Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jan 20 2024 08:09:19 FOUS30 KWBC 200809 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 308 AM EST Sat Jan 20 2024 Day 1 Valid 12Z Sat Jan 20 2024 - 12Z Sun Jan 21 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF NORTHERN CALIFORNIA AND SOUTHWEST OREGON... Overall, no large-scale changes to the previous forecast, with rainfall rates and the threat for excessive runoff expected to increase later this morning across portions of northern California and far southwestern Oregon. As expected, a leading plume of deeper moisture associated with an upper trough and its frontal band moved inland, with precipitation spreading across much of northern California late Friday into this morning. The IVT associated with this leading band is expected to become more diffuse as it pushes further inland this morning. However, amplified westerly winds south of the parent low are expected to tap a secondary surge of deeper moisture, directing it inland as it lifts along the northern California and Oregon coasts later this morning. This moisture along with favorable upper forcing and orographic effects will support heavy rainfall amounts within the highlighted area. HREF neighborhood probabilities continue to indicate locally heavy amounts of 3 inches or more are likely within the Slight Risk area between 12Z Sat and 00Z Sun. These short-term heavy rains, along with the antecedent wet conditions can be expected to produce localized runoff concerns. Pereira Day 2 Valid 12Z Sun Jan 21 2024 - 12Z Mon Jan 22 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF NORTHERN CALIFORNIA... ....California and southwest Oregon... An unsettled period is forecast to continue with widespread precipitation and the potential for locally heavy amounts continuing as a broad upper trough with a series of embedded shortwaves moves across the region. Overall, models continue to indicate the potential for organized heavy amounts to be less than previous day. However, there remains a fairly good deterministic model and ensemble signal for additional locally heavy amounts redeveloping across portions of northern California early Monday.=20 Some models, including the GFS, show another plume of deeper moisture moving inland ahead of an amplifying shortwave Monday morning. This deeper moisture and better forcing is expected to line up across much the same area where heavy rainfall is expected the previous day and may increase any ongoing runoff concerns. .....Southern and central Texas... As a broad upper trough moves across the Southwest into the southern Rockies and High Plains, southerly low level inflow is expected to increase across southern to eastern Texas. PWs are forecast to increase to 1.25-1.5 along a 40-50 kt low level jet extending from the northwestern Gulf of Mexico through eastern Texas. This moisture, interacting with increasing ascent afforded in part by favorable upper jet forcing, will support the development of rainfall across southern to central Texas. Despite ample moisture and forcing, limited instability is expected to help keep rainfall rates and the threat for widespread excessive runoff concerns in check.=20=20 Pereira 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!92oTOT6OvWU3u_Ew2WmRYai8cPvgCPJHy5gRF98kHsV2= UQMmcQk0U5DdSoKG_5tid6XhD3PhZgY54TeiX9Lt8ehYIZU$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!92oTOT6OvWU3u_Ew2WmRYai8cPvgCPJHy5gRF98kHsV2= UQMmcQk0U5DdSoKG_5tid6XhD3PhZgY54TeiX9LtgxsUP5A$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!92oTOT6OvWU3u_Ew2WmRYai8cPvgCPJHy5gRF98kHsV2= UQMmcQk0U5DdSoKG_5tid6XhD3PhZgY54TeiX9LtLWigi3g$=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) .