Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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173 FXUS64 KJAN 031733 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 1233 PM CDT Wed Jul 3 2024 ...New AVIATION... .MESOSCALE UPDATE... Issued at 1110 AM CDT Wed Jul 3 2024 Mesoscale Update: The forecast remains on track, thus no major updates were made to the package. Earlier this morning a few showers popped up just east of the Jackson metro area dropping a quick 2-3in. This will likely be the trend for today, very weak deep layer flow will allow the possibility for any storms that pop up to move very slow potentially causing locally high rainfall amounts. Today we can expect storm coverage to be generally scattered in nature with the greatest chances across the SE half. However, due to instability in excess of 4000J/kg of SBCAPE and temps reaching into the upper 90s, a storm or two has the possibility to be strong with the main threat being strong wind gusts. For heat impacts, the "Excessive Heat Warning" will remain in effect for most areas today with a "Heat Advisory" in effect elsewhere. High temperatures will be dangerously hot with temps climbing into the mid to upper 90s mixed with the high humidity will lead to heat indices to range from 110-120 degrees./KP/ && .DISCUSSION... Issued at 435 AM CDT Wed Jul 3 2024 Today and Tonight: Taking a look at regional METAR obs - or stepping out into the early morning air - confirms that the warm tropical air mass has indeed spread back north across our forecast area. Dew point values at this hour range from about 72 in southeast AR/northwest MS to a balmy 78- 79 in southeast MS and central LA. Overnight showers are festering at the Gulf Coast, and we expect coverage of showers and thunderstorms to increase over more of our forecast area as the day wears on. Before rain becomes too widespread, temperatures climbing into the mid and upper 90s will combine with the humid air to produce heat index values mostly near 110 up to 115-120. Confidence was lowest in the Interstate 59 corridor where rain chances are expected to start earliest in the day, so stuck with a Heat Advisory in those areas. The remainder of the forecast has a greater chance to hit the 110+ heat index values before rain moves in, so an Excessive Heat Warning is in place through the evening. High PWAT values of 2+ inches driven by increased lower level humidity and dry air aloft associated with upper-level ridge over the region will yield steep vertical Theta-E differences and approximately 3000-4000 J/kg of SBCAPE. Flow aloft is very weak and easterly, and the lack of shear will limit storm updraft organization or longevity. Organized severe storms are not expected, but there will be some threat for damaging wind gusts with any of the stronger pulse thunderstorms that develop today. /NF/ Thursday through next Tuesday: High pressure will continue to gradually slide east through the region, where it`ll remain centered and overall remain in control of our weather during the forecast period. At the surface, high pressure will likewise slide further east of the CWA, wedging itself into the region from the east. As this happens, copious amounts of deep moisture will feed into the CWA through early next week. This`ll maintain high humidity levels across the forecast area. Not only that, it will also result in increasing chances for showers and storms each afternoon. These better rain chances will be further aided by a frontal boundary that will drop south into the region Friday afternoon. Over the weekend and into early next week, this boundary is advertised to stall and eventually washout out over the forecast area. As far as temperatures are concerned, dangerous heat stress will continue across much of the forecast area Thursday into Friday. Temperatures will warm into the low and middle 90s both days. This, coupled with the aforementioned high humidity levels over the area, will result in afternoon heat index values climbing above the century mark across the CWA. This will especially be the case Thursday, when indices will be more in the 106-115 range areawide. As a result, a "Heat Advisory" and an "Excessive Heat Warning" have now been hoisted for portions of the CWA for Thursday, i.e. Independence Day. As the frontal boundary sinks into the region Friday afternoon, relief from the heat will come in the way of scattered to numerous showers and storms over the CWA. This frontal boundary is again forecast to stall and washout over the forecast area Saturday into early next week. With some slightly drier air filtering into mainly far northern parts of the area over the weekend, and the better coverage of convection over the CWA, relief from the oppressive heat is expected to be more widespread across the area as highs range from the upper 80s to middle 90s Saturday through Tuesday. However with the boundary washing out early next week, deep moisture will again engulf the entire forecast area ahead of another frontal boundary that`s currently forecast to impede upon the forecast area from the northwest Tuesday night. /19/ && .AVIATION... (18Z TAFS) Issued at 1233 PM CDT Wed Jul 3 2024 VFR flight conditions across the area for the start of the TAF period. Shower/thunderstorm potential will increase this afternoon and into the early evening. Southeasterly winds near 6kts are expected. Near 08-09Z Thursday, patchy fog will be possible especially near central and southern TAF sites, reducing flight conditions to MVFR/possible IFR. Any developed fog will diminish after sunrise, bringing flight conditions to VFR. /SW/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 77 93 77 92 / 10 50 10 70 Meridian 75 94 76 94 / 20 60 10 80 Vicksburg 78 94 78 92 / 10 30 10 60 Hattiesburg 78 94 77 96 / 20 70 10 70 Natchez 77 93 76 93 / 20 40 10 60 Greenville 79 96 78 93 / 10 20 10 60 Greenwood 78 94 78 92 / 10 30 10 70 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Excessive Heat Warning until 8 PM CDT this evening for MSZ018- 019-025>045-047>050-053>056-059>065-072. Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for MSZ018-019-025>027-034>036-040>042-047-053. Heat Advisory from 10 AM to 8 PM CDT Thursday for MSZ028>033- 037>039-043>046-048>052-054>066-072>074. Heat Advisory until 8 PM CDT this evening for MSZ046-051-052-057- 058-066-073-074. LA...Excessive Heat Warning until 8 PM CDT this evening for LAZ007>009-015-016-023>026. Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for LAZ007>009-015-016-023>026. AR...Excessive Heat Warning until 8 PM CDT this evening for ARZ074- 075. Excessive Heat Warning from 10 AM to 8 PM CDT Thursday for ARZ074-075. && $$ KP/19/SW