Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Mar 09 2024 22:37:36 FOUS30 KWBC 092237 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 536 PM EST Sat Mar 09 2024 Day 1 Valid 01Z Sun Mar 10 2024 - 12Z Sun Mar 10 2024 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHEAST.... Mid Atlantic into the Northeast... A strong low tracking northeastward will spread a broad shield of precipitation northeast through the northern Mid-Atlantic States and New England. Maintained the Marginal Risk area where rainfall is expected across the coastal plain, with radar and mesoscale guidance trends leading to a significant shrinking of scale of the risk area. The 18z HREF indicates that hourly rainfall rates should be on the upswing across portions of eastern PA, southeast NY, and southwest New England due to an incoming shortwave from the west. Some thunderstorm development as of late across northern VA could be the first sign of this coming to fruition. Heavy rainfall could result in some instances of urban and small stream flooding over parts of the area where antecedent conditions have kept stream flows elevated and not much recovery time from moderate to heavy rain a few days ago. Rainfall over the past week has broadly been 200-400% of average. Florida... Thunderstorms across portions of FL are progressive and showing a general decline in hourly rain totals. The 18z HREF suggests that this trend is forecast to continue. This led to the removal of the Marginal Risk area. Roth Day 2 Valid 12Z Sun Mar 10 2024 - 12Z Mon Mar 11 2024 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF COASTAL NEW ENGLAND ON SUNDAY... 21Z update... With the latest trends focusing the bulk of the rain near Downeast Maine opted to reduce the western edge of the Marginal over western Maine. Campbell Maintained a Marginal Risk area...mainly confined to eastern Maine...as an area of low pressure pulls away from the region.=20 Areal average rainfall continues to be on an order of 1 to 1.25 inches...enough that there could be isolated problems from flooding/ponding given the antecedent conditions over the past few weeks. Confined the Marginal Risk areas to lower elevations where rainfall is the expected to be the primary precipitation type and attempted to limit the overlap inland where the precipitation type is expected to be snow. The threat of excessive rainfall should be tapering off across the outlook area during the afternoon and evening as dry air filters in behind the departing system and the terrain acts to block too much wrap around precipitation. Bann Day 3 Valid 12Z Mon Mar 11 2024 - 12Z Tue Mar 12 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!9rmqGKMYG3lKExT5rXSjZ0ilgsIrj7a7hsI_wo_elVri= GCDhKnWiWhs4YQdOvrLMdAk8ySUHMXm0-qPlVq60kTeUmCY$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9rmqGKMYG3lKExT5rXSjZ0ilgsIrj7a7hsI_wo_elVri= GCDhKnWiWhs4YQdOvrLMdAk8ySUHMXm0-qPlVq600PO4SSA$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9rmqGKMYG3lKExT5rXSjZ0ilgsIrj7a7hsI_wo_elVri= GCDhKnWiWhs4YQdOvrLMdAk8ySUHMXm0-qPlVq60szdbs4c$=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .