Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 12 2024 00:45:34 FOUS30 KWBC 120045 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 744 PM EST Sun Feb 11 2024 Day 1 Valid 01Z Mon Feb 12 2024 - 12Z Mon Feb 12 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHEAST... The south southwestward shift of the Slight risk area made at 21z still looks in good shape. Increasing low level moisture transport and convergence along this corridor will support continued convective development into tonight. With the low level boundary not moving much, there is a likelihood of some west to east training along this corridor. By late tonight we should see a renewed uptick in convective coverage and intensity over portions of AL and GA as stronger forcing approaches from the west. The heaviest additional rainfall amounts through 12z Monday are currently forecast over central AL into central GA, where a swath of 3-5" is possible. While soil conditions are initially rather dry and thus FFG high...the multiple rounds of convection will likely result in increased saturation and lowered FFG as the night progresses. By the time we see the renewed convective development later tonight flash flooding coverage should increase. This event appears be trending towards a higher end Slight risk across portions of central AL/GA. The Slight risk was earlier expanded into central MS...as this is one location where there is some overlap of heavy rainfall yesterday and additional heavier convection this afternoon/evening. While additional rainfall totals are expected to be lower here compared to areas further east, the more saturated conditions and lower FFG warrant the Slight risk. Chenard Day 2 Valid 12Z Mon Feb 12 2024 - 12Z Tue Feb 13 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHEAST U.S.... 21Z update... Although the locations of the highest QPF have varied over the past few model cycles there continues to be consensus for 1 to 2+ inches to focus across portions of northeast Georgia, South Carolina, North Carolina and into far southern Virginia. An upgrade to a Slight was made with this issuance to reflect the growing threat for excessive rainfall and local flooding concerns, especially across South Carolina. Campbell There is a continuing threat of excessive rainfall on Monday...mainly over the Carolinas...as secondary cyclogenesis begins in response to the large scale system amplifies. At the surface...one area of low pressure forms and heads northeast over the far eastern TN/OH Valleys while a second area of low pressure forms over parts of the Carolinas...supported by the deep layer vertical velocities induced strengthening divergence fields of a coupled of upper level jets. It is this component which results in the continued risk of excessive rainfall over the Southeast from Monday into the early-morning hours on Tuesday. Precipitable water values increase to values at or slightly above 1.75 inches ahead of a cold front sweeping across the region. Deterministic QPF from the GFS and UKMET seem better than the ECMWF and Canadian and tend to be aligned with the WPC deterministic amounts. Given high FFG numbers...especially where spaghetti plots of model QPF are 2 or 3 inches overlap. Bann Day 3 Valid 12Z Tue Feb 13 2024 - 12Z Wed Feb 14 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4FaBT7j1otTf8Ia5dWwq46s4U-qCLUOck-KYITYOvvfK= 6ekaHt1Z9X7qVThESWfjaK1WkkjYvNRBnMuKHQnrho2HC8E$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4FaBT7j1otTf8Ia5dWwq46s4U-qCLUOck-KYITYOvvfK= 6ekaHt1Z9X7qVThESWfjaK1WkkjYvNRBnMuKHQnrXpO-r5M$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4FaBT7j1otTf8Ia5dWwq46s4U-qCLUOck-KYITYOvvfK= 6ekaHt1Z9X7qVThESWfjaK1WkkjYvNRBnMuKHQnrppS6dsw$=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .