Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jan 08 2023 07:48:22 FOUS30 KWBC 080748 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 247 AM EST Sun Jan 08 2023 Day 1 Valid 12Z Sun Jan 08 2023 - 12Z Mon Jan 09 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF NORTHERN AND CENTRAL CALIFORNIA... ....Southwest Oregon into Northern and Central California... The Excessive Rainfall Outlook inherited from yesterday's Day 2 needed no notable changes for the new Day 1 period, 12Z Sun-12Z Mon. The overall environment and synoptic pattern remained similar during this period and forecast reasoning was largely unchanged. There looks to be a relative "lull" for a few hours as one AR wanes and the next approaches. Additional rainfall on top of already saturated soils will keep the threat for excessive rainfall and flash flooding elevated despite the relative lull. As the front moves ashore and the upper shortwave trough pivots across northern-central CA this morning, precipitation coverage and rates from the current Atmospheric River (AR) will be on the wane. Upper level heights will then be on the rise later today ahead of an amplifying, negatively tilted longer wave trough, one with a much more robust and elongated Warm Conveyor Belt with deep-layer subtropical fetch from the central Pacific. Guidance continues to show PWs ~1.25" approaching the Central CA Coast Sunday night, along with even more anomalous low-mid layer moisture transport compared to the previous AR events. Both the GEFS and SREF in fact show 850-700 mb moisture flux ~5 standard deviations above normal directed toward the CA Central Coast by 12Z Monday. While the bulk of this particular event will be during the day Monday (current Day 2), deterministic and probabilistic QPF fields, along with analogs and ERO first guess fields applying the ARI of 24hr QPF, would support continuing with the Slight Risk that was inherited from yesterday's Day 2 ERO. This especially taking into account the anomalously wet soils (above the 90th percentile in the top 1 meter layer per the latest NASA SPoRT), owing to the onslaught of recent AR events. Hurley Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-AWg7hVE-0qSjA8ckfzo_orK2y4lrku94pNuy8i9Zp2_= IJ2jgu8tmni8l9tl6dVfWkFJVzLD-d3LG-b-Ecw8MnH75lw$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-AWg7hVE-0qSjA8ckfzo_orK2y4lrku94pNuy8i9Zp2_= IJ2jgu8tmni8l9tl6dVfWkFJVzLD-d3LG-b-Ecw8Kwpw5_I$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-AWg7hVE-0qSjA8ckfzo_orK2y4lrku94pNuy8i9Zp2_= IJ2jgu8tmni8l9tl6dVfWkFJVzLD-d3LG-b-Ecw8qRSmuT4$=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) .