Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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820 FXUS64 KJAN 050707 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 207 AM CDT Fri Jul 5 2024 ...New AVIATION... .MESOSCALE UPDATE... Issued at 949 PM CDT Thu Jul 4 2024 Local radars showed a few isolated showers over north central Mississippi that were being maintained by outflow boundary collisions. These showers will likely dissipate within the next hour but unlike the last couple of nights, additional convection will be possible prior to sunrise in the north as a weak cold front approaches the area. Similar to the last couple of nights, there were raincooled areas; mostly in the southeast where the greatest coverage of convection occurred. Morning lows remain on track though. /22/ && .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... (06Z TAFS) Issued at 204 AM CDT Fri Jul 5 2024 Will be monitoring for IFR/LIFR category stratus development and a few areas of IFR category br/fg in mainly southeast portions of the area through early morning. Thereafter, attention will turn to convective rainfall potential through much of Friday with emphasis on the aftn, and have included a mention of shra/ts in TAFs given considerable coverage expected with the approaching front. /EC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 74 90 73 91 / 60 40 10 50 Meridian 73 92 71 93 / 60 50 10 50 Vicksburg 73 91 73 90 / 40 30 0 40 Hattiesburg 76 93 75 94 / 60 70 10 70 Natchez 74 90 73 91 / 60 50 10 50 Greenville 73 91 72 92 / 20 10 0 20 Greenwood 73 91 72 93 / 20 10 0 20 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ 22/DC/DL/EC