Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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977 FXUS64 KJAN 261813 AAA AFDJAN Area Forecast Discussion...UPDATED National Weather Service Jackson MS 113 PM CDT Wed Jun 26 2024 ...New AVIATION... .MESOSCALE UPDATE... Issued at 947 AM CDT Wed Jun 26 2024 Satellite imagery showed only a few clouds across the CWA and temperatures were warming up nicely. Portions of the delta were already to 90F resulting in heat index values of 105F. Heat stress conditions will continue to increase into the afternoon warranting the Heat Advisory but, regional radars showed vigorous convection over central Arkansas. This activity was being driven by a shortwave trough topping the ridge to our west and will continue to track toward our CWA. This will support the convective activity that will continue to approach our CWA this morning and drop into our CWA this afternoon. Considering the environment over our CWA that the convection will be moving into, severe storms capable of damaging wind gusts and hail up to quarter size. The severe threat potential is expected to begin in our northwest by noon and progress to the south southeast through the afternoon and into the evening across our southern most zones. /22/ && .DISCUSSION... Issued at 455 AM CDT Wed Jun 26 2024 Today through tonight... Early this morning, water vapor/synoptic analysis indicate 596DM 500mb mean ridge over West TX & northern Mexico while deepening longwave trough/jet energy diving into the northern Plains to Great Lakes, while stronger shortwave is diving southward out of the Mid West. This is helping deep ascent/storm development across the Mid West, with cooling cloud tops in GOES East water vapor imagery. Increased convergence & high moisture pooling ahead of the boundary, well above 90th percentile, near or in excess of the climatological maxima around 2.25 inches, will help rain & storm development to increase, with potential MCS diving down into the Delta by midday & spreading south to southeast through the day into the evening hours. Rain & storm coverage becoming more scattered-numerous during this time. Seasonably warm highs in the low-mid 90s are expected preceding any MCS, with dangerous heat stress now expected to peak between 105-110F degrees. With recent convective allowing models (CAMs) indicating timing being mainly after midday through the evening, heat indices could peak above criteria before midday. Earlier addition of the heat advisory looks good & there was enough confidence to expand eastward along the I-20 corridor & southward into the I-59 corridor as well. Even though there will be some earlier development, there should be a window from 10AM-2PM where heat headlines would be warranted. Added an "Elevated" in the HWO for these areas & expanded the Heat Advisory. With a potential MCS moving into dangerous heat environment, these are usually conducive for severe storms. Mean bulk shear is favorable for organization, nearly 15-20kts in the 0-2/0-3km layer & even up to 30kts in the 0-6km layer & some lapse rates/vertical totals in the 25-27 deg range. Recent convective outlook from SPC was upgraded to a "Slight", which mostly looked good but made expansion southward along I-20 to include Richland & Madison Parishes in LA & more of Warren & Hinds in MS. Recent trends in CAMs look supportive of a more southward expansive MCS. Damaging wind gusts of 60-70mph & quarter size hail remain the main concerns. Expect most of the severe potential to wind down by 9-10PM & some rain chances to persist through daybreak, mainly south of I-20 into the Hwy 84 corridor. Near to slightly seasonably warm lows in the low 70s are expected. /DC/ Thursday through Friday... Early morning global guidance highlight a cold front moving southward across the forecast area starting on Thursday. With the increase in moisture head of the front, showers and thunderstorms will be possible, with higher storm chances (around 70-90%) near the I-20 and I-59 corridor. A few strong thunderstorms cannot be ruled out, and both the GFS and the Euro show a lack of organized convection along/south of the boundary. Heading into Thursday evening, rain chances will begin to diminish across southern portions of our forecast area as the boundary pushes further south out of our CWA. With this boundary pushing further south, a less oppressive airmass/decreased heat stress will filter in some relief to the recent hot and humid conditions on Thursday. As high pressure ridge builds in late week, dangerous heat stress will become the primary concern on Friday. Afternoon highs are expected to peak in the low/mid 90s with dewpoints climbing into the mid/upper 70s. This will yield heat indices in the 105 F - 110 F deg range. An "Elevated" heat risk was introduced for southeast AR, northeast Louisiana and portions of northwest, central and southern MS. Heat headlines may be needed as we get closer. Saturday through Tuesday... The short break from the hot temperatures will unfortunately come to an end on Saturday as global guidance highlights an upper-level high amplifying over Texas. At the same time, an upper-level ridge will build over the southeast CONUS. This will bring oppressive heat and humidity across the area through the weekend. As we head into the new work week, global guidance shows the high pressure weakening, due to height falls from upper level system across the Great Lakes to northeast states. Heat will persist from the weekend into early next week, but increased rain and storm chances make areal configuration more uncertain. We maintained an "Elevated" heat in the HWO graphic areawide Sunday and Monday. Expect further updates to the heat graphics as we get closer to the weekend. Heat related warnings and advisories may be continue to be needed as we get closer. A frontal boundary is expected to push towards the southeast, increasing shower/thunderstorm potential Sunday afternoon and Monday. The potential for severe weather is low around this timeframe, but there are signals in CSU machine learning probs for marginally severe storms late weekend into early next week. Rain chances will start to increase especially for areas east of I-55 heading into Tuesday. /CR/DC/ && .AVIATION... (18Z TAFS) Issued at 1258 PM CDT Wed Jun 26 2024 Scattered to numerous TSRA wl develop across the area this aftn into evening. Away from TSRA activity VFR conditions wl prevail. After 08Z Thu MVFR cigs wl develop areawide and prevail through 16Z. VFR conditions are expected areawide before the end of the TAF period. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 73 90 74 93 / 50 60 10 20 Meridian 71 90 72 93 / 60 60 20 30 Vicksburg 73 90 74 93 / 50 30 10 10 Hattiesburg 75 90 74 94 / 50 80 20 50 Natchez 73 89 73 92 / 50 60 10 20 Greenville 73 90 74 95 / 40 10 0 0 Greenwood 72 90 74 94 / 40 20 0 10 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Heat Advisory until 8 PM CDT this evening for MSZ018-019-025>027- 034>036-040>043-047>066-072>074. LA...Heat Advisory until 8 PM CDT this evening for LAZ007>009-015-016- 023>026. AR...Heat Advisory until 8 PM CDT this evening for ARZ074-075. && $$ DC/CR/22