BBS: TELESC.NET.BR Assunto: HVYRAIN: Excessive Rainfall Discussion De: COD Weather Processor Data: Sat, 9 May 2026 19:51:04 +0000 ----------------------------------------------------------- FOUS30 KWBC 091950 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 350 PM EDT Sat May 9 2026 Day 1 Valid 16Z Sat May 09 2026 - 12Z Sun May 10 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF SOUTHERN LOUISIANA AND SOUTHERN MISSISSIPPI... A complex of storms continues this morning along and south of a quasi-stationary frontal boundary through the FLorida Panhandle, coastal Alabama and Mississippi, and southwest into southeastern Louisiana. While current radar observations and hi-res guidance trends show that much of this line has and will continue to move offshore into the Gulf, guidance suggests forward propagation/potential additional development is likely eastward along the boundary through the Florida Panhandle and north Florida. Hi-res guidance shows rain rates as high as 2"+ per hour and MRMS observations over the last few hours support this with the available deep Gulf moisture south of the boundary. An easterly component to storm movement along the east-west oriented boundary may lead to some more prolonged periods of heavy downpours as well. However, the overall progressive nature of the system as well as locally high FFGs should keep impacts isolated. Meanwhile, the latest 12Z hi-res guidance shows another round of storms developing into the afternoon hours with daytime heating east of a dryline through eastern Texas as an upper-level shortwave approaches the region. Some additional storms are also possible along the outflow/effective boundary west into southwestern Louisiana, and a cluster of storms that has maintained strength over the northwestern Gulf may eventually reach the area as well. Given the noted sources of heavy rainfall potential and moderate HREF probabilities of greater than 3" totals/low probabilities of greater than 5" totals, the Slight Risk was extended west into southwestern Louisiana. The flash flood risk later today is less clear further east across southeastern Louisiana and especially into southern Mississippi as the effective front slides south with this morning's storms. However, given lingering rainfall for much of the area, uncertainty with the incoming cluster of storms over the northwestern Gulf, and at least the HRRR suggesting the potential the additional development further west this afternoon may maintain/progress eastward later this evening/overnight, have left the Slight Risk as is for now. Putnam Day 2 Valid 12Z Sun May 10 2026 - 12Z Mon May 11 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHERN PLAINS AND THE ARKLATEX... ...2030Z Update... Prior synoptic overview of the forecast remains on track. The=20 inherited Marginal was adjusted based on the now-avaible hi-res=20 guidance with a general southwesterly shift to focus on expected=20 convection ahead of the cold front and east of a dryline. Storms=20 may be ongoing at the start of the period further north over=20 Oklahoma and could maintain into Arkansas and even northern=20 Louisiana. Given uncertainty on the extent and duration of these=20 storms and early morning lull in instability, there is no extension of the outlook based on their potential. However, they may=20 ultimately impact the northern extent of new development across=20 Texas later tomorrow afternoon and evening. There could also be the need for a targeted Slight Risk where convective coverage looks to maximize immediately ahead of the cold front with initial cell=20 clustering/merging and upscale growth, currently progged along and=20 south of the I-20 corridor across north-central into central Texas. Some of the hi-res guidance suggests locally heavy totals of 3-4"=20 could be possible. However, given the overall progressive nature of the front, high FFGs, and uncertainty with respect to where this=20 corridor may ultimately set up (with potential overnight/early day=20 convection influence), a Marginal Risk remains sufficient for now. Putnam ...Previous Discussion... The forecast reasoning and outlook area remains largely consistent, with a Marginal Risk area extending from north/central Texas into the ArkLaTex. A cold front dropping south through the Plains will=20 become a primary focus for deepening moisture (PWs increasing to=20 around 1.5 inches) and storm development. Synoptic support will strengthen as shortwave energy moves into the base of a broader-scale trough, placing the region within an area of strong ascent, supported by coupled upper-jet forcing. This combination of moisture and favorable dynamics, along with increasing instability, will promote broadening storm coverage by the afternoon. While storms will eventually gain a more steady southward progression, initial storm organization may be characterized by slow movement and mergers. These factors combined with the potential for high rainfall rates, support the maintenance of the Marginal Risk for localized flash flooding. Pereira Day 3 Valid 12Z Mon May 11 2026 - 12Z Tue May 12 2026 The probability of rainfall exceeding flash flood guidance is less than five percent. Putnam Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8dIbFB8Bn0Q6A03DLBYf-_yMiI1URdEN1datH2kyhhCb= deMLVlqw--5iW_AHzag4DMztygVxM1S7vJokXa5jzvqgrU4$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8dIbFB8Bn0Q6A03DLBYf-_yMiI1URdEN1datH2kyhhCb= deMLVlqw--5iW_AHzag4DMztygVxM1S7vJokXa5jD89vfrc$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8dIbFB8Bn0Q6A03DLBYf-_yMiI1URdEN1datH2kyhhCb= deMLVlqw--5iW_AHzag4DMztygVxM1S7vJokXa5j5Mydo4Q$=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]