, scattered to numerous rain & storms are expected. Mixing will remain limited, keeping dewpoints in the 77-80 degree range. Convective initiation (CI) will be forced early due to moist convergence along the boundary & moist boundary layer. This will also keep cloud cover around longer & initiate earlier. Highs will still remain seasonable in the low to possibly mid 90s, with dangerous heat possible across the good portion of the area. There are too many caveats to add any heat headlines, but left the areawide "Elevated" in the HWO graphics for dangerous heat as is. /DC/ Friday night into Saturday: As a front stalls across the area Friday night, convection ongoing from the daytime may persist into the early evening hours, especially over the southern half of the area, then decrease overnight. The brief surge of drier air coming in from the north will focus convective coverage on Saturday across the southern half of the area, though much of it may actually remain closer to the coast as hinted at by the most recent model runs. Minor airmass relief is possible with the front, albeit with temps still around climatological norms. Dewpoints may dip into the upper 60s over the northern half of the area, with temps mainly in the lower 90s. Given this, heat indices could briefly peak near 105 across south MS, but there are currently no plans to advertise heat stress concerns given the anticipated brevity of these readings, the limited area impacted, and the relative improvement from recent days. Sunday through next Thursday: An upper level pattern characterized by longwave troughing over the central CONUS with southwesterly to westerly upper flow over our area will persist into early next week. With the trough remaining to the west, the surface front will retreat northward allowing a moisture rich airmass to return across the entire area on Sunday. This airmass will result in above average rain chances each day through the remainder of the forecast period, with timing primarily driven by instability and the diurnal cycle. The good news is increased coverage of clouds and precip may spare most areas from the prolific heat stress issues that have plagued the region in recent weeks. Though dewpoints will recover into the middle and upper 70s, temps will remain closer to seasonal averages at most locations, resulting heat indices that are more marginal. Guidance remains rather consistent on the future track of Hurricane Beryl, with no direct impacts on our immediate area. However, it is possible that remnant moisture from the system could serve to enhance rain chances in the area around the middle of next week. The extent to which that might be the case remains to be seen. /DL/ && .AVIATION... (18Z TAFS) Issued at 100 PM CDT Thu Jul 4 2024 Main aviation concerns this aftn will be focused on aftn SHRA & TSRA coverage, with more scattered to numerous for central to southeastern TAF sites, especially at JAN, HKS, MEI, PIB & HEZ. This will wind down by early evening, by 05/01-02Z at the latest. MVFR ceilings will redevelop ahead of a frontal boundary dropping south Friday, with some potentially lower at east-southeast TAF sites of MEI, PIB & HBG. Any lowered flight categories should improve by 05/14-16Z, with an early morning through midday increase in SHRA & VCTS from north to south from approaching front. Light southerly winds will prevail through most of the period before switching more northwesterly through midday Friday. /DC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 77 92 74 90 / 20 80 60 40 Meridian 75 94 73 92 / 20 80 60 50 Vicksburg 78 93 73 91 / 20 70 40 30 Hattiesburg 77 95 76 93 / 20 80 60 70 Natchez 77 93 74 90 / 10 70 60 50 Greenville 78 92 73 91 / 30 70 20 10 Greenwood 77 92 73 91 / 40 70 20 10 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Excessive Heat Warning until 8 PM CDT this evening for MSZ018- 019-025>030-032-034>037-040>043-047-048-053-054-059-060. Heat Advisory until 8 PM CDT this evening for MSZ031-033-038-039- 044>046-049>052-055>058-061>066-072>074. 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. && $$ DC/DL/DC