Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Oct 30 2025 19:33:13 AWUS01 KWNH 301933 FFGMPD MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-310125- Mesoscale Precipitation Discussion 1220 NWS Weather Prediction Center College Park MD 332 PM EDT Thu Oct 30 2025 Areas affected...northern NJ into southern NY/Long Island and CT Concerning...Heavy rainfall...Flash flooding possible Valid 301931Z - 310125Z Summary...Heavy rain across the Tri-State Area through this evening may result in localized flooding/flash flooding. Localized rainfall totals over 3 inches will be possible. Rainfall near 1 inch in 15-30 minutes can be expected. Discussion...19Z radar imagery showed a low-topped squall-line, oriented from south to north, edging east from 40 miles east of ACY through NYC. This line was being aided by strong low level convergence with 45-50 kt from the SSE/SE in the 925-850 mb layer, located north of the triple point of an occluded cyclone over the northern Mid-Atlantic region. The line of showers has been accompanied by 0.50 to 1.00 inches of rain in 15 minutes across northern NJ into the Five Boroughs. Moisture from the Mid-Atlantic coast into southern New England was already anomalous as sampled by area 12Z RAOBs, with PWAT values of 1.2 to 1.5 inches. However, OSPO's ALPW has since shown an increase stemming from Melissa's circulation, especially near and below 700 mb, being drawn northward into NJ and southern NY. The continued addition of this remnant tropical moisture should allow for an increase in rainfall efficiency and locally higher rainfall rate potential into the early evening hours. While the line of showers has been progressive, there is some concern for very brief slowing/stalling given the LEWP-like appearance off the NJ coast, which could result in a quick 1-2 inches as this line continues to advance east through the remainder of the afternoon. As a triple point low becomes better organized south of Long Island this evening, low level flow will maintain a southeasterly orientation, with possible backing. Therefore, some orographic component to lift will be added into the equation for the higher terrain north and west of I-95, combining with increasing right-entrance jet ascent associated with a forecast 130 kt jet streak on the east side of the parent upper low to the west. Farther south and west, instability is expected to remain weak (briefly peaking in the 500-1000 J/kg range) but perhaps sufficient to support a few additional heavy showers from eastern PA and southern NJ, rotating northward into the Tri-State region. Additional rainfall may result in isolated areas of rapid inundation of water. Given below average rainfall over the past few weeks and ongoing drought conditions across portions of the region, any flooding that occurs is likely to remain constrained to urban or other areas with poor drainage. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9FIRi1NKBOaCg4MfFWriOWtP0K6LX9dCRMYV3e6rRPxWaiMPuzVhGNzgIyu1jio3gLQk= znq132MoWRgl8CwwSNIVZGE$ for graphic product... ATTN...WFO...ALY...BGM...BOX...OKX...PHI... ATTN...RFC...RHA...TAR...NWC... LAT...LON 42367414 42157352 42087251 41907210 41397212=20 40707286 40387404 40737491 41357535 42037519=20 42327478=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .