Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Feb 13 2024 00:50:23 FOUS30 KWBC 130050 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 749 PM EST Mon Feb 12 2024 Day 1 Valid 01Z Tue Feb 13 2024 - 12Z Tue Feb 13 2024 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE OHIO VALLEY AND MID ATLANTIC....=20 We will maintain the Marginal risk across portions of KY/TN into the Mid-Atlantic. Hourly rainfall upwards of 0.5" and total rainfall of 1-2" remains possible. Overall the risk of flash flooding is low...but this brief shot of moderate to locally heavy rain may cause some localized excess runoff through the overnight hours. Chenard Day 2 Valid 12Z Tue Feb 13 2024 - 12Z Wed Feb 14 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent.=20 Dolan Day 3 Valid 12Z Wed Feb 14 2024 - 12Z Thu Feb 15 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Portions of coastal OR and northwest CA... As a cyclone in the Pacific swings north a bit astride of the Pacific Northwest coastline, low-level inflow of up to 40 kts out of the south to southwest and precipitable water values at or above 0.75" impact the region. With time, around 250 J/kg of MU CAPE is expected to move near the region per 00z NAM guidance. QPF-wise, the 00z NAM and 00z Canadian Regional amounts are of some minor concern, but other pieces of guidance show less volume. It is a close call as to whether 0.5"+ an hour totals would materialize, which would be of most concern in burn scars. For the time being, the upcoming setup appears just shy of the Marginal Risk threshold, but this could change in later model cycles should the guidance trend somewhat wetter. 20Z Update... The forecast remains on track, and the only area of potential concern is coastal Oregon and northwest California. The Pacific system appears to approach the coast slow enough that flooding concerns shouldn't be expected until the Day 4 timeframe or very late in the Day 3 timeframe (09-12Z on the 15th). The latest runs of the NAM and Canadian Regional models continue to show the highest precipitation amounts compared to other guidance. The 12Z ECMWF has trended slightly wetter and southwards with QPF, while the 12Z GFS remains similar to the 00Z run. At this time, confidence in rain rates reaching high enough to cause flooding in this region is still too low to introduce a Day 3 Marginal Risk area, but it can't be ruled out for future updates when hi-res guidance becomes available. Roth/Dolan Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4c46OgO8FT1FHs_9vJXlxZ6x3PB3xi9TdcZo4faRojVq= w_ckG-vOKy91F-A7WTcVRrQq6CqDI-tc2TCQuijG_io6w60$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4c46OgO8FT1FHs_9vJXlxZ6x3PB3xi9TdcZo4faRojVq= w_ckG-vOKy91F-A7WTcVRrQq6CqDI-tc2TCQuijGDRfpPrI$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4c46OgO8FT1FHs_9vJXlxZ6x3PB3xi9TdcZo4faRojVq= w_ckG-vOKy91F-A7WTcVRrQq6CqDI-tc2TCQuijGX1DszSM$=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) .