Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
Issued by NWS New Orleans/Baton Rouge, LA
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357 FXUS64 KLIX 291154 AFDLIX Area Forecast Discussion National Weather Service New Orleans LA 654 AM CDT Sat Jun 29 2024 ...New AVIATION... .SHORT TERM... (Today through Sunday) Issued at 400 AM CDT Sat Jun 29 2024 Main focus over the next 36 hours is likely to be heat related problems, along with thunderstorm potential. Upper ridging centered over northeast Texas this morning with a weakening shear axis extending from central Alabama to near Houston. At the surface, high pressure centered off the New England coastline had an extension southwestward into the eastern Gulf of Mexico. Radar was much quieter early this morning compared to the previous couple mornings, with only a cluster of showers over the Pearl River Basin north of Slidell at 3 am CDT. A rather uncomfortable morning across the area with much of the area reporting temperatures in the lower and middle 80s at 3 am. The exceptions were 75 to 80 in southwest Mississippi and the adjacent Louisiana parishes. For most of the area, dew points ran between 75 and 80. Near and southeast of the shear axis, precipitable water values were as high as 2.2 inches, as noted on the 00z LIX sounding, but closer to 1.75 in areas to the northwest. The shear axis is gradually forecast to wash out over the next 36 hours. However, moisture content is forecast to remain in the 2.0-2.25 inch range across just about the entire area. This is plenty sufficient for the development of isolated to scattered convection as we reach the convective temperature both days. That is generally forecast to be in the 91-94F range. That should mean only isolated development during the morning hours, with a bit better coverage during the afternoon hours. While instantaneous areal coverage may not exceed much more than 30-40 percent, if that, the 12 hour threat may be closer to 50-60 percent. Most land based convection should also die out with loss of surface heating, before redeveloping over marine areas prior to sunrise Sunday. We shouldn`t have quite the cloud cover today we had Friday morning, which will allow high temperatures to return to the middle 90s for a large portion of the area. Dew points in the mid and upper 70s will produce maximum heat index values in the 108 to 112F range for most of the area this afternoon, with isolated spots exceeding 112F. Current Heat Advisory remains in place. High temperatures Sunday look to be a degree or two hotter as upper ridging presses into the area a little more. So even if the dew points run a degree or two lower on Sunday, we will likely see heat index values nudge upward a bit, potentially at or above 113F in a fair percentage of the area. Excessive Heat Watch remains in place for Sunday with the expectation that it`ll be upgraded to a warning in the afternoon forecast package across some or most of the area. && .LONG TERM... (Sunday night through Friday) Issued at 400 AM CDT Sat Jun 29 2024 Upper ridging is likely to remain close enough to the area to impact much of the workweek. Precipitable water values will continue to exceed 2 inches for much or all of the area for at least Monday and Tuesday, with some drying across the north at midweek. That will mean at least some potential for afternoon thunderstorms Monday and Tuesday across the entire area, and primarily from the Interstate 10 corridor southward beyond that point. Most of the overnight hours should be dry. Expect little or no relief from oppressive heat for much of the week, with the exception of any brief cooling from nearby thunderstorms. Heat Advisory/Excessive Heat Watch/Warning products are expected to be necessary on Monday in later forecasts, and potentially for much of the week. If there is going to be a break in the pattern, at this point it doesn`t appear in the cards until perhaps next weekend. Heat related illnesses have a cumulative effect, so impacts are likely to increase as the week goes on for people that have limited access to cooling. && .AVIATION... (12Z TAFS) Issued at 640 AM CDT Sat Jun 29 2024 At forecast issuance timme, all terminals were experiencing VFR conditions, although KMCB had a brief period of IFR ceilings. There will be a period of MVFR ceilings this morning as the cumulus field develops, but in most areas, cloud bases should lift to or above FL030. Isolated to scattered TSRA are expected to develop as convective temperatures in the lower 90s are reached by around 18z, if not a little earlier. With no particular focus for initiation other than possibly lake/sea breeze boundaries, little confidence in timing of direct impacts. Will use VCTS for now, with amendments as necessary if/when direct impacts are anticipated. Direct impacts would generally entail IFR or lower visibilities, MVFR ceilings and perhaps wind gusts in excess of 30 knots. Most terminals should see convective threat lower considerably by 01z or so. && .MARINE... Issued at 400 AM CDT Sat Jun 29 2024 Primary concerns will be thunderstorm threats for marine interests, which will usually occur during the late night and morning hours. There will be the usual increase in wind speeds during the evening hours across the coastal waters, which could occasionally top out in the 15-20 knot range, but don`t anticipate a need for Small Craft Advisories at this time. && .PRELIMINARY POINT TEMPS/POPS... MCB 92 74 94 75 / 50 30 60 20 BTR 96 78 98 79 / 60 20 50 20 ASD 94 78 96 78 / 60 20 60 30 MSY 94 79 96 81 / 60 20 50 30 GPT 92 78 95 77 / 50 30 60 40 PQL 95 77 97 77 / 50 30 60 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for LAZ034>037-039-046>048-056>060-064-065-071-076>090. Excessive Heat Watch from Sunday morning through Sunday evening for LAZ034>037-039-046>048-056>060-064-065-071-076>090. GM...None. MS...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for MSZ068>071-077-083>088. Excessive Heat Watch from Sunday morning through Sunday evening for MSZ068>071-077-083>088. GM...None. && $$ SHORT TERM...RW LONG TERM....RW AVIATION...RW MARINE...RW