Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Nov 23 2022 15:49:02 FOUS30 KWBC 231548 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1048 AM EST Wed Nov 23 2022 Day 1 Valid 16Z Wed Nov 23 2022 - 12Z Thu Nov 24 2022 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Wegman Day 2 Valid 12Z Thu Nov 24 2022 - 12Z Fri Nov 25 2022 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM EAST TEXAS INTO THE LOWER MISSISSIPPI VALLEY... A widespread multi day heavy precipitation event developing late day 1 and continuing into the day 2 and 3 periods ahead of the developing closed low sinking south through the Southern Rockies into the Southern High Plains at the beginning of the day 2 time period. There are some timing differences after this with the southeastward push of the closed low day 2 into the Southern High Plains with the GFS on the more progressive side compared to the EC, NAM and UKMET. Despite the differences, models agree that low level flow off the western Gulf will continue to strengthen from the south and then south southwest on day 2, spreading anomalous PW values...2 to 2.5+ standard deviations above the mean across the risk areas. This will support the first round of heavy rains spreading east northeastward Thursday into Thursday night from East Texas into the Lower MS Valley. Overall, there is good agreement on this but with both timing differences with the downstream push of the convection and differences with the latitude of the heaviest totals. With respect to the latitude of the heaviest amounts, consensus is to favor the more southern max qpf axes solutions which would fit better with the farther south axis of instability and position of the west to east oriented frontal boundary expected to strengthen along the Gulf coast from the Upper TX coast, eastward along the LA coast. This would be closer to the farther south qpf axes of the FV3LAM, EC and UKMET.=20 Timing of the downstream push of convection is less certain.=20=20 Overall, however, there will be potential for training of cells in a general west southwesterly to east northeasterly direction across the risk area with totals in excess of 5"+ in areas of training. The previous slight risk area was trimmed on the north end to reflect favoring the farther south qpf solutions. The slight risk was expanded farther to the southeast on the south end to cover southeast LA and far southern MS as the EC, EC mean and NAM all suggest a potential axis across these area. Oravec Day 3 Valid 12Z Fri Nov 25 2022 - 12Z Sat Nov 26 2022 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE WEST CENTRAL GULF COAST/LOWER MISSISSIPPI VALLEY REGION... A second day of heavy rains possible day 3 across portions of the west central Gulf Coast/Lower Mississippi Valley region. In the wake of the first round of heavy rains to spread east northeast day 2 from East Texas into the Lower Mississippi Valley, the low level flow is expected to re-strengthen out of the south off the western Gulf ahead of the strong closed low forecast to push east from western to central Texas. There are still differences with the eastward push of the closed low due more to the starting point of the closed low at the beginning of day 3 than timing. Models are in general agreement that additional rains will develop ahead of the associated cold front pushing eastward from East Texas into west central Gulf coastal region. Strong frontal convergence in a continued axis of above average PW values...2 to 2.5+ standard deviations above the mean...along and ahead of this front will support additional heavy rains pressing eastward day 3 across the risk area. There will be potential for overlap of the day 2 heavy precip area with the day 3 heavy precip area from the Upper TX coast, east across much of LA into southern MS. Across these areas a slight risk was depicted, but may possibly need to be upgraded to a moderate depending upon the observed precip amounts day 2 and subsequent additional heavy rains for this day 3 period. Oravec Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5i6Yn2P5hZkETTV9QSEdn-IVO1gkRaYE2QwEyzAqxF4e= sTeU0gElC9nlQ3cNOismaQNzidP63rpACMUStvMTjqoa5uk$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5i6Yn2P5hZkETTV9QSEdn-IVO1gkRaYE2QwEyzAqxF4e= sTeU0gElC9nlQ3cNOismaQNzidP63rpACMUStvMT1FDAz0w$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5i6Yn2P5hZkETTV9QSEdn-IVO1gkRaYE2QwEyzAqxF4e= sTeU0gElC9nlQ3cNOismaQNzidP63rpACMUStvMTeYA-Yi8$=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) .